Determination of Major Ion Concentration and Ionic Strength of Saline Water: A Case Study of Lakes; Nakuru, Bogoria-Kenya and Nata Saltpan Sanctuary –Botswana

Abstract

Lakes Nakuru, Bogoria and Nata salt pan are of great ecological and economic importance. They are home to one of the world’s renowned bird sanctuaries with over 400 bird species, lesser flamingoes and breeding ground for a host of water birds including pelicans and flamingoes. These aquatic ecosystems are however; threatened by environmental pollution mainly due to anthropogenic activities in the catchment basins. The current study therefore, sought to determine the concentration of individual ions of saline waters and ionic strength in Lake Nakuru, Lake Bogoria (Kenya) and Nata Saltpan Sanctuary (Botswana) so as to form the baseline information for periodic monitoring and remediation of such aquatic saline systems amid the environmental pollution. Identification of individual dissolved ions can also be used as an indicator of the source of pollution. Samples were collected during the dry season by stratified sampling technique using Van Dorn Sampler. Water temperatures were generally high and consistent with the ambient air temperatures and pH values were 10.55±0.09, 10.15±0.18 and 9.97±0.33 for Nakuru, Bogoria and Nata saltpan respectively. Mean conductivity of values of 47.77±0.78, 62.50±0.37 and 12.79±0.33 were recorded for Lakes Nakuru, Bogoria and Nata saltpans respectively. Cation concentration were dominated by Na⁺ followed by K⁺, Ca²⁺ and Mg²⁺ and significant amount of trace anions in Lake Nakuru, Bogoria and Nata saltpan. Ionic strength for lakes Nakuru, Bogoria and Nata saltpan waters was 0.166, 0.195 and 0.059 M respectively. The findings of the study showed high level of ions in lakes Nakuru and Bogoria compared to Nata Saltpan. This was attributed to high agricultural and industrial activities in the catchment area.

Key Words: Salinity, Conductivity, Ionic strength, Pollution, Water