arsenic pollution and fractionation in sediments and mine waste samples from different mine sites a characterization of arsenic pollution and its associations with solid mineral phases in sediments and spoil heap samples from four different abandoned mines in spain is performed three of them were mercury mines located in the same mining district in the province of asturias and the other one devoted to arsenic mining is in the province of len a sequential extraction procedure especially developed for arsenic was applied for the study of arsenic partitioning very high total arsenic concentrations ranging 30067000 mgkg1 were found arsenic fractionation in each mine is broadly in accordance with the mineralogy of the area and the extent of the mine workings in almost all the studied samples arsenic appeared predominantly associated with iron oxyhydroxides especially in the amorphous form sediments from cinnabar roasted piles showed a higher arsenic mobility as a consequence of an intense ore treatment posing an evident risk of arsenic spread to the surroundings samples belonging to waste piles where the mining activity was less intense presented a higher proportion of arsenic associated with structural minerals nevertheless it represents a longterm source of arsenic to the environment