西安市城市降尘和土壤尘PM10和PM2.5中碳组分特征

为研究西安市城市降尘和土壤尘PM₁₀和PM_2.5中碳组分污染特征，丰富大气降尘的成分谱库，于2015年4~5月收集了西安市城区5个点位的城市降尘和周边16个点位的土壤尘样品，通过ZDA-CY01颗粒物再悬浮采样器获得PM₁₀和PM_2.5的滤膜样品，使用Model5L-NDIR型OC和EC分析仪测定了样品中的有机碳（OC）和元素碳（EC），定量分析了西安市城市降尘和土壤尘PM₁₀和PM_2.5中碳组分特征及其主要来源.结果表明，不同站点降尘PM₁₀和PM_2.5中OC的占比差异较大，分别为6.0%~19.4%和7.6%~29.8%.不同站点降尘PM₁₀和PM_2.5中EC的占比较小，在城市站点的占比分别为0.6%~2.2%和0.2%~3.6%，而在多数外围土壤尘中几乎检测不到EC的存在.PM₁₀中含碳组分的占比为：城市降尘>外部对照>河滩土>土壤尘，PM_2.5中含碳组分的占比为：城市降尘>土壤尘>外部对照>河滩土.不同站点降尘含碳气溶胶均以OC为主，在城市降尘中相对较低，在PM₁₀和PM_2.5中OC占总碳（TC）的比值分别为85.2%~95.3%和87.9%~98.9%；在土壤尘中OC的占比较高，均超过99%.含碳物质主要集中在细颗粒物中.不同城市站点降尘中碳组分的分布具有一致性，不同土壤尘中碳组分的差异较大.城市和土壤降尘中碳组分主要受生物质燃烧、燃煤、汽油车和柴油车尾气等污染源的影响，PM₁₀和PM_2.5中含碳气溶胶的来源贡献率存在差异.

Pollution Characteristics of Carbonaceous Components in PM10 and PM2.5 of Road Dust Fall and Soil Dust in Xi'an

To investigate the pollution characteristics of carbonaceous components in PM₁₀ and PM_2.5 of road dust fall and soil dust in Xi''an and enrich their source profiles, samples from five sites of road dust fall and 16 sites of soil dust were collected in Xi''an from April to May 2015. The ZDA-CY01 particulate matter resuspension sampler was used to obtain PM₁₀ and PM_2.5 samples, and the Model5L-NDIR OC and EC analyzer were used to determine the concentrations of organic carbon (OC) and elemental carbon (EC) in PM₁₀ and PM_2.5. The pollution and sources of carbonaceous aerosol in PM₁₀ and PM_2.5 were investigated by analyzing OC and EC characteristics, ratio, and the principal component analysis statistical model. The results showed that the proportions of OC in PM₁₀ and PM_2.5 at the various dust fall sites differed, ranging from 6.0% to 19.4% and 7.6% to 29.8%, respectively. The ratios of EC in PM₁₀ and PM_2.5at the different dust fall sites were relatively small, accounting for 0.6%-2.2% and 0.2%-3.6% in urban sites, respectively; however, EC was almost undetectable in most peripheral soil dust. The proportions of carbonaceous components in PM₁₀ and PM_2.5 followed the order of urban road dust fall>external control dust>river beach soil dust>soil dust and urban road dust fall>soil dust>external control dust>river beach soil dust, respectively. OC dominated the carbonaceous aerosols at the different sites, which was relatively low in urban road dust fall. The OC to total carbon (TC) ratios in PM₁₀ and PM_2.5 at urban road dust fall were 85.2%-95.3% and 87.9%-98.9%, respectively. The OC to TC ratios in PM₁₀ and PM_2.5 of soil dust were relatively high, exceeding 99%. Carbonaceous components were primarily concentrated in fine particles. The pollution distribution of carbonaceous components in the urban road dust fall sites was consistent, whereas that in the different soil dust sites were quite different. The carbonaceous components in urban road dust fall and soil dust were primarily affected by pollutant source emissions such as biomass burning, coal burning, gasoline, and diesel vehicle exhaust. There were differences in the source contribution rates of carbonaceous aerosols in PM₁₀ and PM_2.5.