Status of Trace Elements’ Concentrations in Lake Baringo’s Catchment in Kenya: A Review

Abstract

Lake Baringo is one of the two shallow freshwater rift valley lakes characterized by a topographically closed basin, alkaline waters, turbidity, high evaporation rates and seasonal water level changes. The lake water is an important water source, and it sustains a small fishery and high biodiversity. The lake basin is located at a relatively lower altitude in a semi-arid area, along the floor of the rift valley, and therefore it is greatly influenced by materials derived from the steep gradient landscape of the catchment area, anthropogenic activities and geological formations. Cadmium, lead, arsenic’s inorganic species, and mercury are the heavy metals which are considered to be the most toxic amongst the non-essential trace elements to humans, animals and plants in the environment. During the ”Anthropocene” epoch there have been growing concerns as regards metal pollution sources due to increased generation of electronic wastes, uncontrolled solid waste disposal and untreated wastewater, abandoned and active mining operations. Additionally, the remote areas in Kenya and other countries are also exposed to transboundary atmospheric deposits, leaching of terrestrially applied agrochemicals and increased mineral weathering processes which contribute variable loads of metallic contaminants into surface and underground water sources. Potential sources, occurrences and accumulation of trace elements in the aquatic environmental samples are of concerns worldwide due to their known toxicities. Trace elements such as Cd, As, Cu, Fe, Hg, Cr, Mn, Ni, Zn, Sn, and Pb are contaminants known to cause severe toxicity to aquatic organisms and fish species. Increased exposure of toxic trace elements to humans emanates mainly from drinking water, consumption of aquatic species and food intake which leads to accumulation of elevated trace elements, and hence the need or stringent regulation of toxic elements in water, food and other products. Although varying and low levels of trace elements are often reported for most natural lake waters, and appreciably higher amounts in sediments, the bioavailability is what determines actual toxic effects. Therefore, being a Ramsar site, there is need to develop information and database for monitoring water quality changes and understanding anthropogenic impacts on the river and lake ecosystem. This report reviews information on the status of trace elements concentrations in the different lake compartments from previous studies, and the potential implications on water quality, ecosystem health and sustainability.