Dissertations / Theses on the topic 'Environmental aspects of Trace elements in water'

Thesis (MTech (Physical Sciences))--Peninsula Technikon, Cape Town, 1999.
Wet deposition of toxic trace metals is the dominant mode of deposition in terrestrial ecosystems and contributes very significantly to their pollution burden. Wet deposited metals are dissolved in rainwater. They reach the vegatation in a form most favourable for uptake. Reliable analysis of toxic trace metals in rainwater is important in order to determine the impact they make on the environment. In this study, trace metals in rainwater and in dry deposition (as a control measure), have been analysed over a period of a year. These metals include cadmium, copper, cobalt, lead, nickel and zinc. The rainwater was filtered, acidified to pH2 and irradiated with UV-light. Dry deposition samples, were digested by heating in nitric acid before analysis. Differential-pulse anodic stripping voltammetry was used to determine cadmium, lead and zinc. Copper was determined by adsorptive cathodic stripping at pH7 after complexation with catechol. Cobalt and nickel were measured at pH9 by adsorptive cathodic stripping after formation of their dimethylglyoximes. Sampling was done on a daily basis from April 1996 to March 1997, on the campus of the Peninsula Technikon. The samples were collected over a 24-hour period. The total average concentration for the metals was 16.11 flg/dm3 for rainwater and 427flg/dm3 for dry deposition. Meteorological factors such as wind speed, humidity and temperature affect the distribution of pollutants and thus the trace metal levels. The levels of the metallic pollutants were thus evaluated against meteorological data. Differential-pulse stripping voltammetry is shown to be applicable for heavy metal analysis of rainwater.

Concentrations of Fe, Al, Mn and Zn were measured monthly from April to October at 24 rural riverine sites in Ontario and Quebec. Empirical models were developed predicting riverine metal concentrations from a small set of within-stream and catchment variables. Models explained a significant proportion of the variation in Fe (85%), Al (90%), Mn (57%) and Zn (37%). Simple models predicting annual catchment exports of metals from average riverine suspended particulate concentrations and runoff were also developed. These models explained most of the variation in annual exports of Fe (94%), Al (92%), Mn (62%) and Zn (75%) from the 24 catchments.
Models such as these can be used both to estimate catchment exports of metals to lakes, and to estimate riverine metal concentrations without requiring chemical analyses. The models also serve to distinguish background levels from those indicating metal contamination, and will, therefore, be useful in design of water quality guidelines.

Trace elements added to the soil by human activities could contaminate it and occasionally cause a threat to environmental and human health. The toxicity and mobility of a trace element are affected by the element's solubility, which in turn is influenced by the soil properties. When mobile, trace elements can be leached out of the soil. If leaching occurs at a faster rate than atmospheric deposition, element concentrations in the soil will decrease by natural attenuation.
We analyzed soil properties in 40 soils and their soil solutions to obtain a set of equations with the most significant predictors of As, Cd, Co, Cu, Mo, Ni, Pb and Zn in solution. The total element concentration and the pH were the best predicting variables of the amount of element in solution for all trace elements analyzed, while organic carbon and Al or Mn oxides also influenced the solubility of some trace elements. Using the equations predicting elemental solubility, we wrote a model for natural attenuation in the computer program Stella that considers atmospheric deposition as the input for trace elements and leaching as the output. Simulations were carried out for the 40 soils during 1,000 years with steady deposition inputs.
At current atmospheric deposition rates and the neutral to alkaline pH of these soils, attenuation occurred in most soils for Mo. For As, Cd, Co, Cu and Ni it occurred only in soils with abundant total element concentrations or an acidic pH. Minor retention occurred with Pb and Zn. Only Cd and Cu were of concern in leaching waters. The developed model can serve as a decision making tool in the selection of natural attenuation as a remediation strategy.

There are two main components to the research: the theoretical and the experimental. Chapter 2 contains an analysis of the state of soil quality guidelines and the scientific methods used to determine them. A number of recommendations to improve soil quality criteria for trace metals are offered including the importance of considering bioavailability and the need to use realistic conditions, trace metal sources and organisms.
A critical review of the literature dealing with predicting the availability of trace metals to plants is presented in Chapter 3. We found little agreement among hundreds of similar studies which relate plant metal uptake to the amount of metal extracted by selective chemical dissolution procedures. An extensive summary of the data shows clearly that the extraction methods are not widely applicable. Differences between individual soils, their metal retention capacities, as well as plant factors and environmental conditions contribute to the variability of the results. Alternative ways of assessing bioavailability are suggested.
The experimental component of the thesis focuses on the availability of trace metals to plants. In Chapter 4 the uptake of Cu from different soil pools was examined and the free metal ion (Cu2+) was found to be the best predictor of uptake by lettuce (Latuca sativa cv. Buttercrunch), ryegrass (Lolium perenne cv. Barmultra) and radish (Raphanus sativus cv. Cherry Belle).
In Chapters 5 and 6 we examined the effect of low-cost in-situ treatments on the availability of metals to plants in greenhouse and field experiments. Synthetic zeolites, P amendments, organic matter and clean soil were used and their effect on the bioavailability of Cd, Cu, Pb, Ni and Zn evaluated. The plants for the experimental work were lettuce and perennial ryegrass. Only the clean soil treatment was consistently effective in reducing the concentration of metals in the plant. We also wanted to determine whether the trace metals in the plant tissue came from the soil or from direct deposition of pollutants on the leaf surfaces. We found little evidence that metals in plants were a result of atmospheric fallout.
A method for the accurate analysis of total metal concentrations in a range of contaminated soils including those containing oil and grease was developed (Chapter 7). For this research the trace metals of concern are Cd, Cu, Ni, Pb and Zn---all commonly found in urban/industrial soils. The proposed method using HNO3/HClO4 has several advantages over the common HNO3/H2O2 procedure. We were able to digest larger soil samples and hence the final concentration of trace metals was usually in the range for analysis by inductively coupled plasma atomic absorption spectrometry or flame atomic absorption spectrometry.

Urban soils are often contaminated with trace metals and the toxicity of the metals depends, in part, on their speciation in soil solutions. The objectives of this project were to estimate the metal speciation in urban soils and to evaluate the predictability of soil metal pools on plant uptake. The chemical speciation of Cd, Cu, Ni, Pb and Zn was estimated by using the Windermere Humic Aqueous Model (WHAM). In soil solutions, Cd, Ni and Zn were present mainly as free ions when the solutions were acidic and their organic complexes were dominant as the pH was over 7.5. The other two metals mostly formed complexes with organic ligands. The activities of Cd2+, Cu2+, Ni2+, Pb2+ and Zn 2+ were affected by soil pH and total soil metal burdens. All five metals were under-saturated with respect to the minerals which could potentially control the metal solubility.
Metal uptake by plants in the contaminated railway yards was generally not correlated with free, dissolved and total soil metal pools. A pot experiment demonstrated better correlations between the metal pools and the metal content in wild chicory. Multiple regression analysis showed that the metals in the leaves and roots of wild chicory could be adequately predicted by the soil total metals and soil properties such as pH and exchangeable Ca.

This thesis examined a range of methods for sampling soil pore water to investigate the chemistry of trace elements. In particular, the study assessed whether Rhizon samplers, centrifugation, high pressure squeezing and soil suspensions in simulated pore water can be viable approaches for obtaining representative samples of equilibrated soil pore water. Results for metal solubility and speciation were interpreted in terms of both soil morphological effects on trace metal dynamics and artefacts introduced at various stages during sample preparation and handling. The main soil used in the study was an organic-rich sandy silt from a site which has served as a sewage re-processing facility for almost a century. This soil was chosen because of its importance as a long-term repository for metal-enriched sludge applied to arable land, providing a suitable medium on which to study trace metal behaviour. Pore waters were extracted and analysed for major and trace cations and anions, pH, Dissolved Inorganic Carbon (DIC) and Dissolved Organic Carbon (DOC) at two different temperatures (5 degrees Celsius and 15 degrees Celsius), in order to evaluate the extent of bacterial activity, organic decomposition and their consequences on solute composition, during pore water extractions. Speciation was estimated from analysis of pore water chemistry using two software packages (PHREEQCi and WHAM-VI). Pore waters showed different ranges of concentration between the various methods. Different mechanisms and/or chemical reactions were involved during the different extractions; a range of processes was identified, mainly dominated by metal complexation by humus acids and redox reactions. Results revealed that the soil studied was able to partially buffer the free ion activities of the metal ions in pore water with increasing dilutions, but demonstrated virtually no ability to buffer DOC. Identification of the source (i.e. location of pore space) of water extracted was also investigated using water with different isotopic composition (18O/16O). Evidence showed that centrifugation was not able to differentiate between more and less mobile water at FC conditions, rather enhancing the mixing between the two pools of water (native and labelled) by and apparent process of 'infusion'. By contrast, Rhizon samplers appeared to sample water preferentially from the more accessible pool (extra-aggregate), which proved to have a composition showing incomplete mixing with the native water. The results also suggested that mixing of the two pools was rather fast and that was almost completely attained prior to pore water extraction. The study established that the most important factors affecting pore water chemistry during extraction are the conditions to which the samples are exposed during the extraction process. For these reasons Rhizon samplers should be used as a disposable device, and are only applicable for use in high soil moisture soil contents. In contrast, they present no 'side-effects' (providing enough equilibration time) if M2+ (free ion activity) were needed as opposed to Msol (total metal concentration in pore water), as often required in environmental studies. Centrifugation is optimal for bulk solution studies, or when homogenisation represents a key experimental point; targeted studies are also possible. Soil squeezing is subject to severe limitations in the case of prolonged extractions of biologically active soils, due to the effects of anaerobism. Squeezing should only be used for 'fast' extractions of soils. Finally, batch extractions are well suited to studies on M2+ equilibria, but more studies are needed to clarify the effect of soil: solution ratio on metal and DOC solubility.

The Pieman River catchment has seen continuous mining of economic deposits of gold, silver, lead, copper, zinc and tin since the 1870’s. Tributaries of this river which receive mining effluent, either directly or from acid mine drainage (AMID), have total metal concentrations considerably above background levels and are of regulatory concern. The lower Pieman River is however classified as a State Reserve in which recreational fishing and tourism are the major activities. It is therefore important that water entering the lower Pieman River from upstream hydroelectric impoundments is of high quality. Metals in natural waters exist in a variety of dissolved, colloidal and particulate forms. The bioavailability and hence toxicity of heavy metal pollutants is very dependant on their physico form. Knowledge of the speciation of a metal in natural aquatic environments is therefore necessary for understanding its geochemical behaviour and biological availability. Complexation of metal ions by natural ligands in aquatic systems is believed to play a significant role in controlling their chemical speciation. This study has investigated temporal and spatial variation in complexation of metal ions in the Pieman River. The influence of pH, temperature, organic matter, salinity, ionic strength and time has been investigated in a series of field studies and in laboratory-based experiments which simulated natural and anthropogenic disturbances. Labile metals were measured using two techniques in various freshwater and estuarine environments. Diffusive gradients in thin-films (DGT) allowed in situ measurement of solution speciation whilst differential pulse anodic stripping voltammetry (DPASV) was used to measure labile metal species in water samples collected from the catchment. Organic complexation was found to be a significant regulating mechanism for copper speciation and the copper-binding ligand concentration usually exceeded the total copper concentration in the river water. Complexation was highly dependent on pH and at the river-seawater interface was also regulated by salinity, probably as a result of competitive complexation by major ions in seawater (eg. Ca 2+ ions). Zinc complexation was also evident, however total zinc concentrations in the water column often far exceeded the potential binding capacity of available ligands. In addition to organic complexation, Zn speciation may also be associated with adsorption by flocculated or resuspended colloidal Mn and/or Fe oxyhydroxides. Metal ion complexation and hence speciation was found to be highly variable within the Pieman River catchment. This presents major difficulties for environmental managers, as it is therefore not possible to make catchment-wide assumptions about the bioavailability of these metals. These results emphasise the importance of site-specific sampling protocols and speciation testing, ideally incorporating continuous, in situ monitoring.

The U.S. Army Corps of Engineers, Nashville District, maintains ten reservoirs in the Cumberland River Basin in Kentucky and Tennessee, and has been monitoring sediment chemistry in the reservoirs since 1994. The purpose of this study is to evaluate the sediment data collected from the reservoirs from 1994 to 2010 to determine if there are any spatial patterns of the trace elements: arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, and zinc. The results indicated that trace element levels were consistent with national baseline concentrations measured by the U.S. Geological Survey. Center Hill reservoir had the greatest number of trace element concentrations (all except cadmium) that were significantly higher when compared to all other reservoirs. The degree of urbanization in the reservoir basins was based on population density from the 2000 Census and the percentage of developed land using the 2006 national land cover dataset. Aquatic toxicity values were used as a measure of sediment quality. The reservoirs with the worst aquatic toxicity rankings were not the most urban, instead they were the reservoirs with the longest retention times. Therefore, it may be concluded that retention time has a larger effect on Cumberland River Basin sediment concentrations than the type of land use or the degree of urbanization. The results also indicate that it may be prudent to include an evaluation of quality based on aquatic toxicity when monitoring sediment quality, and that when reservoirs are the subject of sediment quality assessments, the consideration of the physical properties of the reservoir, especially the retention time, is essential for a comprehensive evaluation. This may also imply that sediment quality in reservoirs may effectively be regulated by water resource management techniques at the reservoirs that affect retention time.

This thesis is part of a broader project that examines three different approaches to evaluating trace metal contamination in urban brownfields: the measure of total soil metals; calculating bioavailable metals; and the use of species as bioindicators of trace metals in soils. Chapter 1 discusses the problems inherent in each approach such as; inconsistent results due to differences in techniques, extrapolation from laboratory to field, and the influence of species differences and environmental conditions. Chapter 2 is a site description measuring biodiversity, community structure and activity of three urban brownfields. The site description was used to select organisms that were subsequently evaluated for their usefulness as bioindicators of trace metals (chapter 3). Of the three plant species used (dandelion, bladder campion, and chicory), dandelion has the possibility of being a suitable bioindicator of Cd, Ni, and Zn, while bladder campion may be suitable for evaluating Cd, Ni, Pb, and Zn.

An important task of research on trace metals in soils is to evaluate how much metals are potentially bioavailable and may cause toxic effects. In this thesis, the chemical speciation and complexation of cadmium (Cd), copper (Cu), mercury (Hg) and lead (Pb) were examined in eastern Canadian soils collected from different locations around smelters. Our goal is to be able to predict metal binding in the soil solution and on the solid phase under a wide range of field conditions.
In Chapter 2, speciation of Cd, Cu and Pb in the lysimeter soil solutions was determined using an ion exchange technique (IET) involving a resin column. The IET-speciation data were used to estimate the metal-dissolved organic carbon (DOC) binding constants using the non-ideal competitive adsorption (MICA)-Donnan model, which assumed a continuous distribution of binding affinities on the DOC molecule. The published Cd and Pb speciation data in a variety of soils (Chapter 3) were also used to test the effectiveness of two speciation models, the MICA-Donnan model and WinHumicV. Both models satisfactorily predicted the concentrations of Cd2+ and Pb2+. The two chapters of metal speciation demonstrated that the NICA-Donnan model could estimate the binding strength of organic matter in soil solutions.
Proton and metal complexation to the surface of soil particles (Chapters 4 and 5) was investigated using back-titration and batch adsorption procedures. It was shown that the surface binding of H+, Cd2+, Hg2+ and Pb2+ was significantly related to soil organic matter (SOM). Though the soil particle surface was covered by a mixture of organic and mineral components, a two-site distribution could be identified from the titration curves. With the parameters derived from the back-titration and adsorption data, the MICA-Donnan model reasonably predicted the surface complexation of proton and metals. Furthermore, the statistically significant relationships between the model parameters and soil organic matter supported the assumptions in this thesis: (1) Organic matter was the most important sorbent on the particle surface; (2) The MICA-Donnan model may be used to interpret the surface binding data in these soils.

Trace metal contamination of the air-soil-tree system was examined in southern Quebec, where acid deposition and tree dieback have been recorded in high elevation forests. Mn pollution was emphasized due to its large emission from gasoline combustion in Canada. Airborne Cu, Mn, V, and Zn showed higher concentrations than those reported for other remote locations. Significant fluctuation in Mn concentrations during the winter-spring season was explored by air mass back trajectory analysis. The study suggested that high Mn concentrations resulted from the atmospheric long-range transport from Canadian industrialized and metropolitan regions. Metal concentrations in podzolic topsoils were generally higher than their world-wide average values. Concentrations of trace metals in balsam fir (Abies balsamea (L.) Mill) needles were below their suggested potential phytotoxic levels, except for Mn, which also increased with elevation. The scanning of needles with micro-PIXE showed no significant correlation between metal accumulation and epistomatal distribution on foliar surfaces.
Pathways of trace metals deposited in the soil-tree system were elucidated through application of $ sp{54}$Mn and $ sp{65}$Zn on shoot, bark, and soil surfaces in growth-chamber experiments with balsam fir seedlings. Uptake and accumulation by seedlings 70 days after application on the shoot surface was about 25-30% of the remaining activities for $ sp{54}$Mn and $ sp{65}$Zn. Less than 1% of absorbed isotopes was translocated from the bark surface to other plant organs, whereas more than 50% of the radioisotopes absorbed at the shoot moved to the rest of the seedling. Acidic wetness facilitated the metal absorption through tree surfaces. Downward movement of the radioisotopes in podzolic soils was documented, and accumulation in seedlings by root uptake was 5% of the remaining activity for $ sp{54}$Mn and 3% for $ sp{65}$Zn 70 days after application. No appreciable elemental migration from internal tissues to epicuticular wax layers was found, and the leaching ratio was below 0.5 and 1.0% for $ sp{54}$Mn and $ sp{65}$Zn, respectively. This study helps to understand the links between atmospheric deposition and the elevated levels of Mn in trees, and potential effects of acid deposition on the bioaccumulation of toxic metal pollutants in high elevation forests in southern Quebec.

High-pressure homogenization using a new flat valve homogenizer in combination with enzymatic digestion with a crude protease was investigated as a means of releasing Se compounds from zoological and botanical matrices prior to slurry introduction GF-AAS. Timed trials with four zoological certified reference materials (CRMs), three botanical reference materials (RMs), and a food crop indicated that Se release was quantitative after homogenization or became quantitative within 1 h of digestion at 60°C.
The same technique was employed on five animal feed samples.
A new model of homogenizer equipped with ceramic homogenizing valve was evaluated in terms of analyte metal contamination levels within the final sample dispersion.
Five animal feed samples and four wood pulp samples, were investigated for their content of Cu, Fe and Mn using high-pressure homogenization as the sample preparation technique prior to GF-AAS. Dispersions of dried animal feeds were sub-sampled reliably after 7 days of storage at 4°C. Trials on pulp samples indicated that pulps could be sub-sampled reliably after 1 day of storage. (Abstract shortened by UMI.)

A variety of extractants were used to fractionate the trace metals Cd, Cu, Mn, Ni, Pb, and Zn in contaminated urban soils. The metals were mostly held in soil solid phases but not in soluble and exchangeable forms. Except for Mn, extractability of metals by selective chemicals was mainly a function of the contamination level. The speciation of these elements in water, 0.01 M CaCl2, and pH-adjusted water extra was calculated using the chemical equilibrium model MINEQL+. The free ions of Cd, Ni, and Zn were the predominant species in most of the water and 0.01 M CaCl2 extracts while PbCO30 was the main form of Pb. Organically complexed Cu accounted for over of the total dissolved Cu. The solubility of trace metals increased as solution pH was decreased. Metals Cd, Ni, Pb and Zn combined with Cl- at low pH (<5). Organically complexed Cu was shifted to Cu2+ when pH was decreased.
Except for Mn, the activities of the other metals in water, 0.01 M CaCl 2 extracts, and pH-adjusted water extracts were undersaturated with respect to established minerals in soils. MnHPO4 seems to be controlling the solubility of Mn in these extracts.

This study provides an insight into a provincial region of a developing country, namely Río Negro, Argentina and possible links between diet, environmental factors (especially water quality) and human health. Measuring levels of trace elements in scalp hair is a known method for assessing nutritional status. Levels of Ca, Fe, Mg, K, Na, As, Cr, Co, Cu, I, Mn, Mo, Ni, Se, V, Zn, Al, Cd, Pb, Rb and Hg in scalp hair from adolescents of the age 14 to 18 years in a rural and an urban population of Río Negro were analysed by inductively coupled plasma mass spectroscopy (ICP-MS). The hypothesis is that levels of trace elements reflect lifestyle factors such as smoking, beverage and food selection and consumption patterns and are directly linked to dehydration and could be associated with future health problems. Furthermore, environmental factors, such as (i) indecent water systems and governmental subsidised food in the rural/urban population, and (ii) ingestion or inhalation of arsenic (from naturally high sources of water, dust and foodstuffs) may also be linked to present and future health problems. The relationship between environmental and dietary factors could be implicated with the onset of diseases such as diabetes type II, obesity or hypothyroidism. The results show that both study populations in the region are exposed to several trace elements in exceedingly high amounts such as As and Mn through tap water which may induce cancers. Also, regular soft drink consumption is associated with low Cr level in this population. Evidence was not obtained for assessing potential dehydration. In terms of understanding the relationship between these factors, methods for assessing dehydration and dietary consumption need to be perfected, and other demographic issues and methods for quantifying obesity and health status will require further research.

Coastal areas around the world have been recognized as largely impacted by anthropogenic activities resulting in pollution of marine sediments. In Sweden, surveys conducted along the coastline of the Bothnian Bay have identified a total area of about 29 km2 as fiber rich sediments. In the Bureå sea area near Skellefteå vicinity, Västerbotten county, elevated levels of mercury (Hg), methyl-Hg, arsenic (As), copper (Cu), lead (Pb), cadmium (Cd), zinc (Zn) and polycyclic aromatic hydrocarbons (PAH) have been classified and believed to be mainly affected by emissions from a pulp and paper industry formerly active on a nearby headland.  Contaminants in sediments are of concern as continuous dispersion can adversely affect the benthic community. To isolate contaminants and reduce their bioavailability, in-situ thin-layer capping using an active material is one suitable approach. This type of remediation method, using biochar mixed with bentonite clay will be implemented on a pilot scale in the sea area outside of Bureå in the spring of 2021. However, bentonite is a relatively expensive material yielding a need to further develop the selection of capping materials suitable to aid in the deposition of biochar in an active thin-layer cap. In this thesis, biochar-based thin layer caps mixed with bentonite clay, rock dust of two grain sizes and a concrete-based slurry was evaluated on their physicochemical properties and efficiency for preventing release of trace elements from sediment to the overlying water. This was conducted by a laboratory column experiment where four set ups were performed: (1) no capping for sediment control, (2) only capping material for material control, (3) sediment mixed with biochar and (4) sediment capped with each material mixed with biochar. Three times during an 8-week test period, 60 mL of the overlying water in the columns was extracted and sent for trace element analysis.  The experimental set up revealed that the capping layers effectively prevent release of trace elements trough the sediment to the overlying water. The concrete slurry showed suitable settling properties and negligible loss of biochar in the set-up of the columns. Also, the biochar+concrete slurry thin-layer cap displayed the highest efficiency for preventing and/or delaying release of As, P, Cu, Fe, Mn and SO4.

The objective of this study was to investigate the feasibility of the application of low cost high capacity inorganic ion exchange material, synthesized form collected fly ash and acid mine drainage solid residues, for the decontamination of secondary co-disposal process waters, with emphasis on investigating the processes governing the solid/solution interface.

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High concentrations of heavy metals in the soil can affect the sustainability of ecosystems and the health of humans and animals. The metal availability in the environment is related to the characteristics of each element, historical and source of contamination, as well as the properties of each soil. The presence of more than one element is common in contaminated areas and their interaction can affect their behavior in the environment. Researches have been developed to study the behavior of metals in different types of soils and thus help in cases of remediation. In recent years, the soil washing with biosurfactant has been presented as a promising method of remediation with little or no effect on the physico-chemical and microbiological characteristics of the soil, but the costs of obtaining this biosurfactant are still high, because most manufacturers use artificial means for production. Thus, this study had the objective of evaluating the remediation potential of the biosurfactant obtained from the fermentation of cassava water through the action of the bacteria Bacillus subtilis. This biosurfactant was characterized as surfactin, an anionic lipopeptide. Soils of different origins were used, one of them typical of the southwestern state of Paraná and the other from the northwest. The soils were first evaluated according to their potential for adsorption of the elements copper, zinc and lead in monometallic and multimetalic conditions, representing non-competitive and competitive conditions respectively. This evaluation was carried out by tests of adsorption and application of the matematical models of Langmuir and Freündlich. Soils were characterized chemically, physically and mineralogically. After that, it was performed the process of artificial contamination of these soils for application in the experiments of soil washing with biosurfactant in different conditions, having pH and concentration of biosurfactant solution as the main variables. Furthermore, it was also assessed the adsorption s capacity for metals by biosurfactant in liquid medium. The results showed that metals have different behaviors related to the adsorption and desorption to soil and to the biosurfactant. The soil type is also very important for the efficiency of metal removal. The clay soil showed higher adsorption capacity and therefore lower capacity of metal removal when compared to the sandy soil. In general, the soils showed the following sequence of adsorption capacity: Pb > Cu > Zn. The Pb was the element that less desorved by the washing process. It can also be concluded that, when soils are contaminated by more than one element at the same time, its ability to leach is greater than when the element is alone in the medium. This situation occurs because of differences between the competitive processes that take place in the active sites. The washing experiments showed that the biosurfactant was not able to improve the efficiency of removal of metals. The results obtained by the control treatments (only pure water) had very similar values to those that contained biosurfactant. When the wash solution containing the biosurfactant was in high concentrations, decrease in removel efficiency was found in some of the samples. Analysis of high performance liquid chromatography showed that the biosurfactant was adsorbed to soil samples, which is the consequence of not observing the effectiveness of the extractor in the removal of metals. It is notable, however, that the surfactin obtained has the potential to bind to metals, since the tests of adsorption to metals was confirmed by experiments. According to the results obtained, it can be inferred that the surfactin has greater potential for metal removal in liquid media than in solid medium, because of the lower possibility of adsorption. In soil, the results indicated potential use of this biosurfactant as stabilizing of metals in methods of remediation "in situ".
Concentrações elevadas de metais pesados no solo podem afetar a sustentabilidade dos ecossistemas e também a saúde dos seres humanos e animais. A disponibilidade do metal no ambiente está relacionada às características de cada elemento, histórico e fonte de contaminação, bem como às propriedades de cada solo. A presença de mais de um elemento em áreas contaminadas é comum e a interação entre eles pode afetar o seu comportamento no ambiente. Diante do problema, pesquisas vêm sendo realizadas a fim de estudar o comportamento dos metais em diferentes tipos de solos e assim auxiliar nos procesos de remediação. Nos últimos anos, a lavagem do solo com biossurfactante tem sido apresentada como um método promissor de remediação com pequeno ou nenhum efeito sobre as características físico-químicas e microbiológicas do solo, porém os custos de obtenção deste biossurfactante ainda são altos, pois a maioria dos fabricantes utiliza meios artificiais para sua produção. Neste sentido, este trabalho teve como objetivo geral avaliar o potencial de remediação do biossurfactante obtido a partir do bioprocessamento da manipueira pela ação de bactérias Bacillus subtilis. Este biossurfactante foi caracterizado como surfactina, um lipopeptídeo aniônico. Foram utilizados solos de origens distintas, sendo um deles típico da região sudoeste do estado do Paraná e outro da região noroeste. Os solos utilizados foram primeiramente avaliados de acordo com o seu potencial de adsorção dos elementos cobre, zinco e chumbo em condições monometálicas e multimetálicas, representando condições não-competitivas e competitivas, respectivamente. Esta avaliação foi feita por meio de testes de adsorção e aplicação de modelos matemáticos de Langmuir e Freündlich. Os solos foram caracterizados química, física e mineralogicamente. A partir de então realizou-se o processo de contaminação artificial destes solos para posterior aplicação dos experimentos de lavagem com o biossurfactante em diferentes condições, sendo as variáveis pH e concentração da solução de biossurfactante como as principais. Além disso, também foi avaliada a capacidade de adsorção dos metais pelo próprio biossurfactante, em meio líquido. Os resultados mostraram que os metais apresentam comportamentos distintos quanto a adsorção e dessorção ao solo e ao biossurfactante. O tipo de solo também é muito importante para a avaliação da eficiência de remoção de metais. O solo argiloso apresentou maior capacidade de adsorção e consequentemente menor capacidade de remoção dos metais quando comparado ao solo arenoso. De modo geral, os solos apresentaram a seguinte sequência de capacidade de adsorção: Pb > Cu > Zn. O Pb foi o elemento que menos dessorveu pelos processos de lavagem. Foi possível também concluir que quando os solos estão contaminados por mais de um elemento ao mesmo tempo, a capacidade de lixiviar-se é maior do que quando o elemento está sozinho no meio. Esta situação ocorre em virtude dos processos competitivos existentes entre os sítios ativos. Os experimentos de lavagem mostraram que o biossurfactante não foi capaz de melhorar a eficiência de remoção dos metais. Os resultados obtidos pelos tratamentos controle (somente água pura) tiveram valores muito semelhantes aos que continham biossurfactante. Quando a solução de lavagem continha o biossurfactante em altas concentrações, foi encontrada, em algumas amostras, queda na eficiência de remoção. Análises de cromatografia líquida permitiram concluir que o biossurfactante foi adsorvido às amostras de solo, sendo esta a consequência da não observação da eficácia do extrator na remoção dos metais. Cabe ressaltar, entretanto, que a surfactina obtida apresenta potencial de ligar-se aos metais, uma vez que os testes de adsorção desta aos metais foi confirmado pelos experimentos realizados. De acordo com os resultados encontrados, pode-se inferir que a surfactina tem maior potencial de remoção de metais em meio líquido do que em meio sólido, devido a menor possibilidade de adsorção na matriz sólida. Em solo, os resultados indicaram potencial de utilização deste biossurfactante como agente de estabilização dos metais em métodos de remediação in situ .

It is widely accepted that bioavailability, rather than total soil concentration, is preferred when assessing the risk associated with metal contamination. Despite this, debate continues on what constitutes a bioavailable pool and how to best predict bioavailability, especially in relation to crop plants. The overall aim of this thesis was to assess and validate measures of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) bioavailability in a range of soils amended with metal salts and biosolids. Six potential measures of bioavailability were investigated and compared: total metal; 0.04 M EDTA extraction; 0.05 M Ca(NO₃)₂ extraction; soil solution extracted using rhizon probes; effective solution concentration (CE) determined using diffusive gradients in thin films (DGT); and modelled free ion activities (WHAM 6.0). These were compared to shoot metal concentrations obtained from plants grown in three soils with contrasting properties treated with biosolids and metal salts. The first study involved a wheat seedling (Triticum aestivum) assay carried out under controlled environmental conditions on incubated soils treated with metal salts and biosolids. Results showed that the presence of biosolids resulted in increases of DOC, salinity, Ca and Mg in soil solution as well as total concentrations of Cu and Zn, dry matter was also adversely affected by increased levels of salinity. The addition of biosolids did not significantly alter the extractability or solubility of Cd, Cu, Ni and Zn although concentrations of Cd in shoots were significantly lower in plants grown in biosolids amended soils compared with unamended soils. The second study involved a field experiment that used 20 cm diameter by 30 cm deep soil monoliths of the same three soils treated with metals and biosolids, and perennial ryegrass (Lolium perenne) was grown for 24 months. Results revealed the addition of biosolids significantly increased the amount of DOC, salinity, Ca and Mg in solution. The presence of biosolids also significantly altered the bioavailability of Cd, Cu, Ni and Zn, as measured by soil solution, CE and free ion activity. However, this change had little effect on plant metal uptake. The length of time following treatment application had the greatest effect on soil chemistry and metal availability, resulting in pH decreases and increases in DOC, soil solution salinity, Ca and Mg. The free ion activities of each metal increased with time, as did soil solution Cd and Zn and CE-Cu, with results for Zn indicative of migration through the soil profile with time. Plant uptake of Ni and Zn also changed with time. Nickel concentrations in shoots decreased, while concentrations of Zn in shoots increased. The findings from the two studies demonstrated that biosolids increased the amount of DOC, salinity, Ca and Mg present in soil solution. In the lysimeter study measures of metal availability were affected in soils amended with biosolids, but this did not effect shoot concentrations. The overall predictive strengths of the six potential measures of bioavailability was investigated using results from the previously described experiments and related studies carried out by ESR and Lincoln University using nine different soils amended with combinations of biosolids and metal salts. Of the four metals Ni provided the strongest correlations between metal bioavailability and shoot concentrations, with 0.05 M Ca(NO₃)₂ extraction giving the strongest relationship for Ni concentrations in shoots (r² = 0.73). This suggests that the solubility of Ni is highly indicative of shoot concentrations and that Ca(NO₃)₂ is a robust measure of Ni bioavailability. In addition Ca(NO₃)₂ provided the best estimate of Zn bioavailability (r² = 0.65), and CE-Cd provided the best measure of Cd bioavailability, although it could only describe 47 % of shoot Cd concentration. Results for Cu were typical of previously described studies as assays of Cu availability are almost always poorly correlated with shoot concentrations, with total Cu having the strongest relationship (r² = 0.34). Methods based on the extractability and solubility of Cu in soils were poor indicators of Cu concentration in shoots. Overall, the addition of biosolids did not alter the outcome of these bioavailability assays, and results indicated that total metal concentrations present in the soils and biosolids matrix, plus length of time since soil treatment, had a greater affect on metal bioavailability.

Microphytobenthos (MPB), a mixed community of microscopic, photosynthetic organisms, algae and cyanobacteria, inhabiting the top few millimetres of bottom sediment, is a key component of intertidal mudflats. It accounts for a significant proportion of estuarine primary production, forms the base of the food chain and influences sediment distribution and resuspension (through production of extracellular polymeric substances (EPS)). Diatoms dominate the microphytobenthos community in the mid-latitudes of the Northern Hemisphere. Estuarine sediments, are a sink for metal contaminants derived from fluvial, marine and atmospheric sources. Whilst metal releases to estuaries have declined in recent years due to increased regulation and declining industrial activity, metals previously discharged and which are now locked up in saltmarsh sediments remain a concern. For example, there are indications that saltmarshes are already being eroded, due to climate change related sea level rise, in some locations. This erosion may result in the redistribution of historically contaminated sediment to locations, such as the mudflats, where it is more available to biota, such as the MPB. In addition to causing redistribution, climate change effects, such as increasing temperatures and storminess, may also alter the bioavailability of metals to MPB. Increased concentrations of metals within the MPB could potentially increase their transfer to higher organisms through the food chain with potential impacts for biota. Whilst planktonic algae have been well studied with respect to metal uptake from the water column, there has been little research involving MPB and uptake of metals from sediment. The extent to which contaminant uptake by microphytobenthic algae occurs and under what conditions is therefore poorly understood. The research presented uses laboratory, mesocosm and field studies, to gain an understanding of processes governing metal bioavailability and mechanisms for uptake from sediment to the diatoms of the MPB under the complex and variable conditions of intertidal mudflats. A laboratory study using a single diatom species Cylindrotheca closterium found that uptake of cadmium (Cd) varied with sediment properties revealing the importance of sediment particle size and organic matter content in metal bioavailability to diatoms. Additionally, this study showed that the presence of diatoms altered Cd partitioning between sediment, overlying and pore water. Specifically there was an increase in Cd in the overlying and pore water when diatoms were present, indicating that diatoms mobilise metals from the sediment to the water column potentially increasing metal bioavailability to other biota. A study was conducted using an intertidal mesocosm to increase the realism of the study system and examine uptake to a natural MPB community. Diatoms were found to have higher concentrations of all the metals analysed (except tin) than other types of algae (filamentous and sheet macroalgae), confirming their importance as a study organism with respect to metal uptake and potential mobilisation through the food chain. Sediment disturbance was shown to increase metal uptake (iron, aluminium, vanadium and lead) from the sediment to algae. This is of concern due to predicted increases in storminess which are likely to increase sediment disturbance, with the likelihood that uptake of metals to diatoms will increase in the future. However, there were also indications of an antagonistic effect of temperature on disturbance, whilst disturbance increased bioavailability and uptake, increasing temperatures reduced uptake of some metals. This highlights the importance of considering the effects of multiple stressors in complex systems. Field studies showed that concentrations of some metals were related to their position on the mudflat whilst others were related to sampling date, indicating that there may be seasonal controls, such as to the presence of greater diatom biomass in spring and autumn, on metal uptake from the sediment. The research conducted has increased understanding of metal uptake to microphytobenthic diatoms from sediment and the influence they have in transferring metals from sediment to water, however the research also raises a number of new questions. For example, there appeared to be a link between sediment organic matter content and bioavailability of metals to diatoms, although the relative contribution of the diatoms, other algae, cyanobacteria and EPS to the sediment organic matter warrants further investigation. Furthermore, it has shown that the use of laboratory and mesocosm studies for this type of research can produce similar outcomes to those observed in the field but under more controlled and easily manipulated conditions, although field studies will continue to be vital in improving understanding of metals availability and transfer.

Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.
Includes bibliographical references (leaves 113-120).
Abstract --- p.i
Acknowledgement --- p.iii
Table of Contents --- p.iv
List of Tables --- p.viii
List of Figures --- p.xii
Chapter CHAPTER 1. --- INTRODUCTION --- p.1
Chapter 1.1 --- Previous Heavy Metal Studies of Hong Kong Marine Waters and Sediments --- p.4
Chapter 1.2 --- Speciation of Metals in Aquatic Environment --- p.6
Chapter 1.2.1 --- Speciation of Metals in Water --- p.7
Chapter 1.2.2 --- Speciation of Metals in Bottom Sediments --- p.7
Chapter 1.3 --- AVS in Marine Sediments --- p.10
Chapter 1.3.1 --- Formation of AVS --- p.10
Chapter 1.3.2 --- Seasonal and Spatial Variation of AVS --- p.11
Chapter 1.3.3 --- AVS as Mediator of Metal Toxicity --- p.13
Chapter 1.3.4 --- Chemical Basis for AVS Sediment Normalization --- p.15
Chapter 1.3.5 --- Analysis of Pore Water Metals --- p.17
Chapter 1.4 --- Significance of the Research --- p.18
Chapter 1.4.1 --- Importance of Metal Bioavailability Study in Hong Kong --- p.18
Chapter 1.4.2 --- Importance of AVS Study in Hong Kong --- p.19
Chapter 1.4.3 --- Approach of the Present Study --- p.21
Chapter 1.5 --- Organization of the Thesis --- p.22
Chapter CHAPTER 2. --- METHODOLOGY --- p.23
Chapter 2.1 --- Study Area --- p.24
Chapter 2.2 --- Sampling Strategy --- p.25
Chapter 2.2.1 --- Sampling Locations --- p.25
Chapter 2.2.2 --- Sampling Dates --- p.28
Chapter 2.2.3 --- Sample Collection and Handling --- p.28
Chapter 2.3 --- Sample Analysis --- p.32
Chapter 2.3.1 --- Sediment Analysis --- p.32
Chapter 2.3.2 --- Pore Water and Overlying Water Analysis --- p.34
Chapter 2.3.3 --- Limitations --- p.36
Chapter 2.4 --- Statistical Analysis --- p.39
Chapter CHAPTER 3. --- METALS IN WATER AND BOTTOM SEDIMENTS --- p.40
Chapter 3.1 --- Metals in the Water --- p.40
Chapter 3.1.1 --- Variation of Metal Concentrations --- p.41
Chapter 3.1.2 --- Metal Pollution Level of the Overlying Water --- p.42
Chapter 3.2 --- Metals in Bottom Sediments --- p.44
Chapter 3.2.1 --- Spatial Distribution Pattern of Heavy Metals --- p.44
Chapter 3.2.2 --- Temporal Variation of Metal Content in the Bottom Sediments --- p.48
Chapter 3.2.3 --- Metal Pollution Level of the Bottom Sediments --- p.49
Chapter 3.3 --- Conclusion --- p.50
Chapter CHAPTER 4. --- SPECIATION OF METALS IN THE OVERLYING WATER AND BOTTOM SEDIMENTS --- p.51
Chapter 4.1 --- Speciation of Metals in the Overlying Water --- p.51
Chapter 4.1.1 --- Concentration of Labile Metals in the Overlying Water --- p.52
Chapter 4.1.2 --- Seasonal and Spatial Variation in the Concentration of Labile Metals in the Overlying Water --- p.54
Chapter 4.1.3 --- Percentage of Labile Fraction in Total Metals --- p.55
Chapter 4.2 --- Speciation of Metals in the Bottom Sediments --- p.59
Chapter 4.2.1 --- Proportion of Various Metal Species in the Sediments --- p.60
Chapter 4.2.2 --- Variation of the Overlying Water Properties --- p.63
Chapter 4.2.2.1 --- Chemical Properties of the Water in the Study Area --- p.63
Chapter 4.2.2.2 --- Seasonal Variation of Water Properties --- p.67
Chapter 4.2.2.3 --- Stratification of the Water Column --- p.69
Chapter 4.2.3 --- Implication of the Changes of Water Quality on Metal Remobilization --- p.73
Chapter CHAPTER 5. --- VARIATION OF AVS AND ITS ROLE IN METAL TOXICITY MEDIATION --- p.77
Chapter 5.1 --- Variation of AVS in the Study Area --- p.78
Chapter 5.1.1 --- Spatial Variation of AVS --- p.78
Chapter 5.1.2 --- Seasonal Variation of AVS --- p.81
Chapter 5.1.3 --- Vertical Variation of AVS --- p.85
Chapter 5.1.4 --- Effects of AVS Variation on Metal Bioavailability --- p.88
Chapter 5.2 --- Role of AVS in Metal Toxicity Mediation --- p.91
Chapter 5.2.1 --- SEM/AVS Molar Ratio --- p.91
Chapter 5.2.2 --- Fraction of SEM in Total Metals of the Sediments --- p.94
Chapter 5.2.3 --- Labile Metals in Pore Water --- p.96
Chapter 5.2.4 --- Dissolved Sulfides in the Pore Water and Overlying Water --- p.99
Chapter 5.3 --- Conclusion --- p.100
Chapter CHAPTER 6. --- CONCLUSION --- p.102
Chapter 6.1 --- Introduction --- p.102
Chapter 6.2 --- Major Findings --- p.103
Chapter 6.3 --- Practical Implication of the Findings --- p.108
Chapter 6.4 --- Suggestion for Further Studies --- p.110
Bibliography --- p.113
Appendix A. AVS Extraction and Detection Method --- p.121
Appendix B. Sequential Extraction Method for Metals Speciation Analysis --- p.123
Appendix C. Instrument List for the Experiments --- p.125
Appendix D. Monthly Total Rainfall and Mean Temperature of1995 --- p.127
Appendix E. Analytical Results of the Overlying Water --- p.128
Appendix F. Analytical Results of the Bottom Sediments --- p.132
Appendix G. Analytical Results of the Pore Water --- p.136
Appendix H. Concentration (μg/g) and Fraction (%) of Pbin Sediments --- p.140
Appendix I. Concentration (μg/g) and Fraction (%) of Cuin Sediments --- p.142
Appendix J. Concentration (μg/g) and Fraction (%) of Cdin Sediments --- p.144
Appendix K. Concentration (μg/g) and Fraction (%) of Znin Sediments --- p.146
Appendix L. Concentration (μg/g) and Fraction (%) of Niin Sediments --- p.148
Appendix M. Fraction of Different Speciations of Metals in the Sediments --- p.150
Appendix N. Vertical Profile of Dissolved Oxygen in the Overlying Water --- p.155
Appendix O. Vertical Profile of Salinity in the Overlying Water --- p.159
Appendix P. Vertical Profile of Temperature in the Overlying Water --- p.163
Appendix Q. Vertical Profile of pH in the Overlying Water --- p.167

The industrial port of Richards Bay on the eastern seaboard of KwaZulu-Natal, South Africa has undergone rapid growth over the last 25 years. This industrial growth has inevitably led to an increase in the anthropogenic pollutant inputs in the area. However, the degree of this contamination has not previously been assessed not been accompanied by an awareness of its environmental impacts. This project serves to assess the current environmental situation of the area and provide background levels against which the environmental impacts of further growth in the area can be assessed. The main pollution point sources in the area were identified as a pulp and paper plant, a sulfuric acid/fertiliser plant and aluminium smelters. The chemical and physical processes involved within these industries were identified and discussed in detail. The common inorganic pollutants emitted by these industries were identifies as trace metals, sulfur dioxide, NOx gases and fluoride. It was these pollutants that therefore became the focus of this study. Reservoirs within Richards Bay that may become sinks for contamination were identified and water, sediment and soil samples were taken from these reservoirs. The samples were analysed for trace metal contamination, pH, alkalinity and fluoride levels. Analysis of the acidity and alkalinity of water, sediment and soils samples demonstrated that there is presently no long-term acidification of the environment in Richards Bay. The only samples that showed increased acidity were the soils taken from the roadside sites immediately outside the industries. This lack of overall acidification indicates that, at present, there are no detrimental effects of acidic emissions on the hydrosphere and geosphere. Only cursory investigations were conducted into the fluoride levels found in water samples. None of the samples analysed demonstrated detectable amounts of fluoride present. Comprehensive trace metal analyses were performed on the water, sediment and soil samples through the use of ICP-AES. Levels obtained were compared with levels from samples taken from relatively uncontaminated background sites. Trace metal analysis indicated contamination of the freshwater reservoirs when compared with the background, while the soils and saltwater reservoirs remain largely uncontaminated. However, the contaminated areas did not show levels greater than quality guideline concentrations. Further studies should be conducted with regards to the trace metal contamination of the biosphere and the bioavailability of the contaminants already present in the waters, sediments and soils. More detailed investigations should also be conducted into the levels of atmospheric pollutants and fluoride levels in all reservoirs.
Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2004.

Thesis (M.S.)--Indiana University, 2007.
Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Gabriel M. Filippelli, Catherine Souch, Lenore P. Tedesco. Includes vitae. Includes bibliographical references (leaves 80-83).

by Oi-Ming Cheng.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1996.
Includes bibliographical references (leaves 104-108).
Chapter 1 --- INTRODUCTION
Chapter A) --- Sources of zinc and its functional role --- p.10
Chapter B) --- Effects of excessive zinc intake --- p.11
Chapter (a) --- Human --- p.11
Chapter (b) --- Animal --- p.11
Chapter (c) --- Fish --- p.12
Chapter C) --- Techniques in zinc determination --- p.12
Chapter 2 --- ANODIC STRIPPING VOLTAMMETRY
Chapter A) --- Basic principles --- p.16
Chapter (a) --- Cell --- p.16
Chapter (b) --- Electrodeposition and stripping --- p.20
Chapter B) --- Major interferences in anodic stripping and the common solutions to these problems --- p.25
Chapter (a) --- Intermetallic compound formation --- p.25
Chapter (b) --- Overlapping peaks --- p.26
Chapter (c) --- Organic compounds adsorbed at the electrode --- p.28
Chapter 3 --- MUTUAL INTERFERENCE FROM ZINC AND COPPER
Chapter A) --- Introduction --- p.30
Chapter B) --- Review of reported methods to remove copper interference --- p.31
Chapter (a) --- Dual-working electrode approach --- p.31
Chapter (b) --- Adjustment of the deposition potential --- p.31
Chapter (c) --- Standard addition --- p.33
Chapter (d) --- Addition of a third element --- p.33
Chapter C) --- The proposed solution --- p.35
Chapter 4 --- EXPERIMENTAL
Chapter A) --- Proposed method --- p.37
Chapter (a) --- Apparatus --- p.37
Chapter (b) --- Reagents --- p.38
Chapter (c) --- Procedure --- p.40
Chapter B) --- Reference method --- p.45
Chapter (a) --- Apparatus --- p.45
Chapter (b) --- Reagents --- p.45
Chapter (c) --- Procedure --- p.47
Chapter 5 --- RESULTS AND DISCUSSION
Chapter A) --- Optimization of instrumental parameters and working conditions --- p.49
Chapter (a) --- Effect of plating potential on zinc peak current --- p.49
Chapter (b) --- Effect of plating time on zinc peak current --- p.53
Chapter (c) --- Effect of holding time and holding potential on zinc peak current --- p.56
Chapter (d) --- Effect of sweep rate on zinc peak current --- p.58
Chapter (e) --- Effect of final potential and strip time on zinc peak current --- p.61
Chapter (f) --- Effect of pH on the peak current and recovery of zinc in the presence of copper after the sulphide treatment --- p.63
Chapter (g) --- Effect of the concentration of buffer on the peak current --- p.66
Chapter (h) --- Effect of the reaction time of sulphide with copper on the zinc recovery --- p.68
Chapter B) --- "Calibration graph, precision and detection limit" --- p.71
Chapter C) --- Effect of copper on the zinc determination by the proposed method --- p.78
Chapter D) --- Interference studies --- p.80
Chapter E) --- Recovery tests --- p.84
Chapter F) --- Determination of zinc in real samples using the proposed method --- p.86
Chapter (a) --- Clean water samples such as sea water and tap water --- p.86
Chapter (b) --- Contaminated natural water and domestic wastewater samples --- p.91
Chapter (c) --- Air samples --- p.93
Chapter (d) --- Oyster tissue samples --- p.96
Chapter (e) --- Sewage sludge and sediment samples --- p.99
Chapter 6 --- CONCLUSION --- p.102
REFERENCES --- p.104

A dissertation submitted to the Faculty of Science, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science Johannesburg 2017.
The development of the economy of South Africa and many other countries has been highly dependent on mining industries. Minerals such as gold, platinum, diamond and many others have been mined and continue to be mined. Despite the importance of these minerals, their processing comes with social and environmental problems. During the processing of these minerals, trace elements such as copper, chromium, nickel, mercury, uranium, molybdenum and many others are released as wastes into the environment either, directly or indirectly. The release of the elements into the soil is of concern due to the possibility of groundwater system contamination. The presence of these elements in the groundwater system poses serious challenges to the wellbeing of life forms, due to their toxicity, when they exceed threshold limits. From the processing plants, these elements could be released onto the soil, and mobilise to groundwater, increasing the already existing environmental crisis due to water pollution. Once these elements are in the water, access to living organisms becomes easier through the food chain. Some of these elements are not biodegradable and thus persist in the environment as well as in the bodies of living organisms. They can cause serious health problems because of their toxicity effect. In humans, these elements can be carcinogenic, and also cause chronic disorders, kidney failures, defects in infants, bone and vascular diseases which could also be lethal. It is therefore of importance that these elements are neither bioavailable nor bioaccessible to living organisms. When these elements are mobile in the soil, the probability of reaching groundwater increases. Water, an important natural resource should always be protected from such pollutants. The demand for unpolluted water has been rising every year in the world due to increasing population, extended droughts and improper disposal. This research was dedicated to determining the behaviour of elements in an agricultural soil impacted by mining activities. Agricultural soils are sometimes exposed to pollutants that could originate from dust fallout or precipitation; fertilisers and manure; pesticides; and water used for irrigation. Understanding the iv processes that control the distribution of these pollutants in agricultural soils is an important risk assessment measure, considering that such pollutants have the potential of being taken up by crops and vegetables or transported to groundwater. In this study, a soil on a farm that grows vegetables for commercial purpose. Cabbage, spinach, carrots and potatoes are some of the vegetables grown on the plot and sold to markets in Pretoria and Johannesburg. The plot is in the vicinity of smelting operations in the North West Province. The mobility of trace elements in the soil can be controlled, depending on the type and properties of soil. Hence in this research, the ability of the soil to adsorb elements entering the soil is studied. The batch experimental work was performed to determine the effect of pH, initial concentration (5 - 100 mg/L), competing ions (Fe3+, Ca2+, Co2+, Mg2+, K+, Ni2+ and Zn2+), fertilisers (ammonium nitrate, ammonium phosphate and calcium chloride) and plant exudates (acetic acid, citric acid and oxalic acid as well as ethylenediaminetetraacetic acid (EDTA) which is often used as proxy organic ligand (found in manure)) on the adsorption of cadmium (Cd), copper (Cu) and chromium (Cr) onto an agricultural soil. The PHREEQC geochemical modelling code was used to complement experimental methods in predicting processes and to further assess the leaching behaviour of the elements. Powder X-ray diffraction (PXRD) and X-ray fluorescence (XRF) were used to determine the mineralization of the soil. The structural features of the soil were determined using Fourier Transform Infrared spectroscopy (FTIR) and the element content was determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The point of zero charge (PZC) of the soil was found to be 8.3 and the cation exchange capacity (CEC) of 51.6 meq/ 100g. In the absence of fertilisers and plant exudates, the soil exhibited a similar high adsorption for elements at all initial concentrations by all the elements. Most (> 90%) of the elements were adsorbed within the first 3 minutes of contact with the soil. Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms were used to describe the experimental data for the elements. Kinetic rates were modelled using pseudo first-order and pseudo second-order equations. Pseudo v second-order gave the best fit for all the elements (R2 >0.999) indicating chemisorption. The effect of pH on Cd and Cu was insignificant however, the adsorption of Cr decreased with pH. The presence of competing ions decreased the adsorption of cadmium more than that of the other analyte elements. The soil was generally effective in adsorbing and retaining the elements. However, the retention was highly dependent on elemental speciation and prevailing conditions e.g. pH (as in the case of Cu and Cr). Such changes in conditions would have implications for groundwater quality. The effect of plant exudates and EDTA was studied and the results showed that low molecular weight organic acids (LMWOAs) viz acetic acid (AA), citric acid (CA) and oxalic acid (OA) and EDTA significantly (p < 0.05) decreased the adsorption capacity of the elements onto the agricultural soil. AA had the least effect on the adsorption capacity of the elements whereas OA and EDTA strongly prevented the adsorption of the elements. Moreover, some of the elements which were already in the soil including those which were not under study such as Ca and Mg were desorbed from the soil by OA and EDTA. Thus, the mobility of the elements was increased by the presence of plant exudates, increasing groundwater contamination and consequently threatening the health of living organisms. Agrochemicals such as fertilisers, stabilizers and pesticides are constantly applied to agricultural soils to improve the fertility of the soil for better crop production however; their presence may affect the mobility and bioavailability of elements in the soil. The effect of ammonium nitrate and ammonium phosphate as well as calcium chloride on the adsorption of Cd, Cu and Cr onto an agricultural soil was studied. The effects of initial concentrations of the elements (5 – 50 mg/L), concentrations of fertilisers (0.01 – 0.1 mol/L) and pH (3 - 8) on the adsorption of Cd, Cu and Cr were studied. The initial concentration of the elements and the concentration of fertilisers had no significant effect (p > 0.05) on the adsorption capacities of Cu and Cr at pH 5. But, ammonium nitrate and calcium chloride decreased the adsorption capacity of Cd. The adsorption of Cd onto the soil was reduced as the concentration of fertilisers increased. The adsorption of Cd was lower than that of Cu and Cr at all pH values. The agricultural soil was found to vi be an effective adsorbent in preventing the mobility of Cu and Cr in the presence of fertilisers but not for Cd whose adsorption was significantly affected by the presence of ammonium nitrate and calcium chloride. A continuous flow fixed-bed column script with specified conditions simulating the natural environment was utilised in PHREEQC for column studies. The geochemical computer model PHREEQC can simulate solute transport in soil surfaces. The effect of initial concentration (100 and 300 mg/L) of the elements, column bed depth (5 and 10 cm) and pH (3, 5, 7 and 10) were considered in this study. The adsorption capacity was affected by initial concentration of the elements since the breakthrough curves at higher analyte concentrations were reached at lower pore volumes than at low concentrations. This can be attributed to the fast occupation of active sites of the soil at higher concentrations. The results from PHREEQC indicated that the conditions used would lead to the oxidation of Cr3+ to Cr6+ leading to the formation of HCrO4- and Cr2O72- which were not favoured for adsorption by soil surfaces due to high solubility. This could have potential implications on the quality of groundwater in regions with similar conditions. Thus, the leaching of Cr6+ onto the agricultural soil will be high in areas where remediation techniques are not applied. The changing of bed depth from 5 to 10 cm did not have an effect on the adsorption of the elements. The ability of the soil surfaces to adsorb Cd and Cu even at lower bed depth implies that the soil will be effective in preventing the leaching of the elements to groundwater due to strong surface interactions of the elements with the soil. The results from PHREEQC showed that the adsorption of Cd and Cr onto the soil surface was not affected by pH. The results for Cr were contradicting with those obtained from laboratory experiments which could be due to the conditions used in PHREEQC. The change in the speciation of Cu at basic conditions decreased the ability of Cu adsorption onto the soil surfaces. The Cu2+ was converted to Cu(OH)2 which were large in size and thus only a small amount could be adsorbed since the other adsorption sites were covered by the large species. This research had notable outputs in the form of publications which will form an important repository of information.
LG2017

Due to mining activities, the natural vegetation cover in Gatumba area was removed and replaced either by crops or bare wasteland with reduced available arable land. The main aim of the study was to assess the impact of the mining activities on the plant mineral uptake and the dynamics of the vegetation. The vegetation in this area under investigation was diversified and heterogeneous. Trace element concentrations in soils were similar to those in plant parts but some elements were highly concentrated in soils than in plants. According to the bioaccumulation factors of the analyzed trace elements in plant parts, two categories of plants were identified, and these are excluders and accumulators. No toxic levels of the evaluated trace elements were found in the analyzed plant samples. As a recommendation for the adaptation of plants to Gatumba mining environment, the most useful plant species for the revegetation/restitution of the technosols should be Sesbania sesban, Crotalaria dewildemaniana and Tithonia diversifolia subject to further experiments on trace elements bioaccumulation and organic matter production
Environmental Sciences
M.A. Science (Environmental Sciences)

PhDENV
Department of Hydrology and Water Resources
Geothermal springs are natural geological phenomena that occur throughout the world. South Africa is endowed with several springs of this nature. Thirty-one percent of all geothermal springs in the country are found in Limpopo province. The springs are classified according to the residing mountain: Soutpansberg, Waterberg and Drakensberg. This study focused on the geothermal springs within the Soutpansberg region; that is, Mphephu, Siloam, Sagole and Tshipise. The study was aimed at elucidating on the isotopic signatures and trace metals concentrations from the geothermal springs to their environmental media in Soutpansberg region. This study also assessed the interconnectivity of the isotopic signatures within the ecosystem and evaluated the potential human health risks associated with trace metals from geothermal springs and surrounding soils in the study areas. Geothermal springs and boreholes were sampled for a period of twelve months (May 2016 – May, 2017) to accommodate two major seasons in the study areas. The surrounding soils were sampled vertically from a depth of 10 cm to 50 cm for trace metals and isotopic compositions. Three different plants were sampled at each of the study sites, namely, Amarula tree, Guava tree and Mango tree at Siloam; Acacia tree, Fig tree and Amarula tree at Mphephu; Amarula tree, Lowveld mangosteen and Leadwood tree at Sagole; Sausage tree, Amarula tree and Acacia tree at Tshipise. To achieve the objectives, the physicochemical, geochemical and isotopic compositions of the geothermal springs, boreholes, soils and vegetation were analysed using ion chromatography (IC) (Dionex Model DX 500), inductively coupled plasma-mass spectrometer (ICP-MS), HTP-Elemental analyzer, Liquid water isotope analyzer (LWIA-45-EP) and Liquid scintillation analyzer. The temperature, electrical conductivity (EC), pH and total dissolved solid (TDS) of the geothermal springs and boreholes samples were measeured in situ and in the laboratory. Trace metals analysed in geothermal springs, boreholes, soil and vegetation include Beryllium (Be), Chromium (Cr), Manganese (Mn), Cobalt (Co), Nickel (Ni), Copper (Cu), Arsenic (As), Selenium (Se), Cadmium (Cd), Antimony (Sb), Barium (Ba), Vanadium (V), Zinc (Zn), and Mercury (Hg). vii | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg Results obtained from this study in the studied geothermal springs and boreholes were classified according to their temperature as hot and scalding; except for tepid boreholes. This study has provided comprehensive physicochemical, geochemical and isotopic compositions of the geothermal springs within the Soutpansberg region (Siloam, Mphephu, Sagole and Tshipise). The local meteoric line (δD = 7.56δ18O + 10.64) was generated from rainwater in Vhembe district. This is a crucial component for depicting the source and flow path of the geothermal springs/boreholes; and could be used for future isotopic hydrological studies within the locality. Rain formation processes within Soutpansberg occurred under isotopic equilibrium conditions with minor evaporation effect during rainfall. The δD and δ18O values of the geothermal spring water/boreholes confirm that the waters are of meteoric origin, which implies that rainfall is the fundamental component of these groundwaters because they were derived from the infiltration of rainwater, with significant contribution of another type of water in the deeper part of the aquifer. Na-Cl and Na-HCO3 were established as the water types, which are typical of marine and deep groundwaters which are influenced by the ion - exchange process. The reservoir/aquifer temperature of these springs ranges between 95 – 185°C (Na-K geothermometer), which implies most of the waters are mature water (not native). Hence, geothermal springs water is a mixture of the rainwater and salt water. Radiocarbon values of the geothermal springs ranged from 2700 to 7350 BP, this implies that they are submodern and a mixture of submodern and modern waters. Tritium relative age also corroborates with radiocarbon age, that is the groundwaters were recharged before and after 1952. This gives an indication that the rainfall contributes to the geothermal springs recharge. Various radiocarbon correction models were employed and constrained by tritium relative age. Ingerson and Pearson, Eichinger and Fontes and Garnier correction models have been shown to be the most appropriate models for radiocarbon correction of groundwater in this semi-arid region. Although, geothermal springs water and boreholes are not fit for drinking due to high fluoride content, they could be used for the following: domestic uses (drinking exclusive) due to its softness, direct heating in refrigeration, green-housing, spa, therapeutic uses, aquaculture, sericulture, concrete curing, coal washing and power generation. In contrast with mentioned uses, viii | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg the studied geothermal springs are currently used for domestic purposes (drinking inclusive), limited irrigation and spa (swimming and relaxation). This is an eco-hydrological study that shows the interconnectivity of isotopic signatures among water (rainwater, geothermal springs and boreholes), soils and vegetation. The soil-water reflects the rainwater/geothermal springs water in isotopic composition, which is more depleted as a result of isotopic fractionation in soil. δD values of soil-water increase, whereas δ13C values in soil-water decrease with the soil depth at all sites. Two equations connecting δD and δ13C in soil-water were deduced per season for soil-water; δ13C = 0.0812δD - 10.657 in winter; δ13C = -0.0278δD - 21.945 for summer. δ13C in soil-water is induced by Crassulacean Acid Metabolism (CAM) (mixture of C3 and C4 photosynthetic cycles) with a stronger C4 trend, which corroborates with δ13C of the geothermal springs. From literature, Amarula and Acacia trees have been documented for isotopic compositions, while this study has given additional information on other plants including Lowveld, Leadwood, Sausage, Fig, Guava and Mango trees. These plants are categorised as C3, C4 and CAM plants. C3 plants include Amarula, Lowveld and Leadwood trees; C4 plants include Acacia and Sausage trees; and CAM plants include Fig, Guava and Mango trees. This study shows that with CAM soils, there is a possibility of having either C3, C4 or CAM vegetation. This finding has shown that the δD and δ13C isotopes in water, soil and vegetation are interrelated, which has been statistically justified. This study has shown the potential human health risks associated with trace metals concentrations from geothermal springs and their surrounding soils. From the geothermal spring’s water, it was found that As, Cr and Cd were the highest contributors to the cancer risk with children having a higher risk than adults. Whereas in soils, it was found that Cr, As and Co were the highest contributors to the cancer risk in the studied communities. Therefore, the cancer risk is high in the general population; that is 1 in 72-162 individuals in children and 1 in 7-107 individuals for adults. The ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway. Therefore, proper monitoring and control measures to protect human health, particularly in children, should be implemented for safety. The study also explored the use of surrounding trees ix | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg for phytoremediation and found their uptake capacity to be high, thus, they could be used as bio-indicators to assess the level of contamination of trace metals in the soil. In conclusion, this study has eludicated on the isotopic signatures and trace metals concentrations from the geothermal springs and their surrounding soils and vegetation within Soutpansberg. This study has contributed towards the advancement and enhancement of the existing knowledge of the geothermal systems, such that water resource management could be applied successfully in the respective areas with similar characteristics for the benefit of the local communities and society at large. Hence, this study recommends that proper monitoring and control measures need to be put in place to protect human health, especially in children.
NRF

This study assesses the presence of selected trace metals and pops in the Baynespruit River, Sobantu, KwaZulu-Natal. Sediments, plants and water samples were collected along the river during dry and wet season. For metal analysis, the extraction was done using acid digestion and then determined on the inductively coupled plasma atomic emission spectroscopy, for total metals in sediments, plants and water. Bio-available metals in sediments were analysed using atomic absorption spectroscopy. POPs were extracted in sediments using soxhlet extraction, which was followed up by evaporation on the rotary evaporator, sample clean up on a GPC column, further sample concentration on the rotary evaporator and later analysed on GC/MS instrument. Metals of concern in both seasons were Cu, Cr, Pb and Zn which exceeded maximum permissible limits for South African soil, Cr was just about the maximum permissible limit. The targeted POPs were not detected on any site during this work.
Environmental Sciences
M. Sc. (Environmental Science)

Indiana University-Purdue University Indianapolis (IUPUI)
Mercury (Hg) has proven to be a risk to the public, mainly through the consumption of fish. Because of this, many fish consumption advisories have been issued in Indiana. Although much is known about the global cycle of mercury, little is known about how local and regional emission sources of mercury impact local and regional mercury cycling. This study’s objective was to determine the scope of mercury concentration in central Indiana by using a broad grid of soil mercury measurements. Sampling was designed to capture the net retained mercury content in soils, and to determine whether spatial patterns in exist in soil mercury contents that could be related to emission sources of mercury and post-emission transport patterns from wind. Results from this study revealed significant differences in mercury concentrations for soils in central Indiana. The core of the study area, concentrated in the urban area of Indianapolis, exhibited soil mercury contents that were 20 times higher than values in the outskirts of the study area. The spatial pattern resembled a bulls-eye shape centered on Indianapolis, and with comparison to the reported Hg emission from local sources, including a coal-fired power plant, indicates a strong regional deposition signal linked to those emission sources but marked by wind-driven transport to the northeast. This effect of local emission sources resulting in local deposition indicates that limiting mercury emissions will have a net beneficial impact on local environmental quality and human health.

Water pollution is a major threat to human population and dumping of pollutants into water body result in rapid deterioration of water quality and affect the ecological balance in the long run. The present study was undertaken to assess pollution load from river Borkena. In urban and suburban parts of Kombolcha, the use of industrial wastewater for irrigation purpose is a common practice. Local farmers in Borkena watershed use the wastewater to irrigate their agricultural fields for cultivation of vegetables. But they suffered from loss of productivity of leafy vegetables and skin injury because of their exposure to the wastewater during irrigation practices. That is why this study focused on assessing the amount of industrial waste load on river Borkena and its effects on communities in the watershed. The main aim of this study was: to assess the physico-chemical characteristics of River Borkena before and after industrial waste discharges mixed to it by the waste carrier small streams; and its environmental impact on the surrounding communities and vegetable farms. The methodology consisted: 1) Basic survey in order to assess the physical and chemical characteristics of the river water, and 2) a case study performed by focus group discussions with the community authorities and farmers in the study area who used the river water mainly for irrigation purposes. Sampling was conducted at 6 sites in the study area during low and high flow periods with an interval of three months for a period of one year in order to account for the seasonal hydrological cycle of the river water. Laboratory measurements of river water and leafy vegetables for metal concentration were also determined to investigate the effect of the use of the river water for growing vegetables and other personal cases. The findings of this dissertation showed metal concentrations in leafy vegetables and irrigation water are within the permissible limits of FAO/WHO standards and not significant for the time being, but is expected to be a challenge in the near future if not well addressed. The concentrations of metals in leafy vegetables will provide baseline data and it shows that, in the current situation consumption of leafy vegetables grown in the study area may not have health risks in the context of metal concentrations. To avoid the entrance of metals into the food chain, municipal or industrial wastes should not be drained into the river and farmlands without prior treatment. The continuous monitoring of the soil, vegetable plant and irrigation water quality are prerequisites for the prevention of potential river water. Laboratory measurements of river water and leafy vegetables for metal concentration were also determined to investigate the effect of the use of the river water for growing vegetables and other personal cases. The findings of this dissertation showed metal concentrations in leafy vegetables and irrigation water are within the permissible limits of FAO/WHO standards and not significant for the time being, but is expected to be a challenge in the near future if not well addressed. The concentrations of metals in leafy vegetables will provide baseline data and it shows that, in the current situation consumption of leafy vegetables grown in the study area may not have health risks in the context of metal concentrations. To avoid the entrance of metals into the food chain, municipal or industrial wastes should not be drained into the river and farmlands without prior treatment. The continuous monitoring of the soil, vegetable plant and irrigation water quality are prerequisites for the prevention of potential health hazards to human beings. Finally this study fills the gaps in information for concerned regional and federal governmental offices and may use it as an input to design regulations and policies which benefits the communities in the watershed.
Environmental Sciences
Ph. D. (Environmental Science)

Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction with selected physicochemical data, from representative wetland types at a mining site within Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands managed by a copper mining industry. These fishless wetlands are located in a geographic region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling study demonstrated the extent of variation in total Se concentration within the wetlands. With the exception of the sediment compartment, Se concentration did not differ significantly along the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se concentrations between the Creek East and West segments characterize lower Lee Creek as having two segments distinguished by unique processes that influence the sediment Se accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000 to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic invertebrates was more clearly associated with sediment/detritus Se concentrations than with surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera), generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated 1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent of trace metal type (essential or non-essential) or wetland occupation. Organism-specific factors, such as habitat selection and preferential feeding habits, were proposed to influence benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets, trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific processes impacted Se accumulating efficiency, with trace metal concentrations from 4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital organic carbon as dietary sources for the benthic food web. Sediment organic content was not significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological risk assessments based on sound understanding of metal chemistry and the interactions between the sediment matrix and benthic organisms are necessary to provide tools for environmental management.
Graduation date: 2005