南亚热带典型地区农业土壤中多环芳烃和有机氯农药研究

Polycyclic aromatic hydrocarbons and organochlorine pesticides in agricultural soils from typical area of south subtropics, China

参考美国EPA标准方法对南亚热带潮汕地区农业土壤中持久性有机污染物多环芳烃(PAHs)和有机氯农药(OCPs)进行分析,并对其分布和来源进行研究,最后探讨了不同种植方式下污染物的污染特征。结果表明:该区农业土壤中PAHs含量范围从22.1ng/g到1256.9ng/g,与其它地区的污染程度和一些土壤环境质量标准相比,该区处于中等污染水平。高温裂解是土壤PAHs的主要来源。OCPs在被禁止20a后在土壤中仍有残留,残留水平从4.6ng/g到1021.5ng/g,其中HCHs和DDTs的残留未超过国家土壤环境质量标准。早期使用残留是其主要污染源,但新近仍有DDT和硫丹的输入。PAHs和OCPs的污染主要集中在土壤表层和亚表层,且随着深度的加深,污染逐渐减少,但40cm以下,污染变化很小。菜地土壤PAHs污染水平低于稻田土壤,而OCPs污染水平高于稻田土壤。

Persistent Organic Pollutants （POPs） have become widespread in the environment and now represent a global contamination problem. The global transport of POPs is of current interest and concern. Based on the model of global fractionation and distillation, at present, the contributions of POPs from the subtropical regions of China to the pollution to the global environment are paid more and more attention. Recent investigations showed that POPs concentrations in the water, sediment, and atmosphere could be very high in the region. However, there have been few studies on POPs in agricultural ecosystems within this region. The U. S. EPA analytical methods were employed to examine agricultural soils concentrations of Polycyclic Aromatic Hydrocarbons （PAHs） and organochlorine pesticides （OCPs） in typical area of subtropical zone of China. The distribution and main possible sources of these pollutants were studies. Contamination traits in different planting manner were discussed. The results were showed as follows ： （ ! ） The total PAHs concentrations ranged from 22. lng/g to 1256.9 ng/g and the pollution extent was classified as a moderate level in comparison with other investigations and soil quality standards. PAHs isomer ratios suggested that the pyrolytic origins such as fossil fuel combustion related to vehicle exhaust as well as industrial emissions were the dominant source of PAHs. （2） The concentrations of OCPs ranged from 4.6ng/g to 1021.5 ng/g and DDTs and HCHs didn＇t exceed national soil quality standards, suggesting that OCPs contamination still existed after forbidden for a considerable period. OCPs residues might be caused by its persistence and/or some fresh input of DDT and Endosulfan. （3） High PAHs and OCPs concentrations were found in surface and subsurface soils. The total concentrations were declined with depth, but transmission was little under 40cm. （4） The PAHs of vegetable soils were slighter than that of paddy soils, but the OCPs residues were more than ones of paddy soils.