| Because of their high toxicity, accumulation, persistence and other features, persistent organic pollutants (POPs) may have risks to human health. What’s more important, most of the POPs are semi-volatile compounds, making them easily emitting to the air at room temperature and leading to a global pollution then. Therefore, studies of POPs are not only focused on the contamination at high pollution places, but also on areas with little sources such as arctic and Antarctic.Since 1960s, increasing number of studies has found that POPs can exist in the environment and organisms of the Antarctic places. Due to "Global condensing effect" and "grasshopper theory", POPs can volatile from the warmer areas, transport, and finally condense to the higher latitude, higher altitude, and colder regions. Many reports about arctic, antarctic and Tibetan Plateau have identified the "Global condensing effect", suggesting that those places as the important rinks of POPs all over the world. It also suggested that the polar areas and high mountains without pollution sources can be treated as the "barometer" of global pollution, studies of which can provide us some evidences of the interannual variation of contaminant status, as well as transportaion, and transformation of the pollutants to the polar areas.Many studies have carried out to monitoring the pollutions of POPs in the Antarctic. However, when compared to the corresponding studies of the Arctic regions, studies of the former are limited. For example, most of the researches only focused on the southeast part of the Antarctic areas, especially the places near to the research stations. Moreover, historical studies on the pollution analysis of Antarctic are not long, and reports about the transportation mechanism and flux of POPs are scarce.In this thesis, samples of sediment, bird excrement, eggs and penguin tissues were collected from the Prydz Bay and nearby places during the 27-29th Chinese Antarctic Scientific Expeditions. Residues of two kind of classical POPs, i.e., organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in these samples are tested. In the meantime, distribution, origins, and flux of these chemicals in the sediments are discussed. The present studies also discussed the bioaccumulation and biomagnification of OCP sans PCBs through organisms at different tropic levels. The main results include:(1) Total concentrations of PCBs (∑PCBs) in the sediments from the Prydz Bay were from 0.87 to 84 ng/g dry weight (dw) with an average of 2.13 ng/g dw. These data are comparable to those in sediments from arctic and nearby marine areas, but lower than PCBs residues from most of the estuaries and bays all over the world. When compared to other studies in the Antarctic regions, the contaminant levels of PCBs in the Prydz Bay tested in this study are similar to those from eastern part of Antarctic, but obviously lower than those from the Ross Sea and Mike Moldow Bay, which were highly effected by pollutant discharge. Results of congener compositions showed that less chlorinated PCBs such as tri-PCBs, tetra-PCBs and Penta-PCBs accounted for over 75% of ∑PCBs. The correlation analyses further implied that were taken and confirmed that, to a certain extent, if not entirely, PCBs were from the same sources, i.e., the long distance transport. In addition, compound Aroclor 1254 was preliminarily considered as the main industrial source of PCBs in the Prydz Bay.(2) The total concentrations of OCPs (EOCPs, including α-, β-, γ-, δ-HCH, p,p’-DDT, p,p’-DDE, p,p’-DDD, o,/p’-DDT, o,p’-DDD, cis-chlordane and trans-chlordane) ranged from 0.79 to 7.9 ng/g dw, with an average of 2.35 ng/g dw. And the levels of ∑HCHs, ∑chlordanes and ∑DDTs were 0.28 to 1.23 (mean 0.57) ng/g dw, nd to 0.17 (mean 0.07) ng/g dw, and 0.45 to 6.5 (mean 1.7) ng/gdw, respectively. These data are comparable to those in the sediments from other lakes, estuaries and bays in arctic regions and the Chinese Tibet Plateau, but lower than marine areas nearby the pollution sources. The concentrations of OCPs showed a decreasing order of DDTs> HCHs> CHLs, which may be attributable to their differences of production and usage histories, as well as the capabilities of long distance transportation. The average value of o,p’/ p,p’-DDT in the sediments was 0.22, which was similar to that of the technical DDT, implying that pollutions of DDTs in the studied areas possibly origin from the industrial source. The relatively low (DDD+DDE)/DDT contents further indicated that degradation of DDT in the sediment from the Prydz Bay is slow. Moreover,β-HCH and δ-HCH accounted for about 77% of the ∑HCHs, demonstrating that HCHs in the sediments from the Prydz Bay have gone through a long-time degradation. The ratios of α/γ-HCH were obviously smaller than those of the technical HCH, which suggests a possible lindane (pure γ-HCH) input in the studied area. When it comes to chlordanes, trans-chlordane has higher detection frequency than cis-chlordane, which may cause by stronger atmospheric transporting ability and more resistent to microbial degradation of the former.(3) Distributions of PCBs and OCPs in sediments from the Prydz Bay and their influences were analyzed and the flux of POPs in sea areas was estimated. Both concentrations of PCBs and OCPs in surface sediments from Prydz Bay decreased with the distance off shore, which may relate to several combined factors, such as the topograhpy, ocean currents, freezing and melting alternations of sea ice, and sediment type in the Prydz Bay. The local topography and hydrological conditions result in a weak water exchange in the inner part of the Prydz Bay, which may be responsible for the low rate of diffusion of POPs there. PCBs and OCPs both peaked at sites where the majority of sea ice melting in summer time, illustrating that the sea ice melting may be a considerably direct input and positive to the uptake of POPs. Possible reason was that sea ice melting induced POPs into the bay from atmosphere and sea water, and sedimentation of particles had bigger chance adsorbing hydrophobic compounds while mutual exchange between inside and outside bay was weak. In general, the POPs storage in the Prydz Bay was influenced by combined dynamic procedures, seasonal changes of sea ice, and the content of organic carbon. The annual accumulating fluxes of OCPs were calculated by deposition rates and fluxes, and the fluxes for HCHs, DDTs and OCPs were 13.1 ±7.0 kg/a,31.7 ± 14.8 kg/a,46.5 ± 23.6 kg/a, respectively.(4) The concentrations, sources and bioaccumulation mechanisms of POPs in biological habitats of different trophic levels, bird eggs and penguin tissues were measured and analyzed. The POPs contents in different biological habitats were in an order of Brown skuas> Stercorarius maccormickis> penguins> seals> Giant Petrels. The concentrations of pollutants in excrements from different habitats were in good relation to the trophic levels. The origins of specific pollutants were deduced:α to γ ratios were from 3.3 to 7.5 in HCH isomers, implying a historic source of technical mixture; DDTs were mainly from old technical contamination which was also a historic source; PCBs were dominated by highly chlorinated congeners, such as hexa-PCBs and hepta-PCBs, and were more accumulated in high trophic level organisms such as Brown skuas, Stercorarius maccormickis, and Leptonychotes weddelli. POPs in bird eggs showed that:trophic levels and prey habits of the birds in food webs both had an important influence on the concentrations in bird eggs. For example, concentrations of PCBs in Skua eggs were 2 to 3 magnitudes higher than those in Gentoo penguin eggs. Highly chlorinated PCBs were found to increase in eggs as trophic level rised.β-HCH was found to be dominated in seabird eggs, while p,p’-DDE accounted for large amount as the principal metabolites of p,p’-DDT. POPs such as HCHs, DDTs, and PCBs in five organism tissues from Gentoo penguins were in an order of fat> preen gland >> bone> skull> muscle. The o,p’-DDT/p,p’-DDT ratios illustrated that besides the old technical source, there probably existed other sources, such as dicofol, a substitute of DDT. PCB 138, PCB 153 and PCB 180 were three dominating PCBs in penguin tissues.This thesis added to the current studies on POPs in sediments from the Prydz Bay at some degree, supplied the basic data of OCPs and PCBs in estuaries and bays in eastern and western Antarctic, contributed to the further understanding of the transfering, transformation and sedimentation signatures in eastern Antarctic. Meanwhile, this thesis discussed different isomers or congeners of POPs in bird eggs and tissues, which provided realistic evidences to better understand the sources and bioaccumulation of POPs in food webs in western Antarctic regions. |
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