Pollution assessment, spatial distribution and exposure of Cd and Pb in surface soils of abandoned landfill site in Gorgan, north of Iran

The purpose of the present research was Cadmium (Cd) and Lead (Pb) pollution assessment and monitoring the spatial distribution of soil ‎contamination around the municipal landfill site in southwest of Gorgan, Iran. Thus, in a systematic network with a distance of ۲۵۰m, from ۳۲ stations three samples of surface soil (۰ to ‎‎۲۰cm) were obtained and mixed together. In addition, three samples away from the landfill with similar ‎characteristics and geology were used as control. The concentration of heavy metals for the samples was determined using nitric acid and hydrochloric acid and atomic absorption spectrometry. Mean concentrations of Cd and Pb in the soil around the ‎landfill site were ۰.۳۷ and ۱۷.۳۱ mg/kg respectively. The total concentration of Cd and Pb was higher than the control areas. There was a positive correlation between Cd and Pb showing these elements in the soil are from the same origin. Based on our research, soil in the landfill area has a moderate ‎ecological risk index, which is about ۱۲۰. The central parts of the study area have higher concentrations of Cd and Pb than southern parts due to the slope and runoff of the waste leachate. In general, there was an increase in the concentration of Cd and Pb in the sampling sites ‎compared to the control site.