Abstract:
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 imp
