University of Technology, Sydney. Faculty of Science. / The suitability of the Sydney rock oyster (Saccostrea commercialis) as a monitor of heavy metal contamination in estuarine and coastal waters was assessed. Case study I examined the influence of body size (ie: soft tissue dry weight) on the tissue concentrations of Cu, Zn, and Fe. Sampling was replicated both spatially and temporally in order to determine whether the size-metal relationship for these elements varied with geographical location (ie: differing levels of environmental contamination) or season. All oysters were collected from 'wild' populations in the HawkesburyfNepean estuary. Least-squares regression analysis indicated that Cu concentrations were independent of body size at all times. Analysis of covariance (ANCOVA) showed that this relationship did not change with either geographical location or season. Size-metal relalionships for Zn indicated that concentrations for this element varied from being independent of size to being size-dependent with proportionally greater concentrations present in the larger individuals. Yet lests for homogeneily of slopes (ANCOVA) showed that no differences in regression coefficients occurred with geographical location or season. Iron concentrations were size-dependent with proportionally greater concentrations in the smaller individuals. ANCOVA revealed that homogeneity of slopes with geographical location occurred only on two of the four sampling occasions. Further examination of data revealed that the size·range of the individuals sampled may be important in determining size-metal relationship for iron. Case Study II examined the concentrations of Cu and Zn in S. commercialis deployed into the Georges River/Botany Bay and the Port Stephens estuaries. The influence of tissue assimilation/loss on metal concenlralions was also examined. Organisms of a homogenous genetic stock, of a similar size and age, and transplanted to a similar lidal height were utilized. As all organisms were of a similar size and age at the time of their deployment any differences in size during sampling were attributed to growth. Results indicated that tissue loss (ie: 'degrowth') not accompanied by a similar loss of metal resulted in an increase in metal concentrations. The assimilation of new tissue at a greater rate than metal accumulation (ie: 'dilution') resulted in decreased metal concentrations. From these relationships it was apparent that measures must be taken to reduce, account for, or eliminate the effects of growth in bivalve monitoring programs. Unless this problem is addressed, metal concentration values in S. commercialis are likely to give an inaccurate estimation of the level of environmenlal contamination and confound attempts to isolate pollution point sources.

The detection of anthropogenic impacts in our estuaries has become a critical social, political and scientific concern in recent years. Work has focussed on the effects of these impacts on the spatial and temporal patterns of biotic assemblages and searched for bioindicators and biomarkers of pollutants that may act as early warning signs. The estuaries in temperate Southeastern Australia have a diversity of biotic assemblages living in the soft sediment. One of the most abundant macroinvertebrates is the little studies mussel, Xenostrobus securi that is found living with an assemblage of benthic biota including amphipods, crabs, isopods and tanaids, bivalves and gastropods. Two commercial fish species bream and mullet also inhabit these estuaries. Numerous stormwater drains can be found entering the estuaries through the mangrove forests lining the shores. Along with inputs of freshwater, stormwater drains are thought to be responsible for the entry of heavy metals into estuaries. These heavy metals have the potential to alter the patterns of biotic assemblages and bioaccumulate in the tissues of miacroinvertebrates, mussels and fish living within temperate estuaries. Over the time of this study the concentrations of heavy metals in the sediment tissues and shell of X.Securis varies spatially and temporally. Although this study adds substantially to current knowledge there is still more that is needed to establish X. Securis as a bioindicator. Questions remain about uptake, depuration and response to environmental gradients of heavy metals in X. Securis. Before X Securis can be used routinely in monitoring heavy metal contamination these questions need to be further investigated / Doctor of Philosophy (PhD)

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 thesis presents the results of an investigation into the uptake and distribution of cadmium (Cd) in two cultivars of potato (Solanum tuberosum L.) shown to contain different concentrations of Cd in the tuber at maturity. An initial glasshouse trial sought to determine whether differences in tuber Cd between these two cultivars resulted from differences in uptake from the soil, or were due to differences in the allocation of Cd to the various tissues within the plant. Total uptake of Cd from the soil did not differ between cultivars, nor did the yield of tubers. However, there were marked differences in Cd distribution within the plant. Most of the differences in tuber Cd concentration could be accounted for by a large (3-fold) retention of Cd in the roots of cultivar Wilwash. The concentration of Cd in the shoots of Wilwash was also higher than of Kennebec, although to a lesser extent than the roots. Further studies were conducted to trace the pathways of Cd uptake and movement within the plant. A split-pot trial, involving long-term growth of potatoes in 109Cd-labelled soil, was undertaken to determine the overall pattern of Cd distribution and the importance of the root system in supplying Cd to the tubers. The root system of the potato plant is different to many plants, in that the main root system (basal roots) is augmented after tuber initiation by roots extending from the stolon and from the tuber itself. The basal roots were found to be the dominant source of Cd to all tissues and accounted for approximately 85 % of tuber Cd. The remaining tuber Cd was sourced directly from the stolon and tuber roots. However, there was no evidence of a direct link between the main (basal) root system and the stolons. Although Cd was found to accumulate in the periderm of the tubers, there was no uptake into the tuber tissue itself. Isotopic studies were undertaken to investigate the short-term movement of newly absorbed Cd in the xylem and the phloem. Cadmium was found to be highly mobile in both the xylem and phloem, with added Cd being rapidly assimilated into all tissues following both root and foliar application. Newly absorbed Cd was rapidly sequestered by the stems when applied to either the soil or to a source leaf, suggesting that the stems may act as a transitional storage pool when rapid turnover of nutrients and other mineral elements is required during tuber bulking. Inhibition of Cd uptake by zinc (Zn), has been proposed as a method for reducing the concentration of Cd in various agricultural crops, including potatoes. The ability of Zn to reduce Cd uptake was found to be highly dependent upon cultivar and on the concentration of Cd in the external medium. Although competition between Zn and Cd was found for cultivar Wilwash when the external concentration of Cd was low, when the concentration of Cd in the external media was high, increasing Zn served to increase Cd uptake. Both synergistic and competitive responses were also noted for cultivar Kennebec. However, the patterns of response were opposite to those evident in Wilwash. The complexity of these interactions highlighted the possible shortcomings in using soil applied Zn to limit Cd uptake by potatoes. / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004.

There is community concern about toxic contaminants in Chinese herbal medicines. The two areas of contamination that attract most attentions are the nephrotoxic chemical, aristolochic acids found to be present in some Chinese herbs and resulting in renal failure of over 200 patients in Belgium, and heavy metals such as lead, arsenic, cadmium, mercury and chromium, which can cause systemic, CNS, neurological and developmental pathologies. Currently there is a lack of systematic information about the aristolochic acid content in Aristolochia species and related genera, nor have there been any studies on metal contamination conducted in Australia which can provide some scientific basis for assessment of potential risk of Chinese herbal medicines posed to consumers in Australia. This research aimed at addressing these concerns by firstly carrying out a systematic measurement of the contents of aristolochic acids in some relevant raw herbal medicines (CHM) and proprietary medicines (CPM)- 27 CHM, and 7 CPM, and secondly analysing the contents of five heavy metals in 100 CHM, 50 CPM, and 5 commonly used Chinese medicinal formulae (CMF) in the form of raw herbs, and finally evaluating the potential systemic metal toxicity caused by routine ingestions of Chinese medicines in the common form of encapsulated concentrated powder extracts formulated for the treatment of seasonal allergic rhinitis by means of measuring the metal concentrations in blood collected from 71 patients in a randomised double-blind control clinical trial (RCT). Results showed that four of the 37 CHM and two of the 7 CPM contained the banned toxic aristolochic acids. Some of these contaminated medicines could still be purchased over-the-counter in Victoria. Quantitative screening of metal contamination in CHM found that metal concentrations were much lower in the aqueous solutions than in the acid-digested samples. Almost all CHM, CPM and the 5 CMF contained the five heavy metals. Contrary to popular perception, their metal concentrations in the clinically ingested form were extremely low. Their prescribed ingested contents calculated as percentages of the universally recognised regulatory safety standards, the WHO provisional tolerable weekly intake (PTWI), would produce only small percentages of the PTWI for the metal concerned. This was true even when the metal intakes from any forms of Chinese medicines were added to the normal Australian daily dietary metal exposure. These new approaches of analysing the aqueous extractions, as well as interpretation with reference to the WHO regulatory standards and in combination with the Australian normal daily diet, are more relevant and realistic. The RCT in vivo study demonstrated no significant metal accumulation in the blood of both the real treatment group and the placebo control group, thus, attesting to the encouraging finding of the herbal medicine analysis. In conclusion, there is still much to improve in Australia in terms of enforcing the regulation of banning the sale of Chinese herbal medicines that might contain the highly nephrotoxic aristolochic acids. On the other hand, all forms of Chinese medicines in Victoria are safe, and do not appear to pose significant health concerns in terms of metal contamination.

<p>Wetlands water quality is influenced by the anthopogenic activities in the catchments’ areas. Wastewaters from the urban storm, agricultural runoff and sewage treatment often end up in wetlands before flowing to rivers, lakes and the sea. A lot of pollutants are readily transported in these wastewaters, thus subjecting the wetland ecosystem into a continuous resilience. Importantly, heavy metals like Cu, Zn, and Pb etc. are constituents of such pollutants in the wastewaters.</p><p>The study has as a specific objective to investigate the effects of heavy metal Cu, Zn and Pb on denitrification, an important ecosystem process and service. In a wetland situation, denitrification is a permanent nitrogen removal process accounting for about 90% of the total nitrogen removal.</p><p>The research was carried out in the laboratory and sediment samples were taken from a constructed wetland in Linkoping. We employed acetylene inhibition technique in obtaining N2O as a product resulting from nitrate reduction. The treatments (Cu, Zn and Pb) levels were 100 mg/kg, 250 mg/kg, 500 mg/kg and 1000 mg/kg of sediment, in three replicates and a control.</p><p>Samplings of the assay were taken within 24hours. Gas chromatography was used to analyse and quantify N2O in the various samples. A linear regression analysis was carried out with Windows Excel and SPSS to compare the various treatments with the control at 95% confidence level.</p><p>The results show that there were no inhibitions of denitrification at 100 mg/kg sediment treatment level for any of the element. Inhibition of denitrification was observed at treatment levels 500 mg/kg and 1000 mg/kg of sediment. The rate of nitrate reduction was compared from the slope of the regression curve. The rate for Cu at 500 mg and 1000 mg /kg of sediment was moderately related to that of the control, Zn shows a similar trend but a higher rate in some samples, while Pb shows more inhibition.</p>

Wetlands water quality is influenced by the anthopogenic activities in the catchments’ areas. Wastewaters from the urban storm, agricultural runoff and sewage treatment often end up in wetlands before flowing to rivers, lakes and the sea. A lot of pollutants are readily transported in these wastewaters, thus subjecting the wetland ecosystem into a continuous resilience. Importantly, heavy metals like Cu, Zn, and Pb etc. are constituents of such pollutants in the wastewaters. The study has as a specific objective to investigate the effects of heavy metal Cu, Zn and Pb on denitrification, an important ecosystem process and service. In a wetland situation, denitrification is a permanent nitrogen removal process accounting for about 90% of the total nitrogen removal. The research was carried out in the laboratory and sediment samples were taken from a constructed wetland in Linkoping. We employed acetylene inhibition technique in obtaining N2O as a product resulting from nitrate reduction. The treatments (Cu, Zn and Pb) levels were 100 mg/kg, 250 mg/kg, 500 mg/kg and 1000 mg/kg of sediment, in three replicates and a control. Samplings of the assay were taken within 24hours. Gas chromatography was used to analyse and quantify N2O in the various samples. A linear regression analysis was carried out with Windows Excel and SPSS to compare the various treatments with the control at 95% confidence level. The results show that there were no inhibitions of denitrification at 100 mg/kg sediment treatment level for any of the element. Inhibition of denitrification was observed at treatment levels 500 mg/kg and 1000 mg/kg of sediment. The rate of nitrate reduction was compared from the slope of the regression curve. The rate for Cu at 500 mg and 1000 mg /kg of sediment was moderately related to that of the control, Zn shows a similar trend but a higher rate in some samples, while Pb shows more inhibition.

Background The renewed interest in community participation in health research is linked to its potential for bridging gaps between research and practice. Its main attributes are the generation of knowledge that can lead to socially robust, long-lasting solutions and the creation of a colearner relationship between researchers and research users. Following this philosophy, Ecohealth has evolved into a specialized framework for participatory research on the impact of pollution on ecosystems and human health. However, its principles pose considerable challenges. Its outcomes are strongly influenced by contextual factors that are impossible to control for ahead of time. This paper describes how the Ecohealth principles were applied to an epidemiological study of heavy metals exposure among indigenous communities of the Peruvian Amazon. It illustrates how knowledge generated from participatory research does not necessarily imply solving a public health problem. This study aimed to contribute to the understanding of the benefits and barriers of following the basic principles of the Ecohealth approach, and assist researchers working in similar contexts. Research process Based upon their personal experience as participant observers, the authors describe the research process; then, they discuss the most important challenges faced, their implications, and the attempted strategies for resolution. Challenges Challenges were grouped into four themes: (1) building trust; (2) one partnership, many stakeholders, multiple agendas; (3) being a researcher; and (4) communicating complex and unexpected findings. Conclusions Integrating the principles of transdisciplinarity and participation posed a series of challenges to the research process that were difficult, and sometimes impossible to overcome. However, positive outcomes from this experience were the lessons learned by the different actors. Despite the lack of immediate action, it is expected that useful interventions to prevent and control lead exposure in the Corrientes population will be implemented in the medium term. / <p>Funding for the epidemiological study described in this paper came from the Comprehensive Health Care Plan for the Corrientes Native Communities (PEPISCO) and a grant from FAS, the Swedish Council for Working Life and Social Research (grant 2006–1512).</p>

Heavy metals, such as copper and cadmium have been linked to a number of cellular dysfunctions in single and multicellular organisms that are associated with apoptosis. The yeast, Saccharomyces cerevisiae, provides a valuable model for elucidating apoptosis mechanisms, and this study extends that capability to Cu and Cd-induced apoptosis. We demonstrate that S. cerevisiae undergoes a glucose-dependent, programmed cell death in response to low cadmium concentrations, which is initiated within the first hour of Cd exposure. The response was associated with induction of the yeast caspase, Yca1p, and was abolished in YCA1∆ mutant. Other apoptotic markers, including sub-G1 DNA fragmentation and hyper-polarization of mitochondrial membranes, were also evident among Cd-exposed cells. We also show that low levels of copper can induce a similar apoptotic response in yeast within the first hour of exposure. Such cellular responses were verified by analyzing mitochondrial perturbation, generation of superoxide ions, activation of the yeast caspase1, and the eventual fragmentation of nuclear DNA (through TUNEL). In analyzing the response of yeast to the different metals, we also demonstrated that the metal-induced PCD is instigated through the sequential activity of at least two caspase-like proteins (i.e., Yca1 and Atg4), both of which appear to be in involved in the process of inducing mitochondrial stress. The additional caspase-like activity is shown to be derived from an enzyme involved in the latter stages of autophagy (Atg4), and provides an intriguing association of apoptosis with autophagy. Here we also demonstrate that metals such as copper and cadmium causes oxidative damage to mitochondrial proteins. Such oxidative attack is targeted and we show that oxidation of certain crucial proteins is required for apoptosis upon metal exposure. By showing that such targeted protein oxidation is dependent on YCA1 and ATG, we also confirm the finding that in yeast that have been exposed to a heavy metal, YCA1 and ATG are essential for damaging mitochondria and to initiate apoptosis. These novel findings highlight several new perspectives about the mechanism of metal-dependent apoptosis, while opening up future analyses to the power of the yeast model system.

Graduation date: 1993 / Figures in original are black and white photocopies. Best scan available.