Evaluation of arsenite sorption in Spanish soils

Arsenite sorption was studied at different temperatures (30, 40, and 50 deg reesC) to investigate processes that remove arsenite from soil solution (ad sorption or precipitation), and if adsorption was taking place, how many si tes were involved in this process, and their nature. Adsorption was the onl y reaction reducing levels of soluble arsenite in the two alkaline soils us ed in this experiment, Jijona and Agost; however, arsenite precipitation oc curred in an acidic substrate (pH 4.0), Galicia soil. Iron (Fe) oxides and clay minerals were the soil components controlling arsenite sorption in the Jijona soil (pH 7.9 and high levels of Fe oxides). Calcite and clay minera ls were the inorganic constituents involved in arsenite sorption in the Ago st soil (pH 8.0 and high levels of CaCO3). Arsenite sorption was an endothe rmic and non-spontaneous process. The fact that the higher the temperature, the higher the arsenite sorption, however, was likely due to an increase i n the diffusion rate.