Major and trace element geochemistry in Zeekoevlei, South Africa: a lacustrine record of present and past processes

Das, S.K., Routh, J., Roychoudhury, A.N. and Val Klump, J. (2008) Major and trace element geochemistry in Zeekoevlei, South Africa: a lacustrine record of present and past processes. Applied Geochemistry, 23(8), pp. 2496-2511. (doi: 10.1016/j.apgeochem.2008.02.011)

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Publisher's URL: http://dx.doi.org/10.1016/j.apgeochem.2008.02.011

Abstract

This study reports a multi-parameter geochemical investigation in water and sediments of a shallow hyper-eutrophic urban freshwater coastal lake, Zeekoevlei, in South Africa. Zeekoevlei receives a greater fraction of dissolved major and trace elements from natural sources (e.g., chemical weathering and sea salt). Fertilizers, agricultural wastes, raw sewage effluents and road runoff in contrast, constitute the predominant anthropogenic sources, which supply As, Cd, Cu, Pb and Zn in this lake. The overall low dissolved metal load results from negligible industrial pollution, high pH and elevated metal uptake by phytoplankton. However, the surface sediments are highly polluted with Pb, Cd and Zn. Wind-induced sediment resuspension results in increased particulate and dissolved element concentrations in bottom waters. Low C/N ratio (10) indicates primarily an algal source for the sedimentary organic matter. Variation in sedimentary organic C content with depth indicates a change in primary productivity in response to historical events (e.g., seepage from wastewater treatment plant, dredging and urbanization). Primary productivity controls the enrichment of most of the metals in sediments, and elevated productivity with higher accumulation of planktonic debris (and siltation) results in increased element concentration in surface and deeper sediments. Aluminium, Fe and/or Mn oxy-hydroxides, clay minerals and calcareous sediments also play an important role in adsorbing metals in Zeekoevlei sediments.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Das, Dr Supriyo
Authors: Das, S.K., Routh, J., Roychoudhury, A.N., and Val Klump, J.
Subjects:Q Science > QH Natural history
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Applied Geochemistry
ISSN:0883-2927
ISSN (Online):1872-9134
Published Online:29 February 2008

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