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Journal of Chemistry
Volume 2016, Article ID 6092047, 14 pages
Research Article

Arsenic Transfer from As-Rich Sediments to River Water in the Presence of Biofilms

1Departamento Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, Campus Vida, 15782 Santiago de Compostela, Spain
2Unidade de Análise Elemental (RIAIDT), Edificio CACTUS-Lugo, Universidade de Santiago de Compostela, 27002 Lugo, Spain

Received 1 July 2016; Revised 5 August 2016; Accepted 29 August 2016

Academic Editor: Amir Sandler

Copyright © 2016 Diego Martiñá Prieto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The influence of epipsammic biofilms on As release from river sediments was evaluated in a microcosm experiment where biofilms were grown on sediments containing 106 mg kg−1 As, collected in the Anllóns River, and compared with control systems without biofilms. The As transfer to the water column was low (<0.11% of total As in the sediment) and was further reduced by 64% in the presence of biofilms. was the predominant species in the overlying water in both systems. concentration was higher (up to 12% of total dissolved As) in the control systems than in the systems with biofilms, where this species was almost absent. This fact is of toxicological relevance due to the usually higher mobility and toxicity of the reduced species. Control systems exhibited higher As mobility in water, in sulphate solution, and in weak acid medium and higher bioavailability in diffusive gradient in thin films (DGT) devices. Arsenic retained by the biofilm was equally distributed between extracellular and intracellular compartments. Inside the cells, significant concentrations of , monomethylarsonic acid (), and dimethylarsinic acid () were detected, suggesting that active methylation (detoxification) processes are occurring in the intracellular compartment.