Les PCB (polychlorobiphényles), PBDE (éthers de biphényles polybromés) et OCP (pesticides organochlorés) sont des composés d’origine anthropique classés comme POP (polluants organiques persistants) dont l’usage a progressivement été restreint ou interdit. Ces composés, de par leur caractère ubiquiste, persistant et bioaccumulable, sont néanmoins toujours présents dans l’environnement, d’où l’importance de continuer à étudier leur présence, leur dynamique et leur impact. Du fait de la restriction de leurs usages, d’autres composés sont maintenant utilisés pour les remplacer, tels que les retardateurs de flamme alternatifs (RFA). Ces composés bromés et chlorés ont des propriétés physico-chimiques comparables à celles des POP précités et peuvent potentiellement constituer un danger chimique pour l’environnement. Par ailleurs, les RFA sont attendus à des niveaux de concentration plus faibles que les PCB et les PBDE que ce soit dans les compartiments biotiques et abiotiques. Ainsi, l’un des enjeux de ce travail de thèse était de développer une méthode multi-résidus, associant chromatographie en phase gazeuse et spectrométrie de masse à temps de vol, permettant d’analyser simultanément 17 RFA à des niveaux inférieurs au ng.g-1. Les niveaux et profils de contamination en POP et RFA ont ensuite été renseignés dans les compartiments biotiques et abiotiques de différents systèmes aquatiques contrastés. Le caractère bioamplifiable de ces composés a été étudié grâce à la détermination de facteurs d’amplification trophique (TMF) dans l’estuaire de la Gironde et dans le bassin du Rhône, à l’aide d’outils statistiques innovants. Dans l’estuaire de la Gironde il a été mis en évidence que certains RFA étaient autant voire plus bioamplifiables que certains POP historiques. Par ailleurs, dans le bassin du Rhône, l’utilisation des TMF comme outil prédictif, pour le BDE-47 ou la ΣPBDE-DCE par exemple, a été discutée et parait envisageable dans un cadre réglementaire. / PCBs (polychlorinated biphenyls), PBDEs (polybrominated biphenyl ethers) and OCPs (organochlorine pesticides) are anthropogenic compounds classified as POPs (Persistent Organic Pollutants), their use was restricted or prohibited. These compounds are ubiquitous, persistent and bioaccumulative and they are still present in the environment; this is the reason why it is important to continue the study of the fate and impact in the environment. Due to their usage restriction, other compounds are now used to replace them, such as alternative flame retardants (RFAs). These brominated and chlorinated compounds have physicochemical properties comparable to those of POPs and can thus be potentially hazardous to the environment. In addition, RFAs are expected to occur at lower concentrations than PCBs and PBDEs, whether in the biotic and abiotic compartments. Thus, one of the challenges of the present work was to develop a multiresidue method, based on gas chromatography coupled with a time-of-flight mass spectrometer, allowing for the simultaneous analysis of 17 RFAs at levels below ng.g-1. The levels and patterns of POP and RFA contamination were reported in the biotic and abiotic compartments of selected hydrosystems. The biomagnification potential of these compounds was also studied by determining trophic magnification factors (TMF) in the Gironde estuary and in the Rhône basin. In the Gironde estuary, it was shown that some RFA biomagnify as much or more than some historical POPs. Furthermore, in the Rhône basin, the use of TMF for predictive purpose, for BDE-47 or ΣPBDEs-WFD for example, was discussed and found possible.

Les activités humaines sont responsables de l’apport de nombreux micropolluants vers les systèmes aquatiques parmi lesquels les substances poly- et perfluoroalkylées (PFAS) ont été identifiées. Ces molécules sont utilisées depuis les années 1950 comme tensio-actifs dans de nombreuses applications industrielles et produits d’usage courant. Depuis deux décennies, certaines de ces substances, les acides perfluoroalkylés (PFAA) ont particulièrement attiré l’attention en raison de leur caractère ubiquiste et persistant dans l’environnement. Actuellement, il existe un réel manque de connaissance sur l’intégralité de la contamination environnementale par l’ensemble des PFAS. L’objectif global de ces travaux de thèse est de poursuivre les efforts menés depuis le début des années 2000 pour mieux comprendre la dynamique des PFAS depuis leurs sources en milieu urbain, leurs rejets dans les rivières et leur transfert trophique.La première partie consiste à optimiser une configuration de l’échantillonneur passif POCIS (Polar Organic Chemical Integrative Sampler) pour l’analyse ultra-trace de 25 PFAS dans les eaux de surface. Dans un second temps, il est question d’identifier les sources en PFAS sur la métropole de Bordeaux. L’analyse de 30 PFAS dans les eaux usées collectées en raiseau d’assainissement tend à montrer l’importance des apports industriels par rapport aux rejets domestiques pour la quasi-totalité des PFAS étudiés. A noter que les eaux de ruissellement sont également vectrices de contamination en PFAS. La caractérisation des effluents d’entrée et de sortie des quatre principales stations d’épuration des eaux usées (STEU) de la métropole met en évidence une faible efficacité des filières de traitement. L’utilisation d’une approche d’analyse non ciblée par oxydation, la méthode TOP (Total Oxidizable Precursors) révèle des quantités non négligeables de précurseurs de PFAA aussi bien en réseau d’assainissement que dans les effluents de STEU. L’impact de l’exutoire collectant les eaux de ruissellement en provenance de l’aéroport et d’une portion du périphérique de Bordeaux sur les niveaux en PFAS d’une petite rivière périurbaine est également montré. Enfin, la dernière partie renseigne la bioamplification des PFAS en milieu lotique. L’évaluation des concentrations le long de 5 réseaux trophiques du bassin hydrographique Rhône-Méditerranée permet d’une part de confirmer la bioamplification du perfluorooctane sulfonate (PFOS) et des perfluoroalkyles carboxylates (PFCA) à chaîne longue, et d’autre part d’évaluer la variabilité spatiale des facteurs d’amplification trophique (TMF). Le caractère bioamplifiable de PFAS d’intérêt « plus émergent » tels que les 8:2 et 10:2 fluorotélomères sulfonates est mis en évidence dans une rivière localisée à la périphérie de Paris. L’application de la méthode TOP à différents maillons de cette chaîne trophique permet de soutenir l’hypothèse de l’implication de la biotransformation des précurseurs dans la bioamplification apparente des PFAA. / Human activities are responsible for the release of multiple micropollutants into aquatic systems, such as poly- and perfluoroalkylated substances (PFASs). These molecules have been used since the 1950s as surfactants in many industrial applications and commonly used products. For two decades, some of these substances, perfluoroalkylated acids (PFAA), have generated a major concern due to their ubiquitous and persistent behavior in the environment. Currently, there is a real lack of knowledge about the full extent of environmental contamination by all PFASs. The overall objective of this thesis is to continue the efforts undertaken since the early 2000s to gain a better understanding of the dynamics of PFASs, from their sources in urban areas, their releases to aquatic systems, to their trophic transfer.The first part consisted in optimizing a configuration of the Polar Organic Chemical Integrative Sampler (POCIS) for the ultra-trace analysis of 25 PFASs in surface water. In a second time, the dynamics of the PFASs on the Bordeaux conurbation is studied. The analysis of 30 PFASs in wastewater collected in the sewerage network tends to show the importance of industrial inputs compared to domestic discharges for almost all the studied PFASs. Note that urban runoff is also a source of PFAS contamination. The characterization of the influents and effluents of the four main wastewater treatment plants (WWTP) in the metropolis shows a low efficiency of treatment channels. The use of a non-targeted analysis approach by oxidation, the TOP method (Total Oxidizable Precursors) reveals significant amounts of PFAA precursors in the sewerage network as well as in WWTP effluents. The impact of urban and airport storm water discharge on the contamination levels of a small peri-urban river has also been shown. The last part dealt with the biomagnification of PFASs in lotic systems. The evaluation of PFAS concentrations along 5 food webs from the Rhone-Mediterranean watershed enables to confirm the biomagnification of perfluorooctane sulfonate (PFOS) and long-chain perfluoroalkyl carboxylates (PFCA) and to evaluate the spatial variability of trophic magnification factors (TMF). The biomagnification character of PFASs of "more emerging" interest, such as the 8:2 and 10:2 fluorotelomer sulfonates, is observed in a river located on the outskirts of Paris. The application of the TOP method to different trophic levels supports the hypothesis of the involvement of the biotransformation of precursors in the apparent biomagnification of PFAAs.

<p>The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis.</p><p>The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale.</p><p>In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species.</p><p>QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.</p>

The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis. The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale. In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species. QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.

This thesis characterizes major factors influencing the accumulation of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and polybrominated diphenyl ethers (PBDEs), in grizzly bears. Dietary differences among grizzly bears have significant implications for contaminant concentrations and patterns. While salmon-eating bears were dominated by lipophilic PCBs, OC pesticides, and lower-brominated PBDEs, non-salmon-eating bears were dominated by the more volatile PCBs and OC pesticides and higher-brominated PBDEs (e.g. BDE-209). Overall, the ocean-salmon-bear pathway appeared to preferentially select for those contaminants with an intermediate log Kow ~6.5, with salmon delivering up to 70% of OC pesticides, 85% of PBDEs and 90% of PCBs to grizzly bears. Fat utilization by grizzly bears during hibernation results in significant contaminant concentration increases in residual fat (“concentration effect”). Overall, total PCBs increased by 2.21 times from pre- to post-hibernation, and total PBDEs by 1.58 times. Interestingly, the patterns of the two distinct pre-hibernation grizzly bear feeding ecologies (salmon- and non-salmon-eating) converged during hibernation, suggesting that shared metabolic capacities drive POP patterns during hibernation. Relative to salmon, grizzly bears have extremely low biomagnification factors (BMFs) for PCBs (0.147), compared to other marine mammals. Low BMF values were a result of >90% depuration (loss) of PCBs through contaminant metabolism and excretion. The results suggest that grizzly bears only metabolize PCB congeners with meta- and para- vicinal hydrogen (H) atoms, suggesting that they have active cytochrome (CYP) P450 2B/3A-like metabolic enzymes. However, congeners structurally resistant to metabolic biotransformation, and those with ortho- and meta- vicinal H atoms, were not readily metabolized, but rather were lost through excretion. This was evidenced by a significant relationship between total retention (Rtotal) of those congeners and log Kow, as well as a lack of change in that relationship during hibernation. Vegetation and the terrestrial food web were dominated by PBDEs and volatile OC pesticides and PCBs, while salmon and the marine food web were dominated by lipophilic PCBs and OC pesticides, mirroring patterns in grizzly bears within their respective food web. Following consumption of these various foods by the grizzly bears, fecal material closely resembled food in contaminant pattern, suggesting that many of the contaminants may go unabsorbed. While previous work identified major factors (e.g. age, sex, diet) influencing POP behaviour in wildlife and food webs, this research highlights the need to refine our ideas about those factors in order to better assess chemical health risk in wildlife by considering: 1) individual differences in feeding behaviour; 2) integrated dietary histories (temporal changes); 3) unique biological traits affecting POP fate; 4) modes of POP loss other than metabolism; 5) selection of the most recalcitrant congener for more robust analysis of POP behaviour; 6) use of non-invasive techniques to study diet and POP exposure; and, 7) tissue residue guidelines underestimate health risks. Our results also suggest that PBDEs show POP-type characteristics as defined under the Stockholm Convention, and thus should be regulated.

Farmed Southern Bluefin Tuna (SBT) (Thunnus maccoyii) is an important export product for South Australia (SA). It is exported to Japan, China, Korea and the United States for the sushi and sashimi markets. The primary purpose of SBT farming in SA is to fatten wild-caught juvenile fish (2-4 years of age with initial mean weights between 12-20 kg) over a period of approximately five months by feeding a selection of baitfish types. Farmers, farm managers and consumers of SBT all have an interest in managing chemical residues that have the potential to biomagnify in the fatty tissue of the farmed SBT fillets. Of particular interest are chemical residues of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins / dibenzofurans (PCDD/Fs). This research presents the investigations and experimental validation of a predictive model that can be used to address the levels of residues in the fillets of farmed SBT at harvest from feeding (as the source) when applied to SBT aquaculture. An additional industry-focussed aim of this research was to determine if a Longer Term Holding (LTH) farming period, with a duration of an extra 12 months after a typical farming period of approximately five months, could produce SBT with higher condition index (CI) and lipid content, while keeping levels of PCBs and PCDD/Fs low, compared to the typical farming period. The justification for this research is that an adequate quantitative model is essential to help industry achieve targeted concentrations in the final fillet product by making scientific-based decisions on baitfish selection (baitfish strategies for the feeding of SBT), and longer term, to confidently demonstrate to local markets and importing countries that Australia is actively managing levels of PCBs and PCDD/Fs in farmed SBT, to ensure a high quality and safe product is delivered to the consumer. The novelty of this research is underpinned by four integrated stages, and the criteria for an adequate model established. The important criteria included: accurate predictions versus observed data demonstrated through the analysis of residual plots, potential physiological interpretation of model coefficients, parsimony – the model should be as simple as possible (but no simpler) and that the model should be easy to use. Firstly, a logical starting point was the development of a risk framework for residues in SBT. The developed framework was based on conventional principles of microbiological risk assessment highlighted in Codex Alimentarius. The risk framework consists of five governing principles: hazard identification, hazard characterisation, exposure assessment, risk characterisation and model validation. The advantages of the risk framework is that it provides a systematic research approach and permits information to be handled unambiguously, especially important for the niche SBT industry where chemical residue research is carried out for the first time. Secondly, because of a lack of available scientific data in context of this research, commercial-scale experimental field data for levels of PCBs and PCDD/Fs in typical farmed SBT as affected by feeding and growth were collected over 17 months at seven time intervals from Farm Delta Fishing Pty Ltd in 2005/06 (n = 50). Field data from another commercial company, Farm Alpha Fishing Pty Ltd, was collected over the typical farming period specific to this company, spanning 15 weeks at three time intervals in 2006, for validation work (n = 15). The data obtained from Farm Delta Fishing Pty Ltd revealed that whole weight of farmed SBT increased from 18.5 kg to 30.3 kg for a typical farming period, and subsequently to 41.0 kg by the end of the LTH farming period. A maximum mean CI of 24.0 ± 0.5 kg.m⁻³ and a maximum mean lipid content of 17.6 ± 0.5% was achieved at the third time interval of the typical farming period, for the baitfish types and ratios used as feed. There were no significant differences in the CI and lipid between the final harvests of the typical farming and LTH periods, i.e. even after an additional 12 months of farming. PCB and PCDD/F concentrations, however, increased between the final harvests of the typical farming and LTH periods. The data indicated that a typical farming period was sufficient to achieve a maximum CI and lipid content with lower concentrations of PCBs and PCDD/Fs in the fillets relative to the LTH farming period. For the third stage of this research, a quantitative model was synthesised and applied to the PCB and PCDD/F (2,3,7,8-TeCDF) data detected in farmed SBT fillets. Assimilation efficiencies for PCBs and 2,3,7,8-TeCDF in the fillets of SBT were obtained. An assimilation efficiency, or percentage retention (efficiency expressed as a percentage), in the fillet of SBT is a measure of the uptake of a chemical residue from food (baitfish) to the SBT fillet. For the WHO-PCBs, assimilation efficiencies based on SBT fillets ranged between 19.1 – 35.3 % with the exception of PCB 169. The highest assimilation efficiency of 35.3 %, with a range of 30.4 – 40.3 % (at the 95 % confidence level) was attributed to the most toxic PCB congener, PCB 126. An assimilation efficiency of 39.2 % was determined in SBT fillets for the congener 2,3,7,8-TeCDF, which was higher than the assimilation efficiencies determined for the WHO-PCB congeners. A residual plot as predicted value versus observed value indicated that the predictive model was neither under- or over-parameterised. However, when the predictive model was assessed against the data set from Farm Alpha Pty Ltd, the model over-predicted the actual PCB and PCDD/F concentrations. The over-prediction is attributed to possible overfeeding of SBT farmed by Farm Alpha Fishing Pty Ltd. From a food safety point of view, in the absence of ideal predictions because of a lack of ideal validation data sets, an over-prediction instead of under-prediction is preferred. In the fourth stage, the practical application of the predictive model was demonstrated. Because SBT fillets are retailed as tissue group-specific, i.e. akami (low fat), chu-toro (medium fat) and otoro (high fat) fillets, PCB and PCDD/F analyses were carried out on the three tissue groups for selected SBT (n = 7). Dietary modelling on SBT consumption in humans was carried out using findings from the predictive model and tissue-specific data. The baitfish strategy employed for the feeding of farmed SBT consequently affects dietary exposure to SBT consumers. Exposure to PCBs and PCDD/Fs is approximately seven times lower for the consumption of a skin-free, boneless akami fillet than for a comparable otoro fillet of the same size. This dietary exposure assessment accounted only for consumption of SBT tissue-specific fillets. The experimental field study and modelling work on PCB and PCDD/F concentrations in farmed SBT (fillets) outlined in this thesis importantly directs the need to re-evaluate a specific model to better cater for SBT farming practices where SBT fillets are produced for human consumption. Because conditions that normally pertain to commercial farming of wild-caught fish were studied, findings should be of interest to industries where other species of fish (for food) are farmed in sea-cages in the open ocean. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342453 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

Farmed Southern Bluefin Tuna (SBT) (Thunnus maccoyii) is an important export product for South Australia (SA). It is exported to Japan, China, Korea and the United States for the sushi and sashimi markets. The primary purpose of SBT farming in SA is to fatten wild-caught juvenile fish (2-4 years of age with initial mean weights between 12-20 kg) over a period of approximately five months by feeding a selection of baitfish types. Farmers, farm managers and consumers of SBT all have an interest in managing chemical residues that have the potential to biomagnify in the fatty tissue of the farmed SBT fillets. Of particular interest are chemical residues of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins / dibenzofurans (PCDD/Fs). This research presents the investigations and experimental validation of a predictive model that can be used to address the levels of residues in the fillets of farmed SBT at harvest from feeding (as the source) when applied to SBT aquaculture. An additional industry-focussed aim of this research was to determine if a Longer Term Holding (LTH) farming period, with a duration of an extra 12 months after a typical farming period of approximately five months, could produce SBT with higher condition index (CI) and lipid content, while keeping levels of PCBs and PCDD/Fs low, compared to the typical farming period. The justification for this research is that an adequate quantitative model is essential to help industry achieve targeted concentrations in the final fillet product by making scientific-based decisions on baitfish selection (baitfish strategies for the feeding of SBT), and longer term, to confidently demonstrate to local markets and importing countries that Australia is actively managing levels of PCBs and PCDD/Fs in farmed SBT, to ensure a high quality and safe product is delivered to the consumer. The novelty of this research is underpinned by four integrated stages, and the criteria for an adequate model established. The important criteria included: accurate predictions versus observed data demonstrated through the analysis of residual plots, potential physiological interpretation of model coefficients, parsimony – the model should be as simple as possible (but no simpler) and that the model should be easy to use. Firstly, a logical starting point was the development of a risk framework for residues in SBT. The developed framework was based on conventional principles of microbiological risk assessment highlighted in Codex Alimentarius. The risk framework consists of five governing principles: hazard identification, hazard characterisation, exposure assessment, risk characterisation and model validation. The advantages of the risk framework is that it provides a systematic research approach and permits information to be handled unambiguously, especially important for the niche SBT industry where chemical residue research is carried out for the first time. Secondly, because of a lack of available scientific data in context of this research, commercial-scale experimental field data for levels of PCBs and PCDD/Fs in typical farmed SBT as affected by feeding and growth were collected over 17 months at seven time intervals from Farm Delta Fishing Pty Ltd in 2005/06 (n = 50). Field data from another commercial company, Farm Alpha Fishing Pty Ltd, was collected over the typical farming period specific to this company, spanning 15 weeks at three time intervals in 2006, for validation work (n = 15). The data obtained from Farm Delta Fishing Pty Ltd revealed that whole weight of farmed SBT increased from 18.5 kg to 30.3 kg for a typical farming period, and subsequently to 41.0 kg by the end of the LTH farming period. A maximum mean CI of 24.0 ± 0.5 kg.m⁻³ and a maximum mean lipid content of 17.6 ± 0.5% was achieved at the third time interval of the typical farming period, for the baitfish types and ratios used as feed. There were no significant differences in the CI and lipid between the final harvests of the typical farming and LTH periods, i.e. even after an additional 12 months of farming. PCB and PCDD/F concentrations, however, increased between the final harvests of the typical farming and LTH periods. The data indicated that a typical farming period was sufficient to achieve a maximum CI and lipid content with lower concentrations of PCBs and PCDD/Fs in the fillets relative to the LTH farming period. For the third stage of this research, a quantitative model was synthesised and applied to the PCB and PCDD/F (2,3,7,8-TeCDF) data detected in farmed SBT fillets. Assimilation efficiencies for PCBs and 2,3,7,8-TeCDF in the fillets of SBT were obtained. An assimilation efficiency, or percentage retention (efficiency expressed as a percentage), in the fillet of SBT is a measure of the uptake of a chemical residue from food (baitfish) to the SBT fillet. For the WHO-PCBs, assimilation efficiencies based on SBT fillets ranged between 19.1 – 35.3 % with the exception of PCB 169. The highest assimilation efficiency of 35.3 %, with a range of 30.4 – 40.3 % (at the 95 % confidence level) was attributed to the most toxic PCB congener, PCB 126. An assimilation efficiency of 39.2 % was determined in SBT fillets for the congener 2,3,7,8-TeCDF, which was higher than the assimilation efficiencies determined for the WHO-PCB congeners. A residual plot as predicted value versus observed value indicated that the predictive model was neither under- or over-parameterised. However, when the predictive model was assessed against the data set from Farm Alpha Pty Ltd, the model over-predicted the actual PCB and PCDD/F concentrations. The over-prediction is attributed to possible overfeeding of SBT farmed by Farm Alpha Fishing Pty Ltd. From a food safety point of view, in the absence of ideal predictions because of a lack of ideal validation data sets, an over-prediction instead of under-prediction is preferred. In the fourth stage, the practical application of the predictive model was demonstrated. Because SBT fillets are retailed as tissue group-specific, i.e. akami (low fat), chu-toro (medium fat) and otoro (high fat) fillets, PCB and PCDD/F analyses were carried out on the three tissue groups for selected SBT (n = 7). Dietary modelling on SBT consumption in humans was carried out using findings from the predictive model and tissue-specific data. The baitfish strategy employed for the feeding of farmed SBT consequently affects dietary exposure to SBT consumers. Exposure to PCBs and PCDD/Fs is approximately seven times lower for the consumption of a skin-free, boneless akami fillet than for a comparable otoro fillet of the same size. This dietary exposure assessment accounted only for consumption of SBT tissue-specific fillets. The experimental field study and modelling work on PCB and PCDD/F concentrations in farmed SBT (fillets) outlined in this thesis importantly directs the need to re-evaluate a specific model to better cater for SBT farming practices where SBT fillets are produced for human consumption. Because conditions that normally pertain to commercial farming of wild-caught fish were studied, findings should be of interest to industries where other species of fish (for food) are farmed in sea-cages in the open ocean. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342453 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

Farmed Southern Bluefin Tuna (SBT) (Thunnus maccoyii) is an important export product for South Australia (SA). It is exported to Japan, China, Korea and the United States for the sushi and sashimi markets. The primary purpose of SBT farming in SA is to fatten wild-caught juvenile fish (2-4 years of age with initial mean weights between 12-20 kg) over a period of approximately five months by feeding a selection of baitfish types. Farmers, farm managers and consumers of SBT all have an interest in managing chemical residues that have the potential to biomagnify in the fatty tissue of the farmed SBT fillets. Of particular interest are chemical residues of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins / dibenzofurans (PCDD/Fs). This research presents the investigations and experimental validation of a predictive model that can be used to address the levels of residues in the fillets of farmed SBT at harvest from feeding (as the source) when applied to SBT aquaculture. An additional industry-focussed aim of this research was to determine if a Longer Term Holding (LTH) farming period, with a duration of an extra 12 months after a typical farming period of approximately five months, could produce SBT with higher condition index (CI) and lipid content, while keeping levels of PCBs and PCDD/Fs low, compared to the typical farming period. The justification for this research is that an adequate quantitative model is essential to help industry achieve targeted concentrations in the final fillet product by making scientific-based decisions on baitfish selection (baitfish strategies for the feeding of SBT), and longer term, to confidently demonstrate to local markets and importing countries that Australia is actively managing levels of PCBs and PCDD/Fs in farmed SBT, to ensure a high quality and safe product is delivered to the consumer. The novelty of this research is underpinned by four integrated stages, and the criteria for an adequate model established. The important criteria included: accurate predictions versus observed data demonstrated through the analysis of residual plots, potential physiological interpretation of model coefficients, parsimony – the model should be as simple as possible (but no simpler) and that the model should be easy to use. Firstly, a logical starting point was the development of a risk framework for residues in SBT. The developed framework was based on conventional principles of microbiological risk assessment highlighted in Codex Alimentarius. The risk framework consists of five governing principles: hazard identification, hazard characterisation, exposure assessment, risk characterisation and model validation. The advantages of the risk framework is that it provides a systematic research approach and permits information to be handled unambiguously, especially important for the niche SBT industry where chemical residue research is carried out for the first time. Secondly, because of a lack of available scientific data in context of this research, commercial-scale experimental field data for levels of PCBs and PCDD/Fs in typical farmed SBT as affected by feeding and growth were collected over 17 months at seven time intervals from Farm Delta Fishing Pty Ltd in 2005/06 (n = 50). Field data from another commercial company, Farm Alpha Fishing Pty Ltd, was collected over the typical farming period specific to this company, spanning 15 weeks at three time intervals in 2006, for validation work (n = 15). The data obtained from Farm Delta Fishing Pty Ltd revealed that whole weight of farmed SBT increased from 18.5 kg to 30.3 kg for a typical farming period, and subsequently to 41.0 kg by the end of the LTH farming period. A maximum mean CI of 24.0 ± 0.5 kg.m⁻³ and a maximum mean lipid content of 17.6 ± 0.5% was achieved at the third time interval of the typical farming period, for the baitfish types and ratios used as feed. There were no significant differences in the CI and lipid between the final harvests of the typical farming and LTH periods, i.e. even after an additional 12 months of farming. PCB and PCDD/F concentrations, however, increased between the final harvests of the typical farming and LTH periods. The data indicated that a typical farming period was sufficient to achieve a maximum CI and lipid content with lower concentrations of PCBs and PCDD/Fs in the fillets relative to the LTH farming period. For the third stage of this research, a quantitative model was synthesised and applied to the PCB and PCDD/F (2,3,7,8-TeCDF) data detected in farmed SBT fillets. Assimilation efficiencies for PCBs and 2,3,7,8-TeCDF in the fillets of SBT were obtained. An assimilation efficiency, or percentage retention (efficiency expressed as a percentage), in the fillet of SBT is a measure of the uptake of a chemical residue from food (baitfish) to the SBT fillet. For the WHO-PCBs, assimilation efficiencies based on SBT fillets ranged between 19.1 – 35.3 % with the exception of PCB 169. The highest assimilation efficiency of 35.3 %, with a range of 30.4 – 40.3 % (at the 95 % confidence level) was attributed to the most toxic PCB congener, PCB 126. An assimilation efficiency of 39.2 % was determined in SBT fillets for the congener 2,3,7,8-TeCDF, which was higher than the assimilation efficiencies determined for the WHO-PCB congeners. A residual plot as predicted value versus observed value indicated that the predictive model was neither under- or over-parameterised. However, when the predictive model was assessed against the data set from Farm Alpha Pty Ltd, the model over-predicted the actual PCB and PCDD/F concentrations. The over-prediction is attributed to possible overfeeding of SBT farmed by Farm Alpha Fishing Pty Ltd. From a food safety point of view, in the absence of ideal predictions because of a lack of ideal validation data sets, an over-prediction instead of under-prediction is preferred. In the fourth stage, the practical application of the predictive model was demonstrated. Because SBT fillets are retailed as tissue group-specific, i.e. akami (low fat), chu-toro (medium fat) and otoro (high fat) fillets, PCB and PCDD/F analyses were carried out on the three tissue groups for selected SBT (n = 7). Dietary modelling on SBT consumption in humans was carried out using findings from the predictive model and tissue-specific data. The baitfish strategy employed for the feeding of farmed SBT consequently affects dietary exposure to SBT consumers. Exposure to PCBs and PCDD/Fs is approximately seven times lower for the consumption of a skin-free, boneless akami fillet than for a comparable otoro fillet of the same size. This dietary exposure assessment accounted only for consumption of SBT tissue-specific fillets. The experimental field study and modelling work on PCB and PCDD/F concentrations in farmed SBT (fillets) outlined in this thesis importantly directs the need to re-evaluate a specific model to better cater for SBT farming practices where SBT fillets are produced for human consumption. Because conditions that normally pertain to commercial farming of wild-caught fish were studied, findings should be of interest to industries where other species of fish (for food) are farmed in sea-cages in the open ocean. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342453 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2008

Made available in DSpace on 2015-04-20T12:33:48Z (GMT). No. of bitstreams: 1 sandra.pdf: 1382678 bytes, checksum: 9fdac74197bce7873c6927728a23b1d8 (MD5) Previous issue date: 2012-07-17 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / After the proven power of evil mercury (Hg) to human health, studies have focused on identifying the sources and pathways describe biogeochemical circulation in the environment. In Brazil, the use of Hg during the amalgamation of gold was considered the main source of contamination; however, today the contribution due to the deforestation and burning of forests has become relevant. In the Amazon, the dynamics of Hg in rivers (Negro, Madeira, Acre and Tapajós) is well known, but not in the floodplain, environments recognized as Hg methylation places and socioeconomic importance. To extend this knowledge we analyzed Hg levels in the biotic and abiotic components of Grate Lake Manacapuru (AM), the bioconcentration factor, the biomagnification potential to fish community, and bioaccumulation for commercial fish species were calculated. The Hg levels between 75.89 to 283.99 ng.g-1, being significantly higher in the flood and the podzolic soils. 64.3% of Hg levels measured in sediments were within the range of observed values to not contaminated Amazonian rivers (<200 ng.g-1), and 35.7% for highly anthropogenic rivers. The Hg levels water samples ranged from 1.7 to 15.2 ng.l-1. Emergent aquatic macrophytes and its fine particulate matter and periphyton presented high total Hg levels. Macroinvertebrate omnivores/detritivores and piscivorous fish associated with aquatic macrophytes recorded the highest Hg levels (226.4 ng.g-1 and 866.3 ng.g-1 respectively). There biomagnification in fish, the average Hg levels ranged from 45.89 to 527.82 ng.g-1, depending on the trophic category. The biomagnification factors were 0.27 for first order consumers, 0.33 for second order and 0.47 in thirth order. There were significant differences in the bioconcentration and total Hg level between the categories of third trophic level and the others. Plagioscion squamosissimus and Calophysus macropterus presentes Hg levels above those permitted by law (500 ng.g-1), and other six species also present risks to human health. The trophic structure of the community defined by the potential biomagnifications (b=0.15 ng.g-1) were 13 trophic categories, and five trophic levels. There were significant differences in total Hg levels of in relation to the trophic level of omnivores, detritivores, herbivores/frugivores, carnivores/ piscivores and carnivores/insectivores, and overlap in Hg levels of various categories, apparently resulting from the trophic plasticity of organisms and ontogenetic factors. In conclusion, the use of soil facilitates the release of Hg, which is carried by leaching into the aquatic environment where it is retained in the sediment. Sediment resuspension and homogenization of the water, facilitates the distribution and methylation of Hg in the lake, increasing the bioavailability to biota and their transfer into the food chain. The aquatic macrophytes and the periphyton community contribute to methylation, distribution and transfer of Hg in food chains. The processes of bioaccumulation in species are linked primarily to diet, but population factors such as age, growth, and fat levels should contribute to the different bioaccumulation factors observed. / Após de o comprovado poder maléfico do mercúrio (Hg) para a saúde humana, estudos focaram em identificar as fontes e em descrever vias biogeoquímicas de circulação no ambiente. No Brasil, o uso do Hg na amalgamação de ouro foi considerado a principal fonte de contaminação, mas o aporte por desmatamento e queima de florestas é relevante. Na Amazônia, a dinâmica do Hg em rios (Negro, Madeira, Acre e Tapajós) é bem conhecida, mas na várzea não, embora se trate de um ambiente de metilação de Hg e de importância socioeconômica. Para ampliar esse conhecimento analisaram-se teores de Hg em componentes abióticos e bióticos no Lago Grande de Manacapuru (AM), calculou-se fator de bioconcentração, potencial de biomagnificação para a comunidade de peixes relacionando teores de Hg com isótopos estáveis de δN15, e bioacumulação. Teores de Hg em solo variaram de 75,8 a 283,9 ng.g-1 sendo maiores durante a enchente e nos solos podzólicos. 64,3% dos teores de Hg em sedimentos estiveram entre valores citados de rios Amazônicos não contaminados (<200 ng.g-1), e 35,7% em rios altamente antropizados. Teores de Hg na água variaram de 1,7 a 15,2 ng.l-1. Macrófitas aquáticas emergentes e seu material particulado fino e perifiton tiveram altos teores Hg total. Macroinvertebrados onívoros/detritívoros e peixes piscívoros associados às macrófitas aquáticas registraram os maiores teores (226,4 ng.g-1, e 866,3 ng.g-1 respectivamente). Houve biomagnificação em peixes, com teores de Hg total médio variando de 45,8 a 527,8 ng.g-1, em função à categoria trófica. A biomagnificação em consumidores primários foi 0,27, em secundários 0,33 e 0,47 em terciários. Houve diferença significativa na bioconcentração e no teor de Hg entre as categorias tróficas do 3º nível trófico e as demais. Plagioscion squamosissimus e Calophysus macropterus apresentaram teores de Hg acima do permitido (500 ng.g-1), e seis outras espécies apresentam riscos para a saúde humana. A estrutura trófica da comunidade íctica definida pelo potencial de biomagnificação (b=0,15 ng.g-1) foi: 13 categorias tróficas e 5 níveis tróficos. Houve diferença significativa nos teores de Hg de onívoros, detritívoros, herbívoros/frugívoros, carnívoros/piscívoros e carnívoros/ insetívoros, de níveis tróficos diferentes, e sobreposição nos teores de Hg de várias categorias tróficas, aparentemente resultante da plasticidade trófica dos organismos e de fatores ontogênicos. Em conclusão, o uso do solo facilita a liberação do Hg, que é transportado pela lixiviação até o ambiente aquático, onde é retido no sedimento. Ressuspensão dos sedimentos e homogeneização da massa de água facilitam a distribuição e metilação do Hg no lago, aumentando sua biodisponibilidade para a biota e transferência na cadeia trófica. Bancos de macrófitas aquáticas e a comunidade perifítica contribuem com a metilação, distribuição e transferência do Hg nas cadeias alimentares. Bioacumulação nas espécies está atrelada principalmente ao regime alimentar, mas idade, crescimento, e teor de gordura contribuem.

This study examined mercury and methylmercury concentrations in shark species in order to determine differences between shark species and between locations. Stable isotope ratios were determined to see if interaction existed between approximate trophic level and mercury concentrations. Sharks were sampled from Florida Bay where muscle tissue biopsies and blood samples were extracted upon capture. Stable isotope ratios for carbon-13 (δ13C) and nitrogen-15 (δ15N) from freezedried blood samples were compared with levels of organic and inorganic mercury species from tissue samples in seven different shark species, focusing on blacknose, blacktip, bull, and lemon sharks. Pre-caudal length (PCL) was strongly correlated to mercury concentration and δ13C but not with δ15N. Ratios of δ15N between shark species were in agreement with observed trophic-level behavior of blacktip sharks feeding on blacknose sharks, indicated by greater values for δ15N ratios in blacktip sharks. Calculated length-normalized stable isotope ratio values correlated strongly to values for mercury concentrations in blacktip sharks, indicating a potential method for forecasting inorganic or organic mercury concentrations without the use of more expensive mercury tests. This calculation also provided validity for a new metric involving the use of stable carbon isotope ratio divided by length (PCL) to be compared with other metrics. Correlations between δ15N values and mercury values indicate some level of interaction between trophic level and quantity of mercury contaminants in shark muscle tissue.