The fate of arsenic in soils adjacent to an old mine site (Bustarviejo, Spain): mobility and transfer to native flora

The final publication is available at Springer via http://dx.doi.org/10.1007/s11368-009-0099-4
Background, aim, and scope The mobility of arsenic in soils and its transfer to other environmental components present significant environmental risks. The management of polluted land is determined by the availability, mobility, and transfer of inorganic pollutants to different ecosystem compartments. In this paper, the fate of arsenic at this mining site has been evaluated to determine future management practises to minimise such risk. Materials and methods In a field study carried out in the area adjacent to a mining site at Bustarviejo (North Madrid, Spain), samples of soils, plants, and water were collected from areas adjacent to the core of the former mining activity. The following parameters were investigated in soil samples: pH, organic matter, pseudo-total As, P, and Fe, and labile As and P, and a sequential extraction procedure was performed to investigate As speciation in soil. Plant materials were analysed for both As and P. Arsenic concentrations in water samples (surface and soil pore water collected in the field) were also measured. Results are considered in tandem with previous data on metal concentrations in soils and plants from this site. Results Despite high As concentrations in soils impacted by former mining activities (spoil accumulation and drainage from spoil heaps resulted in concentrations of up to 3,000 mg kg-1), it was not present in a labile form. Sequential extraction revealed that arsenic was mainly retained by Al- and Fe-(oxihydr)oxides (up to 80%). Therefore, only a small proportion of the total soil pool was potentially available for plant uptake (0.3% and 7% extracted by (NH4)2SO4 and NH4H2PO4, respectively). There was very limited transfer of arsenic from soil to plants, and concentrations of arsenic in shoot tissues were relatively low (
This study was supported by the Spanish Ministry of Education and Science, project CTM 2007-66401-CO2/TECNO, and by Comunidad de Madrid, project S-0505/AMB/0296. The authors are grateful to the Excmo. Ayuntamiento de Bustarviejo, for admittance to the mine zone and the facilities offered and to Dr. R. Gamarra for his assistance with plant identification. Authors are grateful to L. Beesley for his comments and language corrections.