Metal partitioning and speciation in a mining-impacted estuary by traditional and passive sampling methods

Carlos Ruiz Cánovas; Maria Dolores Basallote; Pedro Borrego; Ricardo Millán-Becerro; Rafael Pérez-López

doi:10.1016/j.scitotenv.2020.137905

Metal partitioning and speciation in a mining-impacted estuary by traditional and passive sampling methods

Sci Total Environ. 2020 Jun 20:722:137905. doi: 10.1016/j.scitotenv.2020.137905. Epub 2020 Mar 12.

Authors

Carlos Ruiz Cánovas¹, Maria Dolores Basallote², Pedro Borrego², Ricardo Millán-Becerro², Rafael Pérez-López²

Affiliations

¹ Department of Earth Sciences and Research Center on Natural Resources, Health and the Environment, University of Huelva, Campus 'El Carmen', Fuerzas Armadas s/n, 21071 Huelva, Spain.. Electronic address: carlos.ruiz@dgeo.uhu.es.
² Department of Earth Sciences and Research Center on Natural Resources, Health and the Environment, University of Huelva, Campus 'El Carmen', Fuerzas Armadas s/n, 21071 Huelva, Spain.

PMID: 32197167
DOI: 10.1016/j.scitotenv.2020.137905

Abstract

This study deals with the metal partitioning and bioavailability of metal/loids in the estuary Ria of Huelva (SW Spain) which is strongly affected by historical mining and industrial activities. To address this issue, traditional (i.e., grab samples) and passive sampling (i.e., diffusive gradient in thin films, DGTs) was carried out in the outer part of the estuary during different tidal cycles in order to determine the dissolved and particulate metal/loid concentrations. The dissolved concentrations exceeded, by several orders of magnitude, those reported in other estuaries worldwide that are affected by anthropogenic activities. A spatial pattern was observed in the metal distribution; a decrease seaward was recorded for some of the elements associated with mining (e.g., Cu, Zn, and Cd), the opposite tendency is observed for others associated with harbor emissions (e.g., Sn, Ni, or Pb). A different metal/loid partitioning pattern was also observed; Fe, and to a lesser extent Pb and Sn, were chiefly found in the particulate matter, while the rest of the elements were mainly found in the dissolved form. The bioavailability of the metal/loids was studied by speciation using both geochemical modeling and DGTs; while concentrations in DGTs supported metal/loid speciation for Zn, Cd, Mn, Co, As, and Sb according to their affinity to form strong or weak complexes, some discrepancies were observed for other elements such as Cu, V, Fe, and Pb, which are prone to forming strong complexes. The main reason behind the unexpectedly high Fe and Pb DGTs concentrations may be associated with their presence in the colloidal particles passing through the DGT. There was a strong positive correlation between dissolved and DGT concentrations for Cd and Mn, and to a lesser extent for Fe and Cu, highlighting the direct relationship between the concentrations in water and availability to living organisms in the estuary.

Keywords: Bioavailability; Diffusive gradient in thin films (DGT); Metal pollution; Metal toxicity; Passive samplers.