浅谈城市污水处理厂设计规模的确定

文章分析了我国城市污水处理厂的建设规模与实际运行情况存在差距的基本原因,并就城市污水处理厂设计中的进水水质、水量预测、工程分期建设等方面的问题进行了探讨.     

Total and subcellular distribution of trace elements (Cd, Cu and Zn) in the liver and kidney of green turtles (Chelonia mydas) from the Mediterranean Sea

This study investigated the subcellular distribution of Cd, Cu and Zn in liver and kidney of green turtles (Chelonia mydas) stranded along the Italian coast of the South Adriatic Sea (Eastern Mediterranean). Cd and Zn mean concentrations did not differ significantly between liver (4.26microgg(-1) and 34.53microgg(-1), respectively) and kidney (5.06microgg(-1) and 26.39microgg(-1), respectively), whereas the levels of Cu were significantly higher in liver (32.75microgg(-1)) than in kidney (8.20microgg(-1)) (p<0.009). Most of Cd, Cu and Zn was present in hepatic and renal cytosol, and their concentrations increased with total levels in both organs, indicating that cytosol has a crucial role in metal accumulation. Cd and Cu in hepatic and renal cytosol were present mostly in metallothionein fractions (MTs), whereas Zn was fractionated into MTs and high-molecular-weight-substances (HMWS). The comparison with the results of other investigations on individuals of the same species collected in different marine areas shows good agreement relatively to essential metals. For Cd our data are comparable with those encountered in specimens from the Mediterranean Sea (Cyprus) confirming the homogeneity of the area comprising the south-eastern basin of the Mediterranean Sea from an ecological point of view.     

Levels and congener profiles of PCBs and PCDD/Fs in blue shark (Prionace glauca) liver from the South-Eastern Mediterranean Sea (Italy)

Liver of blue shark (Prionace glauca) specimens from the South-Eastern Mediterranean Sea were analyzed for the presence of polychlorinated biphenyls (PCBs), including coplanar congeners, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). PCBs were the dominant chemicals, followed by PCDFs and PCDDs. The pattern of PCB congener concentrations in the hepatic tissue was dominated by higher chlorinated compounds. The specific profile of toxic PCDD/F congeners was characterized mainly by 2,3,7,8-TCDF and 2,3,7,8-TCDD, followed by 1,2,3,6,7,8-HxCDD and 2,3,4,6,7,8-HxCDF. The total 2,3,7,8-TCDD toxic equivalent (TEQs) was 149 pg g⁻¹ lipid wt. The profile of TEQ shows that PCDDs present the greatest risk to this species contributing to total toxicity with a percentage approximately of 60%, while the contribution of PCDFs and DL-PCBs is almost the same being 22.4% and 21.6%, respectively. Further investigations are urgently needed to characterize the PCDD/Fs contamination levels not only in elasmobranch fish but in all Mediterranean marine biota.     

Levels and congener pattern of polychlorinated biphenyls in the blubber of the Mediterranean bottlenose dolphins Tursiops truncatus

Isomer specific concentrations of individual polychlorinated biphenyls (PCBs) including toxic non-ortho (IUPAC 77, 126, 169) and mono-ortho (105, 118, 156) coplanar congeners were determined in the blubber of nine bottlenose dolphins (Tursiops truncatus) stranded along the Eastern Italian coast. The total PCB concentrations ranged from 3534 to 24375 ng/g wet wt. The PCB profile was dominated by congeners 138 and 153 collectively accounting for 55% of the total PCB concentrations. Among the most toxic congeners the order of abundance was 126>169>77. The mean total 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent of six coplanar PCBs in the blubber of bottlenose dolphins was 45596 pg/g. Non-ortho congeners contributed greater to the 2,3,7,8-TCDD toxic equivalents than mono-ortho members. Particularly, PCB 126 was the major contributor to the estimated toxic potency of PCBs in dolphins.     

Polychlorinated biphenyl residues in deep-sea fish from Mediterranean Sea

Polychlorinated biphenyls including coplanar congeners were measured in the liver of different species of skates and ghostsharks. The mean concentrations of PCBs in skates (314 ng/g wet wt) were comparable with those in ghostsharks (285 ng/g wet wt). The specific analysis of PCB congeners in skates hepatic tissue revealed a profile dominated by hexa-, penta-, and heptachlorinated congeners followed by trichlorobiphenyls, tetra- and decachlorobiphenyls. A different profile dominated by hexa-, tri-, and pentachlorinated congeners, followed by heptachlorobiphenyl and decachlorobiphenyls was found in ghostsharks liver. The estimated 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) of coplanar PCBs in skates and ghostsharks were 0.48 and 0.33 pg/g wet weight, respectively, with mono-ortho congeners PCB105, 118 and 156 contributing more than 90% to the TEQs.