Assessment Of Heavy Metal Pollution In The Urban Topsoil Of Quanzhou City

With the development of the urbanization, the human activity imports a large amount of pollutants into the urban environment, provoking some serious environmental problems. Among those, the pollution of heavy metal in urban soils is the most serious. The heavy metals in urban soil which are transported through ground dust and food chain may destroy the urban entironment seriously, and even may do harm to the human's health.In the paper, the topsoil of Quanzhou City was regarded as the research object. The survey region was divided into five zones as traffic zone, commercial zone, residential zone, urban green land and industrial zone.47 urban topsoil samples were collected, and 18 kinds of heavy metal elements were analyzed to assess the pollution degree of heavy metals and to discuss their probable sources. The results of the study shows:(1) The concentration characteristics of heavy metals in the urban topsoil of Quanzhou City were analyzed using the statistical software SPSS. The result showed that each heavy metal element has certain enrichment; Mn, Sb, Sn, Cd, Pb, Zn, Cu, Hg, Ni wre much higher than their background values of the local soil environment.(2) Based on the background values of local soil, the heavy metal pollution in the urban topsoil of Quanzhou city was estimated using the Geoaccumulation Index and Potential Ecological Risk Index. The results showed that Sb and Hg were much higher dangerous than other pollutants. The Geoaccumulation Index order of different heavy metals was Hg>Sb>Ni>Sn>Co>Zn>Pb>Li>Cd>Bi>Mn>Cr>As>Fe>V>Cu>Sc>Ti; and the Potential Ecological Risk Index order was Hg>Cd>Cu>Pb>Ni>As>Zn>Co>Cr>V>Mn>Ti. From the functional zones, the pollution consequence was industrial zone > traffic zone > commercial zone > urban green land > residential zone.(3) Based on the environmental quality standard for soils (GB15618-1995), Fuzzy Comprehensive Evaluation was used to estimate the soil environment quality of Quanzhou City. The results showed that Cd was the main pollutant, and the degree of soil environment quality of Quanzhou was gradeâ…¢, which meaning a relatively high level of pollution.(4) Using Health Risk Assessment Model was used to estimate the individual health hazard from the heavy metal pollutants. The analysis shows that the non-cancer hazard indexes and carcinogen risks of metals were both lower than their threshold values. The order of non-cancer hazard indexes of heavy metals in soil was Cr>Pb>Cu>Zn>Hg>Ni, and the order of carcinogen risks of heavy metals was As>Cd. (5) The Factor Analysis was used to predicate the potential sources of heavy metals in the urban topsoil of Quanzhou City. The results showed that Sb, Bi, Sn, Pb, Cu and Zn mainly originated from traffic and industrial contamination; Cd originated from industrial and fertilizer; fossil fuel using and coal-fired were the main sources of As and Hg; Fe, Co, Ni, Cr, Li, Sc and Mn were mainly controlled by natural factors, and they originated from natural sources.