西宁市春季道路扬尘碳组分特征及来源解析

为研究西宁市道路扬尘PM_2.5和PM₁₀中碳组分的特征及其来源，于2019年5月使用样方法采集西宁市78条铺装道路，通过NK-ZXF再悬浮仪器将样品悬浮到滤膜上，并利用热光碳分析仪测定有机碳(OC)和元素碳(EC)组分。结果表明：PM_2.5中ω(TC)为8.49%(环线)~10.38%(支路)，ω(OC)为7.68%(环线)~9.36%(支路)，ω(EC)为0.74%(国道)~1.02%(支路)；PM₁₀中ω(TC)为8.38%(环线)~10.78%(支路)，ω(OC)为7.30%(环线)~9.76%(支路)，ω(EC)为0.59%(高速)~1.09%(环线)。各类型道路中ω(OC) 均明显大于ω(EC)，ω(EC) 在不同道路类型中差异不大。OC在PM₁₀中的质量分数均高于在PM_2.5中的值，表明OC更容易富集到粒径大的颗粒物上。采用最小相关系数法(MRS)估算道路扬尘PM_2.5和PM₁₀中SOC含量，得出SOC分别占OC总量的81.91%和76.25%。以上结果说明道路扬尘存在明显的二次污染。因子分析和OC/EC比值分析表明西宁市春季道路扬尘PM_2.5和PM₁₀主要来源于燃煤、生物质燃烧和机动车尾气排放。本研究可为西宁市道路扬尘污染防治工作及制定环境管理对策提供参考。

Characteristics and source apportionment of carbon components in road dust in Xining City

In order to study the characteristics and sources of carbon components in road dust PM2.5 and PM10 in Xining City, samples were collected by the quadrat sampling method at 78 paved roads in May 2019. The samples were re-suspended on filters by using a NK-ZXF sampler, and the concentrations of organic carbon (OC) and elemental carbon (EC) were determined by Thermal Optical Carbon Analyzer. Results showed that the ω(TC) in PM2.5 of road dust was 8.49% (ring road) ~ 10.38% (access road), ω(OC) was 7.68% (ring road) ~ 9.36% (access road), ω(EC) was 0.74% (national highway) ~ 1.02% (access road); ω(TC) was 8.38% (ring road) in PM10 of road dust to 10.78% (access road), ω(OC) was 7.30% (ring road) ~ 9.76% (access road), ω(EC) was 0.59% (expressway) ~ 1.09% (ring road). ω(OC) was obviously greater than ω(EC) for all road types, and ω(EC) did not vary significantly among all road types. The mass fraction of OC in PM10 was higher than that in PM2.5, indicating that OC was more easily enriched to particles with larger particle size. The minimum correlation coefficient method (MRS) was employed to estimate the SOC content in PM2.5 and PM10 of road dust, and it was found that SOC accounted for 81.91% and 76.25% of the total OC, respectively, which indicated that there was significant secondary pollution in road dust. Factor analysis and the OC/EC ratio analysis showed that PM2.5 and PM10 of road dust in spring in Xining City were mainly derived from coal combustion, biomass burning, and vehicle exhaust. This study can provide a reference for preventing and controlling road dust pollution and developing environmental management countermeasures in Xining City.