Ecological Risk Assessment Of Heavy Metals In Topsoil Around Major Industries Of Ardakan City

Abstract

Introduction:Today, the contamination caused by rapid rate of developing industries has been drawing attention from scientific and environmental communities to itself. This study was conducted to investigate the concentration and distribution of heavy metals in topsoil of industrial area in Ardakan city.

Methods: For this porous, sampling of topsoil (0-5 cm) was performed using 5 transects in an area of 20000 hectares. Concentrations of As, Cd, Cr, Ni, Mo, Pb, V and Zn were measured in 45 samples based on ICP-OES method. Then, Indices including: Contamination level of heavy metal ( ), Potential Ecological Risk of Heavy Metals ( ) and Total Potential Ecological Risk (RI) were calculated. Also Pearson’s correlation was used to assess the relationship between heavy metal’s concentrations.

Results: Results indicated that mean value concentrations of As, Cd, Cr, Mo, Ni, Pb, V and Zn were repectivley 9.85, 0.31, 35.33, 1.001, 43.28, 18.51, 44.8 and 78.3 (mg/kg) in topsoil of studied area. Maximum concentrations of all heavy metals was found in samples collected from downwind and near the major industries except for Mo and Ni.  and RI indices also showed an increase downwind areas. Strongest correlations were found between Cr-Ni, Cd-Zn and As-Cr which indicates that these metals probably have the same source.

Conclusion: Although the ecological risk of the whole area was low in the risk class, the increase in ecological risk in the surrounding and lower parts of factories such as steel and pelletizing, and tile and ceramic industries indicated the dominant role in the distribution and spread of pollution and the necessity of attention to the site selection studies of these industries. Also the results of the present study indicated the necessity of preventive measurements such as Phytoremediation in the lower parts of industrial area of this region.