High geogenic arsenic concentrations in travertines and their spring waters: Assessment of the leachability and estimation of ecological and health risks

Abstract

Continental carbonates and their springs are rarely investigated as a source of toxicity. Remarkably high contents of As (up to 10 g/kg) have been found in travertine deposits and associated spring waters, nearby Ghorveh city (western Iran). Two types of travertines were distinguished: (i) Fissure ridge travertines, in areas with a carbonate-dominated basement, are characterized by a relatively low As content (<15 mg/kg) and low As leaching. Their spring waters contain >150 µg/L of As; (ii) Mound travertines, rich in noncarbonate impurities, occur in areas with volcanic substrates and contain high As concentrations (on average ~1500 mg/kg) with high leachability. Their spring waters have lower As concentrations than equivalent fissure ridge waters. Principal Component Analyses of the elemental and mineralogical composition show the unstable association of As over a wide range of pH values to non-carbonate related elements, in particular iron, related to clay minerals. The high potential release of As may result in adverse ecotoxicological effects in surrounding agricultural soils and crops. An ecological risk assessment, based on enrichment factors and risk indices, confirms the enrichment and very high potential ecological risk of As around mound carbonates. The human health risk assessment based on calculation via exposure factors suggests adverse non-carcinogenic and high carcinogenic risk with regard to As, both for adults and children. However, further investigations are necessary to evaluate the real ecological and human health risks.