内蒙古某灌域表层土壤六氯环己烷空间分布特征及影响因素

为修复灌区内土壤有机氯农药污染，降低六氯环己烷对土壤环境的危害，对内蒙古某灌域表层土壤进行采样，利用气相色谱测定50个土壤样品中六氯环己烷及其异构体的含量，并利用ArcGIS空间分析技术确定表层土壤中六氯环己烷的分布状况。样本中六氯环己烷的检出率为96%，各样本中六氯环己烷的浓度范围为未检出~23.0 ng/g，平均浓度为4.4 ng/g。4种异构体含量平均值顺序为γ-六氯环己烷>δ-六氯环己烷>β-六氯环己烷>α-六氯环己烷。灌域东北部和西南部残留浓度较高，并由这2个方向向中部地区逐渐递减，表层土壤中的六氯环己烷分布受土壤黏粒量、不同种植种类和灌溉水源的影响较大。虽受人类耕作的影响，但表层土壤中的六氯环己烷污染水平相对较低。     

Organochlorine pesticide air-water exchange and bioconcentration in krill in the Ross Sea

Mean hexachlorobenzene (HCB) and hexachlorocyclohexane (HCH) concentrations, measured in seawater and air samples, confirmed the decline in levels of these compounds in Antarctic air and water. However, low α/γ-HCH ratios in air at the beginning of the sampling period suggest a predominance of fresh lindane entering the Antarctic atmosphere during the Austral spring probably due to current use in the Southern Hemisphere. Water-air fugacity ratios demonstrate the potential for HCH gas deposition to coastal Antarctic seas, while the water-air fugacity ratios for HCB imply that volatilization does not account for the observed decrease of HCB in surface seawater. HCH concentrations found in krill samples were correlated with seawater concentrations indicative of bioconcentration of HCHs from seawater.     

Size-related bioaccumulation and between-year variation of organochlorines in ice-associated amphipods from the Arctic Ocean

Organochlorines are found even in organisms living in remote areas such as the Arctic marginal ice zone. Organochlorine concentrations in ice-associated (sympagic) amphipods are related to their diet. Therefore, the size-dependent diet shift of Gammarus wilkitzkii may influence its organochlorine content. In this preliminary study, the organochlorine concentrations in two size classes (small 29 mm and large >29 mm) of G. wilkitzkii were analysed. The concentrations of more lipophilic compounds [e.g. polychlorinated biphenyls (PCBs)] were lower in the small than the large size class, whereas concentrations of less lipophilic compounds [e.g. hexachlorocyclohexanes (HCHs)] did not differ by size class.

Since contamination transport by the atmosphere, ocean currents and sea ice may vary, the organochlorine burden in sympagic organisms may also vary. There are no data available on temporal variation of organochlorine burden in Arctic sympagic fauna. Therefore, we compared organochlorine concentrations in sympagic amphipods (G. wilkitzkii, Apherusa glacialis and Onisimus spp.) between 1998 and 1999. Organochlorine concentrations in all amphipods were low in both years, with sum organochlorines from 50.7 to 621.9 ng g⁻¹ lipid weight. The concentrations of hexachlorobenzene (HCB), chlordanes, DDTs and PCBs were higher in 1999 than 1998, whereas the HCH concentrations were lower in 1999 than 1998. The organochlorine concentrations differed between the taxa in both years in a similar increasing manner from A. glacialis to both G. wilkitzkii and Onisimus spp.

In studies of bioaccumulation relative to body size and temporal variation, a thorough interpretation requires samples from several size classes and years. Nevertheless, the present data provide new knowledge on contaminants in Arctic invertebrates where data are scarce.     

Release of hexachlorocyclohexanes from historically and freshly contaminated soils in China: implications for fate and regulation

Hexachlorocyclohexanes (HCHs) were produced and used in large quantity worldwide and are common soil pollutants. In this study, desorption of α-HCH and γ-HCH from two soil samples collected from a historical pesticide plant in Tianjin, China, was examined. As a comparison, desorption of freshly sorbed γ-HCH was examined, using five typical Chinese soils. Strong resistant desorption was observed for both historically contaminated and freshly contaminated soils, and desorption results were well modeled with a biphasic desorption isotherm. The unique thermodynamic characteristics associated with the desorption-resistant fraction indicated that physical constraint within soil organic matrices was likely the predominant mechanism controlling resistant desorption. Resistant desorption could have significant effects on fate and exposure of HCHs in soil environment. More accurate biphasic desorption models that take into account of the resistant desorption can be used to facilitate regulating, management and remediation of HCH-contaminated sites.