| In recent years, heavy metal pollution associated with soil quality assessment have drawn increasing concern and attention, but there was little research on heavy metals in soils around thermal power plants. Dalate power plant is located in the northern edge of Kabuqi desert, biological soil crusts and the different types of crust widely distributed in Dalate Banner. On the ecological system have important ecological function. There is a close correlation between the content of heavy metals in moss crust or physical and the atmospheric settling. It is conducive to monitor the effect of the accumulation of heavy metals in atmospheric settling by monitoring biological crust around regional power plants. This paper takes the thermalpower plants in Dalate Banner as research area, and uses study the space characteristic and pollution situation of10heavy metal elements in BSC and soil by statistic method to compare the difference of heavy metal’s accumulation in a variety of BSCs. The following is the main content:1. Trough the sampling of heavy metal elements of biologicalsoil crusts in the study area and statistical analysis of the data, weobtained that the contents of Hg, Cd, Pb, Cr, Zn, Cu, Co, Ni andAs in biological soil crusts surrounding the thermal power plant was basicly at national level2, but the amounts of Cd, Cu and Zn enriched in biological soil crusts were respectively2times,2.74times and1.07times of Mongolia soil background values, having a certain degree of pollution.2. By the analysis of the contents of heavy metals in3differe nt types of biological soil crusts, the size order of variation coefficients of various biological soil crusts were: moss crusts> algal crusts> physical crusts, and the variation coefficient of heavy metal elements in moss crusts ranged from36.4%to179.3%, achieved anaverage of56.8%for the sampling points, of which, the variation coefficient of Cu in moss crusts was highest, achieved179.3%, andthe enrichment content variation coefficient of Hg in algae crusts was lowest, which was only15%.3. Among the heavy metal elements of moss crusts and algaecrusts, in addition that Cu-Zn had significant correlation (P <0.05)and Pb-Cr had significant correlation (P <0.01), the rests had nosignificant correlations, showing that most elements did not have good natural companion relations.4. At1km,1.5km,2km,2.5km,3km,3.5km and4kmoff the wind direction from power plant, spatial distribution characteristics of heavy metal pollution were analyzed, showing the fluctuating tendency of decreasing first and increasing later and then decreasing again, and that the content of heavy metal elements of soil in the range of2km-3km from the power plant was significantlyhigher than that in other soil samples.5. From the analysis of time cumulative effect of heavy metalcontent in biological soil crusts, along with the increasing of the development age, all kinds of crusts showed the phenomenon that heavy metal content was higher with the increase of the development time. Heavy metal content in moss crusts manifested the orders as:Zn> Cr> Ni> Pb> Cu> As> Co> Cd> Hg, and heavy metal content algal crusts manifested the orders as: Cr> Zn> Ni> Pb> Cu> As> Co> Cd> Hg, and in physical crusts, in additionthat the contents of Hg and Zn in2008soil samples were slightlyhigher than that in2007soil samples, other elements all showed the tendency of the increase with the increasing age. 6. The enrichment factor was applied for the evaluation of pollution status, from EF and CEF pollution classification results, we found that local heavy metal pollution can be divided into artificialpollution (EF <1, CEF <1), level1mild pollution (1<EF <2,1<CEF <2), level2moderate pollution (2<EF <5,2<CEF<5) and level3significant pollution (5<EF <20,5<CEF <20); from EF and CEF pollution classification results, EF and CEF distribution features of Cd, Pb, Cr, Zn, Cu, Co, Ni and As werenot consistent. Potential ecological risk index of local heavy metalwas RI=14.935, and the results showed that the local heavy metal pollution was mild ecological hazard. |
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