Role of biogenic Fe(III) minerals as a sink and carrier of heavy metals in the Rio Tinto, Spain

Sergey M Abramov; Julian Tejada; Lars Grimm; Franziska Schädler; Aleksandr Bulaev; Elizabeth J Tomaszewski; James M Byrne; Daniel Straub; Harald Thorwarth; Ricardo Amils; Sara Kleindienst; Andreas Kappler

doi:10.1016/j.scitotenv.2020.137294

Role of biogenic Fe(III) minerals as a sink and carrier of heavy metals in the Rio Tinto, Spain

Sci Total Environ. 2020 May 20:718:137294. doi: 10.1016/j.scitotenv.2020.137294. Epub 2020 Feb 22.

Authors

Affiliations

¹ Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany; Microbial Ecology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany. Electronic address: sergey.abramov@uni-tuebingen.de.
² University of Applied Forest Sciences Rottenburg, Schadenweilerhof, D-72108 Rottenburg am Neckar, Germany.
³ Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany.
⁴ Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany; Microbial Ecology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany.
⁵ Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Ave. 33, Bld 2, 119071 Moscow, Russia.
⁶ Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany; Plant and Soil Sciences 250A Harker ISE Lab, University of Delaware Newark, DE 19716, USA.
⁷ Microbial Ecology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany; Quantitative Biology Center (QBiC), University of Tuebingen, Auf der Morgenstelle 10, 72076 Tuebingen, Germany.
⁸ Department of Virology and Microbiology, Centre for Molecular Biology "Severo Ochoa", Autonomous University of Madrid, Calle Nicolás Cabrera 1, Cantoblanco (Campus UAM), 28049 Madrid, Spain.
⁹ Microbial Ecology, Center for Applied Geosciences, University of Tuebingen, Hölderlinstrasse 12, D-72074 Tuebingen, Germany.

PMID: 32097837
DOI: 10.1016/j.scitotenv.2020.137294

Abstract

Oxidation of sulfide ores in the Iberian Pyrite Belt region leads to the presence of extremely high concentration of dissolved heavy metals (HMs) in the acidic water of the Rio Tinto. Fe(II) is microbially oxidized resulting in the formation of suspended particulate matter (SPM) consisting of microbial cells and Fe(III) minerals with co-precipitated HMs. Although substantial amount of HM-bearing SPM is likely deposited to river sediment, a portion can still be transported through estuary to the coastal ocean. Therefore, the mechanisms of SPM formation and transport along the Rio Tinto are important for coastal-estuarine zone. In order to reveal these mechanisms, we performed diurnal sampling of Rio Tinto water, mineralogical and elemental analysis of sediment from the middle course and the estuary of the river. We identified two divergent but interrelated pathways of HM transfer. The first longitudinal pathway is the transport of SPM-associated metals such as As (6.58 μg/L), Pb (3.51 μg/L) and Cr (1.30 μg/L) to the coastal ocean. The second sedimentation pathway contributes to the continuous burial of HMs in the sediment throughout the river. In the middle course, sediment undergoes mineralogical transformations during early diagenesis and traps HMs (e.g. 1.6 mg/g of As, 1.23 mg/g of Pb and 0.1 mg/g of Cr). In the estuary, HMs are accumulated in a distinct anoxic layer of sediment (e.g. 1.5 mg/g of As, 2.09 mg/g of Pb and 0.04 mg/g of Cr). Our results indicate that microbially precipitated Fe(III) minerals (identified as ferrihydrite and schwertmannite) play a key role in maintaining these divergent HM pathways and as a consequence are crucial for HM mobility in the Rio Tinto.

Keywords: Contaminated river; Estuary; Heavy metal; Microbial Fe(II) oxidation; Rio Tinto; Suspended particulate matter.