| A total of 160 samples including 80 soil samples and 80 dust samples were collected from the soils and dusts in 100 m,400 m,1000 m and 1500 m layer around Baqiao CFPP ?coal-fired power plant?, Xi'an city ?the capital city of Shanxi Province, Northwest China?. The content, speciation, distribution, origin, the contamination and risk evaluation of heavy metal elements including As?Ba?Cd?Co?Cr?Cu?Mn? Ni?Pb?V and Zn in both soils and dusts were studied, and finally attained the following conclusions:?1? The study results of statistic analysis showed that the mean contents of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in soils around Baqiao CFPP are 28.6?999.9?0.467? 59.1?99.1?56.5?944.3?51.6?141.4?126.0?186.4 mg·kg-1, which are higher than the background values of Shanxi Province; in particular, the mean contents of Cd?Co and Pb were 5.0,5.6 and 6.6 times of their respective background values, which indicated there were obvious accumulations of these heavy metals in surface soils. While the mean concentration of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in dust around Baqiao CFPP are 84.2?1434.5?1.4?56.8?314.6?69.3?666.7?37.2 223.9?106.5?278.83 mg·kg-1,which are higher than the background values of Shanxi Province; in particular, the mean contents of As?Cd?Co?Cr and Pb were 7.6?14.8? 5.4?5.0 and 10.5 times of their respective background values, which indicated there were obvious accumulations of these heavy metals in dusts.?2? The analysis of chemical speciation characteristics showed that in the soi s around Baqiao CFPP, the migration order of 11 heavy metals was Mn ?72.6%? > Co ?69.2%?> Zn ?58.5%?> Pb ?58.3%?> Cu ?41.3%?> Ba ?32.2%?? Ni ?31.9%?> V ?24.0%?> Cr ?20.6%?; that in dust of Baqiao CFPP, the order is Co ?85.1%?>Pb?64.6%?>Zn?59.7%?>Cu?54.7%?>Mn?41.1%?>Ni?35.1%?>Cr?22.3%? >Ba?21.8%?>V?21.2%?. Co, Mn, Pb and Zn should become a priority objects to be prevented, for they could be easily migrated in both soil and dust, and cause some bad effects on the ecological environment.?3?The analysis of spatial distribution showed that the contents as well as th e chemical speciation of heavy metals of different spheres in both soils and dust s were different. Elements Co?Mn?Pb and Zn should become a priority objects to be prevented and controlled, for they could be easily migrated in both soil and dust in whatever spheres.?4?The study results from multivariate analysis including correlation analysis, principal component analysis and cluster analysis suggested that the 11 heavy metals in soils could be classified as 3 Principal Components ?PCs?. As?Cu?Cd and Pb, having high loads in PC 1, were dominated by traffic, coal combustion and industrial sources. PC 2 including Cr?Mn?Ni and V came from natural sources, and were controlled by parent materials. Ba and Zn with high loads in PC 3, were originated from combined effects of the industrial production activities, traffic emission and the activities of citizen. Co had some loads on different PCs, and was affected by both natural and human sources. The 11 heavy metals in dusts could be classified as 3 Principal Components ?PCs?. As?Cd?Cr?Cu?Pb?V and Zn, having high loads in PC 1, were dominated by traffic, coal combustion and industrial sources. PC 2 including Ba?Co? Cr and Ni were affected by both natural and human sources. Mn with high loads in PC 3, came from natural sources, and were controlled by parent materials?5? The level of heavy metal pollution in the soils and dusts around Baqiao CFPP were evaluated by means of Geo-accumulation Pollution Index, Nemero pollution index, the Pollution Load Index and Hakanson's Potencially Ecological Risk Index. Based on the Shaanxi Soil Element Background Value, the poliution assessment results show that the heavy metal pollution of dust is heavier than soil; the soils around Baqiao CFPP, Xi'an is mainly contaminated by the elements of As?Cd?Co?Cr?Cu?Pb and Zn et al; while the dusts around Baqiao CFPP, Xi'an is mainly contaminated by the elements of Cd, Co, Pb, and Zn et al. |
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