| With the continuous development of industrialization and urbanization in China,the consumption of coal-based fossil fuels has also increased rapidly.Coal-fired power plants ar e main source of coal consumption in China.The coal combustion process is accompanied by a lot of soot,dust and fly ash,which will release various heavy metal elements to pollute the surrounding environment and endanger the surrounding ecological health.Therefore,it is essential to understand the spatial and temporal distribution of heavy metals in the atmosphere and soil environment around coal-fired power plants and carry out corresponding environmental risk assessment to improve environmental quality.In this study,the Shaoguan coal-fired power plant in Yuebei area,Guangdong Province was regarded as the research object.The content of Cd,Pb,Cu,Ni and Zn in the surrounding atmospheric deposition,surface soil and rice were analyzed.The temporal and spatial distribution of heavy metals,the correlation and sources of five heavy metals in different environment were analyzed,and the environmental risks around coal-fired power plants were evaluated.the result showed:(1)Heavy metal in atmospheric deposition flux of in autumn is ranked as Zn>Pb>Cu>Ni>Cd.The Zn,Cd and Pb in atmospheric deposition in this area are more serious.Heavy metal in atmospheric deposition flux fluctuated with time,and were closely related to rainfall.The spatial distribution of heavy metal in atmospheric deposition flux is obviously affected by the discharge of industrial activities in coal-fired power plants.heavy metal atmospheric deposition fluxes mostly existed in dissolved state,which is harmful to the surrounding environment.There was a significant positive correlation between rainfall and sedimentation and dissolved fraction(P<0.01).Source analysis found that Zn,Cd and Cu were seriously affected by coal-fired power plants.The source of Pb was not only related to coal-fired power plants,but also closely related to the emissions of traffic;Ni was more evenly distributed,Ni was not significantly affected by coal-fired power plants,and attributed to the affection of natural dustfall;further verification of PMF model indicated that different elements had different sources The contribution rate of pollution sources were that,Ni:15.6%of traffic source,73%of natural source,11.4%of industrial source;Cu:35.8%of traffic source,25.1%of natural source,39.1%of industrial source;Zn:21%of traffic source,25.8%of natural source 53.2%of industrial sources;Cd:17.8%of traffic sources,14.8%of natural sources,67.4%of industrial sources;Pb:80.4%of traffic sources,4.5%of natural sources,and 15.1%of industrial sources.(2)Distribution of heavy metal in surface soil was different,Pb and Cd were polluted most serious.The spatial distribution of heavy metals in surface soil was different from the spatial distribution of atmospheric deposition.In the overall spatial distribution,heavy metal except Ni in the prevailing wind is the most concentrated,and there are obvious differences between the NNW,SSE and WSW.The correlations among heavy metals such as Zn,Cd and Pb in the surface soil around coal-fired power plants were significant(P<0.05),most likely from heavy metal in atmospheric deposition emitted from the electric coal-fired plant.Source analysis shows that the three elements of Cd,Pb and Zn are mainly derived from the industrial activities of coal-fired power plants.The source of Cu is not only affected by industrial emissions,but also related to the irrigation of farmland sewage in the northern region.The source of Ni is mainly closely related to natural distribution.The PMF model showed the related contribution of heavy metals:Ni:11.5%agricultural source,85.8%natural source,2.7%industrial source;Cu:agricultural source 43.9%,natural source 42.6%,industrial source 13.4%;Zn:agricultural source30.9%,natural source 25.8%,Industrial source 43.3%;Cd:agricultural source 35.2%,natural source:6.7%,industrial source 58.1%;Pb:agricultural source 27.1%,natural source 5.5%,industrial source67.4%.(3)The environmental risk assessment showed that atmospheric deposition and heavy metal pollution in the soil were concentrated in the prevailing wind direction,and Cd pollution is the main element for the environmental risks surrounding the coal-fired power plants.The human health risk assessment showed that the average values of HI and HI_j in the surrounding environment were less than 1.Ingestion was the main way to increase the health risk.Based on the analysis of PMF,the health risks of each source were significantly different.And Pb emitted from industrial sources are the largest sources of atmospheric depositon and surface soil for health risks.The Cd and Pb of rice grain were over-standard,and the correlation analysis showed that the soil physical and chemical indicators,such as,p H,CEC and OM had significant effects on the bioavailability of heavy metals in the soil.The continuous intake of rice grains would cause health risks related to the excessive Ni and Cd health risk. |
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