Water And Water Sediments Interface Nutrient Level And Same Other Water Quality Parametrs Of Upper Awash And Upper Guder Rivers, West Shoa , Oromia, Ethiopia

Abstract

Nutrient pollution occurs when an excessive amount of nutrients, primarily nitrogen and phosphorus, are introduced into water bodies and act as fertilizer, causing excessive algae growth known as eutrophication. Therefore, the objective of the present study is to evaluate the level of nutrient pollution in the rivers water and their water interfaces sediments and quality status of upper Guder and upper Awash rivers, Ethiopia. A longitudinal-based experimental design that includes both qualitative and quantitative primary data collection from water and sediment of the study was used. Ten sites (six from Awash, and four sites from Guder River) were selected for the collection of water and sediment samples. The water temperature, pH, electrical conductivity (EC) and dissolved oxygen (DO) content in the water were measured in situ using a multi probe meter. In addition, the spatial and temporal variation of nutrient concentrations such as nitrite, nitrate, total phosphorus, total nitrogen, and ammonia in the water and sediments was measured in the laboratory. Our result confirmed a significant spatial physicochemical parameters difference with the highest result observed in Awash River (p<0.05), but only temperature and DO contents showed a significant temporal variation (p<0.05). However, the nutrient content the rivers water and sediment samples highest in Guder river, but statistically difference is not significant (p>0.05), but showed a significant spatial variation (p<0.05) with the highest result recorded in A2, A3, A4, GL and GC sites. Similarly, the result showed a significant seasonal variation with the highest result recorded in dry season in the water, but higher in wet season in the sediments (p<0.05). The log-ratio principal component analysis (PCA) for nutrient content in water and sediment samples varied highly on Axis 1 and Axis 2, which together accounted for 80.29% of the total variance. The chlorophyll a content of the water samples ranged between 0.49 and 3.28 µg/L with a mean amount of 1.57±0.78 µg/L and the result showed a significant spatial and temporal variation (p<0.05). The mean WQI were 468.27±78.83 and 404.62±34.60 in dry season and wet season, respectively. Generally, the result showed that the nutrient load is very high both river and surpasses the maximum permitted limit. Similarly, the WQI result shows a poor water quality for drinking in both rivers. Therefore, effective pollutant source management is very important for the health life in the both rivers and the community relaying on the rivers.