The Physico-Chemical Characteristics, Total Trace and Major Elements in Water and Surficial Sediments during Drought Conditions in the Highly Turbid Perennial Rivers, Hotspring and Lake Baringo, Kenya

Abstract

Environmental degradation, climate change impacts and increasing water pollution exacerbates the challenges and threats facing lotic and lentic ecosystems, resulting in the continued loss of aquatic habitats and biodiversity, contamination of drinking water sources and reduced fisheries production. We collected surface water and sediment grab samples during the dry conditions (March 2008 and February – March 2009) and characterized the trace element contents, sources and distribution in major perennial rivers, hot-spring and Lake Baringo, for better resource use planning and management. Dried sieved sediments and water sampled were acid digested with Aqua-Regia and concentrated Nitric acid respectively, before metal analysis using Atomic Absorption Spectrophotometer equipment. Cold vapour technique was used for mercury analysis. Standard method were used for chloride and fluoride determination. Sediments accumulated higher trace elements than those in aqueous phase. Mean F levels in lake (92% of samples) and warm spring (83%) water were above the maximum allowable concentration for drinking water. Lake Baringo surficial sediments exhibited depletion to minimal enrichment for Cr, Mn, Zn, Co, Pb, Ni, Hg and the geo-accumulation index indicated moderate sediment pollution with respect to Ni, Hg, Co, Cu and Zn. River sediments were enriched with Mn, Zn and Cd, Ni, The findings indicate that anthropogenic sources contribute to sediment Cd, Zn and Mn contents in river and lake sediments, besides lithogenic sources. The Ramsar wetland area is sensitive to climatic changes and the previous dry conditions greatly contributed to the changes in the hydrochemistry due to increased processes of evaporative concentration.