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Persistent organochlorines, such as polychlorinated biphenyls, including coplanar congeners and DDT compounds, were measured in the liver of a teleost species: namely, Lophius budegassa. The mean concentrations of PCBs (1249 ng/g wet wt) were comparable with DDTs mean levels (1459 ng/g wet wt). Among DDTs the compound found at the highest concentration was p,p'-DDE representing 76% of the total DDT burden. The PCB profiles were dominated by congeners 153, 180, and 138 accounting for 49.8%, 16.0% and 13.7% of the total PCBs. The total 2,3,7,8-TCDD toxic equivalent (TEQs) of six coplanar PCBs, including mono- and non-ortho congeners, was 0.98 pg/g wet wt. The congeners with highest TEQs values were non-ortho-congeners followed by mono-ortho ones.  相似文献   
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Concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (DDTs), were determined in the liver of two different shark species Prionace glauca (blue shark) and Dalatias licha (kitefin shark) from the Mediterranean Sea. In blue shark liver, the concentrations of PCBs (2482 ngg(-1)) and DDTs (2392 ngg(-1)) were comparable, while in kitefin shark the hepatic concentrations of DDTs (4554 ngg(-1)) were significantly higher than those of PCBs (1827 ngg(-1)). Contamination levels differed between species, with kitefin shark showing consistently higher concentrations of DDTs, and blue shark higher levels of PCBs. Congener-specific PCB profiles, similar between the two species were dominated by the higher chlorinated congeners (hexachlorobiphenyls: 62.8-63.9%, penta-: 15.2-21.3%, hepta-: 13.4-14.5%) with most of the lower chlorinated congeners being absent or present at very low levels. In both species, the total 2,3,7,8-tetrachlorodibenz-p-dioxin toxic equivalent (TEQs) concentrations (blue shark: 2.51 pg/g; kitefin shark: 1.46 pg/g) seem to be relatively modest. Regards to DDT component pattern, p,p'-DDE was dominant in the liver of both species (blue shark: 81.5%; kitefin shark: 38.0%), while the percentage composition of the other metabolites was differently characterized. The composition pattern of DDTs and the low value of p,p'-DDE/DDTs ratio in the specimens from Ionian Sea suggest that organochlorine pesticide contamination is still continuing in this marine environment.  相似文献   
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Persistent organochlorines such as polychlorinated biphenyls including coplanar congeners, DDT compounds and HCB were measured in different tissues (muscle, liver and eggs) of two Mediterranean shark species: namely Centrophorus granulosus and Squalus blainvillei. The concentrations of organochlorines in the tissues and organs of both species were in the order DDTs>PCBs>HCB. The highest values of DDTs, PCBs and HCB were found in liver followed by eggs and muscle. Among DDTs the compound found in greatest concentration was p,p-DDE. The PCB profiles were dominated by congeners 138, 153, and 180. The isomers with higher TEQs values were non- and mono-ortho congeners than di-ortho ones in muscle, liver and eggs of both species. Among the non-ortho, PCB 126 was the major contributing individual to the total TEQs in both species.  相似文献   
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基于游程编码的GIS栅格数据矢量化方法   总被引:18,自引:1,他引:17  
为了克服传统栅格矢量化方法的各种局限性,提出利用栅格的游程编码和区位表在内存中直接进行栅格图形矢量化提取的有效方法,并描述了算法实现步骤.由于栅格游程编码具有提取方便、压缩比适中、和常规栅格之间的转换便捷等特征,所以本方法的采用使得在计算机内存中处理矢量化栅格的规模、精度、复杂程度和速度有较大提高,可广泛应用于栅格型地理空间分析和遥感图像专题要素类型的边界提取等方面,实践表明本文提出算法具有很高的效率,易于实现.  相似文献   
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Heavy metal concentrations in the tissues of marine turtles are presented. The most frequently monitored elements are mercury, cadmium and lead; and the tissues mainly analysed in nearly all the stranded individuals are muscle, liver and kidney. The highest mercury and cadmium levels were found in liver and kidney respectively; the majority of the lead burden existed in bones and carapace, while arsenic was present mainly in muscle tissue. Mercury occurred quite completely as methylmercury in muscle, whereas in liver the main form was the inorganic one. Arsenic was exclusively present in the metallorganic form either in muscle tissue or in liver. Metals in the eggs were mainly present in the yolk. Significantly higher concentration of mercury, copper, zinc and iron were found in yolk than albumen, while shell contained highest levels of manganese and copper. The load of trace metals in these animals strictly correlated with the species seems to depend on their different food behaviour.  相似文献   
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Concentrations of mercury and methylmercury residues were determined in the muscle tissue of three cartilaginous fishes Chimaera monstrosa (ghostshark), Torpedo nobiliana (electric ray) and Myliobatis aquila (eagle ray) from the Mediterranean Sea. The highest mean levels of total mercury were detected in ghostshark (3.14 mg/kg wet weight), followed by electric ray (2.42 mg/kg wet weight), and eagle ray (0.83 mg/kg wet weight). Such a variability is influenced by quite a number of factors, among which size, fish ecology and feeding habits. The percentages of the methylated form to total mercury ranged from a minimum of 72% in eagle ray to a maximum of 83% in ghostshark. Relationship between specimen size and mercury and methylmercury concentrations were found in ghostshark species.  相似文献   
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