北江是珠江的重要支流之一,为确定北江上游流域农田土壤有机氯农药( OCPs)的含量、来源以及分布特征,2010年11月,对该区域水稻田、菜地和果园土壤进行了采样、处理以及GC/MS分析.研究结果表明:27种OCPs中,除环氧七氯、狄氏剂、硫丹I、反式九氯、顺式九氯、异狄氏剂醛和甲氧氯外,其余均有不同程度的检出.总OCPs质量分数为2.71 ～ 62.4 ng·g-1,平均11.9 ng·g-1;含量最高的为DDTs,其次为硫丹和HCHs,其质量分数范围分别为1.82 ～ 60.3、0.103～ 19.6和nd(未检出)～1.74 ng·g-1；水稻田土壤DDTs的含量与果园相当,但明显高于菜地的残留水平.研究区域OCPs的源分析表明,HCHs主要来自于早期商业HCHs和林丹农药的残留,DDTs源于商业DDTs和三氯杀螨醇农药的残留.北江上游流域农田表层土壤OCPs储存量约为342 kg,其中DDTs 243 kg、硫丹63.7 kg、HCHs 15.0 kg.与国内外同类型报道相比,结合我国GB 15618 - 1995《土壤环境质量标准》,研究区域土壤OCPs残留的程度较低.%A large-scale sampling program was conducted to collect soil samples (including paddy, vegetable field and orange orchard soils) from the Beijiang upper watershed in Guangdong province for assessing concentrations, sources and composition of OCPs. Twenty-seven OCPs were measured, and twenty OCPs were detected by the GC/MSD method, excepting for heptachlor epoxide, dieldrin, endosulfan I, trans-nonachlor, cis-nonachlor, endrin ketone and methoxychlor. The concentraions of OCPs ranged from 2.71 to 62.4 ng-g"1, with a mean of 11.9 ng-g"1. DDTs were the dominant contributors for OCPs with a concentration range of 1.82-60.3 ng-g"', followed by endosulfans and HCHs with the concentration ranges of 0.103-19.6 and nd (undetectable)-1.736 ng-g"1, respectively. DDTs levels in paddy soils were comparative to those in orchard soils, while significantly higher than those in vegetable soils. OCPs compositions revealed that the sources of DDTs in soils were associated with historical technical DDT and recent dicofol, which HCHs might originate from recent lindane and historical technical HCHs. The mass inventories of OCPs estimated in agricultural soils were 342 kg, including DDTs (243 kg), endosulfans (63.7 kg), and HCHs (15.0 kg). Comparing with various studies and the "National Environmental Quality Standard for Soils of China" (GB 15618 - 1995), OCP pollutions were generally slight in present study.
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