Evaluation of arsenic in soils and plant uptake using various chemical extraction methods in soils affected by old mining activities

The aims of this study were to assess arsenic concentrations and solubility in soils, and its uptake by plant species growing in an area strongly affected by mining activities in Murcia (SE, Spain) paying attention to the mineralogical composition of the soils and the relation of the same with the bioavailability of this element. For this, extractions were made with several chemical reagents, to determine the bioavailability of the element in different environmental conditions (natural or potential) and, especially, the arsenic bioavailable for the plant uptake. Maximum extraction was achieved using the Mehra and Jackson procedure, while the least effective extractant was an ammonium sulphate solution. The strongest relationship between the As determined by soil chemical extractions and the As measured in plant biomass was found using the oxidisable-organic matter extraction procedure.