Environmental Geochemistry of Potentially Toxic elements in thermal springs in the Sabalan Volcanic Field, NW Iran

School of Geology, University College of Science, University of Tehran, IRAN

^a modabberi@ut.ac.ir, s_modabberi@yahoo.com

Abstract

Thermal springs are widely used by tourists for treatment of dermal diseases and other therapeutic applications. In Iran, thermal springs occur in Northwestern part mainly surrounding the Mount Sabalan which attract hundreds of thousands of tourists annually. Two clusters of springs in Neer and Meshkinshahr areas including 16 thermomineralic springs have been studied in this research and they were sampled twice in May and November in order to investigate the seasonal changes of trace elements in dry and wet seasons. The samples were analyzed in Acme Lab, Canada for 72 elements. Trace element concentrations indicate that most of the elements show concentration well beyond the guideline values for drinking water. While the two sets of samples were taken within a 6 months interval, the elements show slight or no variation from first period to the second and in some cases. Arsenic shows a variation of 5-5834μg/l and the mean As value is 160 times the guideline values (10 μg/l). Other toxic elements with high concentration are B, Fe, Mn, Sb, and Si. Mn and Sb shows exeedance of 12 and 11.5 times respectively. Correlation coefficient and principal component analysis of analytical data indicate that Cl, As, B, Ba, Br, and V show very strong mutual correlation coefficients implying their relationship and common source and fate in the hydrothermal fluid carrying them. These elements fall in the component 1 of PCA. This group of elements is supposed to be derived and sourced from the magmatic-hydrothermal system and through the interaction of hydrothermal fluids with rocks they passed through. Because of discharge of the thermal springs into the nearby streams intended to be used for drinking water and also vast application of spring waters in balneological uses, they may have adverse environmental and health impacts on tourists that expose themselves to this contaminants through balneological applications.