predicting the spatial distribution of cd, as, cr and cu in topsoil of golestan province

heavy metal contamination has been and continues to be a worldwide phenomenon that heavy metals in the soil have an effect on environment and food quality, and may threaten human health. no information is currently available on the distribution pattern of heavy metals concentration in soils of golestan province. the objective of this research was to determine the spatial distribution of cd, as, cr and cu in golestan. during a field survey 216 surface soil samples (0-30 cm) were collected randomly from the whole of golestan province and total concentration of heavy metals was measured by icp. ordinary kriging interpolation was used to determine the spatial distribution of heavy metals. to evaluate the ordinary kriging interpolation models (inverse circular, spherical, exponential and gussian) cross validation technique was applied by error estimation. the results showed that the average concentrations of cd, as, cr and cu in soil of golestan province were up to 0.12, 9.1, 59.6 and 24.42mg/kg, respectively. i shows that heavy metals are not a serious problem at the moment in golestan province. the results of geostatistical analysis showed that exponential, circular, exponential and gussian models were the best model for describing the spatial variability of cd, as, cr and cu respectively. results showed that generally, the golestan soils are free of pollution according to the various standards.