Arsenic fractionation in agricultural acid soils from NW Spain using a sequential extraction procedure

Arsenic fractionation has been studied in nine vineyard soils from a wine-producing area in Galicia (NW Spain) characterized by an unusually high As content. Total As concentrations are 7 to 10 times higher the maximum values allowed by the legislation, reaching maximum value of 200 mg kg−1. The study of As fractionation revealed that those fractions showing strong correlations to crystalline Fe and Al hydrous oxides (rN0.69, pb0.01 and rN0.71, pb0.01 respectively) represented, on average, higher than the 80% of total As. The low levels of mobile and potentially toxic As fractions (b4% of total As) suggest that its toxicity is partially minimized in these soils, although the modifications induced by soil management could promote an increase of As availability.