Concentration levels and spatial distribution of heavy metals in soil surrounding a municipal solid waste incineration plant (Shenzhen)

The municipal solid waste (MSW) incineration has been well known among key sources of heavy metal (HM) emission. To investigate the multivariate relationships and spatial distribution of HMs from this source, 9 HMs (Hg, As, Cd, Cr, Cu, Ni, Pb, Se and Zn) were analysed by multivariate statistical analysis in 80 representative soil samples including surface soils and subsurface soils around the Shenzhen Qingshuihe MSW Incineration Plant (MSWIP). Results show that, the concentrations of Hg, As, Cd, Cr, Cu, Ni, Pb, Se and Zn range 0.012-0.136, 0.23-75.89, not detected (ND)-1.17, 21.7-116.0, ND-61.1, ND-47.0, ND-133.0, ND-16.4 and 8.6-246.9 mg x kg(-1), respectively. No significant elevation of concentrations of HMs in soils is observed, compared with the natural background. Based on the hierarchical cluster and historical analysis, the spatial correlations of HMs have been changed by the impact of MSWIP. According to the similarity of concentration, the HMs can be divided into 3 categories: (1) Cu, Ni, Cr, Se, Zn, Pb; (2) As, Cd; (3) Hg. Factors analysis was also performed and shows that the HM distribution patterns are dominantly affected by 3 principal components: local biogeochemical characteristics (48.6% of variance), impact of the MSWIP (16.6% of variance) as well as topographical characteristics (13.2% of variance). Subsequently the 3 maps of factor scores are calculated and exhibited. This study favors to estimate the long-term effects of HM emission from MSWIP on surrounding soil environment and facilitate the local health risk assessment.