Assessments of heavy metal pollution and hydrochemical characteristics of drinking water sources in Aksaray city

In this study, heavy metal pollution and hydrochemical properties of drinking water sources from Aksaray city were investigated. The water demand for Aksaray city center is fulfilled by three sources. The most important source is Mamasun Dam (60%) which is fed by Karasu and Melendiz Streams; the second is groundwater coming from wells of Baglıköy (28%) and the third is freshwater resources in Helvadere Town (12%). Units which characterized aquifers in the study area include the Paleozoic marbles with high crack and fracture contents, Tertiary terrestrial clastics which generally consist of alternations of sandstone and conglomerate and Quaternary alluvium with levels of unconsolidated sand and gravel. The average annual total precipitation of the study area is 342 mm. Precipitation generally reduced in the 1970 - 1974, 1988 - 1993, 1998 - 2008 in the region and increased at the other periods. The samplings were implemented according to seasonal variation for 1 year. The physical and chemical parameters of the waters changes between 14.7 oC - 18.9 oC for temperature, 6.7 - 8.1 for pH, 159 - 625 µS/cm for electrical conductivity and 135 - 602 mg/L for total dissolved solid. The waters show hydrochemical facies in CaHCO3, MgHCO3 and NaHCO3. The dominant ion abundances shaped in the form of Ca+2 > Mg+2 > (Na+ + K+) / HCO3- > SO4-2 > Cl-. The groundwater is contaminated with Al, As, Ba, Fe, Mn, Li, Sr elements which result from the contact with mafic - ultramafic rocks or sedimentary rocks which were formed due to sedimentary processes of ultramafic rocks. The results of chemical analyses showed that the As content in all of the waters exceed the World Health Organization (WHO, 2012) and European Community (EC, 1998) standards whereas the Al, Ba, Fe, Mn, Li ve Sr values in all the water samples are below the limit values. The arsenic values were found to be ranging between 10 and 50 mg/L in 10 points and were found to be >50 mg/L in 2 stations. Waters carries a potential risk when used as drinking purposes. The waters can be contaminated with arsenic content, as a result of the water being in prolonged contact with volcanic sulfur compounds during the hydrological circulation.