Vertical stratification in sediments from a young oligotrophic South African impoundment: implications in phosphorus cycling |
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Authors: | Twinch A J Breen C M |
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Institution: | (1) Department of Botany, University of Natal, Pietermaritzburg, South Africa;(2) Present address: National Institute for Water Research, P.O. Box 395, 0001 Pretoria, South Africa |
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Abstract: | Changes at the mud surface in Midmar Dam, following impoundment, were studied by examining vertical profiles of selected parameters in sediment cores. Distinct stratification in organic carbon, pH and exchangeable Al3+ was evident. Phosphate adsorption characteristics in the stratified sediments was quantified using Langmuir adsorption isotherms. The adsorption maxima and bonding energy constants in the surface sediments (0–3 cm) were markedly lower than those below 3 cm, indicating that the surface layers are less efficient at binding phosphate than the deeper layers. Radiotracer experiments indicate that the layers comprising the top 3 cm of sediment predominate in PO4-P exchange with the overlying water. |
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Keywords: | impoundment sediment stratification phosphate adsorption exchange |
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