某岩溶水源地地下水中有机氯农药的分布特征

Distribution Characteristics of Organochlorine Pesticides in Groundwater in A Karst Groundwater Source

某水源地的岩溶水是北方一大型城市的主要供水水源,为了解该区地下水中有机氯农药的分布情况,采用气相色谱法对某岩溶水源地76组地下水样进行了测试分析。研究结果表明:地下水中检出10种有机氯农药组分,检出率最高的是β-HCH,为11.84%;有机氯农药的检出质量浓度为0.96～63.77ng/L,平均值为13.50ng/L,远小于饮用水水质标准。在丰水期,地下水中检出的有机氯农药组分较多,检出质量浓度总体上是丰水期高于枯水期、补给区高于径流区和排泄区,并且质量浓度会随着地下水位的升高而变大。地下水中的有机氯农药主要来源于早期使用的农药在环境中的残留,γ-HCH则可能来自于开采井附近农药厂排放的污水。

Karst groundwater in a water source is the major source of drinking water supply in a large city in North China. In order to find out the distribution characteristics of organochlorine pesticides in groundwater of the area, 76 groups of groundwater samples were tested with gas chromatography. The results show that among the 10 kinds of organochlorine pesticides components detected, the highest detected rate was 11.84% for β-HCH. The detected concentrations of organochlorine pesticides ranged from 0.96 ng/L to 63.77 ng/L while the average detected concentration was 13.50 ng/L. The concentrations detected were far less than the standards for drinking water quality. In the wet period, more organochlorine pesticides components in groundwater were detected, and the concentration in the wet period was generally higher than that in the dry period. In the replenishment district, the concentration was generally higher than that in the runoff area and the drainage area. The concentration increased with the groundwater level rising. The organochlorine pesticides are mainly sourced from the residues of pesticides previously used in the environment but γ- HCH is likely to come from the sewage discharged by a pesticide factory in the vicinity of a pumping well.