Chemical Characterizations of PM10 Profiles for Major Emission Sources in Xining, Northwestern China

Abstract

The chemical profiles of emission sources are indispensable for source apportionment using receptor models. To develop current knowledge of PM 10 profiles, the chemical composition of major emission sources were analyzed in Xining. Samples of geological sources (soil dust, road dust and construction derived dust) and industrial fly ash were collected from representative portions using a plastic dustpan and brush and sampled on filters through a re-suspension chamber. Samples of coal combustion source and vehicle exhaust were collected directly on the filters using a dilution stack sampler. Chemical analysis included inductively coupled plasma mass spectrometry for 19 elements (Na, P, K, As, Rb, Mo, Cd, Sn, Sb, La, V, Cr, Mn, Co, Ni, Cu, Zn, T1, and Pb), inductively coupled plasma optical emission spectrometry for 7 elements (Al, Sr, Mg, Ti, Ca, Fe, and Si), ion chromatography for water-soluble ions (Na + , K + , Mg 2+ , Ca 2+ , F -, Cl -, NO 3 -and SO 4 2-) and thermal/optical reflectance analysis for carbonaceous species. Crustal elements (Si, Al, Ca, Fe) predominated in geological sources, whereas trace elements (Pb, Cd, Cr, Zn and Ni) were predominant in industrial fly ash. An abundance of carbon and SO 4 2-was present in coal-combustion source and vehicle exhaust. The coal-combustion boilers were a source of trace elements (Ti, Co, Sr, Sb, Tl). High concentrations of Pb and OC in soil indicated the strong influence of agriculture activities in Xining. Comparison of vehicle exhaust profiles indicated that natural gas was high environmental friendliness in comparison with petroleum products used as motor vehicles fuel. Differences in EC, Cd and NO 3 -between natural gas-powered and gasoline-or diesel-powered vehicle exhaust can be used to differentiate the two types of vehicle emission sources. Differences in source profiles and indicator species between Xining and other cities suggest that source profiles should be developed locally and updated frequently.

China Source Profile Shared Service (CSPSS): The Chinese PM2.5 Database for Source Profiles

“…These profiles are derived from scientific papers including fugitive dust from Chinese Loess Plateau (Cao et al, 2008), Asian dust source areas (Zhang et al, 2014b), north plain , southwest basin (Liu et al, 2016b) and other Chinese regions (Ho et al, 2003;Zhao et al, 2006;Han et al, 2009;Kong et al, 2011;Han et al, 2011;Chen et al, 2012;Han et al, 2014;Kong et al, 2014;Cheng et al, 2015), coal-fired boilers (Zhang et al, 2008;Wang et al, 2009;Pei et al, 2016), industrial sources (Zheng et al, 2013); biomass burning (Zhang et al, 2007;Zhang et al, 2012;Tao et al, 2015) and vehicle exhaust . Source profiles are also collected from source apportionment studies in Chinese cities such as Beijing, Tianjin, Chongqing and so on.…”

Characteristics of PM10 Chemical Source Profiles for Geological Dust from the South-West Region of China

“…In six cities of north China, the values were 2~10 in urban resuspended dust profiles [33]. These ratios were 18-35 in the agricultural soil profile and 45~50 in the natural soil profile, while the values >100 were observed in other soil dust profiles around the world [18,19,34].…”

“…It was highly enriched (8.33% ± 5.36%) in the urban paved road dust, about twofold higher than those in other profiles. In general, the cation (Na + , K + , Mg 2+ and Ca 2+ ) abundances were lower than those in other regions of China [14,18,20]. This may be attributed to acid rain in southwest regions of China; soil acidification can neutralize the cation in soil [35].…”

“…The soil background values are from samples collected in local region as described by the Ministry of Environmental Protection [44]. Enrichment factors (EFs), which are calculated relative to composition of upper continental crust (UCC), have been commonly used in aerosol studies [18,23,45]. The EF where X refers to the concentration of the element interest, and reference element refers to the concentration of crustal soil.…”

“…The source profiles were extracted from the USEPA SPECIATE 4.5 database and other published literature. Profiles included fugitive dust from California (profile numbers 3481 and 4180) [9,50], Chicago (profile number 3982) [51], Arizona [15], Mexico [52], and several Chinese cities [14,[18][19][20][21]24,33,47].…”