太原市雨水中多环芳烃的污染特征

Characteristics of polycyclic aromatic hydrocarbons in rainwater in Taiyuan

对太原市2012年3—10月雨水中16种溶解态多环芳烃(PAHs)的分布特征、沉降通量和来源进行了分析.结果表明,16种PAHs总的(∑16-PAHs)平均浓度为1081.2 ng·L-1(范围为316.8—6272.3 ng·L-1),以2—3环PAHs为主,占75.4%,4环和5—6环PAHs分别占18.2%和6.4%.∑16-PAHs浓度与温度(P<0.05)和电导率(P<0.01)呈显著正相关.同一场降雨不同阶段的∑16-PAHs浓度及其组成与降雨量有关.∑16-PAHs的全年平均沉降通量为481.5 ng·m-2·d-1,9月的沉降通量最高(2342.8 ng·m-2·d-1),其次是7月(1604.4 ng·m-2·d-1),10月的最低(83.3 ng·m-2·d-1),其中2—3环PAHs的沉降通量明显高于4环和5—6环PAHs,∑16-PAHs的月沉降通量与月平均降雨量(P<0.01)和降雨频次(P<0.05)呈显著正相关.利用特征比值法判断PAHs的主要来源是煤燃烧,同时也存在一定的石油燃烧源和少部分的石油源.

Distribution, sources and deposition fluxes of 16 dissolved polycyclic aromatic hydrocarbons（ PAHs） in rainwater samples collected from March to October in 2012 in Taiyuan were investigated in this study. The mean concentration of total 16 PAHs（ ∑ 16-PAHs） was1081. 2 ng·L^-1（ ranged from 316. 8 to 6272. 3 ng·L^-1）. 2—3 ring-PAHs were the major components,accounting for 75. 4%,and 4 ring- and 5—6 ring-PAHs accounted for 18. 2% and6. 4%,respectively. Significant positive correlations between concentrations of ∑ 16-PAHs and temperatures（ P 〈0. 05） / electrical conductivity（ P 〈0. 01） was found. The composition and concentration of ∑ 16-PAHs at different stages of the rain were different as a result of different rainfalls. The mean deposition fluxes of ∑16-PAHs in 2012 was 481. 5 ng·m^-2·d^-1. The highest deposition fluxes occurred in September,followed by July,and the lowest occurred in October.There were significant positive correlations between deposition fluxes of ∑ 16-PAHs in different months and their mean rainfalls（ P 〈0. 01） and frequencies of rains（ P 〈0. 05）. The results of diagnostic ratios of PAHs indicated the sources of PAHs in Taiyuan mainly derived from coal combustion,and also some from petroleum combustion and a little from petroleum.