Heavy metals present in high concentrations in aquatic habitats are bioaccumulated within the tissues of intertidal organisms. The chemical analyses of animal tissues and sediments provide an indication of bioavailability of heavy metals in the environment. Monitoring of the coastal pollution using organisms is widely practiced all over the world.Chemical analysis of the tissues of Pacific oyster, Crassostrea gigas, and river sediments were used in this study to monitor the environmental concentrations, of cadmium, copper, lead and zinc of shallow coastal areas near to the river mouths of Mahurangi, Awaruku, Waiake, Taiorahi and Wairau. All of these river mouths are situated along the northeastern coast of Auckland. Each month, during the period of November 2002 to October 2003, three replicate samples of oysters, and sediments were collected from each of the river mouths for analysis. Three additional replicate samples of oysters were collected separately, in each month in order to calculate the condition index of oysters. Oyster tissues and sediments were analysed with Inductively Coupled Atomic Plasma Emission Spectrometer to detect the concentration levels of cadmium, copper, lead and zinc.The highest level of copper and zinc concentrations in the oyster tissues was observed in the river mouth of Wairau. Wairau river mouth receives water from heavily urbanised and industrialised catchments. A higher concentration of cadmium was observed in the oysters of the river mouth of Mahurangi than in the oysters in the other sites. The reason for this difference could be due to the heavy use of cadmium contaminated fertilizers at the pasture lands situated around the Mahurangi estuary. Therefore, the relationship between the land use of the catchments and the degree of pollution of the estuarine habitats could be established from the data obtained from this study. Higher concentrations of heavy metals were found in the sediments of Waiake, Taiorahi and Wairau compared to the sediments of Mahurangi and Awaruku. Significantly higher level of copper was observed in the sediments of Awaruku. However no clear co-relation was found between heavy metal concentration in oysters and in sediments. Variations of the condition of oysters were closely related to seasonal changes of the life cycle of the oysters. No clear relationship was found between the condition of the oysters and the heavy metal concentration of the river mouth habitats.This study provides evidence that Pacific oysters are good organisms to use as bioindicators of environmental heavy metal levels in shallow coastal waters. The results of this study suggest a clear relationship between the heavy metal concentration in river waters and the land use of the catchment areas of those rivers. The results may be useful in management strategies of the northeastern coastal areas of Auckland.

ABSTRACT This work examined the role of micro-organisms in the biogeochemical cycling of selenium within the benthic ecosystem of Lake Macquarie, a coastal lake in New South Wales with a history of anthropogenic heavy metal contamination. Certain micro-organisms possess the ability to oxidise or reduce selenium (Fleming and Alexander, 1973; Doran and Alexander, 1977), and microbial volatilisation of selenium from contaminated sediments and soils utilising naturally-occurring microflora has been shown in overseas research (Thompson-Eagle and Frankenberger, 1992) to be a potentially effective remediation strategy. In examining the impact of micro-organisms upon the oxidation state of selenium in Lake Macquarie sediments, this work also investigated and characterised selenium (and heavy metal) concentrations, speciation and geochemical phase associations (an indicator of potential bioavailability) in the sediments. Seven distinct bacterial species indigenous to Lake Macquarie were identified in this work with the ability to reduce selenium as selenite to elemental selenium, and selenium as selenate to organic forms of selenium, including volatile methylated selenium compounds. Metabolic parameters calculated for these organisms compared favourably with those reported in the literature by other researchers. Mixed populations of sediment micro-organisms were also isolated and studied in this work for their selenite and selenate reduction abilities. Total reduction of added selenite at levels up to 100 mg/L was recorded for a number of the organisms studied in this work. A maximum specific uptake rate for selenite of 3040 mgSe(IV).(gcells)-1.(h)-1 for one isolate (Shewanella putrefaciens) was determined, exceeding rates reported in the literature by other authors. Use of the indigenous micro-organisms from Lake Macquarie for the bioremediation of selenium containing waste streams was also examined in this work and selenium reduction in an immobilised cell reactor was demonstrated with such organisms. Concentrations, speciation, sediment core profiles and geochemical phase associations for selenium were determined for sediment samples collected at a variety of sites throughout Lake Macquarie and from Wyee Creek, a selenium-impacted fluvial input to the lake. The maximum concentration of selenium obtained in this work for the lake proper was 4.04 mg/kg, considerably lower than values reported over a decade ago (Batley, 1987) but consistent with reported reductions of selenium input into the lake from the lead-zinc smelter. Selective extraction methodology (Tessier et al. and BCR methods) studied geochemical phase association of selenium in Lake Macquarie sediments and found up to 44% of selenium was in bioavailable forms. Of interest and environmental concern was levels of selenium found in sediments of Wyee Creek, which previously received overflows from the ash dam associated with the Vales Point Power Station. Sediment selenium levels of up to 300 mg/kg were determined for this creek. These were an order of magnitude or more greater than those recorded for the lake itself and are of concern as to the potential impact on benthic organisms and those animals, including humans, who consume them. While this work can only provide a 'snapshot' of conditions within Lake Macquarie at the time of the sampling events recorded herein, it does make several important contributions to the understanding of selenium biogeochemistry in Lake Macquarie. These include: presentation of the hypothesis that selenium levels in surficial sediments being deposited in the north of the lake have decreased in recent years as a result of selenium reduction measures undertaken by the lead-zinc smelter; determination that up to 44% of selenium in surficial sediments from the lake is associated with sediment phases in which selenium has the potential to become remobilized and hence possibly bioavailable; and documentation of selenium concentrations in Wyee Creek, identifying the area as having selenium concentrations an order of magnitude or more greater than the lake itself. Concerning the role played by microorganisms in the biogeochemical cycling of selenium in Lake Macquarie, this work has: identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenite to lower oxidation states; identified individual isolated and mixed cultures of bacteria that can reduce selenium as selenate to lower oxidation states; identified volatile methylated selenium compounds in the headspace gases of microorganisms reducing selenate; determined Minimum Inhibitory Concentrations for selenate and selenite for organisms isolated from Lake Macquarie; identified casein hydrolysate as a preferred carbon source for selenium reducing microorganisms from Lake Macquarie; and demonstrated that bioremediation of selenium contaminated waste streams using indigenous organisms from Lake Macquarie is feasible on the laboratory scale. Further research areas suggested by this work include: additional investigations of elevated selenium levels in Wyee Creek sediments; determination of the role of microbes in in-situ selenium reduction; and optimisation of selenium biotreatment/bioremediation of selenium-containing waste streams and sediments. In summary, this work, in rejecting the null hypothesis that the oxidation states of selenium in sediments from Lake Macquarie, NSW, are independent of microbial activity and accepting the alternate hypothesis that these oxidation states are not independent of microbial activity, contributes to the understanding of the role of microorganisms in the biogeochemical cycling of selenium, having applicability to both the specific ecosystem of Lake Macquarie, NSW, and also to selenium cycling in the environment in general. In addition, this work has identified selenium contamination in Wyee Creek, one of the fluvial inputs to Lake Macquarie, which was previously been undocumented in the literature and which may pose significant potential risk to humans and the ecosystem due to sediment selenium levels one or more orders of magnitude higher than those recorded in the lake itself. Finally, this work has also identified a number of microorganisms indigenous to Lake Macquarie with the ability to reduce selenium from toxic, mobile forms to less toxic, immobile or volatile forms, and these organisms have been shown to have the potential for use in treatment of selenium contaminated waste streams and also in the bioremediation of selenium-contaminated sediments.

This study investigated the catchment of an urban wetland on sandy soils in Perth, Western Australia. The wetland is of high conservation value but is currently used as a stormwater-compensating basin. The three main aims of this work were to: 1. determine the importance of stormwater drains in the water and pollutant balance of the lake; 2. evaluate pollutant retention rates by the wetland; and 3. identify current land uses in the catchment, determine their impacts on the wetland and identify tolerable levels of urbanisation for a wetland of this type. Stormwater flowing in and out of the lake subcatchments was monitored for two years for background flows and storm events. Water discharge, physical and chemical characteristics —including nutrients and heavy metals — were measured. Water and pollutant mass balances were determined. There was year-round flow at all sites, except from the smallest subcatchment. Flow characteristics differed between sites and were more influenced by catchment characteristics than rain intensity or duration. More water entered than left the lake in spring. In autumn more water left the lake via the overflow than entered. Due to poor maintenance, many drains overflowed during storm events. When compared to Australian and New Zealand Environment and Conservation Council (ANZECC) water quality guidelines for receiving waters, only pH and conductivity met the recommended criteria. The nutrient and heavy metal loads varied with rainfall during both years of study. Suspended solids, total nitrogen and total phosphorus concentrations were proportional to rainfall, while concentrations of dissolved forms of nutrients were not. Background flows contributed significantly to the pollutant load. More than 85% of total suspended solids, nutrients and heavy metals were retained by the wetland — the only exceptions being copper and some forms of dissolved nutrients. An evaluation of the performance of the lake as a pollutant sink, using published data from constructed wetlands, identified phosphorus as the pollutant that requires the largest area for treatment.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 90-97). Also available on the World Wide Web.

Thesis (Ph.D.) -- University of Western Sydney, 2003. / "Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Lic.-avh. (sammanfattning) Västerås : Mälardalens högskola, 2007. / S. 55-59: Bibliografi.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 148 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical reference.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Restricted until May 2003. Bibliography: leaves 135-141.

Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Bibliography: leaves 243-258.