Determining the Concentration and Contamination Levels of Surface Soil in Baghan Watershed using Pollution Indicators and Geostatistics

Knowledge of the distribution of heavy metal concentrations in different components of soil particles is significant to assess the risk of heavy metals. The objective of this study was to evaluate some pollution indices and spatial variations in their estimation in different components of soil particle size fractions (<2000 and> 63 μm) in the Baghan watershed in the southeast of Bushehr province with an area of about 929 square kilometers. The location of 120 surficial composite soil samples (0-20 cm) was determined by using the Latin hypercube method. Soil pollution was assessed using geochemical indices of contamination factor (CF) and pollution load index (PLI). The kriging method was used in the Arc GIS software to interpolate the spatial variations of CF and PLI. Based on the results, the CF displayed the particles in the size < 2000 microns compared to all metals in moderate pollution conditions (1≤CF <3) and with the fineness of soil particles (particles with a diameter <63 microns) concerning to Cd metal shows significant contamination status and moderate pollution with other metals, respectively. CFZn, CFCu, and CFFe in particle size <2000 microns and CFPb in finer class were fitted with a spherical model and other metal contamination coefficients with an exponential model. CFCd and CFFe have the highest impact ranges at <2000 and < 63 microns, respectively. The results of this research confirm that corrective operation is needed to monitor cadmium status in the studied area.