Comparative evaluation of the concentrations of lead, cadmium and zinc in surficial sediments from two shallow tectonic freshwater lake basins, kenya

Abstract

Sources of metals in the environment are widespread and data on typical concentrations in the various media and environmental settings exits worldwide. Distribution and comparative concentrations of some selected metals in surface sediments of two shallow tectonic freshwater basins were assessed, as useful indicators of the level or magnitude of anthropogenic influences, as well as other aquatic processes, considering the increasing challenges in management of waste disposal. Concentrations of Pb, Cd and Zn in the sediments were detectable in all sites, albeit there were relatively lower levels reported in the column of alkaline waters. In dry weight basis, and in increasing order, the levels were Cd<Pb<Zn in both basins. Cd, Pb and Zn elements are all chalcophiles. However, using a student t-test, the concentrations of Cd and Pb in the sediments showed significant differences (p<0.05) between the two basins. Using freshwater sediment quality guidelines (ISQG) values, all the three metal mean contents in L. Baringo were above these values. Average levels of Zn and Cd were also above the ISQG values. However, all the mean concentrations of Zn, Cd and Pb in surficial sediments were found to be below the probable effect level, and above normal concentrations ranges found in sedimentary and igneous formations. Concentrations of Pb and Zn found are comparable to other relatively large basins, with extensive drainage basins and urban influences. Cadmium sediment levels are a concern, as the evaluation shows increasing accumulation in sediments, with possible future exposure risks to aquatic organisms. Surface runoff, waste discharges and particulate deposition is thought to be significant in these basins, and to understand overall impacts from anthropogenic deposition, it is important that background metal levels are determined together with supporting chemical partitioning to reveal more information on available metal contents.

Temporal Variations in Nutrients Loading in Lake Baringo Basin, Kenya.

“…TDS vales ranged from 300-305mg/l with a mean value of 302.63±2.00 mg/l during dry season while in the wet season, the values ranged from 183-433mg/l with a mean value of 297.5±113.11 mg/l.The results indicates that the TDS values were higher in dry season than wet season. A previous study in Lake Baringo revealed similar results of high TDS (Mwamburi, 2015;Kumar et al,2015).However,(Islam and Azam, 2015;Manohara et al, 2019) in their studies observed high TDS values during the wet seasons resulting from run-off in wet seasons. TDS values were within the acceptable National Environmental Management Authority (NEMA, Kenya) limits of 1200 mg/l for natural water.…”