Toxic Elements in Sediment and Water of the Crocodile River (West) System, South Africa, Following Acid Mine Drainage

Jakob Windisch, Andreas Gradwohl, Beric Michael Gilbert, Quinton Marco Dos Santos, Gabriele Wallner, Annemarie Avenant-Oldewage, Franz Jirsa

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The upper reaches of the Crocodile River (West) system are located in the western basin of the Witwatersrand mountain chain, an area heavily influenced by gold mining. After the spill of highly acidic and contaminated mining-influenced water into the river system in 2002, chemical water treatment was implemented to compensate for the consequences of acid mine drainage. Some studies thereafter have shown metal concentrations of concern in the system, but never considered longer periods of time. For this study, we investigated water and sediments over a period of 13 months from 7 sampling sites in the system. In addition to physico-chemical parameters such as temperature, pH, and electrical conductivity, a multi-element analysis was conducted. We used various versions of atomic-absorption-spectroscopy, total reflection x-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry in filtered and acidified water samples as well as sediment leachates. Concentrations of Ni, Zn, As, Pb, and U in the sediment were clearly elevated at the site closest to the mine as well as further downstream, some of them far exceeding quality guidelines. Moreover, dissolved Mn, Fe, Ni, Zn and U occurred irregularly in concentrations of concern at the site of mining-influenced water inflow. Our findings clearly indicate a risk of further and chronic mobilization of toxic elements from this site and a possible threat to the connected river system.

Original languageEnglish
Article number10531
JournalApplied Sciences (Switzerland)
Volume12
Issue number20
DOIs
Publication statusPublished - Oct 2022

Keywords

  • acute effect value (AEV)
  • arsenic
  • contamination
  • mining-influenced water (MIW)
  • nickel
  • probable effect level (PEL)
  • uranium
  • zinc

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes

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