Consequences of sea level rise for high metal(loid) loads in the Ría of Huelva estuary sediments

Carolin F Kerl; M Dolores Basallote; Merle Käberich; Erica Oldani; Nathalia P Cerón Espejo; Andrea E Colina Blanco; Carlos Ruiz Cánovas; José Miguel Nieto; Britta Planer-Friedrich

doi:10.1016/j.scitotenv.2023.162354

Consequences of sea level rise for high metal(loid) loads in the Ría of Huelva estuary sediments

Sci Total Environ. 2023 May 15:873:162354. doi: 10.1016/j.scitotenv.2023.162354. Epub 2023 Feb 22.

Authors

Carolin F Kerl¹, M Dolores Basallote², Merle Käberich¹, Erica Oldani¹, Nathalia P Cerón Espejo¹, Andrea E Colina Blanco¹, Carlos Ruiz Cánovas², José Miguel Nieto², Britta Planer-Friedrich³

Affiliations

¹ Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, D-95440 Bayreuth, Germany.
² Department of Earth Sciences & Research Center on Natural Resources, Health and the Environment (RENSMA), University of Huelva, Huelva 21071, Spain.
³ Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, D-95440 Bayreuth, Germany. Electronic address: b.planer-friedrich@uni-bayreuth.de.

PMID: 36822435
DOI: 10.1016/j.scitotenv.2023.162354

Abstract

Ría of Huelva, located in southwestern Spain, is a highly metal(loid)-contaminated estuary system where sediments are exceeding action limits in an increasing order for Cd, Zn, Pb, Cu, and As. With a predicted sea level rise over the next 50 years, the estuary will be subject to flooding with brackish water or seawater. To evaluate the risk of metal(loid) mobilization under future climate scenarios, different locations along the estuary were sampled at different depths. Samples were flooded with river water, brackish water, and seawater under different short- and long-term laboratory setups. Potential metal(loid) mobilization showed that water quality standards for As, Pb, Zn, Ni, Cu, and Cd could be exceeded upon seawater flooding. However, metal(loid) mobilization was not predictable solely based on sediment loads. The driving factors for cation and anion mobility were identified to be mainly pH under low salinity and competitive desorption under high salinity conditions. Further drivers such as wave movement or labile C input in C-limited systems were found to enhance metal(loid) mobilization. Long-term flooding of intact sediment cores revealed that sea level rise will have different effects on the estuary system depending on duration of flooding. Short-term flooding in the near future will first affect alkaline sediments and enhance currently low cation mobilization, while anion mobilization due to reductive Fe dissolution will remain high. Once acidic sediments further inland are flooded with seawater, highest contaminant mobilization can be expected as high salinity will further enhance already high cation mobilization under acidic pH. Long-term flooding with seawater will neutralize the sediment pH and limit cation mobilization compared to acidic pH. However, the contaminant load stored in the estuary is so high that, extrapolating data obtained, mobilization could last for >1000 years, e.g. for As, Pb, and Al.

Keywords: Climate change; Contaminants; Metal(loid) mobilization; Mining-impacted estuary; Río Odiel; Río Tinto.