Analysis of Internal Nutrient Load Dynamics from the Sediment in Lake Ziway

Abstract

Article HistoryKeywords Lake Ziway Internal nutrient load Phosphorus flux Sediment depth profile. Lake Ziway is shallow freshwater located in Northern part of Ethiopian Rift Valley. Expansions of the flower industry, widespread fisheries, intensive agricultural activities, fast population growth lead to deterioration of both water and sediment qualities and depletion of aquatic biota. The main objective of this study is to evaluate the internal nutrient load dynamics from the sediment. Nutrients in sediment samples were analyzed according to the standard procedures outlined in EPA, 1994 and phosphorus release rate were estimated with THE methods described in Steinman, et al. [3]. The results of sediment depth profile analyses showed that the mean concentrations of SRP, TP, NO3-N, NO2-N and TN were 27.7, 62, 5.28, 8.51 and 1733 mg/kg, respectively in dry season, and 21.2, 73, 7.99, 28.4, 24.2 and 1750 mg/kg, respectively in wet season. The values for all the studied nutrients distribution were higher at sediment top surface and decline with depth of the sediment profiles in most of the sampling sites and seasons. The results of the seasonal evaluation of phosphorus flux from lake sediments showed that sediments were sources of phosphorus. The findings from the current study indicate that internal sources of nutrients to Lake Ziway vary across time and space. Understanding this variation and internal nutrient load is important in developing mitigation and restoration strategies for the lake ecosystems. Contribution/Originality:The main objective of this study is to evaluate the internal nutrient load dynamics from the sediment. Nutrients in sediment samples were analyzed according to the standard procedures outlined in EPA, 1994 and phosphorus release rate were estimated with THE methods described in Steinman, et al. [3].

Impacts of land-use/land-cover changes on nutrient losses in agricultural catchment, southern Ethiopia

“…Studies conducted in different catchment areas showed that water resources are vulnerable to nutrient loads from agricultural fields, urban drainage systems and industrial centres. Tibebe et al (2018) and Tibebe et al (2020) conducted external nutrient loading and trophic status of Lake Ziway, in the Ethiopian Rift Valley. In their study, water samples from the Ziway River were collected over two years (2014 and 2015) and chemical analysis was determined for nutrient concentrations according to the American Public Health Association (APHA).…”