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961.
962.
963.
Distribution of organochlorine pesticides in seawater of the Bering and Chukchi Sea. 总被引:4,自引:0,他引:4
Zi-Wei Yao Gui-Bin Jiang Heng-Zhen Xu 《Environmental pollution (Barking, Essex : 1987)》2002,116(1):49-56
Organochlorine pesticides (OCPs) in the seawater collected in the Bering and Chukchi Seas during the First Chinese Arctic Research Expedition were confirmed by gas chromatography-mass spectrometry (GC-MS) and analyzed by capillary gas chromatography with micro-electron capture detector (GC-microECD). The average of hexachlorocyclohexanes (HCHs; sum of isomers alpha-, beta-, gamma-, delta-) was nearly equal in the Bering Sea (mean concentration 412.7 pg/l) and in the Chukchi Sea (mean concentration 445.8 pg/l), which showed no obvious latitudinal difference of these two regions. Compared with previously reported studies, concentrations of OCPs in these regions were much lower than the levels in the last decades. The ratio of alpha:gamma HCH was 5.0 and 3.4 for the Bering and Chukchi sea, respectively, which indicated the different pesticide composition in these two regions. Many other OCPs with different residue patterns were also found for the first time in the investigation regions. Heptachlor epoxide (in the Bering Sea) and heptachlor (in the Chukchi Sea) were main OCPs contaminants besides HCHs. 相似文献
964.
965.
The dechlorination and destruction of 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) under basic condition using hydrogen peroxide as the oxidant catalyzed by molybdate ions have been studied. Under ambient conditions of temperature and pressure, more than 95% of millimolar solutions of TCP and PCP can be converted to CO2 and CO, chlorinated and nonchlorinated carboxylic acid in 40 min. Up to 2.4 chloride ions per TCP and 3.5 chloride ions per PCP were released. TOC measurements indicated that 18% and 11% of the carbon was mineralized for TCP and PCP respectively after an hour of reaction. The results of ESR measurements suggested that the reaction possibly proceeded via the pathway with singlet oxygen. 相似文献
966.
Qun-fang Z Zhong-yang L Gui-bin J Rui-qiang Y 《Environmental pollution (Barking, Essex : 1987)》2003,125(3):301-304
In nine batches of sea bivalves collected from Chinese coastal cities during the year of 2000 to 2002, a special sample named Mya arenaria was found to have strong ability of butyltin accumulation compared with the other sampled bivalves in the corresponding batches. Tributyltin compound was the predominant pollutant with the detection rate high up to 100%. Special high levels of g Sn/g were detected in some Mya arenaria samples. The results obtained showed that Mya arenaria was potentially a biomarker to indicate organotin pollution in coastal aquatic environment. 相似文献
967.
968.
Jiang W Zhang S Shan XQ Feng M Zhu YG McLaren RG 《Environmental pollution (Barking, Essex : 1987)》2005,138(2):278-284
Laboratory batch experiments were carried out to study the adsorption of arsenate on 16 Chinese soils with different physicochemical properties. Wide differences in arsenate adsorption were observed, and the Jiangxi and Hubei soils were more effective sorbents for arsenate than other soils. The Langmuir one-surface and two-surface equations were used to model the arsenate adsorption data. Except for the Jiangxi and Hubei soils, the Langmuir one-surface equation gave reasonably good fits to the arsenate adsorption data. However, the Langmuir two-surface equation generally provided a better fit than the Langmuir one-surface equation. For soils with relative high organic matter (OM), dissolved organic carbon (DOC) or extractable phosphate, the Langmuir one-surface and two-surface equations described the adsorption isotherms similarly. In contrast, for soils with relatively low contents of OM, DOC or extractable phosphate, the Langmuir two-surface equation gave the better fit to the arsenate adsorption data. 相似文献
969.
According to the theory of photocatalysis, the efficiency of photocatalysis decreases mostly due to the recombination of photo-generated electron-hole pairs. An electric field across a photocatalyst can promote the separation of photo-generated electrons and holes and prevent them from recombination so as to enhance the efficiency of photocatalysis. And the synergetic decomposition efficiency of photocatalysis and an electric field is greater than that of the simple combine of their single efficiency. The performance of photocatalysis enhanced by electric field (PEEF) and operating conditions such as the direction of the electric field, the voltages between the two electrodes, the material of the electrodes, which may affect the efficiency of PEEF, were investigated in this paper. The results indicate that the system of PEEF abides the established theory of photocatalysis. 相似文献
970.