Effects of Anthropogenic Activities on Selected Water Quality Parameters in Spring Water and Sediments along Amala and Nyangores Tributaries in the Mara River Basin, Kenya

Abstract

Replacing natural forests with commercial crops and/or other small scale farming activities including human settlement have several environmental impacts. The land LISt' practices have the potential of contaminating aquatic ecosystems including spring water that are sources of major rivers like the Amala and Nyang'ores tributaries of the Mara River in Mau Complex, Kenya. Land use activities have been changing in the Mau Complex but no study has determined their impact on the quality of the spring waters. Most residents within Mara River Basin use the spring waters for domestic purposes despite the lack of awareness on their water quality status. The anthropogenic activities could negatively be affecting the physicochemical and other quality parameters of spring water within the Mau River Basin complex and cause water quality problems to users including aquatic life downstream. Therefore this study determined seasonal and site variations in pH, temperature, total nitrogen, ammonium-nitrogen, nitrites, total phosphates, soluble reactive phosphates, zinc, copper, selenium, manganese, chromium, cadmium and lead ions in waters and sediments within springs of Mau Complex that flow into and form the sources of Amala and Nyangores, the main tributaries of Mara River. Water and sediment samples were collected in triplicate from eight (8) springs feeding each tributary during the long dry and long wet seasons. The design of the experiment was a completely randomized design (CRD) in a two factorial arrangement with site (springs) as the main treatments and seasons as the sub treatment. A pH meter, a thermometer, ultraviolet spectrophotometer, and atomic absorption spectrophotometer were used in determining the selected parameters. Analysis of variance (ANOVA) and students t-test at p:SO.OS were used for data analysis. The results showed a water pH range of 6.4 to 6.6 and a temperature range of 13.00 to IS. 79°C (in Nyangores) and IS.21-17.70°C (in Amala) in both wet and dry seasons. The soluble reactive phosphate (SRP) varied significantly in springs, ranging from 42.01 to 22.00 ppb during the dry season to 64.11 to 19.5S ppb during the wet season. The total phosphate (TP) levels of the water samples varied significantly (j7:S0.0S) (ranging from S2.0 I to 362.00 ppb). The concentration levels for all the nutrients fell within the World Health Organization guideline limits for domestic water. Heavy metals (Mn, Cu, Fe Zn, Pb, Cr, Cd, Zn) and Se concentrations in spring water samples differed greatly in springs along Amala and Nyangores. The springs had varying amounts of nutrients and heavy metals in the water. This could cause adverse water quality problems to streams and rivers downstream in the long run. Land use patterns in the complex did not significantly affect the quality of springs within Mara River Basin. These results demonstrate that anthropogenic activities are not yet causing adverse water quality problems and managing the anthropogenic activities is recommended. However, periodic monitoring of the springs to ascertain the quality of the water is also necessary .