In this research, the determination of trace concentrations of heavy metal ions was investigated using peptide modified electrochemical biosensors. The biosensor has several advantages over atomic absorption spectroscopy and inductively coupled plasma mass spectrometry by offering greater simplicity in use and the possibility of determining the bioavailability of heavy metals. Oligopeptides were modified on the electrode surface through the spontaneous self-assembly of thiols on gold. Firstly, 3-mercaptopropionic acid (MPA) was self-assembled onto the gold surface followed by activation of the carboxyl groups using a combination of carbodiimide and succinimide chemistry for coupling of the N-terminus of the peptide to occur. Using this generic strategy, Gly-Gly-His was used for the determination of copper ions. Cu2+ was accumulated at the MPA-Gly-Gly-His modified electrode at open circuit potential followed by electrochemical measurements. The reduction of Cu2+ to form underpotential deposited copper in the Osteryoung square wave voltammogram was used for quantification. The influence of various factors on the performance was investigated and after the optimal conditions had been identified, the biosensor was used for Cu2+ calibration and was applied to the analysis of a real sample. For Cd2+ detection, two different peptides covalently attached to MPA were investigated, g-Glu-Cys-Gly (GSH) and His-Ser-Gln-Lys-Val-Phe, with the latter sensor exhibiting a lower Cd2+ detection limit, higher sensitivity and greater selectivity. Although the success of MPA as a peptide linker to the gold surface had been shown for the detection of Cu2+ and Cd2+, a more viable approach was necessary for the stable detection of a wider range of metal ions. A more stable self-assembled monolayer of thioctic acid (TA) was identified in which human angiotensin I was attached. This alternate modification procedure was superior to MPA-angiotensin I for Pb2+ detection in terms of stability and reusability with the drawback being sensitivity. The newly identified strategy was also applied to the determination of Ag+ using TA-methionine enkephalin modified electrodes. A sensor array for Cu2+ was also investigated as well as an extension to the simultaneous determination of multianalytes using four different modified electrodes. Combining a soft-modelling approach, the responses of Cu2+, Cd2+ and Pb2+ could be deconvoluted.

Urbanisation in coastal catchments has significantly increased not only the input of terrestrial sediment to the marine environment but also the input of contaminants. In Tamaki Estuary, Auckland, heavy metals have accumulated in the upper estuarine muddy sediments and metal contamination has been detected on downstream intertidal sandflats. Sub-lethal levels of heavy metal contamination may affect the growth and behaviour of benthic organisms, which in turn may influence key ecosystem processes and productivity. The aim of this study was to examine whether the burial rate of an ecologically important bivalve species (Austrovenus stutchburyi) differed between a contaminated and a lesser-contaminated site and whether burial rates were affected by density. A secondary aim was to determine whether the burial of Austrovenus affected sediment transport and consequently if this was affected by density. This study demonstrated no consistent difference in burial time between source populations (sites). This was explained by a lack of measured difference in the condition index and heavy metal tissue loading of Austrovenus used throughout this study. The present range of contamination measured in Tamaki Estuary, Auckland, did not have negative biological consequences on the key ecosystem engineer, Austrovenus stutchburyi. Contamination levels in Tamaki Estuary may not be high enough to cause major physiological or behaviour changes to infaunal organisms, such as Austrovenus. Sediment erodability was not significantly correlated with any measured environmental and biotic factors. Austrovenus density was the only predictor variable that could be used to explain any variation in sediment erodability. There was no significant density effects observed between the amounts of sediment eroded for densities gt; 150 ind. m-2. There was a significant difference between sediment void of Austrovenus (0 ind. m-2; smooth, flat undisturbed sediment surface) and sediment containing Austrovenus (gt;150ind. m-2; physical structure on/in the sediment surface, increase in bed roughness). These results indicate that there is little or no effect of Austrovenus on the critical erosion threshold, suggesting that in the absence or presence of Austrovenus the current required to erode 10 g m-2 of sediment would remain somewhere between 28.5 and 30.5 cm s-1. This study found that there was considerable variation in the burial rate of individuals and the greatest variation was recorded in the lowest density treatments (150 ind. m-2), which corresponded to the same density that had the greatest variation in sediment erodability. Further investigations are needed to gain a better understanding into the important roles (the importance of the various feedbacks and limitations and interrelationships) that Austrovenus play in the soft-sediment ecosystem, as losses of this species are likely to have large-scale impacts on the wider soft-sediment communities and ecosystem functioning.

Urban stormwater runoff is recognised as a substantial source of heavy metal contamination, which adversely impacts on water quality of regional receiving waterways. Conventional treatment of urban runoff mostly involves a filtration system using sand to retain particulate matters. Sand provides limited sorption of dissolved metals and the inclusion of commercial sorbents to these treatment systems is not cost effective due to the concentration of dissolved metals in the runoff. Recycled organic materials are by-products or waste from industrial or agricultural operations, and could be alternative low cost sorbents for stormwater treatment systems. The use of recycled sorbents also provides added value to the waste materials and reduces landfill disposal. The research explores the application of compost, zeolite, ash, and recyclable waste in urban runoff treatment, especially for dissolved metal removal. The research combines the two aspects of experimental studies and management analysis to develop a holistic approach to heavy metal control in urban stormwater systems. Experimental results of batch sorption test show that compost is suitable for removing dissolve copper in stormwater treatment. The comparison of the different mixing ratios between compost and glass beads in column test evaluates the optimum mixing sorbent and performance over a long period for copper removal. Substance Flow Analysis (SFA) of copper has been performed in the Upper Parramatta River Catchment, Sydney to identify the sources of copper associated with runoff, effect of using waste material such as compost in urban stormwater treatment and the copper load in urban stormwater runoff. This case study shows the relationship between copper input, copper stock, sorbent type and urban stormwater quality control in the system boundary of the catchment. Different scenarios of source control are evaluated to control copper load from the different sources. Source control focusing on roads and vehicles is the most effective copper control strategy. The combination of source control and stormwater treatment reduces copper in stormwater and receiving water. The thesis applies the analysis from SFA and experimental results to derive both a regional system-wide solution with source control, and an improved design of stormwater treatment for heavy metal removal using recycled organics.

Concentrations of heavy metals (Cu, Cd, Cr, Zn, Mn, Fe and Pb) in the water columns, aquatic plants and sediments of fourteen lakes of varied levels of pollution were measured. Correlation analysis was carried out between heavy metal concentrations in aquatic plants and heavy metal concentrations in water and sediment. The aquatic plants which accumulated heavy metals in their tissues in proportion to that in water and sediments were identified. The aquatic plants studied were: 8/yxa auberti Rich, Cabomba caroliniana Gray, Ceratophyllum demersum L, Ceratopteris thalictroides (L.) Bron, Chara globularis, Eichhornia crassipes Solmn, Hydrilla verticillata Royle, Ipomoea aquatica Forsk, Limnophila aromatica (Lam.) Merr., Ludwigia adscendens (L) Hara, Nelumbo nucifera Gaertn, Nymphaea stallata Linn, Nymphoides indica (L.) Kuntze, Typha angustata Bony & Chaub and Utricularia aurea Lour. Metal uptake by aquatic plants varied between different species and within the same species depending on lake water contamination levels. The level of metal uptake to a great extent was a function of the environment water metal concentration. Results showed that Utricularia accumulated Mn, Zn, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.69, 0.63, 0.69, 0.65 and 0.39 respectively). Hydrilla accumulated Cu, Mn, Zn, Fe, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.65, 0.66, 0.44, 0.72, 0.38, 0.63, and 0.73 respectively). Blyxa leaves accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.74, 0.74, 0.72, 0.60 and 0.82 respectively). Echhornia leaf accumulated only Cr in direct proportion to the overlying waters r2 = 0.81. Nymphaea leaf and Chara did not accumulate any metal in direct proportion to the overlying waters. Roots of Blyxa auberti, Ceratopteris thalictroides, and Eichhornia crassipes contained higher concentrations of heavy metals than their leaves. Roots of Blyxa accumulated Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.91, 0.65 and 0.69 respectively). Echhornia root accumulated Cd in direct proportion to the overlying waters with r2 = 0.90. Nymphaea stem showed no significant correlations between the metal concentrations in the waters and in the plant. Utricularia accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the metals in the underlying sediment extracted by cold hydrochloric acid (r2 = 0.84, 0.51, 0.47, 0.68 and 0.80 respectively). Hydrilla accumulated Cu, Zn, Cr, Cd and Pb in direct proportion to the underlying sediment (r2 = 0.34, 0.37, 0.91, 0.49 and 0.96 respectively). Blyxa accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the underlying sediments (r2 = 0.99, 0.61, 0.82, 0.75 and 0.64 respectively) . Echhornia leaf showed significant correlation between the Cu (r2 = 0.83) and Cr (i2 = 0.88) concentration in underlying sediment and the plant. Nymphaea leaf showed a significant correlation between the Zn (r2 = 0.83) concentration in the plant and the underlying sediments. Roots of Blyxa showed significant correlation between concentrations of Cu, Cr and Pb in sediment extracted by hydrochloric acid and plant (r2 = 0.9, 0.7 and 0.9 respectively). Roots of Echhornia had no significant correlation with the sediment metal concentrations (hydrochloric acid extractable). Two techniques (cold hydrochloric acid extractable and nitric acid extractable) to extract metals from sediment were compared. Based on correlations of metal concentrations in plant tissue and metal extracted from the sediment, it was concluded that the cold hydrochloric acid extractable metal technique is more suitable for determining bioavailable sediment metal concentration in environmental studies. Laboratory studies investigations on the bioaccumulation of Zn and Cu in Hydrilla confirmed that Hydrilla is a good bioindicator of Cu as it accumulated 20360 ug/g dry weight of Cu in 72 hours. Hydrilla showed higher bioaccumulation factor with low concentration of Cu in the solution, in the laboratory studies. Hydrilla was determined to be the best indicator species as it reflected the heavy metal concentration in the environment which was supported by the laboratory studies.

Master of Science / Investigations of fluvial and estuarine sediments have indicated stormwater is an important source of heavy metals to Port Jackson estuary and high concentrations of these sedimentary contaminants are a threat to the healthy functioning of the estuarine ecosystem. Stormwater remediation devices have been installed in stormwater channels entering the estuary, however these devices are mainly for removing gross pollutants and are ineffective in removing heavy metals from stormwater. A thorough characterisation of heavy metal inputs and behaviour has been undertaken by sampling, analysing and modelling heavy metals in stormwater entering Port Jackson estuary to provide a rigorous data base for future remediation efforts. A conceptual model of transport and fate of heavy metals in stormwater entering Port Jackson estuary has also been developed to identify heavy metals, subcatchments and flow regimes requiring remediation, and to assist in designing remediation devices for optimum removal of heavy metals from stormwater. Modelling of stormwater using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) indicated that the average annual discharge of stormwater from the Port Jackson catchment was 215,307 ML. Average annual loadings of arsenic, cadmium, chromium, copper, nickel, lead and zinc in stormwater discharging to Port Jackson estuary were 0.8, 0.5, 1.7, 3.2, 1.1, 3.6 and 17.7 tonnes per year, although comparison to other studies in the catchment suggests these values may be underestimations of actual loadings by 1.3 to 10 times. The proportion of heavy metals discharged under low-flow conditions (<5mm of rainfall in 24 hours), medium-flow conditions (between 5 and 50mm in 24 hours), and high-flow conditions (>50 mm of rainfall in 24 hours) was 6.5%, 62.5% and 31%, respectively. The conceptual model indicates stormwater loadings of copper, lead and zinc pose a risk to the health of riverine and estuarine ecosystems in the catchment and these metals should be targeted for remediation. Stormwater channels which should be prioritised for remediation include the channels entering southern embayments west of Darling Harbour; Duck, Parramatta and Lane Cove Rivers; and the channels and rivers entering Neutral, Long and Sugarloaf Bays. Stormwater loadings of lead are predominantly associated with suspended particulates, whereas loadings of copper and zinc are equally partitioned between dissolved and particulate phases. Stormwater remediation strategies should target both dissolved and particulate phases to ensure effective removal of copper, lead and zinc. Research suggests heavy metals in stormwater discharged to the estuary under high-flow conditions are rapidly exported seaward and bypass the estuary. Preliminary research also suggests that under medium-flow conditions, particulate heavy metals bypass the embayments of Port Jackson and are deposited in the main channel. Once deposited in the main channel, particulate heavy metals are likely to be remobilised and removed from the estuary through multiple phases of resuspension. Although further research is required in this area, this preliminary research suggests remediation should target low-flow conditions. The findings of the current research could be used to identify appropriate remediation strategies for dissolved and particulate phase heavy metals in stormwater discharging to Port Jackson estuary. However, in designing stormwater remediation devices, consideration should also be given to the range of contaminants that may be present in stormwater entering Port Jackson estuary (including suspended solids, nutrients, pesticides and organics).

Thesis (M.Sc.)--University of Guelph (Ont.), 2001. / Adviser: Ray Kostaschuk. Includes bibliographical references.

More than 30,000 potential Superfund sites have been identified. Heavy metals are contaminants at many of these Superfund sites. The average cost of cleanup a single-typical Superfund site currently stands at $20 million, and it is expected that the cost may escalate to $50 million within the next decade. Problems have already been encountered during the inspection of sites, and available technologies have not been effective in treating all sites. Lack of innovative strategies for dealing with contaminated soils is a major obstacle to completing Superfund site cleanup. The characteristics of low molecular weight (LMW) organic acids (citric, oxalic, and succinic acids) can be utilized as an agent in soil washing and flushing to develop an innovative technology in the remediation of the soil contaminated with heavy metals. The objective of the work was the testing of a new remediation technology involving soil flushing and washing with LMW organic acids, designed to permanently remove heavy metals from contaminated soil at Superfund sited. Significant amounts of heavy metals (Cu, Pb, Zn) were removed and formed soluble metal-organic complexes at higher concentrations of organic ligands. At a citric concentration of 100 mM, over 70~80% of copper, lead, and zinc were mobilized and all metals extracted were complexed with citrate ions as various forms. Therefore, the use of citric acid to remove heavy metals from contaminated soils would be less costly that using EDTA. The subsequent pH elevation by hydrated lime, Ca(OH)₂, causes the decomplexation of Pb-citrate and initiates precipitation of lead hydroxide. Results showed that slightly alkaline conditions (pH 8.5), which are much lower than that used with EDTA, are needed for substantial precipitative removal of the lead. Increasing calcium nitrate concentration significantly improved the Pb(II) desorption via a cation exchange reaction, That is, the time required to recover lead from the contaminated soil during a soil column experiment was greatly reduced as the concentration of calcium nitrate in the influent was increased. Varying influent pH had little effort on the rate of lead mobilization in the soil columns due to the buffering capacity of the soil, which maintained the effluent pH at the soil pH. The effluent flow rate had no effect on mobilizing Pb(II) from the soil. A higher concentration of citric acid resulted in a much faster rate of lead mobilization from the contaminated soil. Differences in lead desorption rates between influent pHs of 4.5 and 6 were significantly high. However, lead desorption curves for citrate solution at a lower pH value (pH < 4.5) were nearly identical. The flow rate of effluent has no effect at removing lead in the range of 0.1~1.0 mL/min. Also, lead transport model was developed under the assumption of one-dimensional flow through a homogeneous porous medium. A simplified model was also developed by assuming no dispersion effect, no immobile aqueous-phase zone, and linear desorption kinetics. An analytical solution of the simplified equation was obtained by solving a partial differential equation. The computer simulations were fitted to experimental data using estimates for model parameters which were not obtainable independently in experiments. At higher concentrations and pH of the influent, this model presented here fitted well with the experimental data. / Graduation date: 2013

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 160-168). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 160-168). Also available on the Internet.

Thesis (Ph.D.) in Ecology and EnviroNmental Sciences--University of Maine, 2002. / Includes vita. Bibliography: leaves 219-247.