“…When these wastes react with runoff, surface and rain waters, they can damage ecosystems as As can be transferred to the dissolved fraction. For example, studies on fish collected in a mining area ([Foley et al, 1978], [Orsini et al, 1994], [Casiot et al, 2009] and [Vicente-Martorell et al, 2009]) revealed As concentrations higher than the quality standards (maximum As concentration in whole fish <1 mg kg −1 wet weight according to WHO, 2001). On the other hand, natural attenuation processes can occur and dissolved As is frequently trapped by coprecipitation/sorption reactions with Fe, Mn and Al-oxyhydroxides, complexed with humic substances and/or immobilized by microbial activities ([Hoins et al, 1993], [Ali and Dzombak, 1996] and [Morin and Calas, 2006]).…”