Stream bottom sediments as a means to assess metal contamination in the historic mining district of Almadén (Spain)

Abstract

Located in the southern half of Spain, Almadén is the world’s largest Hg district and mercury has been mined there for over 2000 years. Its slag heaps and old metallurgy plants represent a risk to watercourses that flow through the district and receive the run-off from the mines. This study collected sediment samples along the length of the main watercourses in the mining district. High levels of heavy metals were detected, with Hg levels varying between 1.77 and 255.88 mg kg⁻¹, Pb levels between 20.59 and 131.07 mg kg⁻¹ and Zn levels between 59.06 and 131.07 mg kg⁻¹. The dispersion of these heavy metals in rivers as a result of mining activities has caused sediment quality degradation. As such, when measured using reference indexes such as the SeQI and the EF, sediment quality for the entire district is practically poor, due to anthropogenic contributions, with the concomitant threat to the surrounding environment.

Keywords:

• Almadén
• mercury
• heavy metals
• river bottom sediments
• sediments quality index

Acknowledgements

The authors would like to acknowledge the support of the Environmental Testing Unit and Scientific and Technical Services at the University of Oviedo in performing the analyses.

Additional information

Funding

Funding. This study was co-supported by the Spanish Ministry of Science and Innovation [grant number BES-2010-040150], [grant number CGL2009-13171-C03-03], [grant number CTM2012-33918]; The Asturias Ministry of Education and Science [grant number ECOEMP-2013].