宁夏枸杞园土壤中新烟碱类农药残留特征及风险评估

Distribution characteristics and potential risk of neonicotinoid pesticides in soils from Lycium barbarum L.orchard in Ningxia

【目的】摸清宁夏枸杞园土壤中新烟碱类农药吡虫啉和啶虫脒残留水平和风险状况,为宁夏枸杞产业健康发展提供科学依据。【方法】选择种植1,3,6,9,12,15和18年(弃耕2年)枸杞园,在距离枸杞植株主干3 cm、冠层正下方、冠层边缘和距冠层外缘50 cm 4个水平方向,及树冠正下方0~20,20~40,40~60,60~80和80~100 cm 5个垂直方向分别采集土样,采用高效液相色谱-串联质谱法测定分析土样中吡虫啉和啶虫脒的残留特征,运用风险商值法和美国环境保护署(USEPA)方法,评价宁夏枸杞园土壤中新烟碱类农药吡虫啉和啶虫脒残留引起的环境风险和对人体的暴露风险。【结果】①宁夏枸杞园表层土壤中吡虫啉和啶虫脒残留量分别为ND~162.66 ng/g(平均37.33 ng/g)和ND~101.50 ng/g(平均24.30 ng/g)。水平方向上在树冠正下方2种农药残留量和检出率都较低。0~100 cm土层内,随着土层深度的增加,吡虫啉和啶虫脒的残留量均急剧下降。②种植1~12年,随着种植年限的增加,枸杞园土壤中吡虫啉和啶虫脒的残留量都有逐渐增大趋势。种植15年的土壤新烟碱类农药在80~100 cm土层有明显富集现象。③种植3~15年的表层土壤中新烟碱类农药存在中等环境风险;种植3~12年在20~60 cm土层部分有中低风险,但60~100 cm土层均无潜在环境风险。④宁夏枸杞园土壤中吡虫啉和啶虫脒的暴露风险主要以土壤摄入和皮肤接触为主;儿童对土壤中吡虫啉和啶虫脒的潜在暴露风险远高于成人;目前宁夏枸杞园土壤中新烟碱类农药不会对当地居民的健康带来危害。【结论】宁夏枸杞园土壤中新烟碱类农药残留量较低,对土壤环境有中低风险,但对人体健康无危害。

【Objective】This study determined the residual level and risk of imidacloprid and acetamiprid in soil of Lycium barbarum L.orchards in Ningxia to provide basis for the healthy development of Lycium barbarum L.industry.【Method】In 1,3,6,9,12,15 and 18 years(abandoned for 2 years)old Lycium barbarum L.orchards,soil samples were collected in four horizontal directions(3 cm from plant trunk,directly below canopy,canopy edge and 50 cm from outer edge of canopy)and five vertical directions(0-20,20-40,40-60,60-80 and 80-100 cm directly below canopy),and the residue characteristics of imidacloprid and acetamiprid of soil were determined by liquid chromatography-tandem mass spectrometry.The environmental risks of imidacloprid and acetamiprid were evaluated by risk quotient method,and human body exposure risks were evaluated by the United States Environmental Protection Agency(USEPA)method.【Result】①The overall residues of imidacloprid and acetamiprid were ND-162.66 ng/g(average 37.33 ng/g)and ND-101.50 ng/g(average 24.30 ng/g),respectively.In the horizontal direction,the residues and detection rates of the two pesticides below canopy were low.In 0-100 cm soil layer,the residues decreased sharply with the increase of soil depth.②With the increase of planting years,the residues of imidacloprid and acetamiprid in surface soil increased gradually with the increase of planting years from 1 to 12 years.The neonicotinoid pesticides were enriched in 80-100 cm after 15 years.③There was moderate risk of neonicotinoid pesticides in the surface soil for 3 to 15 years.There was medium to low risk in the 20-60 cm layer for 3 to 12 years,and no potential risk in the 60-100 cm layer.④The main exposure risks of imidacloprid and acetamiprid in soil of Lycium barbarum L.orchards were soil intake and skin contact.The potential exposure risk of children to imidacloprid and acetamiprid in soil was higher than that of adults,but the neonicotinoid pesticides in soil had no harm to residential health.【Conclusion】The residues of neonicotinoids in soil of Lycium barbarum L.orchards in Ningxia were low with medium or low risks to ecological environment and no risks to human health.