北京东南郊灌区土壤和农作物有机农药污染风险评估

Assessment of the contamination risk of organchlorine pesticides in soils and crops of the irrigation district located at the southeastern suburbs of Beijing

为研究北京市东南灌区农作物和表层土壤有机氯农药含量水平,2015年利用气象色谱—质谱仪检测了该灌区土壤和作物样品中23种农药组分含量。结果显示灌区表层土壤农药含量为1.2～83.3μg/kg,均值为28.7μg/kg。土壤样品中六氯苯、莠去津、p,p′-DDE检出率均为100%, p,p′-DDT检出率为17%,其余组分检出率仅为0～11%。表层土壤农药各检测组分占总量比例最高的为莠去津和p,p′-DDE,分别占总量的49.9%和35.2%;其次为六氯苯和p,p′-DDT,分别占总量的5.0%和4.2%。土壤六氯苯、莠去津和DDTs含量分别为0.2～9.8μg/kg(均值为1.4μg/kg)、0.5～76.3μg/kg(均值14.3μg/kg)和0.5～54.4μg/kg(均值为11.4μg/kg),均未超过加拿大、越南和我国土壤标准的限值要求。灌区总体上近期没有DDTs输入。冬小麦籽粒、夏玉米籽粒、菜心和油菜农药含量分别为0.229～0.297,ND～1.29,0.5和0.4μg/kg;其余农作物23种农药含量均低于实验检出限。农作物仅六氯苯和莠去津能检测出,其含量分别为ND～1.39和ND～1.2μg/kg。夏玉米籽粒莠去津含量未超过GB 2763—2014《食品安全国家标准食品中农药最大残留限量》含量限值。

In order to find out the concentration and pollution characteristics of organchlorine pesticides(OCPs)in topsoil and agricultural products in irrigation district at the southeastern suburb of Beijing,23 kinds of OCPs in topsoil samples and crops samples in this district were detected by gas chromatography-mass spectrometry(GC-MS)in 2015.Results showed that the total concentrations of OCPs in topsoil ranged from 1.2 to 83.3 μg/kg,with average concentration of 28.7 μg/kg.Hexachlobenzene,atrazine and p,p′-DDE were found in all soil samples,whereas p,p′-DDT were detectable in 17% of all soil samples,and the rest were detectable in a range of 0~11%.The higher individuals were atrazine and p,p′-DDE,which contributed 49.9% and 35.2% to OCPs,respectively,followed by hexachlobenzene and p,p′-DDT accounting for 5.0% and 4.2% of OCPs,respectively.The concentrations of hexachlobenzene,atrazine,and DDTs in topsoil were 0.2 ~9.8 μg/kg(average concentration of 1.4 μg/kg),0.5 ~ 76.3 μg/kg(average concentrations of 14.3 μg/kg),and 0.5 ~ 54.4 μg/kg(average concentrations of 1 1.4 μg/kg),respectively;the three individuals were lower than the corresponding standards.There were no inputs for DDTs recently in the study area.The concentrations of OCPs in winter wheat grain,summer maize grain,Chinese flowering cabbage and oil seed raped were 0.229~0.297,ND^1.29,0.5 and 0.4μg/kg,respectively;the concentrations of OCPs in the rest crops were lower than the detection limit.Only hexachlobenzene and atrazine in crops were higher than the detection limit,the concentrations were ND^1.39 and ND^1.2μg/kg,respectively.The concentrations of atrazine in summer maize grain were below the standard of National Food Safety Standard-maximum Residue Limits for Pesticides in Food(GB 2763一2014).