我国半干旱区工业化城镇PCBs干沉降及归趋

Dry deposition and fate of PCBs in a semi-arid and industrialized city,China

采用大气被动干沉降采样器,观测了我国半干旱区城市皋兰2018年非取暖季和取暖季18种多氯联苯(PCBs)的大气干沉降通量和污染特征,并利用主成分分析、环境多介质模型对其污染来源、环境归趋行为等进行了分析和研究.研究区∑18PCBs干沉降通量为13.0~158.8ng/(m^(2)·d),呈现园区点较高、取暖季高于非取暖季的特征.干沉降中PCBs以四氯联苯和五氯联苯为主,并且四氯联苯干沉降通量在取暖季明显上升.研究区PCBs污染主要源于含PCBs的产品以及燃烧和工业热过程带来的排放,但燃烧和工业热过程无意产生的PCBs可能对研究区产生更大影响.土壤相是研究区PCB81主要的汇,相间迁移以大气相向土壤相的沉降为主;大气平流输出是研究区PCB81的主要清除途径;污染物排放速率、平流停留时间和平流输入污染物浓度是影响大气相、土壤相PCB81浓度的主要因素.

A passive dry deposition sampler(PAS-DD)was used to monitor the atmospheric dry deposition fluxes and research the contamination characteristics of 18 polychlorinated biphenyls(PCBs)in Gaolan County,a semi-arid region of China,during the non-heating and heating seasons of 2018,and the sources and environmental fate of PCBs were analyzed and simulated using principle component analysis and multimedia environmental model.The PCBs dry deposition fluxes ranged from 13.0 to 158.8ng/(m^(2)·d),and increased significantly during the heating season.Besides,the highest dry deposition flux was observed at the industrial estate.Tetra-PCBs and penta-PCBs were the dominant homologue groups,and the dry deposition fluxes of tetra-PCBs increased during the heating season.PCB-containing products,combustion and industrial thermal processes were considered to be the main PCBs emission sources.However,the unintentionally produced PCBs from combustion and industrial thermal processes may have a greater impact on the PCBs contamination in the study area.Soil was found to be the major PCB81 sink in the study area,and the transport of PCB81 from air to soil was the main environmental transport process;Atmospheric advection was a vital way of removing PCB81;Pollutant emission rate,advective flow residence time,and advective inflow concentration were important factors affecting the concentration of PCB81 in the atmosphere and soil.