Spatial Distribution of Toxicity Unit Index and Environmental Risk Assessment of Some Heavy Metals in Industrial Dust of Ardakan county Based on Geostatistical Analysis in 2018

Background & Aim: Heavy metals are including destructive pollutants of environment which important due to adverse physiological effects on living organisms at low concentrations. Aims of performance this study was to measure the concentration of some heavy metals in industrial dust, as well as evaluate and Spatial Distribution the Toxicity Unit indices and Environmental Risk of metals using kriging geostatistical techniques. Methods: This descriptive-analytical and cross-sectional study was carried out in winter of 2018 by installing 35 dust sampler stations around the some of industries in Ardakan county. To collect dust samples and measurement concentrations of cadmium, chromium, vanadium, manganese and aluminum by ICP-MS, Toxicity Unit and Environmental Risk indices of elements were evaluated. Considering the ratio of Nugget to Sill in spherical, Gaussian, stable and exponential semivariogram models and validation using criteria such as Root mean square, Root mean square standardized and Mean standardized, best method of Kriging was selected for preparing spatial distribution map of indices. Results: Mean concentrations of aluminum, manganese, vanadium, chromium and cadmium were 51109.11, 248.02, 152.74, 59.54 and 2.07 mg/kg, respectively. Environmental Risk of industrial dust was determined in very high class. Toxicity Unit index of industrial dust was less than 4. Results of investigation of semivariogram parameters and validation of criteria showed, best method for spatial distribution of indices was simple kriging method with spherical semivariogram models for Environmental Risk index and stable for Toxicity Unit index. Conclusion: In winter season, cadmium and chromium do not cause acute toxicity in dust. Results this study expressing impact of industrial in increasing environmental risk of heavy metals. Also, direction of local dominant wind has an important role in dispersion of heavy metals.