Physical and chemical characteristics of water in selected locations in Lake Victoria, Tanzania

Abstract

A study conducted during the period of March/April 2002 aimed at measuring physical and chemical parameters in Tanzanian portion of Lake Victoria. Temperature and conductivity values were homogeneous among and within the study stations. Levels of dissolved oxygen (DO) ranged from 4 - 9 mgl-1 and there was significant difference between stations (P < 0.05). Water transparency was poor (< 2 m secchi depth) and differed from one sampling station to another. Ammonium nitrogen (NH4+-N), with few exceptions, showed the highest concentrations both at the bottom and near-surface followed by total phosphates (TP), nitrate nitrogen (NO2+NO3--N), nitrite nitrogen (NO2--N) and Soluble Reactive Silicon (SRSi). Concentrations of NH4+-N, TP and SRSi were high at bottom waters and the reverse was true for NO2+NO3--N and NO2--N. Differences in nutrients and physical water parameters among sampling stations were statistically significant (P < 0.05). However, temperature and nutrient levels at studied areas were higher than that of 50 years ago and the trend reversed for DO and transparency. This indicates that Lake Victoria is receiving organic materials from the catchment area leading to the decline of water quality. Long-term efforts for rehabilitation, conservation and sustainable management of the lake are suggested.

Tanzania Journal of Science Vol. 30 (2) 2004: pp. 65-72