Capability of IRS-P6 LISS III Data for Detecting Zinc Polluted Soils

To evaluate the impacts of polluted soils on human health, it is important to understand the of soil particle size distribution. Polluted soil particles are considered as pollutants and their transportation by water and wind depends on particle size. Applying the of new techniques such as spectrophotometry and remote sensing which enhance feasibility and swift determination of soils pollution risk could be useful due to high costs of soil sampling and laboratory measurements. This research has been carried out to determine spatial distribution of zinc concentration in soil particle size classes using IRS-LISS III reflectance in Southern Isfahan city. There fore, 100 compound soil surface samples have been collected randomly through the area. The samples have been air - dried and soil particle size classes 250-500, 125-250, 75-125, 50-75 and <50 μm have been determined, using appropriate sieves after dispersion the bulk soil samples by ultrasonic apparatus. Total Zn concentration has been measured using Atomic Absorption Spectrophotometer after wet digestion of samples in acid nitric. Results showed that concentration of Zn increases by decreasing soil particle size. Significant negative correlation coefficients have been found between Zn concentration in soil particle size classes and soil spectral reflectance in visible and near infrared bands of IRS-LISS III satellite. Stepwise multiple regression models have been used for estimating Zn concentration in soil particle classes through satellite data and spatial distribution of Zn concentration in soil particle size classes were mapped using stepwise multiple regression equations. Results showed possible estimation of Zn concentration to certain ranges of concentrations using multiple regression models and satellite data so that in size classes <2000, 50-75 and <50 μm concentrations lower than 400 mg kg-1, measured and estimated Zn concentrations are closed to 1:1 line. This is an indication of higher precision in estimating Zn-concentration at lower concentrations. The results also indicated increments of Zn concentration in all soil particle size classes by approaching to the mines.