博斯腾湖流域大气多环芳烃污染特征、干沉降通量及来源

Pollution Characteristics,Dry Deposition Fluxes,and Sources for Atmospheric Polycyclic Aromatic Hydrocarbons in the Bosten Lake Watershed

本研究使用大气被动采样器(PAS-PUF)和干沉降被动采样器(PAS-DD),分别于2016年采暖期和2017年非采暖期对新疆博斯腾湖流域及周边地区15种USEPA优控多环芳烃(PAHs)大气浓度和干沉降进行了观测,并对其污染特征和来源进行了研究.结果表明,采暖期和非采暖期博斯腾湖流域PAHs大气浓度范围分别为6. 38～245. 43 ng·m^(-3)和2. 33～74. 76ng·m^(-3);采暖期与非采暖期均呈现出居民区>湖泊周边>塔中的空间分布.采暖期和非采暖期PAHs大气干沉降通量范围分别为0. 45～18. 10μg·(m^2·d)-1和0. 25～8. 15μg·(m^2·d)-1;采暖期居民区PAHs干沉降通量比湖泊周边和塔中采样点高,但在非采暖期塔中采样点高于其它采样点.整体而言,博斯腾湖流域大气及干沉降中PAHs在采暖期显著高于非采暖期,在采暖期与非采暖期均以菲(Phe)、芴(Flu)、荧蒽(Flua)和芘(Pyr)等3～4环PAHs为主.比值法源解析结果显示,博斯腾湖流域大气和干沉降中PAHs主要来源于煤炭和生物质燃烧; HYSPLIT前向和后向轨迹模拟结果表明,非采暖期居民区较高PAHs排放通过大气传输到达博斯腾湖区,经大气干沉降进入水体,可能会对博斯腾湖水生环境造成影响.

Passive air samplers( PAS-PUF) and passive dry deposition( PAS-DD) samplers were applied in the Bosten Lake watershed located in Xinjiang to estimate the atmospheric concentrations and dry deposition fluxes for 15 US EPA priority polycyclic aromatic hydrocarbons( PAHs) during a heating period in 2016 and no-heating period in 2017,respectively. The results showed that the atmospheric PAHs concentrations in the Bosten oasis area ranged from 6. 38 ng·m-3 to 245. 43 ng·m-3 during the heating period and 2. 33 ng·m-3 to 74. 76 ng·m-3 during the non-heating period. The highest atmospheric PAHs concentrations were found in the residential area,followed by regions near Bosten Lake and Tazhong. The atmospheric dry deposition fluxes of PAHs in the Bosten Lake watershed ranged from 0. 45 μg·( m2·d)-1 to 18. 10 μg·( m2·d)-1 during the heating period and 0. 25 μg·( m2·d)-1 to 8. 15μg·( m2·d)-1 during the non-heating period. During the heating period,the atmospheric dry deposition fluxes in the residential area were significantly higher than those in the regions near Bosten Lake and Tazhong. However,the atmospheric PAHs dry deposition flux in Tazhong was much higher than that in other sites during the heating and no-heating periods. In general,the atmospheric PAHs dry deposition fluxes during the heating period were significantly higher than those during the non-heating period. PAH composition for the atmosphere and dry deposition were dominated by 3 and 4 ring congeners,especially by phenanthrene,fluorine,fluoranthene,and pyrene during two sampling periods. In addition,the congener diagnostic ratio shows that coal and biomass combustion were possible sources of atmospheric PAHs in the Bosten Lake watershed. The forward and backward trajectory analysis based on the HYSPLIT model demonstrated that the higher atmospheric PAH emissions from the residential area would be transported to Bosten Lake,which can affect the aquatic environment of this lake by dry deposition.