Šis tiriamasis darbas buvo atliekamas norint ištirti vario ir kadmio keliamą poveikį vasarinių miežių (Hordeum vulgare L.) morfologiniams ir fiziologiniams rodikliams bei nustatyti Cu ir Cd bioakumuliaciją šiuose augaluose. Sunkieji metalai veikė augalus pavieniui ir sąveikaudami mišinyje. Tiriami augalai buvo 5 dienas auginami mitybinėje terpėje su skirtingomis vario ir kadmio koncentracijomis (Cu ir Cd pavieniui: 0,1 mg/l, 1 mg/l, 5 mg/l, 10 mg/l ir 100 mg/l bei šių sunkiųjų metalų mišinys: 0,1 mg Cu/l+0,1 mg Cd/l, 1 mg Cu/l+1 mg Cd/l, 5 mg Cu/l+5 mg Cd/l, 10 mg Cu/l+10 mg Cd/l ir 100 mg Cu/l+100 mg Cd/l). Buvo nustatinėti šie parametrai: daigelių aukštis, šaknelių ilgis, stiebelių ir šaknelių biomasė, fotosintezės pigmentų kiekis, malono dialdehido kiekis, vario ir kadmio bioakumuliacija vasarinio miežio lapuose ir šaknyse. Tik esant mažiausiai sunkiųjų metalų koncentracijai stiebelių aukščiai ir šaknelių ilgiai yra didesni arba beveik lygūs kontroliniam variantui (p>0,05), tačiau visos kitos vario ir kadmio koncentracijos nuo 1 mg/l statistiškai patikimai (p<0,05) sumažino stiebų ir šaknų augimą. Esant mažiausiai 0,1 mg/l metalų koncentracijai daigų ir šaknų sausoji biomasė buvo (p>0,05) didesnė arba mažesnė nei kontrolės ir sudarė 96 % - 120 % kontrolės lygio. Esant didesnėms sunkiųjų metalų koncentracijoms daigų ir šaknų biomasės sumažėjo (Cd – p>0,05, Cu – p<0,05) ir sudarė 16 % - 90 % kontrolės lygio. Karotinoidų kiekio padidėjimas nustatytas iki 115 % (100 mg Cd/l) –... [toliau žr. visą tekstą] / This study was conducted to investigate the copper and cadmium effects on spring barley (Hordeum vulgare L.) for morphological and physiological parameters and to determine bioaccumulation of Cu and Cd in these plants. Heavy metal effects on plants alone and synergistically in combination. Test plants were grown for 5 days the culture medium containing different concentrations of copper and cadmium (Cd and Cu alone: 0,1 mg/ l, 1 mg/ l, 5 mg/ l, 10 mg/ l and 100 mg/ l, and these heavy metals mixture of 0,1 mg Cu/ l +0,1 mg Cd/ l, 1 mg Cu/ l +1 mg Cd/ l, 5 mg Cu/ l +5 mg Cd/ l, 10 mg Cu / l +10 mg Cd / l and 100 mg Cu/ l +100 mg Cd/ l). The determination of these parameters sprouts height, root length, stem and root biomass, photosynthetic pigments, and a pleasure dialdehyde formed amount of copper and cadmium bioaccumulation of barley leaves and roots. Only at the lowest concentrations of heavy metals in stem height and root length is larger than or nearly equal to the control variant (p>0,05), but all the other copper and cadmium concentration of 1 mg/ l, statistically significant (p<0,05) reduced the stems and root growth. At least 0,1 mg/ l, the concentration of metals in shoot and root dry biomass was (p<0,05) higher or lower than the control was 96% - 120% of control levels. At higher concentrations of heavy metals in shoot and root biomass decreased (Cd - p>0,05, Cu - p<0,05) and accounted for 16% - 90% of control levels. Carotenoid content was determined by 115 % (100... [to full text]

In Canada, regulations against the use of lead (Pb) shot for waterfowl hunting were first established in the early 1990s with the creation of a few non-toxic shot zones, and culminated with a national ban in 1997. Prior to establishment of the first non-toxic shot zones in Canada, a nation-wide survey of Pb accumulation in wing bones of young-of-the-year (YY) dabbling and diving ducks determined the incidence of elevated Pb exposure in different parts of the country (Scheuhammer & Dickson, 1996). The objective of the present study was to determine the incidence of elevated Pb accumulation in the same species several years after the national ban on Pb shot; to survey waterfowl hunters to determine approximate levels of compliance with the Pb shot ban; and to use stable Pb isotope analysis to help determine the relative importance of different sources of Pb exposure. / Wing bones from 721 YY black, mallard, and ring necked ducks, and 579 YY woodcock from selected zones in Ontario, Quebec, BC, and the Maritimes, Canada were analyzed for Pb using flame atomic absorption spectrometry. (Abstract shortened by UMI.)

Baigiamajame magistro darbe nagrinėjamas sunkiųjų metalų (toliau – SM) keliamas pavojus biotinei ir abiotinei aplinkai, vertinamas eksperimento aktualumas, užsienio šalių bei Lietuvos patirtis šioje srityje. Darbo tikslas – nustatyti SM (Cu, Zn, Ni, Cr, Pb, Cd, Pb) mišinio kaupimosi dėsningumus atlantinių lašišų Salmo salar L. audiniuose (inkstuose, žiaunose, raumenyse, kepenyse) eksperimentinėmis sąlygomis. Gauti rezultatai palyginami su ankstesniųjų metų tyrimų duomenimis, kur analogiškomis bandymo sąlygomis buvo tirtos penkios žuvų rūšys. Nustatyta, kad skirtingos žuvų rūšys skirtingai kaupia SM audiniuose. Lašišoje SM kaupėsi tokia mažėjančia seka: raumenys > žiaunos > inkstai > kepenys. Nustatyti Ni DLK viršijimai raumenyse ir žiaunose, o Pb leistinas kiekis viršytas net 3 audiniuose: raumenyse, žiaunose ir kepenyse. Parengto matematinio modeliavimo rezultatai parodė, kad SM kaupimasis lašišų audiniuose yra specifinis metalui ir audiniui, t. y., skirtingi audiniai parodė skirtingą gebėjimą kaupti SM. Darbo pabaigoje pateikiamos išvados ir rekomendacijos. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, metodikos aprašymas ir rezultatų analizė, matematinis modeliavimas, išvados ir rekomendacijos, literatūros sąrašas. Darbo apimtis – 90 p., 48 iliustr., 16 lent., 73 bibliografiniai šaltiniai. / The final master thesis discusses potential risks of heavy metals (hereinafter referred to as HM) to theLeopoldas biotic and abiotic environment, relevance of the experimental investigation, Raimondas Idzelis experience of Lithuania and foreign countries in this field. Aim of the work is to evaluate the accumulation patterns of heavy metal mixture (Cu, Zn, Ni, Cr, Pb, Cd) in the tissues of Atlantic salmon Salmo salar L. (kidneys, gills, muscles, liver) in experimental conditions. Results of the work are compared with previous studies, where five species were investigated in the same conditions. It was found that different species accumulate different amounts of HM in the tissues. Salmon accumulate HM in the following descending order: muscles > gills > kidneys > liver. Maximum permissible amount of Ni was exceeded in muscles and gills, while amount of Pb was exceeded even in the three tissues: muscles, gills and liver. Results of the mathematical model showed that the HM accumulation in salmon is specific for metal and for tissue, i.e. different tissues showed a different ability to accumulate HM. At the end of the work general conclusions and recommendations are presented. Structure: introduction, review of literary sources, description of methodology and analysis of results, mathematical modelling, conclusions and recommendations, references. Thesis consists of: 90 p., 48 pictures, 16 tables, 73 bibliographical entries.

<p>Single-walled carbon nanotubes (SWNT) are highly ordered filamentous nanocarbon structures. As their commercial and industrial use becomes more widespread, it is anticipated that SWNT will enter the environment through waste streams and product degradation. Because of their highly hydrophobic nature, SWNT aggregate and settle out of aqueous environments, especially in saline environments such as estuaries. Therefore, sediments are a likely environmental sink for SWNT once released. It is important to understand how these materials will impact benthic estuarine systems since they are the probable target area for SWNT exposure in addition to containing many lower trophic level organisms whose survvial and contaminant body burdens can have a large impact on the overall ecosystem. Disruptions in lower trophic level organism survival can have negative consequences for higher trophic levels, impacting the overall health of the ecosystem. It is also important to consider contaminant bioaccumulation, trophic transfer and biomagnification. If SWNT are taken up by benthic invertebrates, there is the possibility for trophic transfer, increasing the exposure of SWNT to higher trophic level organisms that otherwise would not have been exposed. If this type of transfer occurs in environmentally important species, the potential for human exposure may increase. My research aims to determine the magnitude of the toxicity and bioaccumulation of SWNT in benthic estuarine systems, as well as determine how they interact with other contaminants in the environment. This research will contribute to the knowledge base necessary for performing environmental risk assessments by providing information on the effects of SWNT to benthic estuarine systems. </p><p> Before investigating the environmental effects of SWNT, it is imperative that a measurement method is established to detect and quantify SWNT once they enter the environment. This research utilized pristine, semiconducting SWNT to develop extraction and measurement methods to detect and quantify these specific materials in environmental media using near infrared fluorescence (NIRF) spectroscopy. Semiconducting SWNT fluoresce in the near infrared (NIR) spectrum when excited with visible&ndashNIR light. This unique optical property can be used to selectively measure SWNT in complex media. </p><p> The fate, bioavailability, bioaccumulation and toxicity of SWNT have not been extensively studied to date. Pristine SWNT are highly hydrophobic and have been shown to strongly associate with natural particulate matter in aquatic environments. In light of this, I have focused my research to examine the influence of sediment and food exposure routes on bioavailability, bioaccumulation, and toxicity of structurally diverse SWNT in several ecologically-important marine invertebrate species. No significant mortality was observed in any organism at concentrations up to 1000 mg/kg. Evidence of biouptake after ingestion was observed for pristine semiconducting SWNT using NIRF spectroscopy and for oxidized <super>14</super>C&ndashSWNT using liquid scintillation counting. After a 24 hour depuration period, the pristine semiconducting SWNT were eliminated from organisms to below the method detection limit (5 &mug/mL), and the <super>14</super>C&ndashSWNT body burden was decreased by an order of magnitude to a bioaccumulation factor (BAF) of <0.01. Neither pristine SWNT nor oxidized <super>14</super>C&ndashSWNT caused environmentally relevant toxicity or bioaccumulation in benthic invertebrates. Overall, the SWNT were not bioavailable and appear to associate with the sediment.</p><p> In addition to investigating the toxicity and bioaccumulation of SWNT as an independent toxicant, it is important to consider how they will interact with other contaminants in the environment (i.e., increase or decrease toxicity and bioaccumulation of co&ndashcontaminants, alter the environmental transport of co&ndashcontaminants, induce degradation of co&ndashcontaminants, etc.). I wanted to investigate the effects of SWNT on a complex mixture of contaminants already present in a natural system. New Bedford Harbor (NBH) sediment, which is contaminated with polychlorinated biphenyls (PCBs), was amended with pristine SWNT to determine if the presence of SWNT would mitigate the toxicity and bioaccumulation of the PCBs in deposit-feeding invertebrates. A dilution series of the NBH sediment was created using uncontaminated Long Island Sound (LIS) sediment to test 25% NBH sediment, 50% NBH sediment, 75% NBH sediment, and 100% NBH sediment. The results of this work showed increased organism survival and decreased bioaccumulation of PCBs in treatments amended with SWNT, with the greatest reduction observed in the 25% NBH sediment treatment group amended with 10 mg SWNT/g dry sediment. Polyethylene (PE) passive samplers indicated a reduction of interstitial water (ITW) PCB concentration of greater than 90% in the 25% NBH sediment + 10 mg SWNT/g dry sediment amendment. The ITW concentration was reduced because PCBs were not desorbing from the SWNT. Lower bioavailability leads to reduced potential for toxic effects, supporting the observation of increased survival and decreased bioaccumulation. Once in the sediment, not only are SWNT not bioavailable, they act as a highly sorptive phase, such as black carbon (BC), into which hydrophobic organic contaminants (HOCs), such as PCBS and polycyclic aromatic hydrocarbons (PAHs), can partition, thereby reducing the toxicity and bioavailability of co-occurring HOCs.</p><p> To more fully understand the impact of SWNT in this environment, their biodegradability also needs to be investigated. Biodegradation of SWNT could lead to release and/or transformation of sorbed HOCs as well as a change in the inherent transport, toxicity, and bioaccumulation of SWNT in the estuarine environment. Because the persistence of SWNT will be a primary determinant of the fate of these materials in the environment, I conducted experiments to determine if the fungus <italic>Trametes versicolor</italic>, the natural bacterial communities present in NBH sediment, and municipal wastewater treatment plant sludge could degrade or mineralize oxidized <super>14</super>C&ndashSWNT. Over a six month time period, no significant degradation or mineralization was observed. In all treatments, approximately 99% of the 14C-SWNT remained associated with the solid phase, with only approximately 0.8% of added <super>14</super>C present as dissolved species and only 0.1% present as <super>14</super>CO₂. These small pools of non-SWNT <super>14</super>C were likely due to trace impurities, as no differences in production were observed between treatments and abiotic (killed) controls.</p> / Dissertation

This dissertation combines laboratory and field experiments to investigate the mechanisms of atropisomer enrichment for chiral polychlorinated biphenyls (PCBs) and their metabolites in organisms. Stereoselective biotransformation and bioaccumulation were identified as two major reasons for the different environmental fate of PCB atropisomers. Other affecting factors, such as presence of nanoparticles and changes in feeding ecology of organisms, also affect the fate of chiral contaminants. In vitro incubations of rat cytochrome P-450 2B1 (CYP2B1) isozyme with chiral PCBs indicated that different biotransformation kinetics and competition among PCB congeners or between atropisomers were two main factors affecting atropisomer enrichment. Different interactions between chiral PCB congeners or atropisomers with rat CYP2B1 may occur at the molecular level. Non-racemic meta-hydroxylated-PCBs (5-OH-PCBs) were the major metabolites. CYP-mediated stereoselective formation of dihydroxylated PCBs from OH-PCBs was observed. Gold nanoparticles affected biotransformation activity of rat CYP2B1 and changed PCB atropisomeric composition, directly by electrostatic interaction, or indirectly by changes to the surrounding ionic strength. Thus, stereoselective metabolism of chiral PCBs and OH-PCBs by CYPs is a major mechanism for atropisomer enrichment of PCBs and their metabolites in the environment, with the degree of enrichment dependent, at least in part, on charged nanoparticles and stereoselective interference of atropisomers with each other at the enzyme level. The atropisomer compositions of chiral PCBs were measured in the marine biota of Cumberland Sound (Canada) and Svalbard (Norway). High trophic level organisms, including harp seal, beluga, and narwhal reported for the first time, had species-specific atropisomer signatures, likely due to a combination of in vivo biotransformation and trophic transfer. PCB chiral signatures in Greenland sharks supported the hypothesis that some of these PCB atropisomer compositions shifted over time and space, possibly due to a change in feeding ecology. To our knowledge, this is the first report to investigate temporal trends of PCB atropisomer signatures in Arctic biota.

Porphyra abbottiae Krishnamurthy (Rhodophyta) is an intertidal red alga harvested by a number of coastal First Nations in British Columbia. The Kwakwaka’wakw have a long history of harvesting P. abbottiae as food and medicine, reflected in the language, songs and stories of the Kwakwaka’wakw oral tradition. Harvesting and drying practices for this alga have undergone changes with the introduction of new technologies and a decrease in time available for seaweed harvesting. The adoption of timesaving equipment into the seaweed harvest has given harvesters the flexibility to work around constraints including work and school obligations, tides, long distances to harvesting sites, and unpredictable weather conditions. Harvesting and drying practices reflect a thorough understanding of the lifecycle, biology, and ecology of P. abbottiae. Timing of the harvest during the seasonal round optimizes the taste and texture of P. abbottiae fronds while avoiding the seaweed in its reproductive stage. Songs and taboos associated with the harvest promote safety and efficiency while harvesting the seaweed. Concerns about potential contamination of edible seaweed led to the second part of this research: testing for metal contamination. Inductively coupled plasma mass spectrometry analysis for selected metals and trace elements revealed the presence of arsenic, cadmium, lead, and mercury in Porphyra abbottiae sampled from the southern Queen Charlotte and Broughton Straits. Mercury concentrations fell below the detection limit of 0.01 ng/mL in 28 of 112 samples. Calcium was the most abundant element measured, averaging 1445 mg/kg dry seaweed. The remaining metals, in decreasing order of concentration, are: Fe>As>Zn>Mn>Cu>Cd>Pb>Cr>Co>Se>Hg. Copper-zinc (r=0.835) and copper-lead (r=0.948) concentrations are significantly correlated (p<0.05), suggesting selective uptake of these elements. PCA analysis suggests that the location of harvesting sites within specific water channels is influencing metal concentrations. Hazard quotients calculated using guidelines set by Health Canada and the World Health Organization revealed that, among the suite of elements surveyed, arsenic followed by cadmium ranked the highest in relative risk for consumers of P. abbottiae. An average 60 kg adult consumer can safely consume approximately 9.4 g dried seaweed per day and not exceed tolerable upper intake limit guidelines. In conclusion, Porphyra abbottiae can be eaten in moderation with minimal risk of chronic metal contamination. Kwakwaka’wakw consumers can also benefit from cultural reconnection with this important traditional food. / Graduate

This thesis provides insights into the transport and fate of contaminants of concern (polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and mercury (Hg)), as well as results on the impacts of these compounds on marine mammal health. Atmospheric transport is known to be a significant pathway for the delivery of contaminants to remote food webs. Air and rain samples were collected from one remote site on the west coast of Vancouver Island, British Columbia (BC), Canada, and from one near-urban site in the Strait of Georgia, BC. While global atmospheric dispersion was observed for the legacy PCBs, 40% of PBDEs detected in BC air appeared to be originating from trans-Pacific transport. It was estimated that 3kg of PCBs and 17kg of PBDEs were deposited every year in the Strait of Georgia. Once deposited, PCBs, PBDEs and Hg biomagnify up the food chain. Harbour seals are non-migratory and can be used to provide signals of local contaminant sources. They have been extensively used as indicators of PCB and PBDE food web contamination in the BC coastal environment. The collection of over 200 harbour seal fur samples from various locations around Vancouver Island, BC and Puget Sound, WA, USA helped us pinpoint three sites where Hg levels were significantly higher than our reference site, Bella Bella (Queen Charlotte Strait, Port Renfrew and central Puget Sound). A combination of anthropogenic sources and marine food web processes appeared to influence the delivery of methylmercury (MeHg) to the top of this coastal marine food chain. Our results also suggested that these Hg levels (1.6-46.9 µg/g) could be a concern for the health of these harbour seals. Genomic techniques were used to generate insights into the implications of contaminant exposure on the health of marine mammals inhabiting industrialized regions (harbour seals from the Northeastern Pacific and Northwestern Atlantic) and remote, supposedly pristine, environment (Arctic beluga whales). In harbour seal blubber, there were positive correlations between the mRNA levels of several genes, including estrogen receptor alpha (Esr1), thyroid hormone receptor alpha (Thra), and glucocorticoid receptor (Nr3c1), and PCB levels. In beluga blubber, aryl hydrocarbon receptor (Ahr) and cytochrome P450 (Cyp1a1) mRNA levels increased with PCBs, consistent with their role in toxicity.While PCB-related toxic responses were observed in both species, additional factors appeared to be affecting the expression of important genes in beluga. Our results suggested that a shift in beluga diet during periods of low sea ice extent, as evidenced by changes in δ13C isotope ratios, had a significant impact on mRNA levels coding for genes involved in growth, metabolism and development. The use of a dual study design to evaluate the long range versus local sources of contaminants highlighted the importance of trans-Pacific transport in the delivery of PBDEs to coastal BC and the occurrence of local Hg sources in this marine environment. However, consistent with previous studies, our results suggested that PCBs remain the top contaminant of concern for marine mammal health. We also raised questions about the potential exacerbation of toxic risks due to PCBs as a consequence of climate changes currently underway in the Arctic. / Graduate / 0768 / 0383 / marie.t.noel@gmail.com

This study sought to characterize the risk to human health from dietary mercury (Hg) exposure in two Inuit communities, Repulse Bay and lgloolik. Hg exposure was estimated using food frequency questionnaires. Body burden was determined by measuring Hg in hair samples. Estimated average daily Hg exposures for women of child-bearing age were 21.3 mug in Repulse Bay, and 6.0 mug in lgloolik; the general population exposures were 43.1 mug in Repulse Bay and 23.2 mug in lgloolik. Average hair concentrations were 2.1 mg/kg and 2.8 mg/kg in Repulse Bay, 2.1 mg/kg and 6.2 mg/kg in lgloolik for women of child-bearing age and the general population respectively. No participants had concentrations above the "at risk" concentration of 30 mg/kg. Significant correlations were observed between hair Hg concentration and traditional food intake. These results do not necessitate direct intervention, but validate continued monitoring of Hg exposure in Nunavut.

ABSTRACT The tropical and subtropical nearshore marine environments of Queensland, Australia sustain diverse and unique marine wildlife. Continuous population growth and land-use changes along the Queensland coastline are known to exert numerous anthropogenic pressures on these marine ecosystems, including the delivery of high sediment loads. Sediments also provide a transport pathway for persistent organic pollutants (POPs) from rural and urban catchments into the marine environment. While such pollutants are known to be elevated in marine sediment and biota from nearshore areas in Queensland, their input and distribution pathways, as well as exposure and associated risks to wildlife populations are only partially understood. Mounting evidence suggests that POPs may contribute to population declines in marine wildlife species; however, limited information is available regarding the accumulation and effects of these contaminants in endangered or threatened marine turtles. This study aimed to redress some of these information gaps using a case study approach in marine turtle habitats of Moreton Bay, and other embayments in Queensland. Among persistent organic pollutants (POPs), dioxins (polychlorinated dibenzo-p-dioxins; PCDDs) and to some extent also dioxin-like PCBs (polychlorinated biphenyls; PCBs) were found to be widespread and often present at elevated (ppb) levels in surface sediments from Moreton Bay. However, while PCDD/F toxic equivalencies (TEQs) are above international (Canadian) sediment quality guidelines at numerous sites in Moreton Bay, in general TEQs across the Bay are relatively low compared to those from contaminated locations near dense industrial activities. POP contamination in surface sediments across Moreton Bay was investigated by a combination of GIS spatial mapping, geostatistical and traditional statistical modalities. High spatial variability and complex spatial distribution patterns were revealed. High resolution GIS kriging model outputs from the mid to southern Bay facilitated identification of distinct sediment contamination zones, with highest PCB and PCDD/F levels present in nearshore locations, associated with nearby river systems. While primarily governed by organic carbon, a multitude of physical, chemical and hydrological factors were identified to influence the spatial variance of PCDD/F concentrations. The main parameters governing PCDD/F spatial distribution were identified as sediment geochemistry, water depth and anthropogenic alterations of the physical environment and, together, all quantifiable explanatory variables (including hydrodynamic flushing) explained ≈75% of spatial PCDD/F variance. Together, the interaction of these parameters results in complex distribution patterns and highly variable concentrations even among neighbouring sites of 1-3 km resolution. These results suggest that prediction models of POP distributions in the nearshore marine environment may require high-resolution validation, and highlights that the design of low resolution monitoring strategies can have profound impacts on the reliability of contaminant information or any subsequent extrapolations. This knowledge and methodology can be utilised to optimise on-going and future near-shore sediment monitoring programs both locally and in other regions around the world. Using the spatial distributions of dioxin-like contaminants within sediments, this study provided an opportunity to assess field-based relationships between habitat contamination and local marine biota contamination. Detectable levels of PCDD/Fs and dioxin-like PCBs were measured in all green, hawksbill, loggerhead and flatback marine turtle tissues. POP concentrations in sediments were found to significantly correlate with those in the herbivorous green turtle from different sediment contamination zones. These findings demonstrate that sediments represent an important secondary contaminant source and lead to redistribution of POPs to the marine food chain. POP concentrations and TEQs clearly increased from sediment to turtles as well as with increasing trophic levels in marine turtle species. The results from this study demonstrate that the extent of sediment contamination within foraging habitats governs marine turtle exposure, while, trophic status and to some extent age influence contaminant exposure within a particular contamination zone. Despite the relatively low TEQ in sediments from Moreton Bay, TEQ levels in green turtle sub-populations foraging from near-shore locations and higher trophic loggerhead and flatback turtles are similar or elevated compared to those reported for other marine wildlife from Moreton Bay and elsewhere, even compared to higher trophic species from locations impacted by dense industrial activities. High bioaccumulation potential of 2,3,7,8-PCDD/F and dioxin-like PCBs compounds were estimated for green turtles using biota to sediment accumulation factors. Selective accumulation of toxicologically more potent (i.e. lower chlorinated) PCDD/Fs was observed for higher trophic marine turtles, resulting in increasing TEQs for the carnivorous species. Biomagnification was also observed for some non-2,3,7,8-substituted dioxin congeners which typically do not accumulate in most biota. These results are proposed to be due to relatively high accumulation efficiency and/or low metabolic capacity for these POP compounds in marine turtles. These findings are also hypothesised to reflect temperature dependant, greater bioavailability of hydrophobic chemicals in sub-tropical and shallow marine systems. An additional pilot study revealed that in contrast to PCDD/Fs and PCBs, levels of persistent flame retardants (polybrominated diphenyl ethers; PBDEs) were relatively low in marine turtles and other marine species (dugong, fish and shellfish) from Moreton Bay. This suggests relatively low level input of these more recent industrial products into the marine environment. However, as elevated levels of PBDEs have been reported in blood from the general population of Australia, ongoing transport from the terrestrial to the marine system and redistribution of these contaminants, similar to PCDD/F and PCBs, would be expected to occur into the future. Limited information is available regarding the sensitivity of reptiles to and effects of POPs, however, studies have shown that reptiles are sensitive to POPs albeit with uncharacterised relative potency. In the absence of robust toxicological information for reptiles or marine turtles, the potential risks associated with PCDD/F and PCB exposure of Queensland turtle populations was evaluated using toxicity for sensitive biological endpoints observed in mammals and birds. Using probabilistic methodology for marine turtles from Queensland, the body burden of up to 31% and 55% of green and loggerhead turtles, respectively, are above the threshold levels where the most sensitive physiological effects are observed in mammals and birds. While this evaluation illustrates that the contaminants investigated have the potential to impact on the health of marine turtle populations, it must be highlighted that it is compromised by the lack of species-specific (and in this case, class-specific) information, the uncertainty of which is often considered to represent a factor of at least 10. The findings of the present study indicate that exposure to POPs has the potential to adversely affect the health of Queensland’s marine turtle populations, and highlight the need for robust information on reptile specific sensitivity to these compounds.

Diss. (sammanfattning) Stockholm : Univ., 2004. / Härtill 5 uppsatser.