滇池流域农田土壤有机氯农药残留特征

在滇池流域农田，重点是滇池滨湖区和入滇河流柴河流域，选择不同土地利用类型、不同种植年限大棚采集土壤样品进行气相色谱（ECD）分析。结果表明，试区土壤中有机氯农药（OCPS）检出率为95.9%，OCPS的残留量范围、平均值分别为nd-63.4 μg·kg-1、6.3 μg·kg-1，以p，p′-DDE为主要残留物，98.3%的样点达到国家《土壤环境质量标准》一级标准（〈50 μg·kg-1）。与国内同类报道相比，滇池周边土壤中OCPS的残留较低。不同土地利用类型有机氯残留量排序为：设施栽培〉水稻田〉露天菜地〉荒草地〉坡耕地；不同大棚种植年限土壤中，棚龄长于15 a的 OCPS残留量要明显高于棚龄短于15 a的，而棚龄短于15 a的，土壤中OCPS含量差异不明显。

Residues Characteristics of Organochlorine Pesticides in the Cultivated Soils from Dianchi Lake Watershed

Surface soils（0-20 cm depth） of typical cultivated field were collected in Dianchi Lake watershed （especially Dianchi Lake side and Chaihe River watershed）, and organoehlorine pesticide residues （OCPs）, represented with DDTs and HCHs, were analyzed by gas chromatography with ECD detector. The results showed that OCPs ranged from none to 63.4 μg·kg^-1 were detected in 95.9% of the soil samples, and the average level was 6.3 μg·kg^-1. The p, p＇-DDE was the main OCPs component, which indicated that the residues in soils were possibly resulted from historical use of OCPs. The concentrations of DDTs and HCHs in 98.3% of samples were lower than 50 μg·kg^-1, which showed that these soils had reached the first level of the National Soil Environment Quality Standard. The effect of soil utilization and history of greenhouse cultivation on the level of pesticide residues in soils were also discussed. The amount of pesticide residues according to different land use in order was shown as follows：greenhouse soil〉paddy soil〉open vegetable soil〉grassland soil〉sloping land soil. The con- centrations of OCPs in soil samples with more than 15 years cultivated history were higher, while the difference of OCPs residues amount was not significant in soils during the first 15 year cultivation in greenhouse. Comparing with the reference data, the pollution burden in soils of Dianchi Lake watershed was lower than those in other areas of China.