农药助剂壬基酚聚氧乙烯醚及代谢物壬基酚在稻田系统中的迁移转化和累积

Nonylphenol polyethoxylates (NPnEOs) are used extensively as pesticide adjuvants, detergents, and lubricants in industrial, agricultural and household applications. Nonylphenol (NP), a main transformation product of NPnEOs, is a hydrophobic compound that has been classified as endocrine disruptors (EDCs), it can be enriched in organism by the transmission of the food chain and harms to the environment and human. The occurrence of NPnEOs in soil is closely related with anthropogenic activities such as pesticide spraying, reclaimed water and sludge application. The previous studies demonstrated that NPnEOs was degraded rapidly into NP in the farmland. However, the main metabolite NP was degraded slowly and accumulated in submerged soil. It has also been confirmed that NP was detected in rice with the μg/kg level. The objectives of this work were to study the fate of NPnEOs in paddy fields with the semi-field and the potting experiments, and to investigate the leading factors that effect on the transport and transformation of NPnEOs and the distribution and accumulation of NP in rice. The source and pathway of NP residues in rice will analyze with the determination data, and the concentrations of NPnEOs in field and NP in rice will detect to evaluate the relationship of dose transfer. These results would be helpful to assess the ecological and rice risk, and also can provide the guidance for the evaluation of the other pesticide adjuvant.

壬基酚聚氧乙烯醚（NPnEOs）作为农药助剂、洗涤剂、润滑剂等在民用和工业领域都有广泛应用，其代谢产物壬基酚（NP）是一种强疏水性内分泌干扰物，对环境和人类的健康危害性极大。NPnEOs通过农药喷施、再生水灌溉或污泥还田等途径进入农田。研究表明农田中NPnEOs可快速降解为NP，但NP降解却非常慢，特别是在淹水土壤中降解更慢，导致了NP大量蓄积。已有报道NP在稻米中有检出，残留含量级别为μg/kg。本项目开展NPnEOs通过水稻植株、田水、土壤进入稻田系统后的迁移转化和代谢物NP的累积行为研究。明确NPnEOs在稻田中的迁移转化特征和影响因素、及代谢物NP在水稻中的分布累积规律，并探讨进入稻田环境中的NPnEOs和累积在水稻中的NP之间剂量传递关系。本项目将为NPnEOs环境生态和稻米质量安全风险评估提供基础数据，也为其它助剂的安全性评估提供借鉴指导意义。

壬基酚聚氧乙烯醚是一种性质稳定、应用广泛的非离子型表面活性剂，也是重要的农药助剂，其主要代谢物壬基酚具有难降解、高毒性和强生物累积特性。关于壬基酚聚氧乙烯醚和代谢物壬基酚在稻田土壤系统中的迁移、转化和累积方面还未见相关研究报道。.项目建立了壬基酚单氧乙烯醚（NP1EO）、壬基酚二氧乙烯醚（NP2EO）和壬基酚（NP）在土壤、水稻根、水稻茎叶、稻米和稻壳中的检测方法。NP2EO在土壤中的降解符合一级动力学方程，其在土壤中的降解速率，随着初始浓度的增加而减慢；温度升高能加快NP2EO在土壤中的降解；土壤中有机质含量的增加可加快NP2EO在土壤中的降解；NP2EO在碱性土壤中的讲解速率较快，而在酸性土壤中较慢。采用半田间水稻生态系统，模拟稻田真实的田间环境，研究了NP、NP1EO和NP2EO在稻田土壤系统中的迁移、转化和累积，以及不同施药浓度对其在稻田土壤、水稻根和茎叶间迁移的影响。结果表明，在不同施药浓度条件下，NP、NP1EO和NP2EO在稻田土壤、水稻根和茎叶中均有不同程度的分布和累积，三者在不同基质内的最终残留量均较低，在米中均未检出NP1EO和NP2EO，只有在中高浓度下NP有微量检出，其检出值分别为0.053 μg/kg和0.107 μg/kg；在不同施药浓度条件下，在稻田土壤、水稻根和茎叶中的NP2EO逐渐降解为NP1EO，NP1EO逐渐降解为NP；NP2EO、NP1EO和NP在稻田土壤、水稻根和茎叶之间均发生迁移，且浓度对其迁移的影响所遵循的规律为：三者均在低浓度条件下主要由根向茎叶中迁移，而高浓度下主要由土壤向根中迁移；NP和NP2EO主要分布于根和茎叶中，而NP1EO主要分布于土壤和根中。本项目将为NPnEOs环境生态和稻米质量安全风险评估提供基础数据，也为其它助剂的安全性评估提供借鉴指导意义。