ABSTRACT
Waters and suspended sediments bearing inorganic forms of arsenic and selenium occur widely and are especially prevalent in sites impacted by mining. These systems present significant concerns for human and ecosystem health and most, if not all, contain natural organic matter (NOM). The chemical and physical properties of NOM suggest its involvement in several critical processes that affect the behavior of As and Se, including oxidation-reduction reactions, competitive interactions affecting sorption, and formation of metal-organic (bridging) complexes. NOM is expected to alter the mobility, transformations, bioavailability, and toxicity of As and Se, and therefore to play an important role in the design of methods to mitigate contamination problems.
