Potentially contaminant sources assessment and hydrogeochemical characteristics of Chromium in Golbou water resources, North Torbat Heydarieh, Khorasan Razavi
Subject Areas :Ali Ghasemi 1 , Mohammad Javad Nematollahi 2 , Hessamaddin Taghavi Sani 3
1 - دانش آموخته کارشناسی ارشد زمین شناسی زیست محیطی، دانشگاه فردوسی مشهد
2 - دانش آموخنه زمین شناسی زیست محیطی، دانشگاه شیراز
3 - دانشجوی کارشناسی ارشد زمین شناسی زیست محیطی،دانشگاه پیام نور مشهد
Keywords: Water resources, chromium, Ophiolite, Hydrogeochemistry, serpentinite,
Abstract :
The study area, located in north Torbat Heydarieh, contains ophiolitic units comprised chromium-bearing minerals such as Spinel. The results obtained from water samples analysis using XRF indicate high chromium concentrations in ophiolite complex as major source. Serpentinite, the dominant lithology in the area, comprises the excess chromium concentration, being responsible for chromium-polluted water resources. As well as average chromium concentration severely decreases from serpentinite to other lithological units. Hydrogeochemical investigation of water resources indicates that the major cations and anions are in the order of Na+>Mg2+>Ca2+>K+ and Cl->HCO3->HSO42-, respectively. Regarding piper diagrams, water samples reflect a variety of facies (water types) including Na-HCO3 (3 samples), Na-Cl (3 samples), Ca-HCO3 (3 samples), Mg-Cl (3 samples) and Mg-HCO3 (2 samples). Comparing with WHO (2011) permissible chromium limit, water resources of the study area reflect excess chromium concentration. Due to limited chromite mining in the area, the anthropogenic activity could not be responsible for the elevated chromium level in the water resources, suggesting the dominant geogenic source of chromium. The abundance of Fe-Mn oxy-hydroxides in most sites of the area leads to chromium oxidation from Cr3+ to Cr6+. Average values of pH> 7.6 and DO> 7.67 mg/l of the water resources also indicate that Cr chiefly occurs as Cr6+, and Cr2O72- and CrO4- deposits.
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