Dissertations / Theses on the topic 'Agricultural water pollution'

Ground water contamination from agricultural nitrates poses potential adverse health effects to a large segment of the rural population of the United States. Contamination is especially prevalent in livestock intensive areas, which produce large quantities of animal waste with substantial nitrogen content. In this study, potential management strategies for reducing nitrate contamination of ground water from agricultural sources were examined using an economic-physical model of a representative dairy farm in Rockingham County, Virginia. A mixed integer programming model with stochastic constraints on nitrate loading to ground water and silage production was used to simulate the impacts of various nitrate loading reduction strategies on estimated farm level net returns over variable costs. A survey of all dairy operations in the county was conducted to assist in specifying the mathematical programming model, identify current nutrient management and quality issues, and gauge farmers’ attitudes toward ground water quality and agricultural chemical use. Results of the model indicate that substantial reductions in current nitrate loadings are possible with relatively minor impacts on farmers’ net returns through the use of currently practiced approaches of cost sharing for manure storage facility construction and nutrient management planning. Greater loading reductions are achievable through presently untried policies of land use restrictions, bans on purchase of commercial fertilizer, and imposition of standards on loadings to ground water. These reductions are achieved, however, at higher costs in terms of reduced net returns. Study results indicate that a wide range of policy options exist for reducing nitrate loading to ground water; these reductions, while varying in cost, do not appear to come at the expense of eliminating the economic viability of the county dairy sector. Model results indicate that reductions in nitrate loading of 40 to 70 percent (on average) could be achieved with reductions in farmers’ net returns of one to 19 percent, respectively, when cost sharing for manure storage construction was provided. Explicit consideration was given to the annual variability in nitrate loading due to weather and other factors. The result was higher policy costs than when average loadings alone were considered.
Ph. D.

The purpose of this study was to investigate the role of soil erosion as a factor in lake pollution and in particular the transport of phosphorus from field soils to streams and lakes in association with mobile sediment. Four land uses were selected as representative of the Slapton Ley catchment area to investigate the levels of phosphorus in the soil. The surface soil samples from the selected land use areas were analysed to determine the water-soluble phosphorus level in solution and exchangeable phosphorus level in sediment. Twelve experimental plots were studied in order to assess the erosional effects of overland flow and thus to determine the level of phosphorus from different land uses which may be influencing the eutrophication of the lake. It was concluded that slope angle, vegetation cover, surficial soil properties, animal influence and agricultural practice are the main factors influencing sediment transportation by overland flow. Estimated results for the agricultural fields indicated that the actual phosphorus loss to the Ley is always greater in sediment than solution and actual phosphorus loss in sediment is greater in arable (root) and cereal than in grass. The point water samples (136) from 13 different sources were grouped. Mean value of phosphorus concentration from the point sources indicated that the agricultural land uses such as arable and cereal provide 2 times more exchangeable phosphorus attached to sediment than the other land uses whereas farm and sewage provided 5 times more soluble phosphorus in water than other sources. Phosphorus concentration during peak discharge was examined for the Cara catchment. The results indicated that the ratio of phosphorus concentration in suspended sediment to phosphorus concentration in water is 240: 0.3 and that there is a linear relationship between phosphorus in water and phosphorus in sediment during the peak discharge. Sediment phosphorus levels in the marsh area were also examined. The results indicated that the top layers of the marsh sediment particularly at the surface, have higher phosphorus concentration than the lower layers and that there are higher levels in sediment than in water. From these results the conclusion was drawn that the soluble phosphorus in water is at highest concentration in sewage works effluent. However this effluent contributes a small proportion of phosphorus load to the Ley compared with the arable (root), cereal and grass lands in the catchment. Agricultural sources, particularly arable sources such as root and cereal play an important role on soil erosion as a factor in lake pollution and in particular in the transport of phosphorus from field soils to streams and lakes in association with mobile sediment in the Slapton Ley catchment.

Concentrations of 17 organochlorine and 14 organophosphorus pesticides were measured in 27 ground and 11 surface water samples collected from a heavily agricultural area, Kumluca, in spring and fall seasons of 2005. The samples were preconcentrated by Solid Phase Extraction. GC-ECD and GC-NPD systems were used for quantitative determination of organochlorine and organophosphorus pesticides respectively. The quality check/quality assurance tests were performed by the analysis of field and laboratory blanks, standard reference materials, spiked control and sample matrices, surrogate standards, sampling and analysis replicates. It is observed that, sample matrix lowers average percent recoveries from 89% to 76%. The uncertainties of measurements were calculated to determine major factors affecting the analysis results. It was observed that uncertainty arising from extraction procedure was generally the highest. The most commonly observed pesticide was endosulfan (70%) and chlorpyriphos (53%) for organophosphorus and organochlorine pesticides. The highest average concentration was observed for heptachlor (26 ng/L) and fenamiphos (184 ng/L). Generally pesticides were detected more often in surface waters, where the concentrations were also higher. The concentrations of organophosphorus pesticides in spring, and organochlorine pesticides in fall season were higher. The high occurrences and detection of degradation products of chlorinated pesticides clearly indicate their intense use before 1980s. It is shown that, in Kumluca environment, degradation of these pesticides mostly occurs in surface waters. It is observed that agricultural activities affect water quality in the region. The total concentration limit (500ng/L) was exceeded for 27% of surface and 14% of ground water samples, at least once in both seasons. The legal limit for a single pesticide (100ng/L) was exceeded by 32 % of surface, 24 % of ground water samples.

Agricultural nonpoint source pollution is recognised as a major cause of water pollution. The characteristics of nonpoint source pollution suggest that an efficient approach should focus on a source control and hence land-use management. Recently, the concept of Payments for Ecosystem Services (PES) has been advanced as an efficient market-based approach to protect in-stream water quality, while simultaneously supporting agriculture. Farmers can be rewarded for the adoption of certain ‘Best Management Practices’ (BMPs) in farming systems. But little is known about the adoption of BMPs in the context of Thai agriculture. This thesis examines the adoption of twelve BMPs on citrus farms in the Ping river basin in northern Thailand. In the context of potential PES development, three studies were undertaken using frameworks from economics and psychology. The first study used a bottom-up engineering approach to estimate economic costs of twelve BMPs at the farm-scale. The total annualised costs, including installation, maintenance, and land opportunity costs of each BMP were compared. The results indicated that land opportunity cost was the largest proportion of total costs. These estimates provided a basis for discussion on how the farmers’ perception of cost may influence their stated adoption intention. The second study used the Theory of Planned Behaviour (TPB), to investigate farmers’ intentions on adoption of twelve BMPs. A survey of 218 citrus farmers was undertaken in the application. Descriptive statistics and frequency of BMP selection were presented. The results showed that soil analysis was the most preferred BMP. A graphical analysis of other preferred measures suggested that these were not always consistent with the known cost information derived (above) and thus farmers’ perceived costs might not be the most important factor influencing adoption decisions. Further analysis based on TPB investigated other factors thought to be significant in farmers’ decision-making. Other potential external and psychological factors influencing adoption were investigated using a multinomial logistic model. The results indicated that the probability of adopting BMPs was associated with other psychological factors and external factors, rather than perceived costs. The significant psychological factors were farmers’ attitudes towards consumers and perception about farm returns, while the significant external factors were, for example, access to information and contribution of family labour to farm workload. The third study was based on the application of Q-Methodology, and aimed to obtain a deeper understanding of farmers’ perception towards BMPs. Seventy two participants were purposively selected from the 218 TPB observations. The results revealed four distinctive farmer groups holding different perceptions towards BMPs. The four groups were conservationist, traditionalist, disinterested, and risk-averse. These provided a specific segmentation to guide policy towards influencing attitudes and behaviours. The results suggested that farmers were not motivated solely by a profit maximisation goal. Overall, key findings from these three studies revealed some fundamental requirements for developing a water-related PES programme. These were: i) factors affecting eligibility to participate; ii) factors affecting desire to participate; and iii) factors affecting ability to participate. This information provided the basis for a set of recommendations addressing the development of the water-related PES programme in the Ping river basin.

Thesis (M.S.)--West Virginia University, 2002.
Title from document title page. Document formatted into pages; contains vii, 59 p. : ill. Includes abstract. Includes bibliographical references (p. 43-45).

For over 30 years, federal and state governments have been engaged in a collective effort to improve the water quality and living resources in the Chesapeake Bay (CB), focusing particularly on reducing delivered nitrogen and phosphorus loads. However, achievement of water quality objectives remains elusive. In Virginia, agriculture represents the single largest source of nutrient loads to the Chesapeake Bay. Despite aggressive regulatory efforts in other nutrient source sectors, state authorities rely on educational programs and voluntary financial assistance programs to induce landowners to adopt best management practices (BMPs) that reduce agricultural nutrient loads. This study explores two economic aspects of efforts to reduce agricultural nonpoint source (NPS) pollution in the Virginia portion of the CB watershed. Firstly, current and possible future transactions costs associated with specific aspects of agricultural NPS participation in water quality trading (WQT) programs are examined in Chapter 1. A case study approach is used to consider the possible cost consequences of expanding the use of NPS credits from agricultural 'working lands' BMPs in Virginia. Findings indicate that overall transactions costs for nutrient trades involving agricultural NPS in Virginia are currently relatively low, due to the type of activities being credited: simple land conversions. Based on best available evidence, the administrative transactions costs of creating credits on agricultural 'working lands' using management and structural BMPs will be 2 to 5 times more costly on a per project basis than for credits generated from land conversions. Compliance monitoring protocols were found to be a significant driver of costs for credits generated from working agricultural lands. These results suggest an important cost/risk tradeoff between verification cost and compliance certainty for program designers to consider. The second study (Chapter 2) considers the economic cost of meeting pollution reduction targets for the Virginia portion of the CB Watershed. Existing cost models are based on simplifying behavioral assumptions about public transactions costs, conservation adoption rates, and implementation costs of agricultural BMPs. This study builds on the existing literature and uses the estimates of transactions costs from Chapter 1 together with information on producer BMP adoption rates to examine the implications of including transactions costs and differential BMP costs and adoption rates when estimating the minimum costs of achieving specified nutrient reduction goals in Virginia. The paper uses a cost-minimizing mathematical programming approach and models a number of different cost scenarios. Results indicate that inclusion of transactions costs substantially affects estimates of total costs of meeting nutrient reduction goals; on average total costs increased by 44 percent, but ranged between 19 and 81 percent depending on the scenario analyzed. Analysis of the modelled scenarios shows that those BMPs that account for the most implementation costs do not necessarily account for the most transactions costs (and vice versa). This suggests that transactions costs should be acknowledged to vary with the type of practices being implemented, rather than being approximated as either a fixed amount or a fixed proportion of implementation costs. In addition, the analysis highlights the disproportionate costs associated with achieving nutrient reductions via high-cost adopters, and suggests there may be a role for education or extension to assist landholders to lower opportunity costs of participating in conservation.
Master of Science

A research project was undertaken to study the hydrology and water quality of a 26 km$ sp2$ intensive agricultural watershed over an 18 month period. Flow and precipitation data were used to establish hydrologic parameters for the watershed and to empirically model hydrologic processes. Water samples taken from the outlet of the watershed were analyzed for nitrate, phosphate, suspended sediment and atrazine. Water quality data were analyzed to establish temporal trends in pollutant concentration and load in the watercourse.
The measured time of concentration was found to be consistent with a mean of 6.89 hours for the 25 storms profiled. The time to peak was found to vary linearly with storm duration. The event recession constant was measured to be 0.9715. Regression analysis was performed on measured hydrologic properties. The strongest relationship was found between the percentage of rainfall appearing as runoff versus the sum of the 72 hour antecedent rainfall plus the storm rainfall.
Spring snowmelt was identified as a significant period of pollutant material export. All pollutant materials displayed seasonal variability in the export process. Temporal variability accounted for poor correlations between observed hydrologic and water quality parameters in the two seasons for which data were available.
Peak pollutant concentrations were associated with high flow events. Maximum observed concentrations for nitrate, phosphate, suspended sediment and atrazine were 8.6 mg/l, 0.478 mg/l, 0.7 g/l, and 8.06 ug/l respectively.

Användandet av obehandlat avloppsvatten inom jordbruket är en växande företeelse i många delar av världen. Speciellt i vattenfattiga områden där avloppsvattnet ses som en värdefull och pålitlig resurs. Det höga näringsinnehållet minskar behovet av konstgödsel och detta ökar böndernas inkomster. Men med användandet av avloppsvattnet följer vissa hälsorisker. Bland annat har man sett en högre förekomst av inälvsmaskar hos bönder som använder orenat avloppsvatten jämfört med de som använder rent vatten. Den här vattenkvalitetstudien har utförts längs floden Musi i Andhra Pradesh, Indien. Musi rinner igenom staden Hyderabad och mycket av stadens avloppsvatten dumpas i floden. Nedströms Hyderabad används detta vatten för bevattning. Längs med floden är dammar byggda, för att avleda vattnet i bevattningskanaler. Reservoirer bildas då flödeshastigheten minskar. Studieområdet sträcker sig från Hyderabad och 28.7 km nedströms. Hypotesen var att reservoirerna fungerar som biodammar och syftet var att kvantifiera dammarnas inverkan på vattenkvaliteten och utvärdera dess lämplighet utifrån ett hälso- och jordbruksperspektiv. Inom studieområdet är reningen med avseende på BOD, Nematoder och E coli 86,9%, 99,9% respektive 99,9%. Trots att reningen är så hög överstiger Nematod- och E coli-koncentrationerna Världshälsoorganisationens riktlinjer och utgör en hälsorisk för bönder och konsumenter. Syre- och salthalt ökar nedströms och den höga salthalten kan ha negativ inverkan på jordbrukets avkastning. Genom att titta på reningsmönster och förändring av olika vattenkvalitetsparametrar är en av slutsatserna av detta arbete att reningen i dammarna motsvarar den rening som sker i de anaeroba bassängerna i ett biodammsystem.

The use of untreated domestic sewage in agriculture is a growing practice in many parts of the world. It is being looked upon as a valuable and reliable resource in water scarce communities. Wastewater is usually rich in nutrients and the use results in high yields without the need for artificial fertilisers. But with the use of untreated wastewater follows a number of associated health risks, e.g. a higher prevalence of helminth infections has been seen among wastewater users compared to non-users. This water quality study was performed along the River Musi in Andhra Pradesh, India. The Musi River flows through the city of Hyderabad carrying the most of the town’s wastewater. Downstream of Hyderabad the wastewater is used by farmers for irrigation. Along the river weirs are constructed which diverts the irrigation water into canals and reservoirs are formed where the flow velocity slows down. The study area stretches from Hyderabad and 28.7 km downstream. The hypothesis was that the existing irrigation infrastructure acts like Wastewater Stabilisation Ponds and the aim was to quantify the impact of the weirs on water quality and to evaluate the irrigation water quality in reference to associated health risks and agricultural suitability. Within the study area the BOD, E coli and Nematode removals were 86.9%, 99.9% and 99.9% respectively. Despite the high removal the E coli and Nematodes, the concentrations exceed WHO guidelines for unrestricted and restricted irrigation, and there exists an excess risk of intestinal nematode- and enteric infections for farmers. Dissolved oxygen and salinity increases downstream and due to the high salinity farmers could experience reduced crop yields. By looking at removal patterns, and the change in water quality parameters, the conclusion can be made that the reservoirs act like anaerobic ponds in a Wastewater Stabilisation Pond system.

There is growing concern that commonly used Pharmaceuticals and Personal Care Products (PPCPs) and pesticides are entering and contaminating drinking water supplies. The use of targeted quantitation of PPCP has been well established but there is an emerging trend to also screen for and identify unexpected environmental pollutants. Chemicals like pesticides hormones and antibiotics are especially of interest because of proven endocrine disrupting effects and a possible development of bacterial resistance. Powerful screening methods are required to detect and quantify the presence of these compounds in our environment. PPCP encompass a wide range of pollutants, including Endocrine Disrupting Compounds (EDC), pesticides, hormones, antibiotics, drugs of abuse, x-ray contrast agents and drinking water disinfection by-products to name a few. In order to properly assess the effects of these compounds on our environment, it is necessary to accurately monitor their presence. The diversity of chemical properties of these compounds makes method development challenging. LC/MS/MS is able to analyse polar, semi-volatile, and thermally labile compounds covering a wide molecular weight range. The new AB SCIEX TripleTOF™5600 LC/MS/MS was used to profile environmental samples for unexpected pollutants, to identify and characterise the chemical composition and structure of the pollutants, and to quantify (based on intensity) the concentration in collected water samples. Liquid Chromatography coupled to tandem Mass Spectrometry (LCMS/ MS) is able to analyse polar, semi-volatile, and thermally labile compounds covering a wide molecular weight range, such as pesticides, antibiotics, drugs of abuse, x-ray contrast agents, drinking water disinfection by-products etc. More recently there is a growing interest from environmental researchers to also screen for and identify non-targeted compounds in environmental samples, including metabolites and degradates, but also completely unexpected pollutants. The new AB SCIEX TripleTOF™5600 LC/MS/MS system is capable of performing highly sensitive and fast MS scanning experiments to search for unknown molecular ions while also performing selective and characteristic MS/MS scanning for further compound identification and, therefore, is the instrument of choice for this challenging task. General unknown screening workflows do not use a target analyte list and compound detection is not based on any prior knowledge, including retention times and information on possible molecular and fragment ions. Therefore, acquired chromatograms are very rich in information and can easily contain thousands of ions from both any compounds present in the sample as well as from the sample matrix itself. Thus, powerful software tools are needed to explore such data to identify the unexpected compound. Water samples were collected both upstream and downstream of two WWTPs (Seymour and Fort Beaufort) and were directly injected on the AB SCIEX TripleTOF™5600 LC/MS/MS after being filtered. 15 sample points along the Kat River, ranging from a point as close to the source as possible to a point just before it joins the Great Fish River were used. The samples collected from the source were used as the control in each of the experiments, the assumption being the closer you get to the source, the less contaminated the water would be for the analysis of pesticides. Points were selected where the Kat River crosses the R67 or on farms where the river was accessible using farm roads. Samples were collected from October 2013 to November 2014.The Peak view software and Analyst software were used in the analysis of PPCPs. The XIC Manager allows you to manage large lists of compounds and perform automatic extracted ion chromatogram (XIC) calculations and review results operations. The results were displayed in the chromatogram pane and the XIC table (see results). The results reported here in this thesis indicate that there is contamination in the Kat River water due to both pesticides and PPCPs. The results also indicate that the food products are also contaminated and hence both the Kat River agricultural produce and its water need to be closely monitored for both pesticide and PPCPs contaminants. Further studies to investigate the quantitative levels of pesticides and PPCPs in the Kat river water to determine if the concentration levels of the detected pesticides are below the reported Maximum Residues Limits will be explored in the future.

Thesis (MSc Food Sc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Food-borne disease outbreaks caused by Escherichia coli have been linked to the use of faecally-polluted irrigation waters. Thus the overall aim of this research was to evaluate irrigation water and agricultural effluents as sources of antibiotic resistant E. coli in the Western Cape. The aim of the first study was to enumerate and characterise E. coli present in irrigation water and in potential contamination sources. Maximum total coliform and E. coli counts for irrigation sites was log 7.862 and log 5.364 MPN.100 mL-1, respectively. Five out of seven irrigation sites had E. coli counts exceeding national and international guidelines for ‘safe’ irrigation water (<1 000 counts.100 mL-1), making it unsafe for the irrigation of fresh produce. In this study, 46.6% of the E. coli strains were characterised in phylogenetic group B1. It has been shown that E. coli in group B1 have the ability to survive and persist in the external environment. Group B1 was also the most common group among isolates from irrigation sites (79.4%), while isolates from environmental sites grouped mainly in group A0 (54.1%). It was concluded that the wide variation of E. coli types present in irrigation water is a concern that should be further investigated. This raises human health implications since the increased exposure to faecal organisms increases the risk of food-borne outbreaks. The E. coli isolates (n = 120) and the marker (n = 37) and reference strains (n = 6), were evaluated for antibiotic resistance to seven medically-important antibiotics from different classes using the Kirby-Bauer disc diffusion method. Thirty-five strains (35/163 = 21.5%) exhibited resistance to one or more antibiotics. Piggery effluent was found to harbour the most antibiotic resistant E. coli isolates (9/35 = 25.7%). Among the resistant E. coli strains, the highest occurrence of antibiotic resistance was to trimethoprim (2.5 μg) (68.6%), tetracycline (30 μg) (57.1%), ampicillin (10 μg) (45.7%) and chloramphenicol (30 μg) (34.3%). Seventy-four percent (26/35) exhibited multiple antibiotic resistances to two or more antibiotics. The antibiotic resistant E. coli strains were evaluated for the presence of pathotypes using Polymerase Chain Reaction analysis to detect Intestinal Pathogenic E. coli (InPEC) and Extra-intestinal Pathogenic E. coli (ExPEC). Five InPEC strains were characterised as four Entero-Pathogenic E. coli (EPEC) strains resistant to three or four antibiotics and one Entero-Aggregative E. coli (EAEC) strain resistant to trimethoprim. The antibiotic resistant EAEC strain also possessed the ExPEC-related gene iutA. Two E. coli isolated from the Mosselbank River were both resistant to chloramphenicol and trimethoprim and also possessed the ExPEC-related gene iutA. It was concluded that the diverse antibiotic resistances of E. coli pathotypes present in irrigation water is a concern that should be further investigated.
AFRIKAANSE OPSOMMING: Voedselverwante siekte uitbrake wat deur Escherichia coli veroorsaak word, is gekoppel aan die gebruik van fekale besoedelde besproeiingswater. Dus was die hoof doel van die navorsing om besproeiingswater en landbou-afvalwater te evalueer as bronne van antibiotika-weerstandbiedende E. coli in die Wes-kaap. Die doel van die eerste studie was om die getalle en eienskappe van E. coli te bepaal wat in besproeiingswater en in ander potensiële besmettingsbronne teenwoordig is. Maksimum totale koliforme en E. coli-tellings vir besproeiingspunte was onderskeidelik log 7.862 en log 5.364 MPN.100 mL-1. Vyf uit sewe besproeiingspunte het E. coli-tellings gehad wat hoër is as die nasionale en internasionale riglyne vir ‘veilige’ besproeiingswater (<1 000 tellings.100 mL-1). Dit maak dit onveilig vir die besproeiing van vars produkte. In hierdie studie was 46.6% van die E. coli-stamme in filogenetiese groep B1 gegroepeer. Dit is reeds bewys dat E. coli in groep B1 oor die vermoë beskik om in die eksterne omgewing te oorleef en voort te bestaan. Groep B1 was ook die mees algemene groep onder die isolate van besproeiingspunte (79.4%), terwyl isolate van omgewingspunte meestal in groep A0 (54.1%) gegroepeer is. Die breë variasie E. coli tipes in die besproeiingswater is bekommerniswaardig en sal gevolglik verder ondersoek moet word. Dit bring gesondsheidsimplikasies mee vir mense aangesien die verhoogde blootstelling aan fekale organismes die risiko van voedselverwante uitbrake verhoog. Die E. coli isolate (n = 120) en die merker (n = 37) en verwysingsstamme (n = 6), is teen sewe medies belangrike antibiotikas uit verskillende klasse getoets vir antibiotika-weerstandbiedendheid. Die Kirby-Bauer skyfie diffusie metode is gebruik. Vyf-en-dertig stamme (35/163 = 21.5%) het weerstand teen een of meer antibiotika getoon. Dit is gevind dat vark-afvalwater die meeste antibiotika-weerstandbiedende E. coli-isolate (9/35 = 25.7%) bevat. Die weerstandbiedende E. coli-stamme het die hoogste antibiotika-weerstandheid getoon teen "trimethoprim" (2.5 μg) (68.6%), tetrasiklien (30 μg) (57.1%), ampisillien (10 μg) (45.7%) en chloramfenikol (30 μg) (34.3%). Vier-en-sewentig persent (26/35) het meervoudige weerstandbiedheid teen twee of meer antibiotikas getoon. Die antibiotika-weerstandbiedende E. Coli stamme is getoets vir die teenwoordigheid van patogene deur van Polimerase Ketting Reaksie analise gebruik te maak om ‘Intestinal Pathogenic’ E. coli (InPEC) en ‘Extra-intestinal Pathogenic’ E. coli (ExPEC) op te spoor. Vyf InPEC-stamme is geklassifiseer as vier ‘Entero-Pathogenic’ E. coli (EPEC)-stamme wat weerstandbiedend teen drie of vier antibiotika getoon het en een ‘Entero-Aggregative’ E. coli (EAEC)-stam wat weerstandbiedendheid getoon het teen "trimethoprim". Die antibiotika-weerstandbiedende EAEC-stam het ook die ExPEC-verwante geen, iutA, besit. Twee E. coli isolate van die Mosselbankrivier het weerstand teen beide chloramfenikol en "trimethoprim" getoon en het ook die ExPEC-verwante geen, iutA, besit. Daar is tot die gevolgtrekking gekom dat die diverse antibiotika-weerstandbiedenheid van E. coli patogene teenwoordig in besproeiingswaters bekommerniswaardig is en verder ondersoek behoort te word.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Two tile-drained agricultural fields in the Pike River watershed of Southern Quebec were instrumented in October 2000 to monitor phosphorus and nitrate concentrations in surface runoff and tile drainage. Data collected from these sites were used as the primary input to test a GIS-based hydrological and water quality simulation model (ArcView SWAT2000) at the field scale. Surface runoff, subsurface flow, sediment yield, nitrate loads and phosphorus loads were the principal parameters evaluated by the model. The SWAT model was calibrated using data collected in the year 2002 while 2003 data was used for validating the model. Particulate phosphorus and total dissolved phosphorus loads in streamflow were also simulated using SWAT and compared with field measurements.
A sensitivity analysis showed that curve number, available soil water content and soil evaporation factors significantly influenced water yield simulations while model performance for water quality parameters was governed mainly by the accuracy of simulating field operations such as fertilization and tillage. The monthly coefficients of performance after calibration ranged from being very good for some parameters (0.27 to 0.66 for total water yield; 0.38 to 0.67 for total phosphorus; and 0.23 to 0.89 for sediments) to being inconsistent for others (0.44 to 2.28 for subsurface flow; 0.63 to 4.36 for surface runoff; and 0.66 to 1.35 for total nitrate loads). Overall, it was found that SWAT results on a seasonal scale were generally more reliable whereas daily or monthly simulations could be improved by using a longer calibration period or incorporating model changes. Short-term impacts of implementing different best management practices for tillage, crop rotation and fertilization were also evaluated using the validated SWAT model. It was found that conservation tillage of corn coupled with pasture or soybean rotations can reduce total phosphorus loads in the range of 25-50% over conventional tillage with corn.

The worldwide persistence of nitrate (NO -) in groundwater is worrying since this compound has been related to human illnesses and to eutrophication of aquatic ecosystems. The main sources of pollution are linked to intensive use of fertilizers and septic system leakage. Since 1991, European directives have been applied to mitigate NO - pollution by limiting N application in agricultural lands. However, due to the long residence time of N in the soil organic matter pool, the outcome of the implemented management practices can be delayed for decades. Consequently, remediation strategies must be developed and optimized. The NO3- reduction to innocuous dinitrogen gas (N2), can occur intrinsically in many environments due to the ubiquity of denitrifying microorganisms. However, the electron donor presence is usually a limiting factor in the contaminated aquifers. Hence, one feasible treatment involves inducing the denitrification by application of an external electron donor. During the implementation of bioremediation strategies, the contaminant removal can be estimated by monitoring its concentrations before and after the treatment. However, this method does not reveal the specific processes involved in the attenuation, making it challenging to focus on the improvement of the remediation approach. Isotopic analyses have proved to be a powerful tool in identifying the sources and transformation processes of groundwater contaminants. During the enzymatic NO3- reduction, the unreacted residual substrate becomes enriched in the heavy isotopes 15N and 18O, allowing to distinguish the biotic reduction from processes such as dilution with non-polluted water that could also lead to a concentration decrease without influencing the isotopic signature. The present thesis focusses on investigating the use of low-cost electron donors to promote the denitrification, and on using isotopic tools to evaluate the denitrification efficiency at field- scale. The tested materials in batch and flow-through experiments were: whey, corn stubble, wheat hay, animal compost, magnetite, siderite and olivine. Different parameters that could affect the biotic NO3- reduction efficiency were evaluated (e.g., temperature, ratio between electron donor and acceptor, harmful by-product accumulation, abiotic reactivity or coexistence of other contaminants) and the isotopic fractionation values (ε15N and ε18O) were determined for all tested conditions. At field-scale, three different polluted water bodies were studied, in which the determined ε15N and ε18O at the laboratory were applied to quantify the natural and/or induced denitrification. In a polluted aquifer in Spain, the NO3- attenuation was evaluated during a long-term induced denitrification strategy by acetic acid injections. In a polluted aquifer in Argentina, the natural NO3- attenuation was evaluated considering changes in the reactivity and isotopic fractionation due to the simultaneous presence of NO - and Cr6+. Finally, in a constructed wetland (CW) treating agricultural runoff water, the NO - attenuation was evaluated before and after application of an electron donor both in the autumn-winter and spring-summer seasons. The laboratory experiments demonstrated that magnetite nanoparticles, corn stubble, wheat hay, animal compost and whey could efficiently promote the denitrification in polluted water bodies. In these biotic experiments, the complete NO3- reduction to N2 was demonstrated by transient or negligible accumulation of other nitrogen compounds such as nitrite (NO2-), ammonium (NH +) or nitrous oxide (N O). However, the N O was found to be the end- product of the abiotic NO - reduction, which can be mediated by ferrous iron, if present. The ε15NNO3/N2 and ε18ONO3/N2 values were calculated for all the batch experiments and for the periods of the flow-through experiment that allowed complete denitrification. For the non- complete denitrification periods, the NO - isotopic characterization showed a mix of denitrified and non-denitrified water at the outflow. The isotopic characterization of NO - and N2O allowed to distinguish the biotic from the abiotic NO - reduction by ferrous iron at the laboratory-scale. A two-stage isotopic fractionation pattern was found for Cr6+, which can be reduced simultaneously to NO -. Also, the carbon compounds isotopic analysis allowed to assess the fate of the studied organic carbon materials to be used as electron donors. In the field-scale studies, the chemical and isotopic characterization allowed to trace the extent of the natural or induced denitrification and to evaluate the safety of the treatments. In a pilot plant to remediate groundwater NO3- pollution (Spain), acetic acid was injected by pulses to an alluvial aquifer for 22 months. According to the isotopic results, the induced denitrification achieved at least 50 % NO3- attenuation. The isotopic analyses also allowed to identify the reoxidation of NO2- to NO3- during the treatment and to recognize a mixture between the denitrified and partially or non-denitrified groundwater in one of the sampling points. In a polluted aquifer with both NO3- and Cr6+ (Argentina), the calculated natural attenuation was 20 % for NO3- and 60 % for Cr6+. For this calculation, the two stage trend observed for the ε53Cr was considered. The attenuation of Cr6+ in a few samples was found to be due by both reduction and dilution. In a CW treating agricultural runoff water, a slight natural NO3- attenuation was only observed when the flow was below 5.5 L/s. According to the isotopic results, after the biostimulation by stubble application, at least 60 % NO3- was removed at 16 L/s. The biostimulation treatment in autumn lasted in one month, while in spring the attenuation remained for three months.
La persistència del nitrat (NO -) en aigües subterrànies és preocupant ja que aquest, pot provocar malalties en humans i eutrofització d’ecosistemes aquàtics. Els principals orígens de contaminació són l’ús intensiu de fertilitzants i les pèrdues dels sistemes sèptics. Tot i que els darrers anys s’ha limitat la quantitat de N aplicat en zones agrícoles, degut al llarg temps de residència del N en la matèria orgànica del sòl, el resultat de les pràctiques implementades, es pot ajornar fins dècades. Per tant, és necessari desenvolupar i optimitzar estratègies de remediació. La reducció del NO - a dinitrogen gas (N ), que és un gas innocu, es dona intrínsecament en molts ambients degut a la ubiqüitat dels microorganismes amb capacitat de desnitrificar. Malauradament, la presència de donadors d’electrons sol ser un factor limitant en aqüífers contaminats per NO -. Per això, un possible tractament consisteix en induir la desnitrificació gràcies a l’aplicació d’un donador d’electrons extern.Durant la implementació d’estratègies de bioremediació, l’eliminació del contaminant es pot determinar mitjançant la monitorització de les seves concentracions abans i després del tractament. Però aquest mètode no mostra el procés específic involucrat en l’atenuació i això dificulta l’optimització de l’estratègia de remediació. Els anàlisis isotòpics resulten útils per identificar fonts i processos de transformació de diversos contaminants en aigües subterrànies. Durant la reducció enzimàtica del NO3-, el substrat residual es va enriquint en els isòtops pesats 15N i 18O. Això permet distingir la reducció biòtica d’altres processos com la dilució amb aigua no contaminada que també podria donar lloc a una disminució de la concentració del NO3- però sense influenciar la seva signatura isotòpica.Aquesta tesi es centra en investigar l’ús de donadors d’electrons de baix cost (sèrum làctic, restes vegetals (blat i panís), compost animal, magnetita, siderita i olivina) per induir la desnitrificació i l’ús d’eines isotòpiques per avaluar l’eficiència de desnitrificació a escala de camp. Durant els experiments al laboratori s’han avaluat diferents paràmetres que poden afectar l’eficiència de la reducció biòtica del NO3- (ex. temperatura, ràtio entre el donador i acceptor d’electrons, acumulació de productes intermedis tòxics, reactivitat abiòtica o coexistència d’altres contaminants) i s’han calculat els valors de fraccionament isotòpic (ε15N i ε18O) per totes les condicions investigades. A escala de camp, s’han estudiat tres masses d’aigua contaminades en les que s’han aplicat els valors de ε15N i ε18O determinats al laboratori per quantificar la desnitrificació natural o induïda. En un aqüífer contaminat a Espanya, l’atenuació del NO3- s’ha avaluat durant una estratègia de desnitrificació induïda mitjançant la injecció d’àcid acètic. En un aqüífer contaminat a Argentina, l’atenuació natural del NO3- s’ha avaluat considerant canvis en la reactivitat i el fraccionament isotòpic degut a la presencia simultània de NO - i Cr6+. En un aiguamoll construït en el qual es tracta aigua d’escorrentia agrícola, l’atenuació del NO - s’ha avaluat abans i després de l’aplicació d’un donador d’electrons tant a la tardor-hivern com a la primavera-estiu.Els experiments de laboratori han demostrat que les nanopartícules de magnetita, les restes vegetals (blat i panís), el compost animal i el sèrum làctic poden induir la desnitrificació en aigües contaminades. En aquests experiments biòtics, la reducció completa del NO - a N ha estat demostrada per una acumulació transient o negligible d’altres compostos nitrogenats com el nitrit (NO -), l’amoni (NH +) o l’òxid nitrós (N O). Tot i això, s’ha vist que el N2O és el producte final de la reducció abiòtica del NO - provocada per l’oxidació de Fe2+, si és present en l’aigua. Els valors de ε15NNO3/N2 i ε18ONO3/N2 s’han calculat pels experiments de tipus batch i pels períodes d’un experiment de tipus flux continu durant els que es va assolir una desnitrificació completa. La caracterització isotòpica del NO - i el N O ha permès distingir la reducció del NO2- biòtica de l’abiòtica per oxidació de Fe2+ al laboratori. Per al Cr6+, un contaminant que es pot reduir simultàniament al NO3-, s’ha observat un fraccionament isotòpic en dos estadis. A més, l’anàlisi isotòpic dels compostos de carboni ha permès avaluar el consum dels donadors d’electrons de carboni orgànic estudiats.En els estudis a escala de camp, la caracterització química i isotòpica ha permès traçar l’eficiència de la desnitrificació natural i/o induïda i avaluar la seguretat dels tractaments. En una planta pilot per remeiar la contaminació de NO3- d’aigües subterrànies (Espanya), s’ha injectat àcid acètic a l’aqüífer durant 22 mesos. D’acord amb els resultats isotòpics, la desnitrificació induïda ha assolit almenys un 50% d’atenuació del NO3-. La caracterització isotòpica també ha permès identificar la reoxidació de NO2- a NO3- durant el tractament i reconèixer una barreja entre aigua desnitrificada i aigua parcialment o no desnitrifricada en un dels punts de mostreig. En un altre aqüífer contaminat amb NO3- i Cr6+ (Argentina), l’atenuació natural calculada ha estat del 20% per al NO3- i del 60 % per al Cr6+. Per a aquest càlcul s’ha tingut en compte el fraccionament isotòpic en dos estadis observat pel Cr6+ en els experiments de laboratori. L’atenuació del Cr6+ en algunes mostres ha estat deguda en part a dilució i en part a reducció. En l’aiguamoll construït, l’atenuació natural del NO3- només es dona quan el flux és inferior a 5.5 L/s. D’acord amb els resultats isotòpics, després de la bioestimulació per aplicació de restes vegetals (panís), s’ha aconseguit una reducció del 60 % del NO3-, a un flux de 16 L/s. El tractament de bioestimulació a l’octubre-hivern ha durat un mes, mentre que a la primavera-estiu s’ha mantingut durant tres mesos.

Water is one of our most vital natural resources for life sustaining and human's economic development and social well-being. Agricultural diffuse water pollution (ADWP), the biggest remaining problem of water pollution in the world, has been realised as a major threat for water quality and the implementation of the EU Water Framework Directive (WFD). Indicative estimates of the costs of water pollution from ADWP are about £225 M per year in the UK, whilst failure to meet the requirements of the EU WFD by 2015 may incur heavy fines. From the technical and scientific points of view, there are three major gaps, namely, "method and tool", "research scale" and "fundamental knowledge" gaps between current ADWP research and the successful implementation of the EU WFD. It is timely to develop integrated catchment-scale numerical modelling tools or methods to handle the ADWP problem at the catchment scale. This thesis describes the development of an integrated catchment-scale modelling approach, ICEMAN, for supporting the effective decision-making of the ADWP sustainable management at the catchment scale, thus helping the implementation of the EU WFD in handling ADWP. In order to quantitatively describe the nutrient process in the complete hydrological cycle, it is necessary to integrate numerical water models into ICEMAN to calculate or simulate the groundwater pollution pathway vulnerability, groundwater pollution risk, water balance in soil, nutrients biochemical cycling in soil, and surface water quality and quantity processes. This study showed that GIS and the Arc Hydro model consisting of the modules of data mining, hydrological analysis, and visualisation can facilitate the developing and applying the ICEMAN by providing data support and powerful functions of spatial analysis. The DRASTIC model was applied in the case study area - Upper Bann Catchment, Northern Ireland for assessing the groundwater pollution pathway vulnerability of general pollutants and pesticide. The results showed that DRASTIC is suitable to be introduced into the ICEMAN for catchment-scale groundwater pollution vulnerability assessment. However, DRASTIC has drawbacks in the groundwater pollution risk assessment, namely, having no risk concept and considering no pollutant dynamic nature with runoff. A D-DRASTIC approach was developed in this study for reliable groundwater pollution risk assessment from diffuse agricultural sources based on DRASTIC within an ArcGIS environment. D-DRASTIC overcomes the pitfalls of applying DRASTIC in groundwater risk assessment. The results of applying D-DRASTIC in the case study showed that D-DRASTIC is helpful in guiding the activities of groundwater pollution prevention at the catchment scale and can be used in the development of ICEMAN. A numerical catchment-scale surface water model capable of the simulation of ADWP is necessary in developing the ICEMAN method. A HSPF model was selected based on the review of popular surface water models and tested in the study area. The calibrated and validated HSPF model can well represent the characteristics of surface water quantity and quality in the study area. Climate change scenario evaluation results in five years showed that when the annual mean temperature increase 3 Celsius the mean yearly total runoff volume will decrease by 11% and the mean daily river flow of five years will decrease by 11%. The results showed that HSPF is a suitable model in simulating the diffuse source surface water pollution and can be integrated into the ICEMAN. ICEMAN was developed by integrating the models of Arc Hydro, DRASTIC, D-DRASTIC, HSPF into an ArcGIS environment. ICEMAN can describe the nutrient biochemical cycles in soil, whole hydrological quantity and quality processes, and groundwater pollution vulnerability and risk, by considering factors in the catchment ADWP process, namely, meteorology, nutrient loading from different land uses, nutrient biochemical cycling in soil, nutrient dynamic nature with runoff and interflow, topography, depth to water, net recharge, aquifer media, soil media, impact of the vadose zone media, hydraulic conductivity of the aquifer, and the relationships between soil water and groundwater. The results of applying ICEMAN in the study area showed that ICEMAN can well support the decision-making of the catchment ADWP sustainable management. In the study area, ICEMAN provides satisfied simulation of river flow and quality, groundwater pollution vulnerability and risk zones, and quantitative descriptions of ADWP process including nutrient biochemical cycle in soil and can help better understand the ADWP characteristics in a specific catchment. In addition, ICEMAN can evaluate the impacts of water management plans on water processes under the climate change. For example, when changing 20% farming land into forest land in the Gamble's Bridge watershed of the study area, the mean concentrations of nitrate, nitrite, NH4, and P04 in river will decrease by 19%, 33%, 31%, and 31% respectively. ICEMAN, transferable to other areas, can bridge gaps of "method and tool" and "research scale" in the implementation the EU WFD in handling ADWP and can act as an important complement of the River Basin Management Plans. This multi-disciplinary study may provide a good starting point for tackling ADWP at the catchment scale in an integrated, quantitative, and sustainable manner. Therefore, the results in this multi-disciplinary study are not only useful for better implementation of the EU WFD, but also helpful for tackling the ADWP problem outside the EU.

In North America, the acceleration of the eutrophication of surface waters due to nutrient pollution is still present. Soil studies have not entirely succeeded in linking nutrient and sediment losses to field hydrology because relationships between discharge and dissolved ions/sediments are complicated by a hysteresis effect which has been only described qualitatively. The objective of this thesis was to better understand the effects of hydrology on N, P, and sediment transfer from agricultural and forest soils to surface waters. This was done by developing a technique, called the H index, to quantify the hysteretic behaviour of ion and sediment transport in stream/overland water. The chemical and sediment concentrations in a stream of a forested watershed in the Sierra Nevada during snowmelt and in overland runoff of two agricultural fields during rain events in the Montreal area were examined. In the stream of the forested watershed, H indices for suspended sediment increased (looser hysteresis loop) with the availability of sediments and the lag between peaks in suspended sediment concentrations and discharge. In agricultural fields, nutrient concentrations increased with time during each event with presence of counterclockwise and clockwise hysteresis. The hysteretic behaviour of suspended sediments was not significantly related with either prior soil moisture content or rainfall characteristics. In order to simultaneously monitor P and N in the stream and soils of the forested watershed, a laboratory study was conducted to investigate the efficacy of various mixedbed exchange resins in absorbing dissolved organic and inorganic N and P. Results showed that mixed-bed resin was adequate for characterizing P on a short-time scale but longer exposure periods were required for N. Results from the resin exchange reveal the possibility that the spring time pulse of NOs'-N in stream water was due to the melting of the snowpack.

A erosão hídrica é a principal causa de degradação do solo em ambientes tropicais e subtropicais úmidos e a perda da camada superficial do solo é o maior desafio para sustentabilidade da agricultura no mundo. Ela afeta a qualidade e o volume dos corpos d\'água e diminuí a qualidade dos solos. Apesar disso, o mercado não é capaz de corrigir estes problemas em razão da sua característica de bens públicos (não-exclusividade e não-rivalidade). Assim, o controle da erosão agrícola gera um serviço benéfico para toda a sociedade, mas os seus custos são exclusivamente dos agricultores. Pagamentos por Serviços Ambientais - PSA são mecanismos de compensações em que os beneficiados pelos serviços pagam os seus provedores. PSA são mecanismos promissores para o financiamento da proteção ambiental e podem complementar as atuais regulações. Entretanto, a literatura atual ainda é limitada em termos de quantificação dos serviços gerados, da sua demanda e sua viabilidade econômica. Este estudo analisa a viabilidade econômica de esquemas de PSA para o controle da poluição hídrica advinda da agricultura no Brasil. O objetivo específico do estudo é estimar ofertas de Serviços Ambientais - SA de conservação do solo. As ofertas de SA foram estimadas para áreas de cana-de-açúcar (na Bacia do Rio Corumbataí) e horticultura (na Sub-Bacia Cabeceiras do Tietê) utilizando uma metodologia de dados mínimos. As ofertas foram estimadas para diferentes práticas agrícolas, permitindo a comparação da eficiência das diferentes práticas na produção do SA. No caso da cana, a implantação e manutenção de florestas nas APPs mostrou-se a prática mais eficiente. Gastos de R$150,00/ha/ano com esta prática conservam cerca de 140.000 Mg de solo, enquanto o mesmo gasto aplicado na prática de não utilização das APPs conserva 70.000 Mg. Os resultados indicam que existe potencial para aplicação do modelo como forma de integrar as políticas públicas agrícolas com as ambientais. O estudo mostra que a adoção de práticas com maior produção de SA depende de incentivos. Nas condições atuais elas não são atrativas na medida em que geram menores retornos aos agricultores. Os incentivos podem ser através de subsídios das práticas adequadas, estímulo à demanda de produtos ambientalmente amigáveis ou pagamentos diretos pelos SA produzidos.
Water erosion is the main cause of soil degradation in tropical and sub-tropical environments and top soil loss is the biggest challenge for sustainable agriculture in the world. It affects water quality and quantity, and decreases soil quality. Despite this, the market is not able to solve these problems because of their public good characteristics (non-rivalness and non-excludability). Agricultural pollution control by farmers is a service society free rides because only farmers pay its costs. Payments for Environmental Services - PES schemes are flexible mechanisms in which providers of these services get paid by their users. PES schemes are considered to be promising mechanisms for financing environmental protection and restoration as well as for complementing and enforcing regulations. However, most of the on-going schemes don\'t use studies to quantify the services produced, to analyze the demand for them, or to check the schemes\' economic viability. This study analyses the economic viability of PES schemes in order to control the agricultural pollution of water resources in Brazil. The specific objective is to estimate the Environmental Services - ES of conservation soil supplies. These supplies were estimated for sugar cane (Corumbataí Watershed) and horticulture areas (Tietê Cabeceiras Subwatershed), using a minimum-data model. The supplies were calculated for different practices, so it is possible to compare the different practices\' efficiency to produce ES. For the sugar cane area it is more efficient to plant trees in the riparian buffer zones. Paying 150 reais per ha per year produces 140.000 Mg of conserved soil through tree planting, while with the same amount, the exclusion of the riparian zones from cultivation produces approximately 70.000 Mg. The results show this model can be applied as a way of integrating agricultural and environmental public policies. It was concluded that incentives are necessary to make the farmers adopt the practices that produce ES, because they are not economically feasible under current market conditions. The incentives could be either subsidies for these practices, fostering the demand for environmental friendly products, or direct payments for the ES produced.

Urban expansion of the City of Vancouver has resulted in increased land development of the municipality of Surrey, and more intensive agriculture on the remaining farmland. From 1980 to 1984 five different fish kills in the Serpentine River attributed to low dissolved oxygen were thought to be caused by a combination of agricultural discharges, high autumn water temperatures, as well as rainfall and river flow patterns. In 1985 an experimental instream aeration system was installed in a lower reach of the river in an attempt to provide additional oxygen during the critical autumn period. This study was undertaken to determine the extent of the agricultural drainage discharge problem. Weekly sampling from July to December, 1987, revealed that organic pollutional loading from dairy farms was high. Nutrients loadings in the river supported a heavy algal growth which resulted in an oxygen deficit during autumn algal die-off and decay. Although the flushing of farm ditches normally exerts an additional oxygen demand on the river, this was not observed in 1987 because the major autumn rains began on Oct 30, and lower water temperatures prevented a rapid exertion of the biodegradable oxygen demand. Implementation of source control of farm animal wastes is strongly recommended, along with a program of public education on conservation and management of natural habitat. Harvesting of filamentous algae in the river may eventually prove necessary for successful rehabilitation as diffused river aeration appears to be having a very small effect.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

Nutrient loadings to the Chesapeake Bay are a source of concern for water quality agencies. In particular, excess nitrogen loadings from agricultural production activities threaten water quality in the Bay. Questions have been raised about how effectively traditional BMPs can control nitrogen loss from crop production. This study examines agricultural nitrogen pollution control from an input management perspective. Using an economic and physical model, seven production systems and nitrogen management strategies are compared in terms of input use, profitability, and nitrogen loss potential. Results suggest that several of the production systems will reduce residual nitrogen without reducing profits. However, it is recognized that factors in addition to profitability will influence producers' nitrogen management decisions. Therefore, using the results of a farmer survey, adoption models are estimated to examine the impact of production system characteristics and producer characteristics on the decision to use an alternative production system and nitrogen management strategy. Finally, a sensitivity analysis is conducted to examine the impact of alternative policy tools on adoption incentives. Both financial incentives and education and information programs are found to be important tools for influencing producers' decisions. Producers' interest in the alternative systems and desire for information on the systems suggest that agricultural research will contribute by assuring that producers have access to adequate information on the alternative systems.
Ph. D.

Thesis (M. Tech. (Agriculture)) -- Central University of Technology, Free state, 2011
Quality assessment of agricultural water used for fertigation in the Boland district. The study was undertaken to determine the influence of seasonal changes on the water quality (chemical and microbial analyses) of five different rivers in the Boland. The data was collected in the five most important water sources that are used for irrigation purposes in the district, i.e. Berg river, Eerste river, Klapmuts River, Klippies river and Krom river. The samples were collected from all sites once every three weeks for a period of six months. The sampling was carried out during specific periods in summer (December, 2006 to February, 2007) and winter (June to August, 2007). The results of the study showed that Klapmuts river recorded the highest levels of chloride and iron, especially in summer. However, chloride levels were far below the levels set by the Department of Water Affairs and Forestry. Results obtained from this study show the presence of pathogens in some of the rivers assessed which may have resulted from the leaching of these pathogens from nearby agricultural land, livestock watering or informal settlements in the catchment areas. The bigger rivers recorded low levels of micro-elements and this might have been affected by winter rainfall. In the Berg River, many sources of nitrate pollution seem to be present in the catchment area. The levels of iron in all the rivers assessed were far more than the levels set by the Department of Water Affairs and Forestry in all rivers assessed and these might be due to the pH levels and interaction between the rivers and seasons. Iron and manganese levels should be kept low as this may cause production problems by blocking irrigation drippers. The water samples tested for bacterial and fungal density showed Klapmuts and Eerste rivers were positive for Phytophthora cinnamomi during winter. Phytophthora citricola and Phytophthora cactorum were detected in the Klapmuts and Klippies rivers in summer. The Berg-, Klapmuts-, Krom- and Eerste rivers tested positive for species of the genera Pythium and Fusarium. Similar organisms were detected in the Eerste river mainly during summer on the fourth sampling date, while Krom river only tested positive for Pythium during summer. The total bacterial and algal density differed significantly between the seasons and was highest in winter. This might be due to high rain water influx and efflux and/or moist and aerobic conditions and air temperature. There is an increased need for farmers to sterilize feeding water (chlorination) due to high microbial count.

Field scale research shows concentrated flow paths (CFPs) are prevalent in agricultural watersheds. They are an important source of soil erosion in cropland and significantly contribute to the transport and delivery of agricultural pollutants such as sediment and nutrients to nearby water resources. High resolution LiDAR data have enabled the investigation of the prevalence of concentrated flow at a large geographic extent. This study focused on identifying CFPs in 389 agricultural fields in Jackson County in southern Illinois and estimating the contribution of the CFPs to drainage of the fields. Addressing the lack of literature on factors influencing CFP characteristics, this study also investigates various topographical and soil factors that influence CFP development. LiDAR derived DEMs with a cell resolution of 3 meters were used to identify areas of flow concentration and delineate a drainage basin of each CFP using the Hydrology tools in the Spatial Analyst toolbox in ArcMap 10.3.1. Information on the topographical and soil characteristics were obtained from the DEMs and SSURGO database using the Soil Data Viewer 6.2 extension for ArcMap. Multiple regression analysis in SAS v. 9.4 was used to identify factors influencing CFP characteristics, while CART analysis in R v. 3.3.1 was conducted to detect linear dependencies among predictor variables. An average of 5 CFPs per agricultural field were observed in the study area with a minimum of 0 and maximum of 17 CFPs, but only two fields had no CFPs indicating a high prevalence of CFPs throughout the study area. The mean percent of field area drained by CFPs was estimated to be 81 percent with minimum of 36 percent and ii maximum of 100 percent. The majority of the fields, 85 percent, had more than 70 percent of their area drained by CFPs. Statistically significant regression equations were found for all CFP characteristics with slope, LS factor, K factor and organic matter as the factors influencing CFP characteristics. However, the factors only explained 2 to 22 percent of variation observed. Both multiple regression and CART analysis indicated slope as the most important influencing factor. Variation in CFP characteristics followed regional trends with higher values in the floodplain region and lower values in the rough hills region suggesting residual variation could be explained by other environmental factors along with topographical and climatological factors which were not included in the study. Results from this study highlight the prevalence of CFPs at a regional scale and their substantial contribution to field drainage identifying a need for research in quantifying the impacts of CFP on soil loss and water quality. This study also reports a need of future research to identify important factors controlling CFP formation and development that could help build empirical and physical models to accurately predict CFP locations and morphology. Such information could be useful in designing and targeting conservation practices that protect both soil health and water quality.

The objectives of the study were to investigate the sorption and degradation of a glucuronide conjugated natural hormone, 17?-estradio1-3-glucuronide (E2-3G), and its estrogenic metabolites in soil-water systems. Radiolabeled E2-3G was first synthesized in the laboratory. Soil-water batch experiments were then conducted using natural and sterilized topsoil (0-6 cm) and subsoil (18-24 cm) with the radiolabeled E2-3G to investigate the effects of soil organic matter content and microbial activity. The aqueous dissipation of 14C in the batch experiments followed a biphasic pattern with an initial rapid dissipation phase followed by a second slower phase. Significant differences in total aqueous 14C dissipation were observed for the different initial concentrations for both soils, with greater persistence of intact E2-3G at higher initial concentrations.
National Science Foundation [Grant No. 0730492]

The objectives of the study were to investigate the sorption and degradation of a glucuronide conjugated natural hormone, 17β-estradio1-3-glucuronide (E2-3G), and its estrogenic metabolites in soil-water systems. Radiolabeled E2-3G was first synthesized in the laboratory. Soil-water batch experiments were then conducted using natural and sterilized topsoil (0-6 cm) and subsoil (18-24 cm) with the radiolabeled E2-3G to investigate the effects of soil organic matter content and microbial activity. The aqueous dissipation of 14C in the batch experiments followed a biphasic pattern with an initial rapid dissipation phase followed by a second slower phase. Significant differences in total aqueous 14C dissipation were observed for the different initial concentrations for both soils, with greater persistence of intact E2-3G at higher initial concentrations.
National Science Foundation [Grant No. 0730492]

The purpose of this study is to review existing literature of factors that influence farmers’ decision to participate in conservation programs. This study is also intended to collect county data and information on conservation programs and participation in the Kentucky River watershed region, which can be analyzed and used to draw differences in characteristics of the region that would suggest willingness to participate in a trading scheme for improvements in water quality. The results suggest that more participation in a trading scheme from some counties than others should be expected. Counties with more farms and larger farms will probably have higher rates of participation in conservation programs. The cost-share amounts being paid by current government programs must be considered as the minimum staring point to negotiate in a trading scheme. To target the impact of watersheds, such as the Kentucky River in the Mississippi system, that discharges significant amounts of pollutants into the Gulf of Mexico, policy makers and program administrators should be advising and stimulating the adoption of practices with the best abatement performance for such pollutants considering technical complementarity between practices.

Chemical pollution of freshwater is a worldwide environmental problem
eutrophication, heavy metals and salinity are amongst the most widely used indicators of pollution. The aim of this study was to assess the status of nutrients, heavy metals and salinity, and the seasonal variation int he Bottelary River.

The aquatic environment and zoobenthos are closely related in a water body. In recent years, the use of zoobenthos to evaluate water quality is getting more attention as this approach is less polluting and less costly. This study was conducted to assess the diversity of zoobenthos in the canals affected by leachate and agricultural activities. Five sediment samples were collected in two campaigns, one in April and one in October 2018. Water samples were also collected at the same time for zoobenthos to assess the water quality and serve as a reference for assessing the effectiveness of using zoobenthos as water quality indication. In total, 17 species of zoobenthos belonging to six families and four classes were identified, of which Limnodrilus hoffmeisteri and Tendipes species being present regularly at sampling sites through the surveys. The calculations of the Shannon-Wiener diversity index (H'), rapid bioassessment protocol (RBP III), and associated average score per taxon (ASPT) indices based on species composition indicated that the water environment surrounding the landfill was moderately to severely polluted. However, the water quality index (WQI) calculated based on the physical and chemical properties shows that the level of water pollution in canals was less than that evaluated using zoobenthos. This can be explained by the fact that zoobenthos also affected the properties of sediments which depend on the water column. The findings in this study showed that the aquatic environment around the landfill is heavily contaminated as result of waste disposal and agricultural activities. The use of both zoobenthos combined with physical and chemical indicators could be useful in assessing the canals’ water status.
Môi trường nước và động vật đáy có liên quan mật thiết với nhau trong một thủy vực. Trong những năm gần đây, việc sử dụng động vật đáy để đánh giá chất lượng môi trường nước mặt được quan tâm vì phương pháp này ít gây ô nhiễm môi trường và ít tốn kém chi phí. Nghiên cứu được tiến hành để đánh giá sự phân bố của động vật đáy trong hệ thống kênh rạch chịu tác động từ nước rỉ rác và các hoạt động sản xuất nông nghiệp. Năm mẫu động vật đáy được thu hai đợt, đợt 1 vào tháng 4 và đợt 2 vào tháng 10 năm 2018. Mẫu nước cũng được thu để đánh giá chất lượng nước và làm cơ sở đánh giá hiệu quả của việc sử dụng động vật đáy làm chỉ thị chất lượng môi trường nước. Kết quả nghiên cứu cho thấy thành phần động vật đáy phát hiện 17 loài thuộc 6 họ và 4 lớp, trong đó các loài Limnodrilus hoffmeisteri và loài Tendipes hiện diện thường xuyên ở tất cả các điểm thu mẫu qua hai đợt khảo sát. Dựa vào thành phần loài tính toán các chỉ số Shannon-Wiener (H’), chỉ số đánh giá nhanh sinh học (RBP III), và chỉ số tính điểm trung bình bình theo họ (ASPT) cho thấy môi trường ô nhiễm rất nặng trong khi đó chỉ số WQI được tính toán dựa vào các chỉ tiêu lý hóa cho thấy mức độ ô nhiễm nước ở kênh xung quanh bãi rác chỉ ở mức nhẹ hơn. Như vậy, việc sử dụng động vật đáy cho kết quả đánh giá chất lượng nước với mức độ ô nhiễm cao hơn. Điều này có thể giải thích là do động vật đáy chịu ảnh hưởng bởi đặc tính nền đáy và cột nước bên trên nền đáy. Kết quả nghiên cứu cho thấy môi trường nước xung quanh bãi rác bị ô nhiễm nặng do xả thải và hoạt động sản xuất nông nghiệp. Việc sử dụng động vật đáy kết hợp với các chỉ tiêu lý, hóa có thể hữu ích hơn trong việc đánh giá hiện trạng nước kênh.

Thesis (MSc)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: Runoff is generally regarded as one of the most important routes of nonpoint source pesticide pollution in agricultural surface waters. Of major concern is the fact that low, sub-lethal levels of pesticide exposure are responsible for negative ecotoxicological effects, stressing the need for methods capable of identifying problem areas where populations could be at risk. Predicted average losses of three pesticides in tributaries of nine sub-catchments of the Lourens River were calculated through use of a GIS-based runoff model. There was a significant (p < 0.005) positive correlation between the predicted average loss and mean measured concentrations of the insecticides both in water and suspended sediments (R2 between 0.75 and 0.9), indicating that the model could serve as a powerful tool for the risk assessment and management of surface waters in South African orchard areas. Based on field relevant exposure scenanos, the potential effects of azinphos-methyl on macroinvertebrate communities were evaluated in a combined microcosm and field approach. Microcosms were contaminated for 1 h with AZP (control, 0.2; 1,5and 20 ug/L; three replicates each) and acute effects on survival were evaluated 6 days after exposure. The sensitivity or tolerance of 12 core taxa was determined based on their response to the exposure scenarios and compared to field tolerance/sensitivity as was established by a field investigation at a control and contaminated site of the Lourens River. The sensitivity/tolerance of ten of the 12 taxa corresponded to that which was found in the field. Thus microcosm studies employing a field relevant design can be successfully linked to field studies and indicate that transient pesticide contamination affects the aquatic communities of the Lourens River.
AFRIKAANSE OPSOMMING Afloop word oor die algemeen beskou as een van die belangrikste roetes van niepuntbron pestisiedbesoedeling in landbou oppervlakwaters. Die feit dat lae, sub-letale vlakke van pestisiedblootstelling negatiewe ektoksikologiese gevolge kan hê, is van groot belang. Dit beklemtoon die behoefte aan metodes om probleemgebiede te kan identifiseer waar bevolkings aan risiko onderhewig is. 'n GIS-gebaseerde afloopmodel is gebruik om die gemidddelde verlies van drie pestisiede in die sytakke van nege sub-opvangsgebiede van die Lourensrivier te voorspel. Daar was 'n beduidende (p < 0.005) positiewe korrelasie tussen die voorspelde gemiddelde verlies en gemete konsentrasies van insektisiede in beide die water en sediment (R2 between 0.75 and 0.9) fases, wat aandui dat die model as 'n kragtige hulpmiddel vir risikobestuur van oppervlakwaters in Suid Afrikaanse boord-gebiede kan dien. Die potensiële gevolge van azinfos-rnetiel (AZP) op makroinvertebraat gemeenskappe is deur middel van 'n gekombineerde mikrokosmos (wat op veldrelevante blootstellings gebaseer is) en veldbenadering bepaal. Mikrokosmosse is vir 1 h met AZP gekontamineer (kontrole; 1; 0.2; 1; 5 en 20 ~g1L; drie replikate elk), en die akute gevolge op oorlewing is ge-evalueer na ses dae van blootstelling. Die sensitiwiteit of toleransie van 12 sleutel taksa is deur middel van hulle respons op die blootstellingsreeks bepaal, en met hulle veldtoleransie/sensitiwiteit vergelyk wat in 'n veldstudie by 'n kontrole- en gekontamineerde gebied in die Lourensrivier bepaal is. Die sensitiwiteit/toleransie van 10 van die 12 taksa in die mikrokosmos eksperimente het ooreengestem met die wat in die veld gevind is. Mikrokosmosstudies wat op 'n veldrelevante ontwerp gebaseer is, kan dus suksesvol aan veldstudies gekoppel word, en dui aan dat oorgedraagde pestisiedkontaminasie die akwatiese gemeenskap van die Lourensrivier beinvloed.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第20005号
農博第2189号
新制||農||1045(附属図書館)
学位論文||H28||N5014(農学部図書室)
33101
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 藤原 正幸, 教授 村上 章, 准教授 宇波 耕一
学位規則第4条第1項該当

Endocrine disrupting compounds and pesticides have been detected in rivers and irrigation canals of Southern Alberta, a semiarid region with irrigation-dependent crop production, intensive livestock operations, and a growing human population. However, little is known about the effects of agricultural runoff or wastewater treatment plant (WWTP) effluent in Southern Alberta on fish. Reproductive effects of WWTP effluents from the cities of Lethbridge and Medicine Hat, as well as agricultural runoff in the Lethbridge Northern Irrigation District canals, were investigated in a field study with wild fathead minnows (FHMN) in the Oldman and the South Saskatchewan rivers, in Alberta, Canada, and in a laboratory study with laboratory reared FHMN exposed in vivo to the city of Lethbridge WWTP effluent for 21 days. Biochemical and morphological endpoints were measured to characterize reproductive status. Liver vitellogenin, a biomarker of exposure to estrogen mimics, was analyzed using quantitative RT-PCR, and gonadal histology was used to determine sex, gonadal maturity, and intersex. Adverse reproductive effects were detected in FHMN exposed for 21 days to 10 and 25% of Lethbridge WWTP effluent. In the field, effluents from both Lethbridge and Medicine Hat had an effect on the reproductive systems of FHMN. In canals, reproductive effects were detected in wild fathead minnows in years when water quality in irrigation drain canals decreased. Exposure to pesticides was estimated using acetylcholinesterase (AChE) inhibition. Exposure to Lethbridge WWTP effluent did not inhibit AChE, whereas results from the field study were inconclusive. In conclusion, reproductive systems of fathead minnows in Southern Alberta were impacted by anthropogenic chemicals.
xi, 104 leaves : ill. (some col.), maps ; 29 cm

Phosphorous concentrations exceed water quality guidelines in most of the major rivers in southern Quebec. The problem is particularly acute in the Pike River, which drains into the Missisquoi Bay of Lake Champlain, in southeastern Quebec. Elevated phosphorus concentrations can lead to a reduction in the palatability of drinking water, a decrease in diversity of aquatic life and loss of recreational opportunities. All of these problems have been observed in the Bay.
Two agricultural fields (the Marchand and Gagnon sites) located on the Pike River watershed, in southeastern Quebec were selected and equipped with instrumentation to measure and evaluate the partitioning of phosphorus between surface runoff and subsurface drainage, on a year round basis. The snowmelt event was the dominant surface and subsurface event for the 2000/2001 hydrological year. On the Marchand site surface flow data was incomplete as a result of a failure of the surface runoff flume. On both sites the IF 200 subsurface flow meters failed, which resulted in missing subsurface flow data during certain runoff events. Therefore, the majority of the comparisons made relate to the Gagnon site.
The 2000/2001 hydrological year was unusually dry, which resulted in a limited number of surface and subsurface runoff events. The annual depth of surface runoff for the Gagnon site was 87.5 mm/ha, of which only 0.2mm occurred outside the snowmelt event. The estimated depth of subsurface runoff of the snowmelt event at the Gagnon site based upon a water balance equation was 93.7 mm/ha, or 51.7% of the total volume that occurred on the Gagnon field during the snowmelt event.
The total phosphorus load in surface runoff for the spring snowmelt at the Gagnon site was 166.4 g/ha, whereas the estimated total phosphorus load in subsurface drainage was 98.2 g/ha, or 37.1% of the total load. Subsurface drains can therefore be a significant pathway for phosphorus losses.