Assessment of groundwater pollution in Kerman urban areas



In this article, groundwater samples in urban areas of Kerman studied to assess the degree of pollution by heavy metals and major ions and other water quality parameters as a consequence of geology and anthropogenic sources. 43 samples were collected and analyzed by Graphite Furnace atomic absorption spectrometry, titration and potentiometery for some heavy metals (Cd, Cr, Cu, Mn, Pb and Zn), major ions (Na+ , Ca2+, Mg2+ , Cl- , SO42- and HCO3 –) and NO3- as well as, electrical conductivity, total dissolved solids, total hardness and pH. So, the concentrations were compared with standard levels for drinking and agricultural purposes. The concentrations of most trace elements and major ions showed enrichment beneath the city. Also, the concentrations of Na+, Mg2+, Cl-, SO42- and HCO3- have greatly increased in the 1994 to 2006 period, which is being ascribed to the pollution as a result of thousands of absorption wells which are the main sewage disposal method in Kerman city. Isoconcentration maps of selected heavy metals and major ions indicate considerable increase in Cl-, Na+ and Mg2+ and sulfate concentrations toward northwest of the Kerman city, presumably as a result of dissolution of evaporative minerals, such as gypsum and halite. Also, concentrations of some ions like nitrate and partly bicarbonate at Kerman city center was high due to pollution caused municipal sewage. Toxic trace elements concentrations (Pb, Cr, Mn) in city center groundwater showed pollution caused by anthropogenic contamination and Cd due to geological formation. Therefore, holding of urban and industrial sewage treatment is very necessary. Most of soils and sediment of Kerman basement consist of clay minerals and medium to alkaline pH, causes low mobility of heavy metals in soils of Kerman and natural remediation in Kerman urban environment.