ارزیابی کیفیت منابع آب زیرزمینی آبخوان ورامین از نظر قابلیت شرب: آلودگی با فلزات سنگین

Background and Objective: Irrigation of agricultural lands with treated wastewater in the main part of the Varamin plain, the highly populated urban areas of the middle part of the plain, and the presence of industries have increased the actual risk of heavy metal contamination of groundwater. Therefore, the concentrations of heavy metals were investigated in this study in order to assess the risk of using groundwater of Varamin aquifer for drinking purposes. Materials and Methods: A total of 78 groundwater samples were collected to measure the concentrations of Cu, Pb, Zn, Cr, Cd, Fe, Co, and Mn ions. The bivariate correlation analysis has been used to describe the correlation between hydrochemical parameters in the Varamin area. Heavy Metal Evaluation Index (HEI) and Heavy Metal Pollution Index (HPI) of the groundwater were determined to determine the feasibility of drinking supply in Varamin plain. Results: The average concentrations of cadmium in dry and wet periods were 7.5 and 8 μg/L, respectively. In the wet period, the average concentration of lead in the groundwater of the Varamin plain was 12.5 μg/L. The concentrations of both heavy metals were more than the permissible amount for drinking. Pearson correlation analysis of qualitative data of the water samples of the Varamin plain showed a strong correlation between some heavy metals such as Pb and Co with Cd, Cu and Mn. This reflected a similar source of contamination of the groundwater, inter-correlations, and the same mobility behaviors in the aquifer media. The results obtained from HEI and HPI showed that the pollution of Varamin aquifer in most parts was not dangerous with respect to the heavy metals concentrations, but in some areas, significant variations in the concentrations of some metals can be observed. Conclusion: It may be expected that the risk of groundwater contamination continues with respect to heavy metals due to the persistence of contamination sources in the Varamin plain. Hence, some measured should be taken with regards to the agricultural recycle water, dispose of domestic and industrial wastewater, and the quality of transferring treated effluent from Tehran to the plain.