[Sorption isotherms and sorption thermodynamics of faecal sterols on offshore sediment].

Experiments of faecal sterols adsorption from aqueous solutions onto Dalian offshore sediment were done by a batch equilibrium method,and the sorption of 12 kinds of faecal sterols in sediment were investigated in this paper. It was shown that the adsorption equilibrium time was 24 h, and after 24 h the variation tendency of 5 kinds of fingerprint values was stable. It indicated that adsorption isothermal data was interpreted by the Henry, Freundlich, Langmuir, Duhinin-Radushkevich(D-R) and Temkin equations, and demonstrated that the other 4 isotherms provided stronger data fitting than the Langumir isotherm. It inferred that from D-R model the mean free energy of adsorption process of 12 kinds of faecal sterols was from 7 071.1 J x mol(-1) to 9 128.7 J x mol(-1), and concluded that it was mainly physical adsorption of the sorptive process of 12 kinds of faecal sterols in sediment. It discovered that from the Temkin model the value of K(f) of cholestanone was the maximum, and extrapolated that cholestanone was adsorbed most easily on sediment. It stated that the enthalpy and entropy change of the adsorption were both less than zero, and inferred that the adsorption process was exothermic and spontaneous.

Distribution of organochlorine pesticides in seawater of the Bering and Chukchi Sea.

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.