Study On Scource Profiles And Risk Assessment Of Heavy Metals In Power Plants’ Coal Dust

This study made power plants’ coal ashes as research object, the ashes under dust catcher was collected and the contents of chemical composition were measured in PM_2.5 and PM₁₀, source profiles of coal dust were established, the differences between source profiles which using anthracite and coal gangue as fuels were analyzed. The degree of heavy metal elements in coal dust was evaluated using enrichment factor method and geological accumulation index method. The degree of similarity of coal dust source profiles between this study and other cities were compared using the coefficient of divergence method. The health risk of heavy metals in the coal dust were evaluated. The results showed as follows:（1）The source profiles of power plants’ coal dust were compared by elements, ions and carbon. Ca, Si, SO₄^2- were the most abundant chemical composition content in the source profiles, and the main components in coal dust were Ca, Si, SO₄^2-, OC, EC, Fe, Al, Mg, K, Ca²⁺, Cl^-. The earth elements,trace elements, EC and OC were more likely enriched in PM_2.5. The power plants’ coal dust showed acid.（2）The biggest difference between anthracite and coal gangue source profiles was that the content of Ca and Si in coal gangue’s PM_2.5 and PM₁₀ were obviously higher than in anthracite. It was related to the high content Ca and Si in coal gangue.（3）The results of the enrichment factor showed that Cd, Cu, Cr, Ni, Pb, V,Zn seven kinds of metal elements had different degree of enrichment in coal dust of PM_2.5 and PM₁₀, Zn showed strong enrichment, V showed significant enrichment. The degree of enrichment of Zn and V were obviously higher in coal gangue PM_2.5 and PM₁₀ than in anthracite.（4）The results of geological accumulation index showed that in coal dust PM_2.5 and PM₁₀, Zn showed serious pollution and V showed severe pollution. In coal gangue PM_2.5 and PM₁₀, the degree of pollution of V and Cr was higher than in anthracite, and Ni, Pb, Zn showed the contrary results.（5）The results of coefficient of divergence showed that the PM_2.5 source profile of this study may be similar to Shanghai, Ningbo and Hangzhou cities,and wasn’t similar to Beijing, Nanjing, Texas/Mexico and Colorado. The PM₁₀ source profile of this study may be similar to Hangzhou, Jinan and Zhengzhou cities, and wasn’t similar to Beijing and Chengdu.（6）The results of health risk assessment of heavy metals showed that the heavy metals in power plants’ coal dust PM_2.5 had more risk than PM₁₀. V had the highest contribution to the non-cancer risk and Co had the lowest. As had the highest contribution to the cancer risk and Co had the lowest.