土壤中两种二苯醚除草剂环境化学过程及其生物有效性的影响机理

Bioavailability is an important factor in assessing the risk of pesticide in the environment. Bioavailability of pesticide in soil is affected by environmental condition and physicochemical property. But the total concentration can't reflect actual bioavailability. To scientific evaluate the environmental and ecological risks of the diphenylethers herbicides, this project, which takes the freely dissolved concentration of the fomesafen and oxyfluorfen as the core and the biotoxicity and the bioaccumulation effect as the evaluation approach, will detect the freely dissolved concentration of these two diphenylethers herbicides in soil and predict the bioavailability by the chemical method (mild solvent extraction, Accelerated Solvent Extraction, centrifugal ultrafiltration and negligible depletion solid phase microextraction). By using the combined method of static（batch adsorption experiment）and dynamic（soil column experiment）adsorption experiments, the behavior characteristics of pesticides in different kinds of soils, like adsorption - desorption and vertical transfer, would be systematically studied. And based on the relations between the freely dissolved concentration and biotoxicity and the bioaccumulation effect, it also explores the influence mechanism of soil physical-chemical proprieties (soil constitution, pH, organic matter content, etc.) to the bioavailability. All those works would provide a theoretical basis to prevent and control the transfer of pesticides from the soil environment to organism.

生物有效性是影响环境中农药生态风险评估的关键因子。土壤中农药的生物有效性受环境条件、土壤理化性质等因素影响，而土壤中总浓度不能反映真正的生物有效性。为科学评价二苯醚类除草剂的环境生态风险，本项目以氟磺胺草醚和乙氧氟草醚的自由溶解态浓度为核心，以生物毒性和累积效应为评价方式，采用化学方法（温和溶剂提取，加速溶剂萃取，超滤离心和微损耗固相微萃取）测定土壤中两种二苯醚类除草剂的自由溶解态浓度，预测评价其生物有效性。采用静态吸附实验（批量吸附试验）与动态实验（土壤柱试验）相结合的方法，系统研究农药在不同类型土壤中的吸附-解吸、纵向迁移等行为特性。基于自由溶解态浓度与生物毒性和累积效应的相关性，探明土壤本身组成、pH、有机质含量等理化性质对其生物有效性的影响机理。为预防和控制农药从土壤环境向生物体内传输提供理论基础。

生物有效性是影响环境中农药生态风险评估的关键因子。土壤中农药的生物有效性受环境条件、土壤理化性质等因素影响，而土壤中总浓度不能反映真正的生物有效性。为科学评价氟磺胺草醚等农药的环境生态风险，本项目以氟磺胺草醚、噻虫啉、氟虫腈和乙虫腈的生物有效性为核心，以生物毒性和累积效应为评价方式，采用化学方法（温和溶剂提取，加速溶剂萃取，超滤离心和微损耗固相微萃取）测定土壤中两种二苯醚类除草剂的自由溶解态浓度，预测评价其生物有效性。结果表明Tenax提取浓度可以较为准确地预测噻虫啉等农药对蚯蚓、玉米等有益生物的生物有效性。通过向土壤中添加不同种类、不同水平的生物炭，发现土壤及水沉积物中生物炭的添加对农药对蚯蚓及玉米等的生物有效性有明显影响，可以有效地降低蚯蚓体内及玉米种的农药浓度。研究结果可为科学准确的评价氟磺胺草醚、噻虫啉、氟虫腈和乙虫腈的环境风险提供依据，为预防和控制农药从土壤环境向生物体内传输提供基础。对于保障作物、环境安全及人类健康都具有重要指导意义。