An experimental study was made of accumulation and loss of heavy metals by the aquatic moss Rhynchostegium riparioides and of the processes involved. The information gained were used to assess the effectiveness of this species as a monitor. Growth of Rhynchostegium continued throughout the year with peaks in spring and autumn. There were positive correlations between growth and water and air temperatures. Strong differences in growth rates in the four streams were not related to nutrient or heavy metal concentrations. Various patterns of mesh bag were tested as containers for transplanted Rhynchostegium to be used as a monitor. No significant differences in accumulation by moss were found between boulders or bags, or in accumulation with different patterns of bags. Accumulation was reduced slightly at the centre of bags packed with large quantities of moss. The physiology of Zn accumulation was also studied. A large part of accumulation (> 70%) in the early stages (< 12 h) was in a form readily exchanged for competing cations such as Ca and Ni; over longer time periods there was significant accumulation into a more tightly bound compartment. There was no evidence that uptake into this latter compartment was under the direct control of the plant's metabolism. There was differential accumulation of Cr(III) and Cr(VI) in laboratory experiments; during a case study it was possible to "predict" the speciation of Cr in the water by the concentrations accumulated by the moss. These results confirm that bryophytes are useful as monitors of heavy metal pollution in a wide range of circumstances. A range of such applications are outlined, along with recommendations for standard methods for using moss bags.

On-line systems for monitoring mercury in liquid and gaseous production and waste streams have been developed, utilising atomic fluorescence spectrometry (AFS) as the basis for detection. Instrumentation has been designed for unattended continuous operation. Laboratory chemistries for the vapour generation of mercury, normally performed off-line in batch mode, have been adapted and optimised for continuous, flow-injection analysis for varying sample types and chemical forms of mercury. The system has typical analysis cycle of 7 minutes, a limit of detection of 10 pg ml ˉ¹ a linear range up to 100 µg ml ˉ¹ and has been applied in industrial environments for the continuous monitoring of mercury in incineration wastewater and sulphuric acid. The system was validated by on-site trials for periods of one week, during which time comparative off-line laboratory measurements showed good agreement. An automated system for monitoring mercury in natural gas streams has also been developed and validated by laboratory and on-site industrial trials. A heated pressure let-down system was designed in order to facilitate sampling of high-pressure gas streams without condensation of heavier fractions. The heated sampling line was interfaced with an automated system for trapping mercury, from variable volumes of gas, onto gold amalgamation traps, with subsequent desorbtion and analysis by AFS. The method detection limit for a 58 litre sample of natural gas was 30 pg m ˉ³ which was sufficient to determine residual mercury in natural gas streams even after mercury scrubbing had been performed. The system was validated by laboratory trials and spiking experiments during on-site trials at a gas processing facility, which resulted in complete installation and commissioning.

The primary aim of this thesis was to establish the mode of action of the heavy metal, copper, on the cardiac physiology of the blue mussel, Mytilus edulis. Exposure of specimens of M.edulis to dissolved copper led to a decrease in heart rate and an increase in heart rate variability (HRV). The concentration of copper causing a 50% reduction in heart rate was found to be 0.8µM, while the concentration causing a 50% increase in HRV was 0.06µM (48 h EC50s). Simultaneous measurements of valve activity indicated that the observed bradycardia was not caused by valve closure. Subsequently, it was considered that copper might directly affect cardiac physiology by disrupting important cellular functions of the heart. Four different ionic currents were identified and characterised in M.edulis ventricular myocytes: two outward potassium currents, a sodium current and a calcium conductance. Copper ions had no effect on the ionic currents of M.edulis heart cells at concentrations shown to inhibit the cardiac activity of whole animals. Clearly, the bradycardia measured in whole animals was not due to a change in the configuration of the ventricular action potential. It was recognised that copper could still directly affect cardiac physiology in mussels by altering excitation-contraction coupling, contractile protein function or myocardial energy production. To determine whether this was the case, recordings of heart contractions from isolated ventricular strips were made using an isometric force transducer. Using isolated strips, inhibition of cardiac activity was only induced by exposure to copper concentrations ≥1 mM. Thus, the fall in heart rate measured in the whole animals dosed with copper could not be attributed to direct cardiomyopathy. Control of the. beating of M. edulis heart is known to be exercised by nerves from the visceral ganglion (VG) that contains both excitatory and inhibitory fibres. Following the removal of the VG (in vivo), exposure to copper had no effect on the heart rate of whole animals as occurred in the initial experiments. This suggests that copper affects the heart rate in M.edulis via a neuronal pathway. The principal cardioexcitatory and cardioinhibitory transmitters in molluscs are thought to be serotonin and acetylcholine, respectively, The effect of copper on the heart rate of M.edulis could not be abolished by depletion of the monoamine content of the animal using reserpine. However, pre-treatment of mussels with α-bungarotoxin considerably reduced the sensitivity of the heart to copper. These results indicated that the influence of copper on the heart of M.edulis might be mediated by a change in the activity of cholinergic nerves to the heart. Acetylcholine is known to have a biphasic action on the heart of M.edulis, low doses depress and high doses excite (the endpoint of both responses resulting in a cessation of the heart beat). In the final experiments of this series, mussels were injected with either benzoquinonium or D-tubocurarine, prior to copper exposure, in an attempt to selectively block the inhibitory or excitatory cholinoreceptors of the heart. Only benzoquinoniuin decreased the susceptibility of the heart to copper, suggesting that copper affects the cardiac activity of blue mussels by stimulating inhibitory cholinergic nerves to the heart. It is suggested that there may be a chemosensory mechanism present in mussels which responds to increased levels of metals in seawater leading to changes in a number of physiological functions. The last result chapter of this thesis examined the effects of the organophosphorous pesticide, dimethoate, on cardiac and acetylcholinesterase (AChE) activity in the common shore crab Carcinus maenas. Cardiac activity was measured non-invasively before and during dimethoate exposure. Heart rates decreased in a concentration-dependent manner. Serial measurements of AChE activity in haemolymph samples taken from crabs before and after exposure indicated that 2 mg 1ˉ¹ dimethoate also significantly reduced AChE activity. The percentage inhibition in AChE activity was correlated with the percentage reduction in heart rate following dimethoate exposure. This suggests that organophosphates may directly affect neuronal control of the heart. These experiments indicate that non-destructive, serial measurements of cardiac activity and AChE activity are valuable biomarkers of organophosphate exposure and adverse effects.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Estuaries support productive and diverse ecosystems, based on the abundant food and diverse habitats. However with increasing human pressures, many estuaries along the coastline of Australia have become degraded. The primary objective of this study was to investigate the effects of estuarine metal contaminants on the physiology, and the subsequent accumulation, in the smooth toadfish, Tetractenos glaber, and their prey items in estuaries in the Sydney region, south eastern Australia. Toadfish and sediments were collected during three seasonal sampling periods (June 2002, September 2002 and January 2003) in four estuaries in the Sydney region (Port Hacking River, Cowan Creek, Parramatta River and Lake Macquarie). Sediment and toadfish tissue metal concentrations varied both spatially and temporally, with highest concentrations exhibited in the metal contaminated estuaries (Lake Macquarie and Parramatta River) during spring 2002 and summer 2003. Toadfish accumulated metals in different tissue, however field experiments were limited in determining the main pathways of accumulation. Controlled laboratory kinetic experiments using radioisotopes of 109Cd and 75Se, indicated that differences in the relative contributions of water and food in the accumulation of these metals are generally governed by the physiology of the toadfish and the type of prey eaten. The distribution of metals in fish organs is important for better understanding metal kinetics and their subsequent toxicity. Toadfish exposed to 109Cd in both water or food showed a shift in distribution from gut lining at the end of the uptake phase to the excretory organs, such as liver, by the end of the loss phase, suggesting that the main uptake pathway for water exposure was via the gut and not the gills, due to fish drinking large amounts of water to maintain osmoregulation. There was no appreciable shift in the distribution of 75Se from the uptake or loss phases, being mostly associated with the excretory organs (gills, liver and kidneys). Further investigation into the accumulation of metals in toadfish prey items revealed that differences in uptake and loss of 109Cd and 75Se were influenced by their aqueous speciation, as well as differences in animal physiology, sequestration, storage and excitation mechanisms. The uptake rates and CFs of 109Cd and 75Se were highest, and the biological half-lives the longest, in pygmy mussels, ghost shrimps and polychaetes relative to the semaphore and soldier crabs. Elevated metal concentrations in certain toadfish tissues from the four estuaries were linked to reduced lipid concentrations and increased protein concentrations, which may be detrimental for growth, reproductive output and survivorship of the fish. A closer investigation into the nutritional value and metal concentrations of toadfish prey items in a selected metal contaminated estuary (Parramatta River) revealed that toadfish from the more contaminated sites within the estuary may grow faster due to higher nutritional value of prey items on a local scale, however on a larger spatial scale, this was not evident. Further investigation is required to determine whether larger toadfish size can be attributed to physiological acclimation or genetic resistance through generations of continuous metal exposure. Many studies have assessed metal concentrations in water, sediments and biota in the field, however few studies have combined both field and laboratory experiments to examine the effects of metals on fish physiology and reproduction, and metal transfer pathways in aquatic biota. This study has contributed to a better understanding of metal accumulation and its physiological effects in estuarine biota and highlights the high spatial and temporal variability in responses of organisms to environmental metal pollution.

Thesis (Ph. D.)--Rutgers University, 2010. / "Graduate Program in Environmental Science." Includes bibliographical references (p. 104-113).

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 99-112). Also available on the World Wide Web.

Thesis supervisor: Sarah C. Larsen. Includes bibliographic references (p. 80-86).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 156-171). Also available in electronic version.