Geochemical baseline of major anions and heavy metals in groundwaters and drinking waters around the urban areas of Kerman city, southeastern Iran

Abstract

In order to investigate the environmental geochemistry of groundwaters in the urban areas of Kerman city, 50 samples of natural groundwaters, urban groundwaters and drinking waters were collected. High values of salinity (5.8 ‰), electrical conductivity (10,270 μS/cm), total dissolved solids (TDS) (5,140 mg/kg), fluorine (4.9 mg/kg), chlorine (3,974 mg/kg), bromine (1.6 mg/kg) and sulfate (4,306 mg/kg) in the northern part of the studied area are caused by dissolution of evaporate bed rocks and Quaternary salt plains. Low values of salinity (0.5 ‰), electrical conductivity (973 μS/cm), TDS (486 mg/kg), fluorine (0.8 mg/kg), chlorine (297 mg/kg), bromine (0.25 mg/kg) and sulfate (262 mg/kg) are only reported in the southern part of the Kerman city. High values of nitrate (NO3 −) range from 134 to 725 mg/kg and nitrite (NO2 −) content is variable between 0.04 to 23.45 mg/kg. These values indicate mixing of groundwaters with wastewaters. The heavy metal values in groundwaters around the Kerman city show 20.5 μg/kg Cu, 5.88 μg/kg Mo, 16.2 μg/kg Pb, 70 μg/kg Zn, 11.6 μg/kg Cr, 1.99 μg/kg Co, 4.13 μg/kg Ni, respectively. Furthermore, the natural aquifers of Kerman city contain 24 μg/kg Cu, 8.15 μg/kg Mo, 18.25 Pb, μg/kg, 193 μg/kg Zn, 14.7 μg/kg Cr, 3.97 μg/kg Co and 7.45 μg/kg Ni, respectively. The results demonstrate that the main sources of contamination are related to the natural evaporates, mixing of groundwaters with wastewaters and constructional materials in the area.