东海多溴联苯醚的大气沉降、海-气交换及其季节性源-汇作用

The East China Sea (ECS) is one of the major transport paths of continental outflow from East China and North China to Northwest Pacific Ocean when northwesterly winds prevail. Therefore, understanding the air-water exchange of pollutants in the ECS is essential to assess their regional/global cycle. Does the ECS act as a sink or a source for PBDEs in the atmosphere? In order to answer this proposed question, a remote island in ECS as a stationary sampling point and shipboard sampling were selected in this study. Concentrations and composition of PBDEs in air (particle/gas), precipitation and surface water from the ECS were determined to estimate the fluxes of dry/wet deposition and air-water exchange. The objectives of this work are to reveal that: 1) the contributions of different input modes (dry/wet deposition and air-water exchange) to PBDEs in ECS; 2) the seasonal source-to-sink effect in air-water exchange and its main controlling factors. This is a new exploration for the study of POPs in China seas. This work could provide evidence for estimating the budget of PBDEs in ECS, and will be useful for evaluating the ecological risk assessment in ECS.

在东亚冬季风的驱动下，东海是我国大陆大气污染物向西北太平洋传输的主要路径，已成为污染物海-气相互作用研究的关键海区。本课题围绕新型持久性有机污染物多溴联苯醚（PBDEs）在东海的年净通量是“由大气向海输入为主，还是由海向大气挥发为主导”这一重要科学问题，选择远离大陆的东海小岛作为长期观测点，结合东海典型季节的走航观测，分析东海大气颗粒相、气相、降水以及海水中PBDEs的浓度与组成，估算PBDEs在东海的干、湿沉降和海-气交换通量；揭示东海PBDEs海-气交换过程的季节性源-汇作用及其机制。本研究具有鲜明的区域特色，是中国海区POPs研究的新探索，对估算东海PBDEs收支具有重要的科学价值，也可为东海生态风险评估提供科学依据。

在东亚季风的驱动下，东海是我国大陆大气污染向西北太平洋传输的主要路径，已成为污染物海-气交换作用研究的关键海区。本项目通过研究东中国海沉积柱中多溴联苯醚（PBDEs）的沉积记录，揭示了PBDEs污染企业在中国的响应，尤其是电子电器产品在中国的生产和使用是中国PBDEs污染的重要影响因素。通过对PBDEs大气干-湿沉降以及海-气交换的研究，得出BDE-209呈现从大气到海洋的净输入，大河口可作为持久性有机污染物的源-汇缓冲区。通过对航次PCBs气粒分配研究，发现气团中PCBs的大气分配过程并未达到平衡，其可能与春季陆源传输干扰有关。通过对比有机质吸收模型和有机质吸收颗粒物表面吸附模型预测值，结果表明PCBs在大气中分配同时受制于这两种作用。本项目研究了长江口-东海DDTs和HCHs的大气沉降以及海气交换，发现HCHs的海气交换通量与大气干湿沉降通量相当，DDTs的海气交换通量是大气干湿沉降总量的5倍。此结果表明目前在HCHs的浓度趋于环境背景值的情况下，河流以及亚洲沙尘的输入对长江口HCHs的影响有限。