Spatial distribution of heavy metals in soils of the Bafra plain in Turkey

Abstract

For analyzing the spatial distribution of the Cd, Co, Cu, Ni, Pb, Zn, and heavy metal (HM) sources on the Bafra deltaic plain (the central Black Sea district of Turkey), 108 soil samples were collected from the 0- to 20-cm layer in an area of about 100 thousand ha. The soil enrichment factor (the ratio between the metal concentration in the soil samples and its content in the earth's crust (EF)) was calculated to reveal the origin of the heavy metal (HM) pollution (natural or anthropogenic). Kriging interpolation and maps of the soil's enrichment factors were used for the characterization of the spatial HM distribution. The maximal EF was found for Cd (12.826), while smaller EF values characterized the Pb, Ni, Co, and Cu. In some districts of the studied region, the Cd, Cu, and Zn concentrations were somewhat greater, probably, due to the application of high rates of phosphorus fertilizers and intense soil cultivation. A content exceeding the critical value was recorded for Ni. Probably, this fact was related to the elevated content of this metal in the parent rocks. None of the investigated soils can be referred to the category of polluted ones.