Chemical characteristics of atmospheric fallout in the south of Xi'an during the dust episodes of 2001-2012 (NW China)

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• 作者：Xiaoping Li ; Linna Feng ; Chunchang Huang ; Xiangyang Yan ; Xu Zhang
• 关键词：Atmospheric fallouts (AFs) ; Water-soluble ions ; Heavy metals ; Dust episodes ; Xi'an ; Chemical composition ; Multivariate analysis
• 刊名：Atmospheric Environment
• 出版年：February, 2014
• 年：2014
• 卷：83
• 期：Complete
• 页码：109-118
• 全文大小：1949 K

文摘

Atmospheric fallouts (AFs) were collected in the south of Xi'an, NW China, during the dust episodes of 2001-2012. The chemical characteristics of total 68 AF samples including their chemical compositions, size distribution and magnetic susceptibility were studied. The contamination degree and the source of heavy metals in AF were also explored with enrichment factor method and multivariate statistical analysis. The results showed that the particle mass size distribution of AFs dominated by coarse particles (PM10-50) in dust days. The concentrations of 26 elements associated with AFs determined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) in studied sites varied from 92.90 to 188.10聽mg聽kg^鈭? for Cr, 31.40 and 63.00聽mg聽kg^鈭? for Cu, 16.60 to 167.30 for Pb and 106.60 to 196.80 for Zn. Their average concentrations found in this study were 139.22聽卤聽29.41聽mg聽kg^鈭?, 46.93聽卤聽10.56聽mg聽kg^鈭?, 78.42聽卤聽46.52聽mg聽kg^鈭? and 150.61聽卤聽32.84聽mg聽kg^鈭?, respectively, which exceeded their corresponding recommended background values more than two times. While, other elements, such as Br varied from 1.10 to 5.90 with 3.34聽卤聽1.60聽mg聽kg^鈭? mean, Cs from 2.90 to 10.90 with mean of 7.23聽卤聽2.47聽mg聽kg^鈭?, Ga between 6.90 and 20.80 with 15.23聽卤聽3.59聽mg聽kg^鈭?, Rb in the range of 62.10-124.20 with the average of 80.69聽卤聽16.89聽mg聽kg^鈭?, Y from 9.90 to 35.00 with 20.43聽卤聽6.27聽mg聽kg^鈭? average, La from 29.60 to 54.20 with mean of 37.28聽卤聽8.28聽mg聽kg^鈭? and V with average of 81.97聽卤聽8.93聽mg聽kg^鈭? in the 57.7-92.10聽mg聽kg^鈭?. Multivariate statistical analysis (principal component analysis and clustering analysis) was suggested that the principal element elements, Al, Fe, Si, K, Ca, Na, Mg, coupled with the trace elements Co, V, Ce, Mn, Ni, Ga, Y, Rb, La, Br, Cs were predominated by crustal material sources, whereas, Cr, Cu, Ba, Sr, As, Pb and Zn were highly influenced by anthropogenic activities. Simultaneously, the water-soluble ions (WS-ions) of NH₄⁺, SO₄^{2鈭?/sup>, SO₃2鈭?/sup>, NO₃鈭?/sup>, SiO₄4鈭?/sup>, HSO₄鈭?/sup> contained in APs identified by FT-IR spectroscopy were possible originated from coal combustion. The results were also confirmed and consistent with the observations of magnetic susceptibility (MS), enrichment factor (EFs) and contamination evaluation analysis. With such rates of atmospheric fallouts that contain elevated levels of toxic elements during the dust storm condition, actions should be taken to continually examine and understand of the potential impacts of AFs on surface ecosystem, water resource, and human health in the dust storm condition.}