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Dissertations / Theses on the topic 'Phosphorus retention'

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Published: 4 June 2021
Last updated: 13 February 2022

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1

DʹAngelo, Donna Jean. "Mechanisms governing phosphorus retention in streams /." This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08252008-162550/.

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2

D'Angelo, Donna Jean. "Mechanisms governing phosphorus retention in streams." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39241.

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3

Wang, Naiming. "Modelling Phosphorus Retention in Freshwater Wetlands." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1382617535.

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4

Li, Shijie. "Phosphorus retention and release from agricultural ditch networks." Thesis, Ulster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646851.

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The potential of agricultural drainage ditch sediments to release and retain phosphorus (P) was investigated at six sites in two sub-catchments of the River Blackwater in Counties Monaghan and Armagh, Ireland. The bed sediment was sampled on a fortnightly basis between April 2008 and March 2009: the sediment (top 1 cm) was analysed for total P, individual P fractions (with a modified Psenner sequential extraction scheme), equilibrium P concentration (EPCo), iron (Fe) and manganese (Mn) concentrations; sediment pore water (top 5 cm) and stream water were analysed for soluble reactive P (SRP). In relation to variation in stream discharge, sediment total P (TP) decreased rapidly during the largest storms, followed by calmer hydrological conditions and recovery in sediment TP. This provides field evidence of sediment TP depletion during storms, demonstrating the physical basis of the sediment's net P release in this study. This is also consistent with the interpretation of storm P-discharge hysteresis, where stream P concentration does not follow the rising and falling limbs of the hydrograph, that high discharge events can mobilise P retained in bed sediment. In terms of sediment P fractionation, the reductant-soluble bicarbonate-dithionite (BO) fraction was by far the largest, in terms of concentration and contribution ratio to TP (medians: 41 % - 62%), and the most sensitive to change in discharge, which suggests that the redox-sensitive binding of P to Fe and Mn hydroxides in the BO fraction was the dominant chemical process controlling sediment P. In addition, an inverse relationship was observed between Fe/P ratio in the BO fraction and sediment TP, but the BO-Fe data has been shown to be compromised due to analytical delays and inadequate sample preservation. This observation would have further indicated the chemical basis to sediment P retention during the recovery from storms: a decrease in Fe/P ratio points to the uptake of P by the reductant-soluble amorphous Fe hydroxide in this fraction. The comparison between sediment EPCo (medians: 0.005 - 0.041 mg P L-1 ) and stream P concentration (medians: 0.023 - 0.129 mg P L-1 ) generally indicated potential for sediment P retention. This was in spite of consistently reducing conditions in the bed sediment and the presence of high pore water P concentration at P-enriched sites (highest median: 2.133 mg P L-1 ). No evidence was found that supports the hypothesis that potential sediment P release contributed to the stream water SRP concentration during the stable low flow periods of the summer. This indicates that rural point sources are more likely to be responsible. Therefore, the ditches acted as temporary storage of P from catchment sources, chemically retaining P during low flow periods, before physically releasing the accumulated P load during episodic high discharge events. Under non-storm conditions, the bed sediment was clearly a P sink, mitigating nutrient enrichment in situ and downstream, by removing in-stream P and delaying downstream transport of P loading from catchment sources. There is a need to understand better the potential P release upon physical disturbance by storm flow - in particular the environmental implications of the dominance of the BD-TP fraction and the reductant-soluble Fe-P binding mechanism in the mobilised bed sediment.
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5

Kaye, Kriss Young. "Phosphorus accumulation in bottom sediments of retention/detention ponds." Master's thesis, University of Central Florida, 1993. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/71670.

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University of Central Florida College of Engineering Thesis
Laboratory and field studies were conducted to characterize phosphorus in bottom sediments for retention/detention ponds. The laboratory studies, including batch and column experiments, were conducted to assess possible removal processes. Sediment core samples were collected from detention ponds receiving urban runoff. These cores were analyzed for phosphorus at different layers including accumulated top sediments and the lower parent soil beneath it at a depth of 1, 3, 5, 10 and greater than 10 cm. The phosphorus accumulation rate was found to decline with calculated overflow rates from an average storm. Also attenuation of phosphorus with sediment depth followed an exponential decline. Batch experiments showed a higher adsorption capacity to remove phosphorus for top accumulated sediments than the lower parent soil, which is consistent with data from field studies showing greater phosphorus in the sediments. Phosphorus adsorptioncan be described by the Freundlich and Linear isotherms. Mass transfer rates varied with phosphorus concentration and contact time. A generalized model was developed to predict phosphorus removal in column studies.
M.S.
Masters
Civil and Environmental Engineering
Engineering
Environmental Engineering
136 p.
x, 136 leaves, bound : ill. ; 28 cm.
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6

Greiner, Megan K. "An Analysis of Wetland Total Phosphorus Retention and Watershed Structure." W&M ScholarWorks, 1995. https://scholarworks.wm.edu/etd/1539617694.

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7

Johannesson, Karin. "Particulate phosphorus accumulation and net retention in constructed wetlands receiving agricultural runoff : Critical analysis of factors affecting retention estimates." Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-117116.

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Övergödning är ett allvarligt miljöproblem, som bland annat orsakar omfattande blomningar av alger och blågrönbakterier. I söt- och brackvatten är fosfor ofta det mest begränsande näringsämnet för dessa organismer, varför en minskning av fosfortillförseln är nödvändig för att nå förbättringar. I Sverige beräknas jordbruket bidra med 44 % av fosforbelastningen till Egentliga Östersjön, och olika åtgärder för att minska fosforförlusterna från jordbruksmark tillämpas runtom i Sverige. Våtmarker anläggs ofta för att fånga näringsämnen och partiklar från jordbruksmark innan de läcker ut i vattendrag och slutligen i Östersjön. Tidigare utvärderingar av anlagda våtmarker i Sverige har visat på en varierande och relativt låg fastläggning av fosfor. Osäkerheten kring dessa utvärderingar är dock ganska hög, och bottnar i kunskapsluckor både vad gäller processer för fastläggning och transport av fosfor från mindre jordbruksområden. I denna avhandling utreds därför hur anlagda våtmarker fungerar som fällor för jordpartiklar och partikelbunden fosfor i områden med höga fosforförluster. Sju anlagda våtmarker i jordbruksområden med mycket lerjordar studerades, och mängden fosfor och partiklar som fastlades på botten varierade mycket mellan olika våtmarker (13-108 ton partiklar/ha/yr och 11-175 kg fosfor/ha/yr). De faktorer i området uppströms som var kopplade till fosforfastläggning var lutningen i området, markens lerhalt och innehåll av växttillgänglig fosfor samt områdets djurtäthet. Resultat från fyra våtmarker visade på en hög resuspension (partiklar från botten virvlas tillbaka upp i vattnet), men en del av de uppvirvlade partiklarna kom troligtvis från erosion från våtmarkernas sidor och inte från det material som fastlades på botten. Man såg även indikationer på resuspension från vattenprover tagna i utloppet av en annan våtmark. Där var partikelbunden fosfor klart dominerande, vilket kan ha varit en konsekvens av resuspension från botten. Variationerna av fosforkoncentrationer vid in- och utlopp i sju anlagda våtmarker studerades, för att kritiskt kunna granska tidigare retentionsskattningar. Det var stora variationer i sambanden mellan vattenflöde och fosforkoncentrationer mellan de olika våtmarkerna. De faktorer som påverkade sambandet mellan flöde och koncentration var 1) om det var varm eller kall årstid (d v s sommar eller vinter), 2) om det var högt eller lågt vattenflöde, samt 3) om inflödet bestod av ett dräneringsrör eller ett öppet dike/åfåra. I våtmarker med öppet dike som inflöde var flödes-koncentrationssambandet av totalfosfor negativt vid låga flöden och positivt vid höga flöden. De olika sambanden visar hur viktig sättet att provta vatten är, då inkommande mängd fosfor både kan över- och underskattas om man inte är medveten om sådana variationer. Vid automatisk provtagning styrd av flödesmätningen sker detta ofta i utloppet, men eftersom vattnet har en viss uppehållstid i våtmarken (speciellt sommartid) kan retentionsberäkningen påverkas av att all provtagningen styrs av flödet i utloppet.     För att identifiera vilka områden som bidrar med mest näring och partiklar valdes ett stort område dominerat av jordbruksmark ut – för att undersöka hur man skulle kunna bedöma var anlagda våtmarker skulle kunna göra mest nytta. Området delades in i tio mindre områden, och vattenprover samlades in från diken och åfåror. Resultaten visade på stora skillnader i fosfordynamik mellan olika delområden med olika jordtyper, trots att de hade liknande markanvändning. Det fanns ofta en koppling mellan höga fosforkoncentrationer i vattnet och en hög andel lerjordar i området. För partiklar fanns det en tendens till samband mellan höga koncentrationer och hög andel vinterbar mark. En anlagd våtmark skulle antagligen ha högst effekt om den placerades nedströms områden som är känsliga för erosion – områden med hög andel lerjordar eller med hög andel vinterbar mark.
Eutrophication is one of the more serious current environmental problems, causing algal blooms and anoxic bottoms. In fresh and brackish water, phosphorus (P) is often the most limiting nutrient, and various mitigating strategies are used to reduce the load of P to sensitive recipients. In the agricultural sector, this includes both on-field measures (e.g. managing P inputs) and measures at the field edge (e.g. buffer zones and constructed wetlands). Previous evaluations of constructed wetlands (CWs) in Sweden have indicated a variable and relatively low P retention. However, the uncertainties in the estimates are large, and related to an incomplete knowledge about both retention processes and factors determining the P load from agricultural land. Hence, the overall aim of this thesis was to investigate possible reasons for the variation in wetland P retention estimates, and to assess the P retention in wetlands located in agricultural areas where losses are expected to be high. When comparing seven CWs located downstream small catchments with predominantly arable land, the particle and P net accumulation varied considerably (13-108 t particles ha-1 yr-1 and 11-175 kg P ha-1 yr-1, respectively). Catchment factors that were statistically correlated with accumulation of particles and P in the CWs were the slope of the arable land, the P content of the top soil, the animal density (expressed as livestock units per arable land) and the percentage clay in the topsoils. In four of the wetlands, resuspension was studied using sediment traps and plates. The results showed that up to 87 % of the settled material was resuspended, and indicated that erosion of the wetland sides and bottom probably contributed a substantial part of the trapped particles. In order to critically evaluate existing retention data from earlier investigations, the temporal dynamics of P concentrations and P retention in seven CWs were evaluated. The relationships between water flow and concentration (from grab sampling) varied, and depended on the season (warm or cold period of the year), water flow (high or low) and the inlet type (drainage pipe or open ditch). In CWs that received water through an open ditch, flow-concentration relationships were negative during low flow periods but positive during high flow periods. These differences in flow-concentration relationship have implications for water sampling, since P loads can be both over- and underestimated with grab or automatic sampling guided by clock-time. Also composite automatic sampling, regulated from the water flow at the outlet, can lead to errors in transport calculations since the same ‘water parcel’ is not measured at in and out (difference depending on how long the water retention time is in the CW). This may have an effect on estimates of P retention in both past, present and future investigations of constructed wetlands. Finally, a synoptic sampling approach with ten sampling points was used in an agriculturally dominated catchment area (160 km2) to identify differences in nutrient transport dynamics and areas with the highest losses. Spatial differences in P concentrations were strongly correlated with some of the catchment factors, for instance with soil type, and particle concentrations were weakly correlated to agricultural practices associated with bare soils during winter. This supports the practice to focus P mitigation measures – such as constructed wetlands – to erosion sensitive areas.
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8

Lindqvist, Johanna. "Referensvåtmarker för uppföljning av växtnäringsretention i anlagda våtmarker." Thesis, Halmstad University, School of Business and Engineering (SET), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2613.

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One of the environmental problems today in seas, lakes and streams is eutrophication. This is often caused by nutrients such as phosphorus (P) and nitrogen (N) that leak from agricultural areas. A measure to partly prevent the nutrient discharge is to construct or restore wetlands.

In order to control the efficiency of nutrient reduction of existing wetlands in the county, the administrative board in Västra Götaland wants to find different criterias for reference wetlands. These reference wetlands should represent other wetlands and be used in future evaluations of reduction of nutrients and design of constructed wetlands.

According to the administrative board in Västra Götaland the reference wetlands should have a catchment area of about 50 hectare consisting of at least 70 % arable land, to represent wetlands created to remove nutrients. The surface area should exceed 0,5 hectare and the inlet-nitrogen concentration should be around 5 mg N-1.

This report investigates nitrogen and phosphorus retention in two wetlands, Härstad and Åmot in the county of Västra Götaland, and if they fulfill the criteria of being a reference wetlands. In addition to this, a tracer study was performed in one of these wetlands with the purpose to study the hydraulic efficency.

Neither the wetland in Åmot or Härstad achieves the guidelines of about 5 mg N l-1 in the incoming water. Therefore, they can be seen as inappropriate as reference wetlands according to their nitrogen retention. The wetland of Härstad, however, has significantly better N retention than the wetland of Åmot. Results from the report shows that N retention in the wetland of Härstad was relatively high not only due a higher N load, but also due to that N was largely in the form of NO3- facilitating efficient transformation of NO3- to N2 by denitrification bacteria. Nitrogen removal was much lower in the wetland in Åmot due to that N in incoming water was not in the form of NO3- and could therefore not be efficiently transformed to N2 by denitrification.

Incoming total phosphorus to the Härstad and Åmot wetlands exceeded 100 µg P l-1, which means "extremely high" tot-P concentrations according to environmental quality criteria from the Swedish Environment Protection Agency. Phosphorus load per wetland area was slightly higher in the wetland in Åmot than in the Härstad wetland. In spite of this, P retention per wetland area as well as relative P retention was clearly higher in the Härstad wetland. This can be explained by that P in incoming water to the Härstad wetland was to a larger degree than in the Åmot wetland bound to particles, facilitating P retention through sedimentation.

According to the tracer study, the Härstad wetland has a hydraulic efficency (λ) of about 0,13 which means it has a low hydraulic efficiency. The effective volume ratio (e) in Härstad was calculated to 18 % which means that the water has an inadequate spreading in the wetland, which is not good for the nutrient elimination in this wetland.

This study illustrates the difficulties in finding representative reference wetlands due to potential differences between wetlands in nutrient concentrations in incoming water, the degree that incoming P is bound to particles, the degree that incoming N is in the form of NO3-, and hydraulic efficiency.

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9

Johannesson, Karin. "Phosphorus retention in a constructed wetland - the role of sediment accretion." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-12529.

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A low-loaded constructed wetland was investigated with respect to phosphorus retention. Since the main long-term phosphorus retention mechanism is sedimentation and sediment accretion, the study focused on these processes. The purpose of the study was 1) to investigate how the calculated value of phosphorus retention (Pin – Pout), corresponded with the measured amount of phosphorus in the sediment, 2) to find out where in the wetland the phosphorus had accumulated, and in what form it was retained, and 3) to investigate the role of vegetation. The calculated value was 12 kg ha-1 and the measured value was 104 kg ha-1, which indicated the importance of internal phosphorus circulation, where plants probably take phosphorus from the underlying clay. Hence, vegetation could possibly increase the total phosphorus content in the wetland. The composition of phosphorus in the sediment was analysed using sequential fractionation. The dominating form of phosphorus in the sediment was iron-bound phosphorus (29 %). In total, 48 % of the phosphorus was stable, i.e. tightly bound in the sediment, and 35 % was relatively stable. The bioavailable fraction, which could cause eutrophication in downstream waters, was 17 % of the total phosphorus content, or 41 kg ha-1. The amount of total phosphorus was significantly higher near the inlet, compared to the outlet, which is explained by rapid sedimentation of particulate phosphorus entering the wetland. The phosphorus amount near the inlet represented 80 % of the total phosphorus load – which indicates the importance of internal circulation of phosphorus, both biological and geochemical.

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10

Thompson, Lisa C. "The influence of hydraulic retention time on planktonic biomass in lakes and reservoirs /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56754.

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Hydraulic retention time (HRT) might contribute to the substantial variation in phosphorus-chlorphyll and chlorophyll-zooplankton models because rapid flushing might depress plankton development. However, for a world-wide data set. HRT was not correlated with chlorophyll. Total phosphorus had no effect on chlorphyll when hypereutrophic sites were considered separately, but chlorophyll was negatively related to HRT. Short term HRT, averaged over periods up to one month, was not correlated with chlorophyll, or zooplankton biomass, in seven impoundments on the St. Lawrence and Ottawa Rivers. The size distribution of algae was not affected by HRT. The proportion of rotifer to total zooplankton biomass was positively related to HRT, but this trend disappeared when nauplius biomass was removed from the total. These results indicate that rapid flushing does not necessarily reduce planktonic biomass and that short term HRT is not useful for the prediction and management of planktonic biomass in these systems.
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11

Senior, Anna. "Catchment factors affecting particle and phosphorus retention in constructed wetlands receiving agricultural runoff." Thesis, Linköpings universitet, Biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-74262.

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Eight agricultural catchments in south Sweden were investigated for factors that may affect phosphorus (P) load and retention in the downstream situated wetlands (WL). P load is known to affect retention, and is determined by hydrological and geographical catchment characteristics. The wetlands were small (0.02-0.88%) in relation to their catchments (CA) and varied in design. Net sedimentation and P retention was determined with sedimentation plates during one year. The variables that best explained differences in particles and TP retention were the hydraulic load (q), TP load and the wetland length to width ratio. Contrary to expectations there was no correlation between factors that could be associated with erosion (i.e. slope and soil clay content) and retention of neither particles nor TP. Generally, the highest amounts of settled particles and P were found close to the wetland inlets, but soil disturbance (i.e. tillage) and high q increased the settling distance. It was likely that the smallest clay particles were too unaggregated to settle within these wetlands. Factors not included, such as wetland vegetation and bioturbation may have a large impact on P retention and this should be further investigated. The study also points to the difficulties in scaling down geological and P loss data from a regional to a local scale, as there can be large local deviations from the regional standard values. An easy method for identification of local “hotspots” for P losses should be of value for planning the location of future wetlands.
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Sachdeva, Vanita. "Biochar-induced soil stability influences phosphorus retention in the agricultural field in Quebec." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121318.

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Surface runoff from agricultural fields is the largest non-point source of phosphorus (P) that pollutes surface water in humid temperate regions. Best management practices have attempted to reduce P loading and improve P retention in agricultural soils but significant losses continue to occur, emphasizing the need for novel solutions. The objective of this research project was to determine whether biochar amendments in an agricultural soil could reduce P loss in surface runoff by increasing water infiltration or by improving soil stability. Experimental plots were established in St-Francois-Xavier-de-Brompton, Quebec, Canada on an agricultural field amended with three types of biochar (Dynamotive, Pyrovac, and Basques) applied at two application rates (5 and 10 t ha-1), and one unamended control plot. First, a 30-minute rainfall simulation was conducted using the Cornell Sprinkle Infiltrometer to assess runoff volume, time-until-ponding, infiltration rate, and water holding capacity (WHC), as well as P concentration and load in runoff. Second, soil samples from the experimental plots were fractionated using a wet-sieve method to determine the proportion of macro- and micro-aggregates. Each fraction was analyzed for total organic C and total P to locate biochar presence and determine whether additional P was retained in macro- or micro-aggregate fractions of biochar-amended soils. Water dynamics in the rainfall simulation showed no significant differences, however, runoff contained significantly less ortho-P in soil amended with Dynamotive biochar at 5 t ha-1 (p=0.048) and significantly less particulate P from soil amended with Pyrovac biochar at 5 t ha-1 (p=0.012) and Dynamotive and Basques biochars at 10 t ha-1 (p=0.024 and p=0.047, respectively). Soils amended with biochar at 5 t ha-1 and 10 t ha-1 also had significantly greater microaggregate stability (p=0.032 and p=0.046, respectively), which corresponded to significantly more organic C content (p=0.013 and p<0.01, respectively). Macroaggregates from biochar-amended soils also contained significantly higher organic C and total P concentrations (p<0.05 for both biochar rates) than the control soil. This suggests that the reduction in particulate P concentration in runoff is the result of biochar integration within the microaggregate structure, which indirectly promotes P retention in macroaggregates.
Les eaux de ruissellement associées aux champs agricoles sont la plus grande source de charges diffuses de phosphore (P) affectant l'eau de surface en régions tempérées. Les pratiques de gestions optimales tentent de réduire la charge en polluants phosphorés ainsi que d'améliorer la rétention de P dans les sols agricoles, mais malheureusement, des pertes significatives continues d'être recensées, accentuant le besoin pour de nouvelles solutions. L'objectif de cette recherche était de déterminer si des amendements de biocharbon dans les sols agricoles pourrait réduire la charge en phosphore par ruissellement en augmentant l'infiltration de l'eau dans les sols et en améliorant la stabilité des sols. Des parcelles expérimentales ont été établies à St-Francois-Xavier-de-Brompton, Québec, Canada dans un champ agricole amendé avec trois types de biocharbon (Dynamotive, Pyrovac, and Basques) utilisant deux différentes doses d'application (5 et 10 t ha-1), et un sans biocharbon. Premièrement une simulation de précipitation de pluie de 30 minutes a été effectuée à l'aide de Cornell Sprinkle Infiltromètre pour mesurer les niveaux de ruissellements, la durée avant le début du ruissellement, le taux d'infiltration, la capacité de rétention de l'eau, ainsi que la teneur et la charge total de P dans l'eau de ruissellement. Deuxièmement, des échantillons de sols des différentes parcelles on été fractionnées selon la technique de tamisage humide pour déterminer la proportion de macros et micros agrégats. Chacune des fractions a été analysé pour leur quantité de C organique ainsi que le niveau total de P afin de localiser la présence de biocharbon et afin de déterminer si plus de P a été retenu dans les fractions contenant les macro ou les micros agrégats de sols amendés avec du biocharbon. La dynamique de l'eau dans la simulation de précipitation a démontré aucune différence significative, cependant le contenue du ruissellement avait significativement moins d'orthophosphate dans le sol amendé avec le biocharbon Dynamotive à 5 t ha-1 (p=0.048) et il y avait significativement moins de P particulaire avec le sol amendé avec le biocharbon Pyrovac à 5 t ha-1 (p=0.012), le biocharbon Dynamotive et le biocharbon Basques à 10 t ha-¬1 (p=0.024 et p=0.047, respectivement). Les sols amendés avec du biocharbon à 5 t ha-1 et à 10 t ha-1 avaient aussi, de façon significative, des micros agrégats plus stables (p=0.032 et p=0.046, respectivement), ce qui correspond à une plus grande quantité de C organique (p=0.013 et p<0.01, respectivement). Les macros agrégats des sols amendés en biocharbon avaient des concentrations de C organique et P totales plus élevées (p<0.05 pour les deux concentrations de biocharbon) que le sol témoin. Cela suggère que la réduction de la concentration de P particulaire dans l'eau de ruissellement est la conséquence de l'intégration du biocharbon dans la structure des micros agrégats, ce qui encourage la rétention dans les macros agrégats.
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Simon, Susan M. "Phosphorus retention and release of soils in a constructed wetland for wastewater treatment." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002848.

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14

Zeng, Fengzhencheng. "Phosphorus Retention and Regeneration of EAF Steel Slag and a Synthetic Iron Oxyhydroxide." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512067344406673.

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15

Richardson, Bree Lacey. "HYDROLOGICAL AND BIOGEOCHEMICAL MECHANISMS DRIVING NITROGEN AND PHOSPHORUS RETENTION IN A FRESHWATER ESTUARY." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1529269594773022.

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16

Forbes, Margaret G. "Phosphorus Retention and Fractionation in Masonry Sand and Light Weight Expanded Shale Used as Substrate in a Subsurface Flow Wetland." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3183/.

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Constructed wetlands are considered an inefficient technology for long-term phosphorus (P) removal. The P retention effectiveness of subsurface wetlands can be improved by using appropriate substrates. The objectives of this study were to: (i) use sorption isotherms to estimate the P sorption capacity of the two materials, masonry sand and light weight expanded shale; (ii) describe dissolved P removal in small (2.7 m3) subsurface flow wetlands; (iii) quantify the forms of P retained by the substrates in the pilot cells; and (iv) use resulting data to assess the technical and economic feasibility of the most promising system to remove P. The P sorption capacity of masonry sand and expanded shale, as determined with Langmuir isotherms, was 60 mg/kg and 971 mg/kg respectively. In the pilot cells receiving secondarily treated wastewater, cells containing expanded shale retained a greater proportion of the incoming P (50.8 percent) than cells containing masonry sand (14.5 percent). After a year of operation, samples were analyzed for total P (TP) and total inorganic P (TIP). Subsamples were fractionated into labile-P, Fe+Al-bound P, humic-P, Ca+Mg-bound P, and residual-P. Means and standard deviations of TP retained by the expanded shale and masonry sand were 349 + 169 and 11.9 + 18.6 mg/kg respectively. The largest forms of P retained by the expanded shale pilot cells were Fe+Al- bound P (108 mg/kg), followed by labile-P (46.7 mg/kg) and humic-P (39.8). Increases in the P forms of masonry sand were greatest in labile-P (7.5 mg/kg). The cost of an expanded shale wetland is within the range of costs conventional technologies for P removal. Accurate cost comparisons are dependent upon expansion capacity of the system under consideration. Materials with a high P sorption capacity also have potential for enhancing P removal in other constructed wetland applications such as stormwater wetlands and wetlands for treating agricultural runoff.
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17

Pinney, Jenae Elizabeth. "Influence of light and algae on nutrient transformations at the sediment-water interface of an agricultural stream." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76801.

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The sediment-water interface is an active biogeochemical zone within streams, where solutes come in contact with mineral surfaces, biota, and reducing conditions. Here, we sought to examine the influence of light, the sediment water interface, and algae on dissolved organic carbon (DOC), nitrogen, and phosphorus within Maple Creek, an agriculturally impacted stream located in Fremont, Nebraska. Simultaneous continuous injection experiments into replicate open- and closed-bottom chambers were used to control the hydrologic residence time. A bromide tracer was injected, and samples were taken for nutrient analysis in the surface and subsurface water at depths up to 8 cm. Dissolved oxygen (DO) and temperature were recorded in order to monitor biotic production. Experiments were conducted over 10 hours, encompassing both light and dark conditions. Results show a strong biotic influence at the sediment-water interface causing nutrient uptake and changes in carbon quality. Changes are especially pronounced during peak photosynthesis hours. The open-bottom mesocosms consistently showed removal of N and P from the surface water to the subsurface. An increase in DOC flux was observed in the open-bottom mesocosms and the organic matter pool exhibited evidence of microbial reduction. The closed-bottom mesocosm showed NH?⁺ increased likely due to photochemical oxidation. These results show the importance of promoting exchange through the subsurface and across the sediment-water interface due to the positive impact it has on nutrient retention.
Master of Science
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18

Michel, Gérard-Alain. "Silvopasture as an approach to enhancing phosphorus and nitrate retention in pasturelands of Florida." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015829.

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19

Whitehead, Peter. "Phosphorus retention from dairy slurry in four grassland soils and release to soil solution." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250638.

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20

Herrmann, Inga. "Filter beds for on-site wastewater treatment : Towards more reliable estimations of phosphorus retention." Doctoral thesis, Luleå tekniska universitet, Arkitektur och vatten, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18275.

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Phosphorus (P) is an important plant nutrient and essential for life. However, thephosphate rock used for fertilizer production is a non-renewable resource and itsproduction is expected to peak. At the same time, the discharge of P into naturalwaters is causing eutrophication, a severe problem in areas such as the Baltic Sea. Onsitewastewater treatment facilities in Sweden contribute substantially to this discharge because of their inadequate retention of P. Filter beds are a potentially useful technique to capture P in on-site facilities. However, many variables need to be considered when the P retention of potential filter materials is estimated in laboratory tests prior to designing full-scale filters. The overall aim of this thesis was therefore to increase the reliability of forecasting P retention in full-scale filters by increasing the understanding of P retention in P filters under varying conditions and by identifying measures that could lead to more reliable methods of testing filter materials at laboratory scale.The effects of influent type, influent P concentration, loading rate and ambienttemperature on the filter materials Filtra P, Filtralite P, Top16 and Polonite wereinvestigated in filter column experiments using 22 factorial designs. Furthermore, the P binding mechanism was studied using mineral phase investigations and by determining the reaction time of the P in the filter. In addition, filter performance was estimated by means of hydro-geochemical transport modelling.The investigated factors significantly (Į = 0.05) affected the retention of P in the filter materials showing that it is important to consider those factors when designing laboratory filter experiments and full-scale filters. Using secondary wastewater as an influent instead of P solution decreased the P binding capacity of Filtralite P, probably due to organic compounds contained in the wastewater. Increasing influent P concentration decreased the number of bed volumes treated before breakthrough in Filtra P by 82%. The loading rate was shown to be an important design parameter. Increasing the loading rate, something commonly done in the laboratory to accelerate the testing, significantly increased the amount of washed-out particulate P in Filtra P and Filtralite P. However, the residence time was also shown to be important; it should be maximised in filter tests as far as practical constraints allow. Increasing the temperature from 4.3 to 16.5°C increased the P binding capacity in both Top16 and Polonite which was attributed to an enhanced precipitation of calcium phosphates. This indicates that results obtained from experimental filters at room temperature might overestimate filter performance in the field where the temperature can be lower. In addition, full-scale filters might function better in warm rather than cool climates. The results further showed that it is crucial to measure both the concentration of dissolved P and particulate P in the filter effluent, as P-containing particles were observed to escape from the experimental filters in this study. Hydroxylapatite was detected in the outflow hose of the Filtra P columns indicating that this mineral phase may form in the filters under certain conditions. The geochemical models, however, indicated that the only precipitated calcium phosphate compound was amorphous tricalcium phosphate.Two hydro-geochemical transport models were developed that satisfactorily described the experimentally derived P breakthrough curves and effluent pH of the filter columns with Filtralite P. The simulations suggested that calcium oxide, calcite and the calcium-silicate phase wollastonite supplied the Ca2+ and OH- ions required for the precipitation of phosphate.
Godkänd; 2014; 20140408 (ingher); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Inga Herrmann Ämne: VA-teknik/Sanitary Engineering Avhandling: Filter Beds for On-Site Wastewater Treatment Towards More Reliable Estimations of Phosphorus Retention Opponent: Professor Petter Jenssen, Institutt for miljøvitenskap, Norwegian University of Life Sciences, Ås, Norge Ordförande: Professor Maria Viklander, Avd för arkitektur och vatten, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 13 juni 2014, kl 10.00 Plats: F1031, Luleå tekniska universitet
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21

Johannesson, Karin. "Analysis of phosphorus retention variations in constructed wetlands receiving variable loads from arable land." Licentiate thesis, Linköping University, Linköping, Sweden, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-20140.

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22

Eger, Caitlin Genet. "Nutrient Retention in Roadside Retrofit Rain Gardens." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343837490.

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23

Howlett, David. "Environmental amelioration potential of silvopastoral agroforestry systems of Spain soil carbon sequestration and phosphorus retention /." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024983.

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24

Anderson, Malin. "Dynamics of phosphorus transport and retention in a wetland receiving drainage water from agricultural clay soils." Thesis, Linköpings universitet, Ekologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68773.

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A constructed wetland (0.08 ha) receiving drainage water from a small agricultural catchment (22 ha) with clay soil, was investigated with respect to phosphorus dynamics and retention. The aim was to evaluate the function of the wetland with respect to phosphorus retention, and relate that to gross sedimentation as measured with sediment traps. Hydraulic load and phosphorus retention were estimated for 2003-2010 based on monitoring data. Furthermore, water quality dynamics was studied during three intensive sampling periods of 3-5 days during 2010. For each period, phosphorus retention was calculated and the relationship between flow and phosphorus concentrations analysed. Additionally, the gross sedimentation rate was estimated using sediment traps, and the phosphorus, carbon and nitrogen content analysed. The results suggested that there was no net retention of phosphorus during 2003-2010, except for 04/05. During the intensive sampling periods, release of phosphorus from the wetland mainly occurred during high flow. Sediment analyses showed that settling of inflow particles mostly occurred in the inlet pond, while the sediment found in a shallow vegetated area and outlet pond likely originated from internal processes rather than from the catchment. In fact, the gross sedimentation of phosphorus during April-July and July-August, respectively, exceeded the measured phosphorus inflow. The results showed that short periods with rapid flow increases were crucial for the wetlands function and thus high frequency sampling must be done during these periods. Furthermore, it seems that the particles lost from the catchment during high flows are too small to settle in the wetland.
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25

Renouf, Karen Ann. "Riparian buffer zones of the Canterbury agricultural landscape and their effectiveness for nitrogen and phosphorus retention." Thesis, University of Canterbury. Biological Sciences, 2013. http://hdl.handle.net/10092/8897.

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Waterways in New Zealand have been severely degraded by agricultural activities during the past two centuries and land-use intensification is set to continue. Diffuse-source inputs are widely perceived to be a significant problem in low-lying areas, and riparian buffer zones are identified as a strategy to reduce land-use impacts. I surveyed the width and vegetative composition of riparian areas adjacent to 88 narrow farm waterways on the Canterbury Plains during the summer of 2009-2010. I investigated soil phosphorus and nitrogen availability at agriculture/riparian boundaries adjacent to high-intensity (dairy) and low-intensity (dry-stock grazing) pastures, and compared nutrient retention by fenced-off grass filter strips with that of native-planted buffers. Finally, I used growth metrics of three species commonly occurring in native buffers (Cordyline australis, Plagianthus regius and Pittosporum tenuifolium) and seasonal grass biomass accumulation, to assess growth response in relation to nutrient and moisture status of shallow (10cm) riparian soils. Riparian margins of Canterbury’s agricultural waterways were commonly between 2 – 5 metres wide. Most were dominated by exotic pasture grasses and annual/perennial forbs or, exotic shrubs and trees, as opposed to native vegetation. Nutrient availability at the agriculture/riparian boundary appeared to be influenced more by seasonal effects and site-specific characteristics, than land-use. While nutrient retention was variable, it was generally higher in native-vegetated buffers than in grass buffers and also strongly influenced by season and site context. Accumulated grass biomass, and to a lesser extent native riparian species, appeared to be influenced primarily by soil moisture within shallow riparian soils, rather than nutrient status. Of the three trees assessed, the unique surface-root structures of Cordyline australis may confer an advantage for uptake of near-surface water and nutrients. However, on lowland plains, established native riparian trees that acquire nutrient resources from throughout the soil profile and shallow ground-waters also constitute an essential component of buffer systems to ensure optimal nutrient removal. This thesis recommends continuing use of narrow grass buffers in combination with down-slope planting with a range of native species to optimise nutrient uptake depth and storage longevity. It also suggests further study of plant/soil/nutrient interactions and, nutrient flow within riparian buffers in the context of topography to ensure that land-manager revegetation efforts live up to expectations.
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26

Somuah, Lilian. "Educating Primary Care Nurses on Phosphorus Management in Chronic Kidney Disease Patients." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5785.

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Fifteen percent of adults in the United States have been diagnosed with chronic kidney disease (CKD). CKD is the slow, progressive, and irreversible loss of kidney function. The most effective means of controlling CKD is by managing dietary phosphorus intake. It is important that staff nurses be educated about effective patient education tools to improve dietary phosphorus management. The purpose of this project was to educate primary care nurses about phosphorus management in CKD patients through the introduction of the phosphorus pyramid as a visual tool. The project sought to understand if an educational intervention regarding phosphorus management in CKD patients could increase the primary care nurse's knowledge. The John Hopkins evidence-based practice model informed the development of this project. Ten primary care nurses participated in a 45-minute education program which focused on the use of the Phosphorus Pyramid. A pre and post-test of knowledge was completed via a Likert scale questionnaire that measured knowledge related to the educational objectives of the program. The posttest scores showed an increase of 15% overall in staff's knowledge regarding dietary phosphorus management, the participants were more likely to correctly answer questions related to the phosphorus content of food and drink. The phosphorus pyramid will serve as a user-friendly tool to assist patients in identifying high phosphorus foods that need to be avoided and low phosphorus foods that are recommended to incorporate in their renal diet. This project supports social change by improving the healthcare team's knowledge regarding dietary recommendations for CKD patients thereby contributing to improved patient outcomes and reduced healthcare costs.
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27

Kiser, Larry Christopher. "Nutrient Retention and Cycling in Southeastern U.S. Loblolly Pine (Pinus taeda L.) and Sweetgum (Liquidambar styraciflua L.) Plantations." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28989.

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Forest plantations in the southeastern U.S. are fertilized to increase growth on infertile, sandy soils. Nitrogen (N) and phosphorus (P) are the most common growth limiting nutrients. A key question that arises following fertilization of these soils is whether the applied fertilizer benefits only the current trees in the stand or also improves long-term site quality. The objectives of this study were to compare accumulation of N and P in the forest floor and mineral soil among unfertilized and fertilized plantations, determine soluble and residual N and P fractions and soluble carbohydrate and phenol fractions in foliage and litter, determine whether higher N in the forest floor from fertilization resulted in increased release of N from the forest floor and increased mineral soil N availability, and determine loblolly pine forest floor decomposition rate and release of nutrients in a simulated disturbance environment. Research was conducted at a 25-year old loblolly pine (Pinus taeda L.) plantation in NC (SETRES) and 13-year old loblolly pine and sweetgum (Liquidambar styraciflua L.) plantations in GA (Mt. Pleasant). Fertilization resulted in increases in mineral soil N that were likely to be temporary and not sustained following cessation of fertilization N applications. This was likely due to an inability of acidic, sandy mineral soils to retain NH4-N and NO3-N. The forest floor accumulated N due to slow release of N during decomposition. Fertilization with N results in only temporary increases in mineral soil N availability that occur during fertilizer application and from forest floor decomposition. Future changes in N availability are primarily determined by decomposition of the forest floor following a disturbance that accelerates decomposition. In contrast to N, fertilization of loblolly pine and sweetgum with P results in a long-term increase in site P availability. Fertilization with P has lasting effects by increasing mineral soil P in stable forms that can be made available for plant uptake over time suggesting increased supply of P to trees in the next rotation. Retention of P in the mineral soil was likely due to the tendency of acidic, sandy mineral soils to accumulate P in Al- and Fe-phosphates.
Ph. D.
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28

Shetterly, Benjamin James. "Soil Phosphorus Characterization and Vulnerability to Release in Urban Stormwater Bioretention Facilities." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4354.

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Modern urban stormwater infrastructure includes vegetated bioretention facilities (BRFs) that are designed to detain water and pollutants. Phosphorus (P) is a pollutant in stormwater which can be retained in BRF soils in mineral, plant, and microbial pools. We explored soil properties and phosphorus forms in the soils of 16 operational BRFs in Portland, OR. Since soil hydrology can significantly impact P retention, we selected BRFs along an infiltration rate (IR) gradient. We conducted sequential fractionation and tests of P pools and measured P release in a subset of soils after drying and flooding samples for ten days. We hypothesized that mineral or organic soil P forms would be correlated with IR, and that vulnerability to P release would depend on the interaction of drying and flooding treatments with P forms and pools. IR did not significantly explain differences in P forms. Soil TP was elevated across all sites, compared with TP in agriculturally-impacted wetlands and was substantially composed of soil organic matter (OM)-associated P. Phosphorus sorbed to mineral Fe and Al oxides- was variable but positively correlated with water-extractable P. The concentration gradient of water-extractable P was primarily controlled by overall P pools. Experimentally induced P releases were seen in 5 of 6 soils exposed to drying conditions, presumably released through microbial mineralization of OM. Only one site showed significant P release following the flooding treatment. Our measurements supported the idea that Fe and Al oxides provide P sorption capacity in these BRF soils. Variable inputs of P to BRFs through stormwater and litterfall may contribute to variability in P profiles and P release vulnerability across sites. Design specifications and management decisions relating to bioretention soils (e.g. establishment of acceptable soil test P levels, focusing on P forms known to influence vulnerability of P release) may benefit from detailed biogeochemical investigations.
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29

Lewandowski, Jörg. "Untersuchungen zum Einfluss seeinterner Verfahren auf die Phosphor-Diagenese in Sedimenten." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2002. http://dx.doi.org/10.18452/14836.

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Viele seeinterne Maßnahmen zielen darauf, die Phytoplanktonentwicklung über die Verfügbarkeit von Phosphor (P) im Wasserkörper zu steuern. Die meisten Restaurierungsverfahren sollen über eine Erhöhung der P-Bruttosedimentation oder Verminderung der P-Rücklösung die P-Retention im Sediment beeinflussen. Daher sind Sedimentuntersuchungen zur Abschätzung der P-Retention und ihrer Veränderung unter dem Einfluss der erwogenen Maßnahmen eine wichtige Voraussetzung für die Auswahl des im konkreten Einzelfall am besten geeigneten Verfahrens. Eine durch Fragebögen und Literaturauswertung vorgenommene Analyse legt offen, dass die Sedimentuntersuchungen häufig nicht oder mit ungeeigneten Methoden erfolgten und die Therapieversuche daher in der Vergangenheit oft nicht die erwartete Wirkung hatten. Mit einer Kosten-Nutzen-Abschätzung wird gezeigt, dass sich Voruntersuchungen auch finanziell rechnen, obwohl sie aufwendig und teuer sind. Die Forschung der letzten Jahre hat das Prozessverständnis für die Kopplung der verschiedenen Kreisläufe und das Zusammenspiel von chemischen und biologischen Prozessen erheblich vervollständigt. Wegen der Komplexität ist es jedoch immer noch sehr schwierig, die Wirkung eines technischen Eingriffs genau vorherzusagen. Es werden Untersuchungsmethoden benötigt, die die beteiligten Prozesse und Zustandsgrößen mit ausreichender räumlicher und zeitlicher Auflösung erfassen. Besonders wichtige Größen für seeinterne Maßnahmen sind das P-Freisetzungspotential und die P-Freisetzungsrate. Verschiedene Bestimmungsmethoden für die beiden Größen werden in der Arbeit beschrieben, weiterentwickelt, gegenübergestellt, mit Beispielen veranschaulicht und im Bezug auf ihre Vor- und Nachteile diskutiert. Das P-Freisetzungspotential kann aus der Veränderung der Gesamtphosphorgehalte im Sedimenttiefenprofil, aus den P-Bindungsformen der oberen Sedimentschicht oder aus Desorptionsuntersuchungen mit Sediment der oberen Schicht abgeleitet werden. Die P-Freisetzungrate kann als Konzentrationsanstieg des Freiwassers in Säulenversuchen, in Flux-Kammern oder im Hypolimnion gemessen werden. Alternativ ist es möglich, sie aus dem Konzentrationsgradienten des gelösten Phosphors an der Sediment-Wasser-Grenze mit Filtration, Zentrifugation, Sensoren oder Dialysesammlern zu ermitteln. Ein spezielles Augenmerk wird auf die kleinräumige horizontale Heterogenität der P-Porenwasserkonzentrationen gelegt, da diese Variabilitäten zu fehlerhaften P-Freisetzungsraten führen können. Ein neues Probenahmegerät, ein zweidimensionaler Porenwassersammler, wurde entwickelt, um die P-Porenwasserkonzentrationen mit hoher horizontaler und vertikaler Auflösung messen zu können. Das neue Probenahmegerät erwies sich zur Klärung der Frage, wie viele unabhängige Messungen in einem konkreten Fall für zuverlässige Ergebnisse erforderlich sind, als geeignet. Der Einsatz des zweidimensionalen Porenwassersammlers identifizierte biologische Aktivität als Hauptursache räumlicher Variabilität. Ferner wurde deutlich, dass die räumliche Variabilität der P-Porenwasserkonzentrationen in flachen Gewässern größer als in tiefen Gewässern ist. Bei der Probenahmeplanung und Ergebnisauswertung sollte die räumliche Variabilität auf jeden Fall ausreichend berücksichtigt werden. An einem konkreten Anwendungsfall (Auensee) werden die vorgestellten Untersuchungsmethoden eingesetzt, um die Auswahl von Restaurierungsverfahren zu demonstrieren. Erst die kombinierte Interpretation von P-Freisetzungspotential und P-Freisetzungsrate erlaubt, die richtigen Schlussfolgerungen für das Untersuchungsgewässer zu ziehen. In einem weiteren Fallbeispiel (Süßer See) wird gezeigt, dass Nachuntersuchungen nicht nur zur Erfolgskontrolle notwendig sind, sondern auch um wissenschaftliche Erkenntnisse zu gewinnen. Im dargestellten Fall wird anhand von Laborversuchen und einer konzeptionellen Modellierung gezeigt, dass eine mit Neusediment überdeckte P-sorbierende Schicht auch bei noch vorhandener Sorptionskapazität keinen nennenswerten Einfluss auf die P-Konzentrationen im Wasserkörper hat. Die mit der vorliegenden Dissertation erfolge Zusammenschau und kritische Bewertung der Untersuchungsmethoden soll auch dazu dienen, die Lücke zwischen wissenschaftlichem Prozessverständnis und wasserwirtschaftlicher Praxis zu verkleinern.
Many internal restoration measures in lakes are directed to control of phytoplankton development by limiting the availability of phosphorus (P). Most such measures are aimed at changing P retention in sediment by increasing gross P sedimentation, or reducing P release (Chapter 2). Thus, pre- and post-restoration investigations of the lake sediment, including estimating the actual P retention and its predicted change caused by the considered measure, are an important means for choosing the most appropriate restoration technique and to determine whether restoration was successful. However, our questionnaires and literature study reveal that, in the past, pre-restoration investigations were frequently either omitted or inadequate. Consequently, effectiveness of lake restorations was often low. In contrast, appropriate pre-restoration investigations, increase the prospect of success. Our cost-benefit estimation proves that pre-restoration investigations, though expensive, reduce costs of lake restorations and increase the cost-benefit relationship (Appendix 1). Last years research has improved the knowledge of the complex coupling of the chemical cycles involved, and of the chemical and biological processes in the lake ecosystem. However, it is still difficult to estimate the effects of a technical measure, because we lack investigation methods that record the involved processes with the necessary temporal and spatial resolution. To evaluate internal measures, the P release potential and the P release rate are necessary. In this dissertation, the methods to determine the P release potential and the P release rate are developed, described, exemplified, compared, and their advantages and disadvantages are discussed. The P release potential can be derived from the change of total phosphorus in the sediment depth profile, from P binding forms, or from P desorption experiments in laboratory (Chapter 3). The P release rate can be measured in the water column as increase of phosphorus in core experiments, in flux chambers, or in the hypolimnion of stratified lakes. Alternatively, the P release rate can be determined from P concentration gradients at the sediment-water interface with filtration, centrifugation, microsensors, or dialysis samplers (Chapter 4). Special attention of this dissertation is focussed on pore water inheterogeneity because in might result in incorrect P release rates. A new device, a two-dimensional pore water sampler, was developed to measure pore water P concentrations with high horizontal and vertical resolution. The new device is shown to be applicable to particular lakes to determine how many independent measurements are necessary to get reliable results. Our use of the two-dimensional pore water sampler determined biological activity as the main cause of the spatial heterogeneity of pore water P concentrations and revealed that the spatial variability is larger in shallow lakes than in deep lakes. The variability should be taken into account when planning a sampling program or evaluating results (Appendix 2). The proposed sediment investigation methods to determine the P release potential and the P release rate are used at Lake Auensee to demonstrate their use for choosing the most appropriate restoration technique. The case study of Lake Auensee points out that only a combined interpretation of P release potential and P release rate leads to the correct conclusion (Appendix 3). Post-restoration investigations are necessary to check whether a restoration was successful or not, and to gain scientific insight. A study of Lake Süsser See is used as an example for post-restoration investigations of the sediment. Core experiments and a conceptual model are used to show that a buried layer, even with P sorption capacity, has no impact on the P release (Appendix 4). Furthermore, the surveys and critical evaluations contained in this dissertation should decrease the gap between scientific understanding of processes in a lake and practical water management.
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30

Gabriel, Oliver. "Der Einfluss der Hydrologie auf die Phosphor-Freisetzung und -Retention in einem teilvernässten Spreewald Polder." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2012. http://dx.doi.org/10.18452/16488.

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Natürliche Niederungsgebiete wirken als effektive Phosphor Senke. Landwirtschaftliche Nutzung und Drainage führt zur Transformation zu Phosphor Quellen. Dem Spreewald, ein Feuchtgebiet und seiner Funktionsweise als Phosphor Quelle oder –Senke, kommt im Einzugsgebiet der Spree eine wichtige Rolle zu. Die vorhandenen Kenntnisse der Phosphor Umsatzprozesse und des Phosphor Austausches zwischen den Flächen und dem Fließgewässernetz sind jedoch gering. Praktikable Ansätze zur Beschreibung des Phosphor Austauschverhaltens von Nährstoffen in den ausgedehnten Polderregionen liegen nicht vor. Anhand hydrologischer, geohydraulischer und biogeochemischer Prozessuntersuchungen in einer Polderlandschaft mit typischer Stauhaltung konnten die Phosphor Freisetzungs- und Retentionsprozesse ausgewiesen werden. Unter Nutzung verschiedener Modellansätze (geohydraulische Modellierung, Stofftransportmodellierung und Statistische Modelle) und der Berechnung von Phosphor Prozessraten werden horizontale und vertikale Phosphor Fluxe in den Flächen-Wasser Übergangszonen quantifiziert. Die Ergebnisse gehen in ein Phosphor Bilanzmodell ein, das die P-Quellen und Senkenfunktion von Polder Teilflächen (überstaut, genutzt) und des gesamten Polders in Monatsschritten abbildet. Die biogeochemischen Phosphor Umsatzprozesse sowie der horizontale und vertikale Transport werden wesentlich von den hydrologischen und den klimatischen Bedingungen gesteuert. Sie stellen die primären Einflussgrößen der P Senken oder -Quellenfunktion dar. Im Polder wird die Phosphor Netto Freisetzung der genutzten Bereiche durch eine hohe Phosphor Netto Retention in den überstauten Flächen abgemindert. Szenario Untersuchungen zeigen, dass sinkende Grabenwasserstände zu einer erheblichen Erhöhung der Phosphor Emissionen aus dem Grundwasserpfad führen. Ansteigende Phosphor Fluxe bei sinkenden Wasserständen legen ein zunehmendes Eutrophierungsrisiko in den Gräben sowie für unterhalb gelegene aquatische Systeme nahe.
Natural wetlands effectively retain phosphorus. Agricultural cultivation and drainage by ditches transform them to phosphorus sources. In the Spree catchment, the Spreewald, a large scaled lowland has a strategic importance operating as a phosphorus sink or phosphorus source. Anyhow, knowledge of its phosphorus turnover processes and the phosphorus exchange behavior between the plain and the river and ditch network are marginal. Practicable approaches to reproduce the phosphorus exchange behavior in its typical polder areas are missing. Based on process investigations in a polder area with typical weir regulation, phosphorus retention and remobilization processes are characterized. Combining different model approaches (groundwater modeling, matter transport modeling and statistical models) and calculating process rates, the horizontal and vertical phosphor fluxes in the water soil/sediment transition zones are quantified. The outcomes are used as input data for a phosphorus balance model reproducing the phosphorus source and sink character of used and rewetted polder areas and for the whole polder in monthly time steps. Results from process and transport investigations point out that biogeochemical turnover processes and horizontal or vertical phosphorus transport are driven by hydrological and climatological conditions. Net phosphorus release found in the extensive used polder areas is counteracted by significant net phosphorus retention in the rewetted parts. Scenario analyses identify decreasing ditch water levels to cause a considerable increase of phosphorus emissions from the groundwater pathway. Consequently, the increasing phosphorus fluxes at decreasing water levels provoke a growing risk for eutrophication in the ditches but also in the downstream aquatic systems.
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31

Corbee, Gabriella. "Phosphorus accumulation in constructed wetlands : A study of 10 wetlands constructed on agricultural clay soils in Södermanland." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448096.

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Eutrophication is a major problem causing algal blooms and impaired water quality, especially regarding coastal areas and seas. It is a result of an excessive supply of nutrients such as phosphorus (P), where agriculture accounts for the largest share of the anthropogenic nutrient load. Furthermore, arable fields with clay soils have been shown to have among the highest P-losses. In this study, 10 constructed wetlands located in agricultural areas with high clay content in the topsoil were examined. The aims were to investigate how the P accumulation is related to wetland design and catchment factors and to see if there is an optimal hydraulic load (HL) and wetland size for P accumulation. The study is based on P analyses of sediment cores sampled in March 2021, calculations of catchment factors in ArcMap, water flow calculations, and statistical analyses. Sedimentation of particles with associated P is considered to be the primary process for P retention in wetlands. Accordingly, the results showed that the P accumulation was positively correlated to particle retention. The total P accumulation varied between 8 and 96 kg ha-1 yr-1 and the total particle accumulation was 7-130 t ha-1 yr-1. The wetland design factors, including wetland area, water depth, and length-to-width ratio (L:W), had no significant influence on the P accumulation. However, water depths greater than 1.5 m inhibited the P retention which suggested that the water depth should be limited to approximately 1 m to avoid too large particle settling distances.  The proportion of agricultural land within each catchment did not show any correlation to the P accumulation. The clay content in the topsoil was however positively correlated to both particle and P accumulation. This suggested that the sedimentation process was promoted even though the inflowing particles potentially consisted of a large proportion of clay particles, which have a low sedimentation velocity. The erosion risk of the catchment area had no significant influence on the P accumulation, meaning that a high expected particle load did not entail an increased particle and associated P accumulation. High HL values of 450 and 850 m yr-1 were shown to counteract the P retention. This corresponded to wetlands smaller than 0.1% of the catchment area. A possible turning point of HL where the P accumulation is inhibited could also be distinguished, ranging between HL 200 and 300 m yr-1. An optimal HL for increased P accumulation could not be determined due to such few observations. However, it could be concluded that an HL up to approximately 210 m yr-1 had a positive influence on the particle and P accumulation and that wetlands should be larger than 0.1% of the catchment area to efficiently retain P.
Övergödning är ett stort problem som orsakar algblomningar och försämrad vattenkvalitet, särskilt vid kustområden och hav. Övergödningen orsakas av ett för stort utsläpp av näringsämnen såsom fosfor (P), där jordbruket står för den största antropogena näringsbelastningen. Åkermark med lerjord har dessutom visat sig ha bland den högsta utlakningen av P. I denna studie har 10 våtmarker anlagda i jordbruksområden med hög lerhalt undersökts. Syftet var att undersöka hur P-ackumuleringen är relaterad till våtmarksutformningen och abiotiska faktorer i avrinningsområdet. Projektet syftade även till att undersöka ifall det finns en optimal hydraulisk belastning (HL) för P-ackumulering. Studien baserades på P-analyser av sedimentproppar provtagna i mars 2021, beräkningar av avrinningsområdesfaktorer i ArcMap, flödesberäkningar samt statistiska analyser.  Den primära reningsprocessen för P i våtmarker är genom sedimentation av partiklar med bundet P. Följaktligen visade resultatet att P-ackumuleringen var positivt korrelerad med partikelretentionen. Den totala P-ackumuleringen varierade mellan 8 och 96 kg ha-1 år-1 och den totala partikelackumuleringen var 7-130 ton ha-1 år-1. Våtmarksutformningen, vilket innefattade våtmarksarea, vattendjup och längd-bredförhållande (L:W), hade ingen signifikant betydelse för P-ackumuleringen. Vattendjup större än 1,5 m hämmade emellertid P-ackumuleringen vilket indikerade att vattendjupet bör begränsas till cirka 1 m för att partiklar ska hinna sedimentera.  Andelen jordbruksmark i avrinningsområdet hade ingen korrelation med P-ackumuleringen. Lerhalten i avrinningsområdet var däremot positivt korrelerad till både partikel- och P-ackumuleringen. Detta indikerade att sedimentationen främjats trots att de inflödande partiklarna potentiellt bestod av en stor andel lerpartiklar, vilka har en långsam sedimentationshastighet. Erosionsrisken i avrinningsområdet hade ingen signifikant påverkan på P-ackumuleringen. En hög förväntad partikelbelastning resulterade därmed inte en ökad partikel- och P-ackumulering. Höga HL-värden på 450 och 850 m år-1 motverkade P-ackumulationen, vilket motsvarade våtmarker som utgjorde mindre än 0,1 % av avrinningsområdet. En möjlig brytpunkt där HL hämmar P-ackumulationen kunde urskiljas i intervallet HL 200-300 m år-1. På grund av för få observationer kunde inte en optimal HL för ökad P-ackumulation fastställas. Det kunde dock konstateras att en HL upp till cirka 210 m år-1 hade en positiv inverkan på partikel- och P-ackumulationen och att våtmarker bör utgöra minst 0,1 % av avrinningsområdet för att effektivt ansamla P.
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32

Chan, Pacheco Carlos Roberto. "Integrating enhanced biological phosphorus removal (EBPR) in a resource recovery scenario." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666850.

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La presente tesis doctoral se enfoca en evaluar un sistema de eliminación biológica de fósforo (enhanced biological phosphorus removal, EBPR) orientado a un escenario de recuperación de recursos. Los resultados obtenidos se dividieron en cuatro capítulos, los cuales aparecen en los capítulos 4, 5, 6 y 7. Los temas estudiados en cada capítulo se resumen a continuación: Capítulo 4. Se estudió a largo plazo un sistema SBR-EBPR cuya configuración fue modificada con la finalidad de obtener un líquido altamente enriquecido con P. La configuración del sistema SBR-EBPR consistió en incluir una etapa de extracción de sobrenadante al final de la etapa anaeróbica (después de un periodo de sedimentación). El líquido extraído tiene la mayor concentración de P en el ciclo SBR, lo cual implica que la disponibilidad de este nutriente estaría limitada para los requerimientos metabólicos de los microrganismos responsables de este proceso, comprometiendo la eficiencia del proceso EBPR. Por ello se evaluaron diferentes volúmenes de extracción. Capítulo 5. Se estudió el comportamiento de la actividad EBPR usando tiempos de retención celular (TRC) cortos, esto con la finalidad de evaluar su posible integración en sistemas energéticamente eficientes, como el proceso A/B. Con este fin, se operaron tres diferentes reactores secuenciales (por lotes) con una configuración convencional a 25 ºC y a TRC de entre 3-14 días. Capítulo 6. La influencia de la temperatura y el SRT sobre el proceso EBPR fueron evaluadas, a corto y largo plazo. En este capítulo se usaron tres sistemas EBPR, los cuales se operaron a temperaturas de entre 10-20 ºC y a TRC de entre 3.5-15 días. Capítulo 7. La biomasa obtenida de los diferentes sistemas (SBR-EBPR), usados en el capítulo 6 se metió a pruebas de digestión anaerobia, esto con la finalidad de evaluar su potencial de producción de metano. Debido a que cada biomasa contenía diferentes concentraciones de PHA, la influencia del contenido de PHA sobre la de producción de metano también fue evaluada.
This doctoral thesis focuses on evaluating an EBPR (enhanced biological phosphorus removal process) system oriented to the scenario of resource recovery. The results obtained are divided into four chapters, which are presented in chapters 4, 5, 6 and 7. The topics studied in each chapter are summarized below: Chapter 4. A SBR-EBPR system was studied in the long term by modifying its configuration in order to obtain an anaerobic supernatant enriched in phosphorus. The configuration of system SBR-EBPR included one stage for the extraction of supernatant at the end of anaerobic stage (after a period of sedimentation). The extracted liquid has the largest concentration of P in the SBR cycle, which implies that the availability of this nutrient would be limited for the metabolic requirements of the PAO, compromising the efficiency of the process EBPR. For this reason, different extraction volumes were assessed. Chapter 5. The behavior of the EBPR activity using short cell retention times (SRT) was studied in order to assess the possibility of its integration to energetically efficient systems, such as the A/B process. With this purpose, different SBR were operated with a conventional configuration. These SBR were operated at 25 °C and at 3-14 days SRT. Chapter 6. the influence of temperature and SRT on the EBPR process was assessed (in both the short and long terms) using three EBRP systems. These systems were operated at t temperatures between 10-20 ºC and at TRC between 3.5-15 days. Chapter 7. The biomass obtained in the different operational periods of the SBR-EBPR systems used in chapter 6 was subjected to an anaerobic digestion test to evaluate its methane production. Because each biomass contained different concentrations of PHA, the influence of PHA content on methane production was also evaluated.
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33

Besancon, Axelle. "Technologies and multi-barrier systems for sustainable groundwater recharge and irrigation." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5726.

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Managed aquifer recharge (MAR) consists of artificially replenishing groundwater to facilitate reuse and/or the associated environmental benefits. Meanwhile, soil aquifer treatment (SAT) is a process of geo-purification designed and operated to improve the quality of the infiltrating water and is thus a type of MAR. SAT consists of a basin operating under rotation of drying and wetting periods. Often, SAT involves water of impaired quality applied onto soil and consequently it implies various risks of health, geochemical and physical nature with difficult or irreversible remediation. To study the effect of pre-treatment on SAT a pilot plant including conventional activated sludge (CAS), a membrane bioreactor (MBR), tertiary and secondary vertical flow reed beds (VFRB) and SAT soil columns. The sludge retention time (SRT) in the CAS and MBR processes was changed every 6 months to look at the impact of SRT on SAT. Each unit and treatment train effluent was characterised to determine the impact of effluent quality on SAT performance. This study showed that tertiary VFRB, especially when fed with MBR effluent, was the best option for SAT and irrigation reuse as it provided the best compliance with reuse standards and the best fertilisation potential. However, long-term clogging occurred in SAT after tertiary VFRB, suggesting the need for a longer resting period or shorter wetting period. This study also highlighted the importance of total suspended solids (TSS) content for SAT removal mechanisms and infiltration rate. In particular, SAT fed with high TSS content effluent was susceptible to temperature variation. Hence the duration of wetting and flooding periods should be adapted according to the season. Further, variation in SRT only indirectly affected pollutants removal by the system including CAS treatment set up at 6 d SRT where the N compounds balance was favourable to an autotrophic N removal.
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34

Debruler, Daniel Gary. "Soil Carbon, Nutrients, and Phosphorus Fractions: Responses to Weed Control and Harvest Residual Retention in two 10-Year-Old Douglas-fir (Pseudotsuga menziesii) Stands of the Pacific Northwest." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50486.

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Intensive forest management techniques such as whole-tree harvesting and use of herbicides to control weeds can have an effect on nutrient cycling and nutrient pool sizes in the mineral soil. This study was conducted to measure differences in soil carbon (C), nutrient pools, or phosphorus (P) fractions associated with harvest-intensity (bole-only vs. whole-tree harvest) and weed-control treatments (initial weed control vs. five years of annual weed control) after ten years. Soil C, nitrogen (N), and P, and exchangeable calcium (Ca), potassium (K), magnesium (Mg), and Hedley P fractions were measured prior to treatment establishment and after ten years in two Douglas-fir (Pseudotsuga menziesii) plantations in the Pacific Northwest. We observed increases in most nutrient concentrations with initial weed control compared with annual weed control at Matlock, with opposite trends at Molalla. Exchangeable Ca and Mg content showed responses to weed control treatments. Harvesting treatments had no significant effects on soil C and nutrient pools at either site. Total P and many of the Hedley P fractions decreased over time, but these effects were ameliorated with the less-intensive initial-weed-control-only treatment at Matlock and the more-intensive annual-weed-control at Molalla. Ten-year responses suggest that harvesting intensity has not impacted potential for maintaining soil C and nutrient pools, with the exception of P, for long-term productivity. Knowledge of the on-site vegetative communities and their role in nutrient cycling is required to anticipate what effect weed control might have on nutrient pools through ensuing stand development.
Master of Science
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35

Isenberg, William. "Sources and Fates of Nutrients in the Tidal, Freshwater James River." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2686.

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Tidal freshwater reaches of estuaries may play an important role in mitigating nutrient fluxes from watersheds to the coastal zone due to their location at the interface between riverine and estuarine systems. We developed annual N and P budgets for the tidal, freshwater James River over 4 calendar years (2007-2010) taking into account riverine inputs at the Fall Line, local points sources (including CSO events), ungagued inputs, riverine outputs, and tidal exchange. The tidal freshwater James River experiences high areal loading rates of TN (383 mg/m2/d) and TP (70 mg/m2/d) due to the combined effects of large watershed area and local point source discharges. On an annual basis, riverine sources dominated TN and TP inputs (59% and 84%, respectively), whereas during low discharge summer months (May-Oct) point sources were more important. Proportional retention of TP inputs (59±7%) was greater than TN retention (27±4%) with annual absolute retention being 1,800±350 kg TP/d, and 5,900±2,700 kg TN/d. Proportional retention of TN and dissolved inorganic fractions of N and P was highest during the low discharge summer months due to reduced loading rates and increased residence times and biotic activity. TP retention was greatest during high discharge winter months (Nov-Apr) when loading rates were highest. High retention during this period of low biotic activity suggests that trapping of riverine derived particulate-bound P via sedimentation was an important mechanism of P retention. Understanding this seasonal variation in nutrient inputs and retention can help to inform management decisions regarding reducing nutrient inputs to the Chesapeake Bay and improving local water quality.
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36

Dorozynska, Dorota. "En studie av retentionen i floden Oder och dess avrinningsområden, Polen." Thesis, Linköping University, Linköping University, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2597.

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Nutrient enrichment is the main cause of the increasing eutrophication process in the Baltic Sea during last century. A prerequisite counteract this process the load of nutrients to the Sea must be investigated. The large contribution of nutrients to the Sea is caused by emission from the rivers within the drainage basin. For the total emission of nutrient into the Sea the retention process in the rivers has big influence. This process in the river system has been assumed as a not important part of the nutrient cycle. However some investigators have pointed out that the retention process occurs in the river and be an important part of the nutrient dynamics in the river. For the object of investigation the Odra River Basin was chosen, as an example of a large river basin in the Baltic Sea Drainage Basin. The Odra River is mainly localized in Poland and contributes substantially to the eutrophication of the Baltic Proper. The Odra River is one of the least dammed major rivers of the Baltic Proper and as such of especial interest in retention studies. The phosphorus was chosen as an example of nutrient in the eutrophication process. The purpose of the investigation is to determine the phosphorus retention within the river. Two different models were used to calculate the retention process in the river. The"Multiple Regression Model"turned out to be insignificant, therefore the results were computed by using a “similarity model”, based on similarities between load from monitored tributary basins and the rest of the sub-basin. The retention in the Odra River in the amounted to -4608 t yr-1, which is 43% of the total phosphorus emission to the Odra River. There is also stated that in the Notec and the Warta rivers the retention process occur in the amount of -1940 t yr-1 and -3007 t yr-1 respectively.

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37

Paull, Rachel May. "Evaluating the Role of Biotic and Abiotic Ecosystem Components on the Retention and Removal of Ditch Nutrients in Ditches of Different Construction." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1594220539737151.

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38

Oliveira, Celso Luiz Borges de. "Dinamica da retenção de fosforo de aguas residuais em sistemas de alagados construidos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256941.

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Orientador: Jose Teixeira Filho
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
Made available in DSpace on 2018-08-15T05:17:02Z (GMT). No. of bitstreams: 1 Oliveira_CelsoLuizBorgesde_D.pdf: 7803925 bytes, checksum: 1a75de816c7680ca4e07299a55d9967d (MD5) Previous issue date: 2006
Resumo: Este estudo objetivou avaliar a dinâmica na retenção do fósforo no sistema de alagados construídos de fluxo subsuperficial, que funciona como tratamento secundário da água de esgoto da Faculdade de Engenharia Agrícola da Universidade Estadual de Campinas, Campinas (SP), e encontra-se em operação desde setembro de 1998. O experimento teve início em maio de 2003 e término em agosto de 2004, totalizando quinze amostragens, com medidas horárias durante oito a dez horas por dia. Foram anotadas as vazões de entrada e saída dos leitos e simultaneamente coletadas as amostras para análise do fósforo, pH e condutividade elétrica. A determinação do teor de fósforo foi feita pelo método AOAC Official Method 973.55 - Phosphorus in water. As plantas da Typha passaram por quatro cortes e as de Arroz por três cortes durante os quinze meses do experimento. Os resultados demonstraram que as maiores taxas de retenção do fósforo ocorreram nos leitos cultivados com a Typha, atingindo percentuais médios de até 92%. A utilização do Arroz é uma alternativa, quando manejadoadequadamente, em função do seu ciclo reprodutivo, com cortes próximos ao estágio deformação de grãos. As opções pelas culturas da Typha e do Arroz não são excludentes, considerando a sua eficiência na retirada de fósforo da água residuária, pois, a depender do seu estágio de desenvolvimento, o período e o número de cortes realizados, essas plantas podempromover uma eficiente redução nos teores de fósforo nesse tipo de efluente quando tratadosnos sistemas de alagados construídos
Abstract: This study objectified to evaluate dynamics phosphorus removal subsurface flow constructed wetlands systems as treatment secondary of sewer of the School of Agricultural Engineering of the State University of Campinas, Campinas (SP) and meets in it operates since September of 1998. The experiment was being in May of 2003 and during still in August of 2004, when had been carried through fifteen samplings, with measures hours with along eight at ten hours per day. They had been record the inflow and outflow the streambeds and simultaneously collected the samples for analysis of phosphorus, pH and electrical conductivity. The phosphorus rates were determined by method of AOAC Official Method 973.55. Phosphorus in water. With the data of diary inflow flow, per concentrations of phosphorus results of analyses of the samples had been calculated loads horary of phosphorus, in mg P.h-1. The Cattail have cutted plants of Typha had passed for four cuts and of Rice for three cuts during the fifteen months of the experiment. The results had demonstrated that the biggest taxes of withdrawal and/or removal of match had occurred in the cultivated rectangular stream beds with the Typha and the use of the Rice is an alternative of use when management in function of its reproductive cycle, with cuts next to the period of training to formation of grains. The used plants are not exculpatory, when of the choice for its efficiency in the withdrawal of match of the residuary water, therefore to depend on its period of training of development, the period and the number of carried through cuts, can promote greater purifications in the water that passes for the treatment stream beds
Doutorado
Agua e Solo
Doutor em Engenharia Agrícola
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39

Eriksson, Elin. "Initial nutrient retention capacity in a constructed wetland : Evaluating the effectiveness of a newly constructed wetland to reduce eutrophication symptoms in a Baltic Sea bay in northern Sweden." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184268.

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Since the turn of the last century, a substantial increase in nutrient load to the Baltic Sea is apparent. Adding the ongoing environmental change with raising temperatures and increased precipitation, this will continue to have a prominent environmental impact on our coastal ecosystems, especially in northern latitudes. Constructed wetlands are becoming more important as a mitigation measure to retain nutrients, however, they are until this day not well studied in northern latitudes. In this paper, nutrient retention in a newly constructed wetland is studied during its first month after activation, as well as potential downstream effects in associated sea bay. An additional literature study compiles information about the current knowledge, use and functionality of wetlands surrounding the Baltic Sea. This is done to widen knowledge regarding effectiveness of wetlands as nutrient traps in general, as well as to compare with the studied wetland. A net retention of 30 % for dissolved organic carbon (DOC) and total phosphorus (TP) was found, as well as 27 % for total nitrogen (TN), 25 % for phosphate (PO43-) and 21 % for nitrate (NO3-). TP was found to be within range of expected retention capacity, when comparing with wetlands included in the synthesis. TN retention, however, seemed to be somewhat greater than in other wetland studies. Furthermore, the retention varied and seemed to be highest during an increased discharge, in the beginning and end of March. This was partly reflected by greater inlet concentrations and transports in most of the parameters during the initial time period. Decreasing temporal trends was seen in concentrations of DOC, total nutrients and NO3- concentrations in the sea bay, indicating an immediate downstream effect of the wetland installation. Findings from the synthesis indicate that there are very few studies in, and thus little knowledge about, wetlands in northern climate. Overall, the results from the pioneer northern wetland in Sörleviken suggest that net retention is possible during its first month post-activation.
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40

Thiere, Geraldine. "Biodiversity and ecosystem functioning in created agricultural wetlands." Doctoral thesis, Högskolan i Halmstad, Våtmarkscentrum, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2968.

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This doctoral dissertation was produced in a cooperation between Halmstad University (Wetland Research Centre, School of Business and Engineering) and Lund University (Limnology & Marine Biology, Department of Ecology). Abstract . Wetland creation at large, regional scales is implemented as a measure to abate the biodiversity loss in agricultural landscapes and the eutrophication of watersheds and coastal areas by non-point source nutrient pollution (mainly nitrogen). The consequences of creating many new wetlands for biodiversity conservation and nutrient reten- tion (ecosystem functioning) in agricultural landscapes are still relatively unknown, both on local (per wetland) and regional (per landscape) scales. In Sweden, wetland creation has progressed already since the 1990s, and by now larger numbers of created wetlands are present, mainly in the intensively farmed landscapes of southwestern Sweden. This thesis aimed to investigate the following aspects in these systems: (i) their large-scale effects on biodiversity, (ii) their functional diversity of bacterial denitrifiers, (iii) the abiotic and biotic influences on wetland ecosystem functioning, (iv) the potential for biodiversity-function links, and (v) the potential for functional links and joint functioning.(i) Created wetlands hosted diverse assemblages of macroinvertebrates and plants. They maintained a similar com- position and diversity as natural ponds in agricultural landscapes. The environmental conditions per wetland did hardly affect macroinvertebrate and plant assemblages, and the prerequisites for nutrient retention did neither. In landscapes were wetland creation efforts had increased the total density of small water bodies by more than 30%, macroinver- tebrate diversity of created wetlands was facilitated on both local and regional scales. (ii) Diverse communities of denitrifying bacteria with the capacity for conducting different denitrification steps (functional types) were present in all investigated wetlands. The richness of denitrifying bacteria communities was affected by nitrate concentration and hydraulic loading rate, which may potentially be relevant for the nitrogen retention function of created wetlands. The diversity across different functional types of bacterial denitrifiers increased with nitrate concentration. (iii) Both abiotic and biotic factors influenced ecosystem functions of created wetlands. Variation in nitrogen retention was associated to nitrate load, but even to vegetation parameters. In wetlands with constant nitrate load, planted emergent vegetation facilitated nitrogen retention compared to other vegetation types. In wetlands with variable loads, nitrogen retention was facilitated if nitrate load was high and many different vegetation types were present; nitrogen load could explain the majority of the variation in nitrogen retention compared to vegetation parameters. Phosporus retention of created wetlands was best explained by vegetation parameters. Litter decomposition was inhibited at high nitrate to phosphorus ratios. Methane production increased with age and decreased with plant cover. (iv) Biodiversity may facilitate wetland ecosystem functions, particularly in dynamic wetland ecosystems. Nitrogen retention increased with vegetation type diversity, phosphorus retention capacity with plant richness, and litter decomposition with macroinvertebrate diversity. (v) Created wetlands have the capacity of sustaining several parallel ecosystem services. Some wetland functions were coupled; nitrogen retention increased with fast litter decomposition. On the other hand, methane emission and nitro- gen retention were independent of each other, as were nitrogen and phosphorus retention.In conclusion, created wetlands have the potential to at least partly abate the lost biodiversity and multifunctionality caused by the past extensive destruction of natural wetlands in agricultural landscapes.

[Paper II] Milenkovski S., Thiere G., Weisner S.E.B., Berglund O. & Lindgren P.-E. Variation of eubacterial and denitrifying bacterial biofilm communities among constructed wetlands. Submitted manuscript. [Paper V] Thiere G. & Weisner S.E.B. Influence of biotic and abiotic parameters on ecosystem functioning of created wetlands. Manuscript.

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41

Ma, Yulin. "The Fundamental Studies of Polybenzimidazole/Phosphoric Acid Polymer Electrolyte for Fuel Cells." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089835902.

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42

Serra, Gasa Alexandra. "Fate and effects of copper in fluvial ecosystems: the role of periphyton." Doctoral thesis, Universitat de Girona, 2009. http://hdl.handle.net/10803/7876.

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L'activitat humana és una de les majors causes d'elevades concentracions de nutrients i substàncies tòxiques en els ecosistemes fluvials. Entre la gran varietat de factors que alteren aquests ecosistemes, l'eutrofització i la contaminació per metalls pesants són dos dels principals problemes ambientals en països desenvolupats. Els biofilms fluvials (també anomenats comunitats perifítiques) representen una eina valuosa per avaluar els efectes dels contaminants (ex. nutrients i metalls) en els ecosistemes aquàtics. Aquest treball pretén investigar el destí i els efectes del Cu en els ecosistemes fluvials centrant-se en les comunitats perifítiques. Diferents metodologies han estat desenvolupades i/o adaptades per investigar específicament la dinàmica del Cu, la seva toxicitat i bioacumulació en comunitats perifítiques naturals, i la interacció entre l'eutrofització i la toxicitat del Cu en aquests ecosistemes.
Human activity is one of the major causes of elevated concentrations of nutrients and toxic substances in fluvial ecosystems. Among the many ecosystem stressors, eutrophication and metal pollution are two of the major environmental problems in many developed countries. Fluvial biofilms (periphyton communities) are a useful tool for monitoring the effects of pollutants (e.g. nutrients and metals) into aquatic ecosytems. The present study aims to investigate the fate and effects of Cu in fluvial ecosystems focusing on periphyton communities. Different methodologies have been developed and/or adapted to specifically investigate the dynamics of Cu, its toxicity and bioaccumulation on natural periphyton communities, and the interaction between eutrophication and Cu toxicity in these ecosystems.
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43

Bercoff, Alexandra. "Investigation of the treatment process at Kungsberget's wastewater treatment plant under periods of irregular and low loads." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-210159.

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At Kungsberget ski-resort in Gävleborg county all wastewater produced at the facility is treated on-site. The treatment takes place at their own wastewater treatment plant in a so-called Sequence Batch Reactor (SBR), which has been in operation for about a year before this study. Kungsberget AB is currently in charge of the facility but their goal is to hand responsibility over to Sandviken Energy AB. In order for this handover to occur Kungsberget has to produce three approved treatment results. This means that the concentrations of BOD7 needs to lie under 0.3 mg/l and total phosphorous under 10 mg/l in the effluent water for three consecutive samples. The results show momentaneous values. These limits are stated in the permit Kungsberget received from the Environmental Protection Division. Kungsberget has had problems with high and fluctuating phosphorous concentrations and therefore the transfer has not yet taken place. In this project several parameters have been analysed in order to obtain an overview of prevailing influent and effluent concentrations. Some of the parameters that have been analysed are; phosphorous, nitrogen, BOD7, suspended solids and pH. A lot of time and effort has been put into elucidating operational routines at the wastewater treatment plant (WWTP) and gaining knowledge from available literature regarding different parameters’ effect on treatment results.   Kungsberget has had problems adapting operating routines and reaching stable treatment results as the load is highly effected of seasonal fluctuation. This has not been taken into account earlier and the WWTP has been operated in the same manner all year around. Suggestions to how operating routines can be modified in to better meeting the needs have been produced and alternative treatment methods have been presented in the report. Two of the suggestions include biological phosphorous removal and adding carrier media to increase bacteria growth. An aerobic solids retention time has been calculated in order to evaluate whether nitrifying bacteria have enough time for grow and maintain a stable population. The calculation was carried out by measuring suspended solids and aeration time and the result was a solids retention time of approximately 6 days.
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44

Gabriel, Oliver [Verfasser], Gunnar [Akademischer Betreuer] Nützmann, Matthias [Akademischer Betreuer] Zessner, and Hilmar [Akademischer Betreuer] Schröder. "Der Einfluss der Hydrologie auf die Phosphor-Freisetzung und -Retention in einem teilvernässten Spreewald Polder / Oliver Gabriel. Gutachter: Gunnar Nützmann ; Matthias Zessner ; Hilmar Schröder." Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2012. http://d-nb.info/1021482145/34.

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45

Scholz, Maria Fernanda Costa. "Influência do modo de aplicação e viscosidade do ácido fosfórico 37% na adesão de pinos de fibra de vidro em condutos radiculares." Universidade Estadual de Ponta Grossa, 2018. http://tede2.uepg.br/jspui/handle/prefix/2587.

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Abstract:
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O objetivo do presente estudo foi avaliar a influência da viscosidade do ácido fosfórico e do modo de aplicação nos valores de resistência de união de pino de fibra de vidro cimentados na dentina radicular através do teste de pushout. Raízes de 32 pré-molares foram preparadas endodonticamente e divididas em 4 grupos (n = 8) de acordo com a combinação dos seguintes fatores: viscosidade do ácido e forma de aplicação. Após aplicação do adesivo Universal no interior dos condutos, foram realizadas as cimentações dos pinos com o cimento resinoso RelyX ARC. Em seguida, as raízes foram seccionadas transversalmente em 6 fatias de aproximadamente 1 mm e o teste de push-out foi realizado a uma velocidade de 0,5 mm/min. Os resultados de resistência de união foram submetidos a uma análise de variância de três fatores de medidas repetidas e teste de Tukey (alpha = 0.05). A interação dupla modo de aplicação vs. viscosidade do ácido (p = 0,0002) e o terço radicular (p < 0,0001) foram estatisticamente significantes. O maior valor de resistência de união foi observado no grupo condicionado com ácido fosfórico líquido sob o modo de aplicação sônica (p < 0,05) sendo todos os outros grupos semelhantes entre si. Quanto ao terço radicular, observou-se maior valor de resistência de união no terço cervical, seguido do terço médio e do terço apical terço apical (p < 0,05). Pelos resultados pode-se concluir que uma melhor adesão de pinos de fibra de vidro ao conduto radicular pode ser obtida através do condicionamento com ácido fosfórico líquido com aplicação sônica.
The aim of the present study was to evaluate the influence of the etchant viscosity (liquid or gel) and the application mode (passive or sonic) on the pushout bond strength values of fiberglass post to root dentin and the conditioning pattern on the smear-layer covered root dentin before cementation. The roots of premolars were prepared endodontically and divided into 4 groups (n = 8) according to the combination of the main factors: phosphoric acid viscosity (liquid gel) and application mode (passive or sonic). After the application of the universal adhesive into the root canals, the fiberglass posts were cemented with cementation system RelyX ARC. Then, the roots were sectioned transversely 6 slices of approximately 1 mm and the push-out test performed at a speed 0.5 mm/min. The results were submitted to a repeated measures three-way ANOVA and Tukey’s test (alpha = 0.05). The cross-product interaction mode of application vs. etchant viscosity (p = 0.0002) and the main factor root third (p < 0.0001) were statistically significant. The highest bond strength value was observed when the conditioning of the root canal was performed with a liquid phosphoric acid under sonic application mode (p < 0.05), being all other groups similar one another (p < 0.05). Regarding the root third, the highest push-out bond strength value was observed in the cervical third, followed by the medium third and the apical thirds (p < 0,05). The most common fracture pattern was the mixed failure. By the partial results one may conclude that a better bonding of fiberglass posts to root canals can be achieved when the conduits are conditioned with a
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46

Zhang, Wei. "Improvement of phosphorus and heavy metals retention in stormwater treatment." 2006. http://digital.library.okstate.edu/etd/umi-okstate-1966.pdf.

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47

"Phosphorus retention and release characteristics of wetland sediments in Hong Kong." 2007. http://library.cuhk.edu.hk/record=b5893199.

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Abstract:
Lai, Yuk Fo.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.
Includes bibliographical references (leaves 169-191).
Abstracts in English and Chinese.
Abstract --- p.i
Abstract (in Chinese) --- p.iv
Dedication --- p.v
Acknowledgement --- p.vi
Table of contents --- p.viii
List of tables --- p.xii
List of figures --- p.xiii
List of plates --- p.xv
List of symbols and abbreviations --- p.xvi
Chapter Chapter One --- Introduction
Chapter 1.1 --- Introduction --- p.1
Chapter 1.2 --- Research background --- p.1
Chapter 1.2.1 --- Wetlands and water quality --- p.1
Chapter 1.2.2 --- The role of sediments in eutrophication control --- p.3
Chapter 1.2.3 --- Wetlands in ecological mitigation --- p.4
Chapter 1.2.4 --- Previous studies of wetland pollution in Hong Kong --- p.6
Chapter 1.3 --- Conceptual framework --- p.8
Chapter 1.4 --- Objectives of the study --- p.12
Chapter 1.5 --- Significance of study --- p.13
Chapter 1.6 --- Organization of the thesis --- p.14
Chapter Chapter Two --- Literature Review
Chapter 2.1 --- Introduction --- p.15
Chapter 2.2 --- Quantification of phosphorus retention in wetlands --- p.16
Chapter 2.2.1 --- Input-output concentration approach --- p.16
Chapter 2.2.2 --- Mass balance approach --- p.18
Chapter 2.2.3 --- Phosphorus removal efficiency --- p.19
Chapter 2.3 --- Phosphorus sorption by wetland sediments --- p.20
Chapter 2.3.1 --- Sorption and its significance --- p.20
Chapter 2.3.2 --- Phosphorus sorption maxima --- p.22
Chapter 2.3.3 --- Adsorption-desorption equilibrium --- p.23
Chapter 2.3.4 --- Phosphorus sorption kinetics --- p.24
Chapter 2.4 --- Phosphorus exchange across the sediment-water interface --- p.24
Chapter 2.4.1 --- Phosphorus mobilization and transport mechanisms --- p.25
Chapter 2.4.2 --- Phosphorus flux from aquatic sediments --- p.26
Chapter 2.5 --- Phosphorus fractionation in wetland sediments --- p.29
Chapter 2.5.1 --- Major sediment phosphorus fractions --- p.29
Chapter 2.5.2 --- Phosphorus fractionation methods --- p.30
Chapter 2.5.3 --- Relationships between phosphorus fractions and bioavailability . --- p.32
Chapter 2.6 --- Factors affecting sediment-water phosphorus exchange --- p.33
Chapter 2.6.1 --- pH --- p.34
Chapter 2.6.2 --- Redox potential --- p.34
Chapter 2.6.3 --- Temperature --- p.35
Chapter 2.6.4 --- Salinity --- p.35
Chapter 2.6.5 --- Sediment properties --- p.36
Chapter Chapter Three --- Methodology
Chapter 3.1 --- Overall study approach --- p.38
Chapter 3.2 --- Geographical setting of Hong Kong --- p.41
Chapter 3.2.1 --- Climate --- p.42
Chapter 3.2.2 --- Geology and landform --- p.44
Chapter 3.2.3 --- Soil --- p.45
Chapter 3.2.4 --- Vegetation --- p.45
Chapter 3.3 --- Study sites --- p.46
Chapter 3.3.1 --- Site selection --- p.46
Chapter 3.3.2 --- Site description --- p.48
Chapter 3.3.2.1 --- The Hong Kong Wetland Park --- p.48
Chapter 3.3.2.2 --- Mai Po Marshes Nature Reserve --- p.50
Chapter 3.4 --- Sampling strategy --- p.53
Chapter 3.4.1 --- Sampling locations --- p.53
Chapter 3.4.2 --- Sampling dates --- p.57
Chapter 3.4.3 --- Sample collection and treatment --- p.58
Chapter 3.5 --- Sample analysis --- p.60
Chapter 3.5.1 --- Analysis of sediment samples --- p.61
Chapter 3.5.1.1 --- Sediment texture --- p.61
Chapter 3.5.1.2 --- Sediment pH --- p.61
Chapter 3.5.1.3 --- Redox potential --- p.61
Chapter 3.5.1.4 --- Sediment moisture --- p.62
Chapter 3.5.1.5 --- Organic matter --- p.62
Chapter 3.5.1.6 --- Total Kjeldahl nitrogen --- p.63
Chapter 3.5.1.7 --- "Total Fe, Al, and P" --- p.63
Chapter 3.5.1.8 --- "Oxalate-extractable Fe, Al, and P" --- p.63
Chapter 3.5.2 --- Analysis of water samples --- p.64
Chapter 3.5.2.1 --- "Water pH, conductivity, salinity, turbidity, temperature and DO" --- p.64
Chapter 3.5.2.2 --- Orthophosphate --- p.64
Chapter 3.5.2.3 --- Total nitrogen and phosphorus --- p.65
Chapter 3.5.3 --- Determination of phosphorus exchange characteristics --- p.65
Chapter 3.6 --- Statistical analysis --- p.65
Chapter Chapter Four --- Phosphorus Fractionation in Wetland Sediments in Hong Kong
Chapter 4.1 --- Introduction --- p.67
Chapter 4.2 --- Methodology --- p.68
Chapter 4.2.1 --- Sample collection and analysis --- p.68
Chapter 4.2.2 --- Phosphorus fractionation --- p.69
Chapter 4.2.3 --- Statistical analysis --- p.72
Chapter 4.3 --- Results and discussion --- p.72
Chapter 4.3.1 --- Physico-chemical properties of sediments --- p.72
Chapter 4.3.2 --- Physico-chemical properties of overlying water --- p.78
Chapter 4.3.3 --- Phosphorus fractionation in sediments --- p.82
Chapter 4.3.3.1 --- Phosphorus fractions in sediments of the Hong Kong Wetland Park --- p.82
Chapter 4.3.3.2 --- Phosphorus fractions in sediments of the Mai Po Marshes --- p.89
Chapter 4.3.3.3 --- Phosphorus fractions in relation to mobility and bioavailability --- p.96
Chapter 4.4 --- Conclusions --- p.100
Chapter Chapter Five --- Phosphorus Sorption by Wetland Sediments in Hong Kong
Chapter 5.1 --- Introduction --- p.103
Chapter 5.2 --- Methodology --- p.104
Chapter 5.2.1 --- Sample collection and analysis --- p.104
Chapter 5.2.2 --- Batch incubation experiments --- p.105
Chapter 5.2.3 --- Sorption kinetics --- p.106
Chapter 5.2.4 --- Effects of selected environmental factors on phosphorus sorption --- p.106
Chapter 5.2.5 --- Estimation of sorption parameters --- p.107
Chapter 5.2.6 --- Statistical analysis --- p.109
Chapter 5.3 --- Results and discussion --- p.109
Chapter 5.3.1 --- Phosphorus sorption parameters of wetland sediments --- p.109
Chapter 5.3.1.1 --- Phosphorus adsorption isotherms --- p.109
Chapter 5.3.1.2 --- The role of sediments in phosphate buffering --- p.116
Chapter 5.3.1.3 --- Relationships between phosphorus sorption parameters and physico-chemical properties of sediments --- p.121
Chapter 5.3.2 --- Kinetics of phosphorus adsorption --- p.124
Chapter 5.3.3 --- Effects of environmental factors on phosphorus sorption --- p.128
Chapter 5.3.3.1 --- Effects of pH --- p.128
Chapter 5.3.3.2 --- Effects of salinity --- p.131
Chapter 5.3.3.3 --- Effects of temperature --- p.133
Chapter 5.4 --- Conclusions --- p.136
Chapter Chapter Six --- Phosphorus Flux from Wetland Sediments in Hong Kong
Chapter 6.1 --- Introduction --- p.139
Chapter 6.2 --- Methodology --- p.140
Chapter 6.2.1 --- Sample collection and analysis --- p.140
Chapter 6.2.2 --- Core incubation experiments --- p.141
Chapter 6.2.3 --- Estimation of phosphorus flux --- p.142
Chapter 6.2.4 --- Statistical analysis --- p.142
Chapter 6.3 --- Results and discussion --- p.143
Chapter 6.3.1 --- Phosphorus flux from wetland sediments --- p.143
Chapter 6.3.1.1 --- Phosphorus flux from sediments in the Hong Kong Wetland Park --- p.143
Chapter 6.3.1.2 --- Phosphorus flux from sediments in the Mai Po Marshes --- p.147
Chapter 6.3.2 --- Effects of redox conditions on sediment phosphorus flux --- p.152
Chapter 6.4 --- Conclusions --- p.156
Chapter Chapter Seven --- Conclusion
Chapter 7.1 --- Introduction --- p.159
Chapter 7.2 --- Summary of major findings --- p.159
Chapter 7.3 --- Limitations of study --- p.166
Chapter 7.4 --- Suggestions for future study --- p.166
References --- p.169
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48

Houser, Jeffrey Neil. "Food web structure and experimental enrichment effects on Phosphorus sedimentation and retention /." 1998. http://catalog.hathitrust.org/api/volumes/oclc/41639440.html.

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Abstract:
Thesis (M.S.)--University of Wisconsin--Madison, 1998.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 37-45).
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49

Shieh, Shiow-Wen, and 謝琇雯. "The Effect of Hydraulic Retention Time on Phosphorus Removal in AOAO Process." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/45980599271507862214.

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Abstract:
碩士
國立雲林科技大學
環境與安全工程系碩士班
90
The Effect of Hydraulic Retention Time on Phosphorus Removal in AOAO Process Student：Shiow-Wen Shieh Advisor：Terng-Jou Wan Institute of Environmental and Safety Engineering, National Yunlin University of Science & Technology abstract This study focuses the effects of hydraulic retention time on phosphorous removal in Anaerobic-aerobic-anoxic-aerobic process (AOAO processed). In addition, the variation of carbon and phosphorous are compared between batch reactors and continuous reactors. The influent substrates were adopted from the influent of the first anaerobic digester in wastewater treatment plant on the swine farms. The variation if anaerobic phosphorous released decreased and tend to be stable under reaction time of 1 hr. The higher the hydraulic retention time, the more anaerobic phosphorous released. The amount of anaerobic phosphorous released can be up to 253% under the hydraulic retention time of 3 days. Under the different HRT, the removal efficiencies of COD are more than 90% in AOAO pilot plant. Total phosphorous removal rate increase with the HRT increase. The removal rate of total phosphorous was 68% under the HRT of 3 days. The maximum removal rate of phosphate was about 64% under the HRT of 2 days. The effect of carbon sources addition on the anaerobic phosphorous released was evaluated. The amount of anaerobic phosphorous released in the system with carbon sources addition was higher than of the system without carbon sources addition. The amount of anaerobic phosphorous released in the system with carbon sources was up to 253%, and the amount anaerobic phosphorous released in the system without carbon sources was about 22%. The extracellular enzymes utilization in anaerobic phosphorous accumulating organisms were affected under low carbon sources, so that there was not enough carbon sources for the anaerobic phosphorous released and polyhydroxybutyrate (PHB) synthesized. According to the mechanisms of polyhydroxybutyrate (PHB) synthesized in anaerobic conditions, there were no significant effects of HRT on the amount of polyhydroxybutyrate (PHB) synthesized. The amount of polyhydroxyvalerate (PHV) synthesized (15 mgPHV/g•MLSS) was higher than the amount of polyhydroxybutyrate (PHB)synthesized (12 mgPHV/g•MLSS) in the polyhydroxyalkanoutes (PHAs) synthesized.
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50

Aldridge, Kane T. "Phosphorus retention and metabolism : indicators of stream deterioration across a rural-urban gradient?" 2005. http://hdl.handle.net/2440/37980.

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Much attention has been paid to the effects of anthropogenic impacts upon physical and chemical conditions in freshwater ecosystems. However, impacts upon the functioning of these ecosystems and services that they provide remain relatively unknown. The objective of this thesis was to examine the validity of the general hypothesis that the deterioration of ecosystems may be reflected in their capacity to process resources. Changes in stream phosphorus retention and metabolism were investigated across a rural-urban gradient in the Torrens River Catchment, South Australia, where channel structures of rural reaches are less modified than urban reaches. In a stream with an intact upper rural catchment (First Creek), a reach with an un-modified channel structure retained 60% ± 12.1 filterable reactive phosphorus (FRP) and had an average uptake length of 79 m ± 3.4. In comparison, degraded and engineered reaches of First Creek retained less FRP and had longer uptake lengths. In Fourth Creek, which is influenced by agriculture, there were no differences in FRP retention between the reaches. Reduced FRP retention in impacted reaches were a result of decreased contact time, reduced period of continuous flow and increased nutrient availability. Although abiotic benthic FRP uptake rates (up to 6.8 μg m [ superscript minus 2 ] s [ superscript minus 1 ] ± 0.36) were consistently greater than biotic uptake rates (up to 3.6 μg m [ superscript minus 2 ] s [ superscript minus 1 ] ± 0.52), decreased total benthic uptake rates in impacted reaches were mainly due to decreased biotic uptake. Metabolic rates were measured within benthic chambers containing rocks and gravel and scaled up to the stream reach. At chamber and reach scales, metabolic rates in the unmodified reach of First Creek were consistently low (community respiration (CR) up to 113 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 47.4 and gross primary production (GPP) up to 234 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 89.5), with a positive net ecosystem production (NEP). In comparison, the degraded reach of First Creek switched between having a negative and positive NEP. Reaches of Fourth Creek also experienced considerable variation and had higher metabolic rates than First Creek (CR up to 371 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 62.1 and GPP up to 847 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 66.1). Increased metabolic rates in impacted reaches were attributed to increased light availability and reduced grazing by higher trophic levels, promoting autotrophic organisms. The altered ecosystem functions were considered to reflect a reduced capacity of deteriorated streams to process resources. However, the addition of coarse particulate organic matter to a degraded-urban stream reach increased CR and reduced NEP to levels more akin to those experienced within pristine streams. Furthermore, percent FRP retention increased, primarily through increased demand for phosphorus of the microbial community. Although this demonstrated that rehabilitation of in-stream attributes might restore important ecosystem functions in impacted streams, successful restoration will only be achieved if the over-riding causes of in-stream degradation are addressed.
Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.
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