Groundwater quality assessment specially the effect of chromite ores in Jovien, Sabzevar, NE Iran

Jovien aquifer is located in northeast of Iran. This aquifer is recharged by mountains formed by ophiolitic ultramafic rocks with chromite ore deposits. Purpose of this study was determination of the groundwater quality and chromite deposites in Jovein area. Groundwater sampling was collected from 22 wells in the study area. Major and minor ions and trace metal compositions of groundwater were studied to evaluat hydrogeochemical processes that were likely to affect the quality of water in the study area. The results show that groundwater in the area is weakly alkaline with a mean pH of 1.84 and oxidizing with DO mean of 1.6 mg/l. The dominant cation in the area is Na, followed by Mg, Ca. The dominant anion is HCO3 -, followed by Cl- and SO4 2-. Water type is Na- Mg- HCO3. Groundwater samples are mostly located in good- acceptable for drinking purpose and suitable for irrigation. Multivariate statistical techniques such as cluster analysis (CA) and factor analysis/principal component analysis (PCA) were employed to examine the chemical compositions of groundwater and to identify factors that influenced each. The first cluster indicates salinity factor, the second one show weathering effects and the third cluster is represent the result of mine effects, alkalinity and oxidizing environment. Factor analysis yielded four significant factors explaining 182.18 of the total variance. PC8with 136 of the total variance comprised EC, TDS, Cl, SO4, Si, Se, Li, Mo, Cu, B, Ca, Na variables which show total soluble salt and chemical changes in groundwater direction flow. PC2 with 182.18 of the total variance was only interpreted by Cr 2 and shows effect of chromite ores and chromium minning in the environment. PC3 that described 182.33 of the total variance, had strong positive loadings on HCO3, Al, K and Mg, negative loading on pH and moderate positive loading for TDS and was expressed as weathering effects in the study area. PC4 with 188.61 of the total variance has high positive loading for V, As and Mo which are sensitive to redox condition, may demonstrated oxidizing alkaline environments. Factor score plot revealed the influence of flow direction from the south to the north and east to west of the study area.Most of trace elements were below WHO standard except Cr which showed values higher than WHO standard. Cr concentrations are not homogeneous in the study area. Spatially, there are three fields which could be recognized on the basis of chromium concentration in the study area.

کلیدواژه ها:

groundwater quality ، Factor analysis ، Chromium concentration ، Jovein aquifer