Investigating the Origin of Some Heavy Metals in Groundwater of Marand Plain Using Multivariate Statistical Methods

Marand plain is one of the fertile plains of East Azarbaijan Province, in which due to the scarcity of surface waters, groundwater is the main resource for irrigation. In this study, multivariate statistical methods including correlation coefficient, factor analysis and cluster analysis were used to investigate the groundwater quality and origin of some heavy metals. For this purpose, 25 samples were collected from the existing groundwater resources and concentrations of some heavy metals, major ions and some species and minor ions (NO3 -, F- and SiO2) were measured. The results of cluster analysis put the water samples into two distinct groups. The first group is representative of fresh and deep groundwater and the second group is representative of saline and high hardness groundwater. Based on the correlation matrix, concentrations of metals such as Fe, Mn, Cr, Al, Ba and As are not highly correlated with major ions (Ca2, Mg2, K, Na, Cl , HCO3 - and SO4 2-) which represent entrance of these metals into groundwater through human activities. Cd and Pb have a relatively high correlation with major ions, which may indicate that the source of these metals is dissolution of rocks and formations. Factor analysis shows that variations in groundwater quality of the plain are influenced by three main factors including: 1- the effect of evaporate and salt formations, natural weathering of minerals and ion exchange process,
2- leakage from municipal wastewater and domestic absorption wells and agricultural fertilizers leaching and
3- weathering of potassium bearing silicates and application of agricultural fertilizers.