辽北农田土壤除草剂和有机氯农药残留特征

Residual Characteristics of Herbicides and Organochlorine Pesticides in Agricultural Soils in Northern Liaoning Province

采用GC-MS法对辽北农田土壤中3种除草剂和8种有机氯农药残留量进行分析。结果表明：阿特拉津和乙草胺100%检出,最大残留量分别为21.20ngg-1和203.18ngg-1,半衰期分别约为18.2~23.6d、25.4~43.8d,阿特拉津在农田中降解速率较实验室和小区实验要快,而乙草胺降解速率则较慢。施用5个月后,二者在玉米地残留量仍显著高于未施药的蔬菜地和水稻地,长期使用使得蔬菜地和水稻地普遍受到污染。丁草胺在水稻地全部检出,最大残留量为30.87ngg-1。8种有机氯农药仅六氯苯、狄氏剂和艾氏剂有检出,其中六氯苯100%检出,其残留量呈蔬菜地〉水稻地〉玉米地的规律,最大残留量为7.07ngg-1,狄氏剂和艾氏剂检出率和残留量较低。所有检出农药均呈正偏态分布。与国外相关标准及国内外残留现状相比,辽北农田土壤中阿特拉津和8种有机氯农药残留水平较低,乙草胺残留水平相对较高。

The agricultural soil samples collected from northern Liaoning Province were analyzed for 3 herbicides and 8 organochlorine pesticides （OCPs） using gas chromatography- mass spectrometry （GC- MS）. The results showed that atrazine and acetochlor were detected in all the samples with the highest values of 21.20 ng g-1 and 203.18 ng g-1, respectively. Their half- lives were 18.2 - 23.6 d、25.4 - 43.8 d,and atrazine dissipation rate in agricultural field was relatively faster than that in lab experiment and field plot experiment, while acetochlor dissipation rate was relatively slower. 5 months after pesticides application, their residues in maize field were still significantly higher than that in vegetable field and paddy field which didn＇t apply the two pesticides. Due to the long- term use, the vegetable field and paddy field have been contaminated. Butachlor was detected in all of the paddy field. Its highest value was 30.87 ng g-1. Only HCB, dieldrin and aldrin were detected among the 8 OCPs. HCB was detected in all the samples. The order of its residues from highest to lowest was vegetable field, paddy field and maize field. Its highest value was 7.07 ng g-1. The residues and detection rate of dieldrin and aldrin were relatively lower. All the detected pesticides were positive skew distribution. Compared with other countries＇ environmental quality standard for soil and other areas＇ residual state, atraznine and 8 OCPs residues in the agricultural soils of northern Liaoning Province were lower; acetochlor residual level was relatively higher.