توزیع مکانی کادمیوم در شالیزارهای جنوب غربی اصفهان با استفاده از زمین آمار و GIS

Abstract

The paddy soils in Lenjan area exposed to pollution owing to uncontrolled discharge of sewage sludge, wastewater and unessential fertilizers. Little information exists on Cadmium (Cd) distribution in paddy soils of Isfahan Province, this study was therefore investigated the spatial variability of cadmium which is considered as the most toxic metals. 90 soil samples (0-20 cm) were collected from study area. Soil properties such as pH, EC, calcium carbonate equivalent, soil texture, organic matter and cation exchange capacity were measured. The total and available Cd concentrations of soil samples analyzed by atomic absorption spectrophotometer. In addition, estimation of spatial data performed via kriging interpolation method (ordinary and blocky kriging) and by GIS. The total and available concentration of Cd in the study area were averagely 1.747 and 0.073 mgkg-1 respectively, which were much higher than the standard limit and classified in high pollution. Geostatistical analysis result was shown that exponential and spherical models for the total and available Cd concentration were best model, respectively. The most effective range of total and available Cd was 1011 and 1050 meter respectively and correlation ratio was weak in this range. Evaluation of correlation coefficient, MEE and RMSE parameters showed that both methods of kriging for data estimation in comparison with real data had acted in an appropriate manner. The result also showed that human activities such as industrial and urban wastewater entering to the water resources and application of excessive fertilizers had an impact on cadmium concentrations significantly.