Influence of parent material and soil use on arsenic forms in soils: A case study in the Amblés Valley (Castilla-León, Spain)

• Levels of As and GBC in soils of Amblés Valley (Spain) have been evaluated.
• The influence of parent material and anthropogenic activities on As was studied.
• Distribution of As is closely related to the geological material.
• Anthropogenic activities could enhance the mobility of As in soils.
• Iron and Al oxides, clay, SOM and pH were the main controlling factors for As mobility in these soils.

The total, water soluble and extractable concentrations with EDTA of As from topsoils from the Amblés Valley (Ávila, Spain) were determined. The geochemical baseline concentrations of total As were established, and the relationships between the concentration of the different As forms and soil properties were investigated. Total As content in soils was related with parent material, whereas anthropogenic activities affected its mobility. Iron, aluminium, clay content, soil organic matter and soil pH were the main controlling factors for As soil concentrations. The geochemical baseline concentrations obtained (mg kg− 1) were 7.3–35 in soils on granite parent material and 2.2–6.8 in soils on alluvium–colluvium parent material for total As. The baseline concentration values for the water soluble and EDTA extractable As forms were also established. For water soluble As, the baseline concentrations (mg kg− 1) were 0.06 for natural soils and 0.37 for agricultural and industrial soils, respectively, and the baseline concentrations for As extractable with EDTA were 0.39 mg kg− 1.