Mineral Composition and Total Organic Carbon Content of the Channel and Floodplain Sediments of the Swartkops Estuary, Port Elizabeth, South Africa
Mineral composition and the total organic carbon content of channel and floodplain sediments from the Swartkops estuary were determined to discover the various sources and factors controlling their abundance and distribution. Mineral compositions were determined using several techniques including petrographic microscope, X-ray powder diffraction (XRD), scanning electron microscope (SEM), and Raman spectroscopy. Total organic carbon contents (TOC) were determined using a Loss-on-ignition (LOI) technique. Sediment in the estuary consists of four main mineralogical groups, including quartz, calcite, carbonate materials and clay minerals. The predominant mineralogical type is quartz contained in the sands at ~30%, which is sourced from inland and transported into the estuary by river streams. The subordinate is the skeletal carbonate material (bioclasts) at ~20% which is mainly derived in situ at the sea. The coarse-grain fraction of the sands that enters the estuary from the sea through the tidal inlet consists largely of calcite (CaCO3) at ~20%. Other common mineral constituent in the estuary are mud/clay minerals at ~23%. The clay mineral assemblage consists mainly of kaolinite, chlorite, smectite, and very scarce glauconite. Small amounts of heavy minerals (iron and titanium oxides) are also consisting at ~7%. Total organic carbon content (TOC) for the channel and floodplain sediments vary from 0.00 to 9.76 wt. % and 0.10 to12.34 wt. %, respectively.