Sedimentological data from the Limpopo River Basin dams, southern Africa, 2018-2021

The data set contains grain size distributions, organic matter (OM) content and trace metal distribution (including Fe, Zn, Cu, Cr and Pb) of 37 shallow cores of sediments sampled from dams across the Limpopo River Basin. The dams include: Gaborone, Lotsane and Shashe dams in Botswana; Houtrivier, Nwanedi and Mutshedzi dams in South Africa; Ripple Creek and Zhovhe dams in Zimbabwe; and Massingir Dam in Mozambique. Data from two cores sampled from an oxbow lake in Mozambique are also included. The cores were collected with a gravity corer using PVC pipes of 5 cm diameter by a team from Botswana International University of Science and Technology (BIUST) led by Dr. Franchi between July 2018 and April 2021.

Grain size analysis was carried on wet samples dispersed in water and analysed with a Malvern Mastersizer 3000 laser diffraction particle size analyser at Botswana International University of Science and Technology (BIUST), Palapye (Botswana).b A few grams of the samples were dispersed into a glass container with half a spoon of sodium hexametaphosphate to prevent clays from flocculation. The data are reported as 10th percentile (Dx10), median (Dx50) and 90th percentile (Dx90). The organic matter content was determined using Loss on Ignition (LOI) method whereby the samples were dried at 60 C for 24 hours to remove water content. The dried samples were placed in the funnel furnace at 550 C for 2 hours and then weighed again to determine LOI. Data are reported as percentage of mass loss during the ignition phase as compared with the initial mass of dried sample. The sediments have been analysed for trace metal distribution using ICP-OES and ICP-MS on samples of sediments partially digested with aqua regia. All data are raw and unprocessed.