大尺度环境下我国粮食产地手性农药的残留行为机制和风险分析

The use of chiral pesticides, such as triazoles and neonicotinoids, is large in China's grain producing areas, causing heavy pesticide pollution because of their slow degradation. The previous study from the applicant showed that, the enantiomer toxicity of these pesticides is greatly different, and may have different degrees of environmental risks under different environmental conditions. However, current evaluation do not distinguish the difference between enantiomers and environmental impacts, resulting in inaccurate assessments and potential threats to grain production and safety of the producing areas. Based on the partition from China's grain producing areas, the project will adopt GPS for positioning sampling and the technique of chiral chromatography tandem mass spectrometry. In the total of 10 wheat, rice and maize producing areas in China, for the first time, this project is planned to conduct research on residual behavior of 27 kinds of commonly used chiral pesticides including triazoles, neonicotinoids and other pesticides at different niches. By analyzing the relationship between environmental selection pressure generated by the factors of crop types, soil conditions, climatic factors and other factors, the key driving factors of mechanism of residual behavior of chiral pesticides at grain production areas in China could be explicit. The project is also aimed at analyzing their environmental toxicity effect and revealing the conditions of environmental risks of producing areas. That will provide reference basis for accurate risk assessment and scientific use of chiral pesticides..

三唑类及新烟碱类等手性农药在我国粮食生产中用量大，降解慢，产地污染重，申请人前期研究发现，该类农药对映体之间毒性差异大，不同环境条件下具有不同环境风险，而当前的评估不区分对映体差别和环境影响，通常导致评估结果不准确，给粮食生产及产地带了潜在威胁。本项目基于我国粮食产地分区，采用GPS定位采样和手性色谱串联质谱分析技术，在我国小麦、水稻、玉米共10个主产区，首次在大尺度环境下研究我国常用三唑类、新烟碱类等27种手性农药在粮食产区不同生态位的残留特征，通过解析作物类型、土壤条件、气候等因素产生的环境选择压与农药对映体残留行为关系，揭示手性农药在我国粮食产区的残留行为机制及关键驱动因子，明确其毒性效应和粮食产地环境风险，为手性农药的准确风险评价和科学使用提供依据。

本项目选取了我国3个小麦主产区、3个玉米主产区和4个水稻主产区，探究了多种典型农药在不同粮食产区土壤及农产品中的残留特征，并对其进行风险评估。明确了我国3种粮食主产区中的农药残留特征存在农药类型差异性、区域差异性和时间差异性。3种粮食产区土壤中存在农药多残留现象。试验采集的土壤中至少可检出16种农药。不同类型农药在粮食产区土壤中的残留水平具有差异性。在小麦产区土壤中，氯氟氰菊酯、吡虫啉和氯氰菊酯的平均残留浓度最高；在玉米产区土壤中，莠去津和烟嘧磺隆的平均残留浓度最高；在水稻产区土壤中，氯虫苯甲酰胺和硝磺草酮的平均残留浓度最高。从农药类别角度，在小麦产区土壤中杀虫剂残留水平相对较高，玉米产区土壤中除草剂残留水平相对较高，在水稻产区土壤中杀虫剂和除草剂残留水平相对较高。此外，产地土壤中的农药残留水平存在区域差异。在小麦产区，山东省土壤中农药总残留水平最高，内蒙古自治区最低；在玉米产区，土壤中农药总残留水平为：黄淮海夏玉米区 > 北方春玉米区 > 南方夏玉米区；在水稻产区，土壤样品中农药总残留水平为：东北稻区 > 华南稻区 > 黄淮海稻区 > 长江中下游稻区。同时产地土壤中的农药残留水平还存在时间差异性。北方冬麦区和春麦土壤中农药总残留均在6月份最高，在南方冬麦区在4-5月份较高；黄淮海夏玉米区、南方夏玉米区和北方春玉米区土壤中农药总残留分别在7月、8月和6月份最高；东北稻区农药总残留在7月份最高，而在华南稻区、黄淮海稻区和长江中下游稻区均在8月份最高。在3种粮食产区成熟期籽粒中存在多种农药残留现象，至少可检出2种农药。另外，明确了手性杀菌剂戊唑醇和腈菌唑农田土壤中的残留水平的差异性。探究了三种新烟碱类杀虫剂在3种粮食产区土壤中母体和代谢物间的关系，发现吡虫啉、啶虫脒和噻虫嗪的5种代谢物的检出率均为100%，其总残留水平是3个母体总和的2.4倍。评估了在小麦、玉米和水稻种可检出农药的膳食风险，风险均可接受。评估了4种新的手性杀菌剂抑霉唑、噁唑菌酮、氟噻唑吡乙酮和氯氟醚菌唑的对映体选择性行为特征，提出相关建议。本项目研究结果对农药的安全使用、风险评估及科学管理提供重要科学数据。