[Spatial Distribution, Pollution Assessment, and Source Analysis of Soil Heavy Metals Under Different Land Use Types...

To ascertain the status of the surface soil heavy metal pollution in the southern area of Laizhou Bay, 263 surface soil samples were collected from seven different land use types in the study area and the contents and pH of eight soil heavy metals （As, Cr, Ni, Cu, Zn, Cd, Pb, and Hg） were determined. The pollution assessment was carried out using the geo-accumulation index method, Nemerow comprehensive index method, and potential ecological risk index method. Then, the source of heavy metal pollution was discussed using correlation analysis and the source analysis was carried out through positive matrix factorization （PMF）. The results showed that the surface soil in the study area was weakly alkaline； As, Ni, Zn, and Hg slightly exceeded the background values of Weifang and the spatial distribution of heavy metals showed a trend of low in the north and high in the south. The results of the geo-accumulation index indicated that the study area was pollution free and the geo-accumulation index of different land types was arranged in the order of As>Ni>Zn>Cr>Pb>Hg>Cu>Cd. The results of the Nemerow comprehensive pollution index indicated that the study area was lightly polluted and the Nemerow comprehensive pollution index of different land types was arranged in the order of town>grassland>forest>agricultural land>vegetable land>industrial land>mudflat. The results of the potential ecological risk index indicated that the study area belonged to low ecological risk and the potential ecological risk index of different land types was arranged in the order of agricultural land>town>forest land>grassland>vegetable land>industrial land>mudflat. The results of PMF analysis indicated that the heavy metal pollution sources in the study area mainly included natural sources, transportation sources, agricultural sources, and industrial sources, with contribution rates of 38.06%, 26.38%, 26.21%, and 9.35%, respectively.