Mercury, Silver and Other Trace Elements in Three Cyprinid Fish Species from the Vaal Dam, South Africa
- Author(s)
- Christof Plessl, Martin Friedrich Sigmund, Sarah Theiner, Annemarie Avenant-Oldewage, Bernhard Keppler, Franz Jirsa
- Abstract
Amongst the publicly recognized pollutants like mercury (Hg), lead (Pb), cadmium (Cd) and zinc (Zn), one of the more recently discovered threats for aquatic environments is silver (Ag), due to its use in many everyday household and hygienic products, and its consequent discharge into the environment. The Vaal Dam, a large and important freshwater reservoir in South Africa, has been under investigation regarding heavy metals in the past, but comprehensive studies on Hg and Ag are missing, and not all fish species have been studied to date. For this study we therefore investigated trace element levels in sediment and in three fish species, namely smallmouth yellowfish Labeobarbus aeneus, largemouth yellowfish L. kimberleyensis and moggel Labeo umbratus. We analyzed Ag, Cd, Cr, Cu, Hg, Pb, Se and Zn in muscle and liver tissues to complete the picture of metal levels in the lake. This is the first record for trace elements in L. aeneus as well as the first report for Hg and Ag levels in L. kimberleyensis and L. umbratus. Silver was below the LOD in muscle but well detectable in liver and measured concentrations may reflect background values as a base to monitor future developments. Mercury levels surpassed environmental quality guidelines, but stayed below maximum allowances for human consumption. In L. umbratus they were lower compared to the other two species, which reflects the lower trophic level occupied by this species. Levels of Cu, Zn and Cd were highest in the liver of L. umbratus, showing extremely high levels for Cu. The survey shows some degree of trace element contamination of three fish species from the Vaal Dam, but to a rather low degree. It does not pose a health risk for humans consuming fish; nevertheless, Hg levels might pose a risk to piscivorous animals.
- Organisation(s)
- Department of Inorganic Chemistry, Department of Analytical Chemistry
- External organisation(s)
- University of Johannesburg (UJ)
- Publication date
- 07-2018
- Austrian Fields of Science 2012
- 104023 Environmental chemistry, 104003 Inorganic chemistry
- Sustainable Development Goals
- SDG 3 - Good Health and Well-being, SDG 15 - Life on Land
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/mercury-silver-and-other-trace-elements-in-three-cyprinid-fish-species-from-the-vaal-dam-south-africa(15ef20f4-9a65-4f1e-9041-8eceb064531d).html