考虑积雪覆盖与气候变化条件下PBDEs的大气排放、迁移转化及归趋行为研究

Polybrominated diphenyl ethers (PBDEs) are a class of persistent toxic substances (PTSs) which are ubiquitous in the environment. It has become hot-spot of global research due to its health hazard and widespread sources. Aiming at current condition of related monitoring that is only for typical areas and conventional medium in China, however, current research is insufficient under a national scale on snow and snow cover in alpine region, atmospheric emissions, migration and transformation, and environmental fate of PBDEs. Through monitoring the pollution levels of PBDEs in atmosphere, snow and snow cover media, measuring physical parameters of different vertical layers of snow covers, and analyzing the influence factors of migration and transformation of PBDEs in snow cover, in this study, a model of air-snow exchange during freezing and snowmelt period will be established and air-snow partitioning and secondary emissions from snow cover will be explored. In order to understand and calculate the atmospheric emissions of PBDEs, this study will establish a model for calculation gridded emission amount, and thus compile gridded emission inventory of PBDE congeners that is as input data of multimedia environmental model. Chinese gridded industrial pollutants emission and residue model (ChnGIPERM) that added module of air-snow partitioning will be employed to research on environmental behavior of PBDEs under the condition of snow cover and to explore key environmental factors, and thus to reveal response behavior on climate change, meanwhile to compile a high resolution gridded residue inventories of PBDE congeners in a national scale of China. The results have great significance for revealing the distribution characteristics of snow and snow cover, air-snow exchange and environmental fate of PBDEs.

多溴联苯醚（PBDEs）是环境中普遍存在的一类持久性有毒物质，因其具有健康危害及来源广泛等特点，已成为全球研究的热点。针对目前我国仅对典型地区及常规环境介质进行相关监测，而对高寒地区积雪雪被介质、国家尺度PBDE大气排放、迁移转化及环境归趋研究不足的现状，通过监测大气、积雪及雪被介质中PBDE的污染水平，测定雪被垂直分层物理参数，分析PBDE在雪被中迁移转化行为的影响因素，建立冻融期PBDE的气-雪交换模式，研究PBDE的气-雪分配及二次排放行为；建立PBDE排放清单模型，以其排放清单为输入数据，使用加入气-雪交换模块的中国网格化工业污染物排放残留模型，研究积雪覆盖条件下PBDE的环境行为并探寻主控环境因子，揭示其对气候变化的响应行为，同时绘制高分辨率的我国国家尺度的PBDE残留清单。研究成果对揭示PBDE在积雪、雪被中的分布特征、气-雪交换及环境归趋行为具有重要的现实意义。

本项目针对典型持久性有机污染物（persistent organic pollutants, POPs）的排放清单、迁移转化和环境分布行为进行了初步研究。本研究将多氯联苯（polychlorinated biphenyls, PCBs）的排放源分为故意生产、非故意产生和电子垃圾拆解三种类型，分析了中国三种类型PCBs的历史排放，并建立了1950年-2010年中国网格化多氯联苯排放清单；共评估8个主要排放源非故意产生PCBs排放8.56吨，约占非故意排放总量的96.3%；同时将网格化排放清单数据与2004年和2008年大气监测数据进行了对比，表明二者之间存在显著相关关系。应用中国网格化工业污染物排放残留模型（Chinese Gridded Industrial Pollutants Emission and Residue Model, ChnGIPERM）对PCBs的环境分布行为和归趋，主要包括土-气交换、时空变异和非源区PCBs二次排放的时空异质性特征进行了研究。结果表明：长距离大气传输和温度是影响PCBs二次排放与残留分布格局的主要因素；土壤残留被认为是PCB28的重要环境归宿；排放源的强度和与非源区的距离强烈影响着PCB28的时空变异。排放格局、大气传输、土壤有机碳、土壤垂直迁移、环境温度和降水均会影响PCB28的分布特征和土-气交换行为。中国履行《斯德哥尔摩公约》之后，环境中PCBs呈现明显的降低趋势；同时，本研究建立了针对PCBs和其他有机污染物的逆向管理框架。有机氯农药（organochlorine pesticides, OCPs）的土-气交换行为及其分馏效应的研究结果表明，在土壤有机质含量一定的情况下，日均温度最大时六六六（HCHs）和滴滴涕（DDTs）之间土-气分配系数（KSA）的差异比日均温度最小时高出一个数量级，HCHs比DDTs更容易挥发重新释放进入环境中而进行二次分配，土壤有机质质量分数每提高1%而引起的KSA值的变化率不同，且这种变化会随着有机质含量的提高而趋于平稳。本项目的研究成果对丰富和发展POPs的清单编制技术与地球化学循环过程理论具有重要的学术价值和战略意义。