ETD Collection

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Author: search.filters.author.Spratt, Jesse PatrickSubject: search.filters.subject.Ecology

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    A Palaeolimnological determination of a regional industrial signal in the sediments of Mpumalanga Highveld Pans
    (2020) Spratt, Jesse Patrick
    Fresh water endorheic wetlands are a scarce resource in South Africa and are threatened by human activities such as mining, abstraction, farming and other industry. The Mpumalanga Lake District (MLD) is a unique region comprising of over 300 endorheic pans differing in type. This provided the ideal regional setting for a pilot palaeolimnological study. The overall aim was to identify a regional industrial signal for anthropogenic influence by understanding the uniqueness of these pans through a palaeolimnological approach using historical lake sediments. A historical sediment record was established in order to identify any temporal changes in physiochemical characteristics over the last approximately 130 years. Four sites were selected so as to analyse a spatial aspect of contamination and to compare physical characteristics of pans in the MLD. Sediment samples were collected in the form of four lake sediment cores which were sub-sampled at 0.5 cm in order to understand down core trends. A bathymetric approach was adopted in which GPS, depth and water quality data were obtained in order to understand the physiochemical characteristics and morphology of these pans. Analyses performed included radio-isotopic dating through 210Pb, organic carbon content analysis through Loss on Ignition methods, sediment grain size analysis using laser diffraction and the analysis of the composition of major elements in these lake sediments using x-ray fluorescence (XRF) spectrometry. Bathymetry data was used to produce maps representing the physical morphological characteristics of these pans. Sediment data including major elements, organic carbon content and grain size data was analysed statistically and represented graphically in order to understand down core trends. Identified was the uniqueness of these pans and the MLD region as a whole. The pans differed in size, depth and in terms of the sediment properties of organic carbon, carbonate and sediment grain size distribution. Results showed a distinct difference between sites TPE compared to the other three sites in terms of bathymetry and limnology. It was determined that there are multiple fluctuations throughout the sediment record which represents a seasonal variation in climatic conditions. An attempt to observe trends of environmental and climatic change was made with varied success. An identification of a possible regional industrial signal was made with respect to major element compositional changes however the distinction between natural and anthropogenic sources was difficult to determine