基于单体碳、氮稳定同位素技术研究水中亚硝胺的降解机理

Nitrosamines (NAMs), a class of organic compounds with high toxicity and carcinogenicity, are ubiquitous in the water environment because of their hydrophilic characteristic. The loss of NAMs in the environment mainly caused by the degradation (photodegradation and microbial degradation) during the transport in water and soil. Degradation usually leads to isotope fractionations and the compound-specific stable isotope analysis (CSIA) has been proved as an accurate and promising method to quantify the degradation of organic compounds. In this project, a new detection method on the CSIA of C and N for typical NAMs in soils and water media is developed and based on which, three groups of laboratory experiments involving the photodegradation in water, degradation in soil and transport of NAMs in water and soil columns are set up. By detecting the concentrations and calculating the enrichment factor for typical NAMs for which stable C and N isotope fractionation occurs during degradation and transport by CSIA, this project aims at studying on the degradation kinetics and pathways of NAMs, and searching and establishing an innovative approach for properly indicating the corresponding degradation mechanisms based on CSIA characteristics of C and N of NAMs. Results will be helpful in developing the understanding of environmental behaviors of NAMs and offering scientific basis for pollution control and remediations of NAMs in the water environment.

亚硝胺（简称NAMs）是一类对人类具有高毒性和强致癌性的亲水性有机化合物，在我国自然水体中广泛存在。本项目拟建立水和土壤中典型NAMs的单体碳、氮稳定同位素分析测试技术；在室内模拟水中NAMs的自然光降解、NAMs在土壤中的降解，以及NAMs在土柱中的迁移、分布和降解过程，通过对反应物在降解过程中浓度的变化，以及典型NAMs的C、N同位素分馏效应，研究水中NAMs的降解动力学特征和反应路径，探索并建立基于二维单体C、N稳定同位素技术合理推测NAMs降解机理的新方法。研究结果有助于加深对NAMs类污染物环境行为的了解，并为水体NAMs污染的治理和修复提供科学依据。

亚硝胺在我国珠三角流域广泛存在，来源不明，排入水环境后的衰减机制还不清楚。本项目以珠三角流域为主要研究地区，（1）建立了基于UPLC-MS/MS的水和土壤中亚硝胺的分析测试技术；（2）对NDMA单体碳稳定同位素（C-CSIA）的分析测试进行了初探；（3）对珠三角地区的源-汇机制进行了研究;（4）根据母体化合物和降解产物的含量变化，研究了典型亚硝胺在水环境中的降解机制。本研究取得的主要创新成果包括：（1）对亚硝胺的来源和进入水环境后的衰减行为进行了研究，研究成果已发表在Water Research （第一作者）和Environmental Research （通讯作者）。（2）研究模拟了自然光和地下水中微生物作用下NDMA、NMOR、NDBA的降解动力学机制，并推导了三种化合物的降解路径。