多溴联苯醚在大气颗粒中的粒径分配规律及气-粒分配模型

Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants, which exhibit multiple toxicities. Atmosphere is an ideal medium for PBDEs transmission and diffusion. The environmental behaviors of PBDEs existing in different scale particles are much different in migration ability and human health risk, so it is very necessary to study size distributions of PBDEs in particles. In former researches, the effects of brominating rate to PBDEs gas-particle distributions had been studied, while size distributions have not been revealed. Still the theoretical value and the measured value of distribution coefficient KP could not coupled well with each other. Two important reasons were attributed to the fiber adsorption of PBDEs in gas phases when collection particles and the inaccuracy of KP definition equation. In this project, an active sampler based on the directive current corona discharge will be employed to extinct the errors induced by fiber samplers, and the size distributions of PBDEs will be comprehensively studied. Furthermore, the definition equation of KP will be improved by replacing “the concentration of total suspended particulate” by “the concentration of particulate with PBDEs”. This research will reveal the fate behaviors of PBDEs in atmosphere and promote the development of gas-particle distribution models. And it will also be helpful for China to perform the duties of “Stockholm Convention on Persistent Organic Pollutants”.

多溴联苯醚（PBDEs）是应用广泛的半挥发性阻燃剂，具有多种毒性。大气是PBDEs传播和扩散的重要介质，赋存于不同粒径颗粒中的PBDEs的环境行为存在显著差异，研究PBDEs的粒径分配规律，有助于掌握其迁移能力和对人体健康的危害程度。以往研究主要探讨了含溴数量对BDE单体气-粒分配规律的影响，而PBDEs在颗粒相中的粒径分配规律尚未明确；而且因为滤膜采样误差和气-粒分配系数KP定义式计算误差，造成KP的实测值与模拟值无法很好耦合。本项目用基于静电除尘机理的主动采样器采集颗粒物，避免滤膜采样对分析精度的影响，系统研究各温度下PBDEs的粒径分配规律；用“含有PBEDs的颗粒物浓度”代替Kp定义式中“总悬浮颗粒物浓度”，提高KP定义式精度。本项目将促进对PBDEs大气归趋行为的了解，促进包括PBDEs的半挥发性污染物气-粒分配理论的发展，为我国更好的履行《斯德哥尔摩公约》提供科学依据。

根据项目申请书，本项目研究主要完成了采样器和采样方法建立、区域环境空气PBDEs污染水平、特征（特别是粒径分配）研究、气粒分配模型改进等研究内容。获得了上海市区域大气近10年PBDEs污染水平、特征、来源和变化趋势等关键信息；通过实验室研究建立了半挥发性有机化合物（以BDE-209为例）的粒径分配系数的计算方法，并指出了研究粒径分配对气粒分配模型研究的重要性和必要性，以及区域大气颗粒物浓度对讨论半挥发性有机化合物污染水平和特征的重要性；获知了环境空气PBDEs粒径分配规律，提出一种按粒径分配改进气粒分配系数计算式的方法Kpi，并用实地数据在两种气粒分配模型中进行了验证，确定改进后的Kpi相对传统Kp具有更好的精确性；得到了三个重要结论：1）改进后的Kpi高于Kp值；2）Kp、KPi的模型拟合线斜率均偏离模型理论值1/-1；3）分配系数的改进（即KPi）显著改变了模型拟合线的截距；上述三个结论具有重要的理论意义，揭示了传统Kp中化合物在“可悬浮颗粒物中均匀分布”之假设引起地不确定性，解释了长期困扰学者的理论模型与实地数据无法耦合的问题。本研究的结果和结论将促进对PBDEs大气归趋行为的了解，促进包括PBDEs的半挥发性污染物气-粒分配理论的发展，为我国更好的履行《斯德哥尔摩公约》提供科学依据。