No abstract

No abstract

Water quality and fish species are studied in selected catchments of Lake Victoria. The major aim of the study is to establish the relationship between the environmental quality and fish communities in the selected study sites of Lake Victoria. Physico-chemical characteristics of water in selected sites were determined on-site while nutrients and heavy metals were determined in the laboratory using standard methods. Fish samples were collected using experimental multifilament gillnets with varying mesh sizes. Fish identification was done using external morphological characteristics and identification keys. Physico-chemical results in Thruston bay revealed rise in water column temperature and turbidity as compared to those measured by earlier studies on the lake. Dissolved oxygen (DO) ranged from 0.9 mg L -1 in Yala catchment to 11.56 mg L -1 in Thruston bay. Phosphorus (P) ranged from 9.78 g L -1 to 120.67 g L -1 in Thruston bay and in Yala catchment, it ranged from 185.2 g L -1 to 1526.9 g L -1. The nitrate-nitrogen loading in the Geita catchment ranged from 130 to 7465 kg N between the years 2006 and 2008. The results in the inshore sites show a potential for higher photosynthetic rates than in the offshore sites implying that there is more food for the fish in the inshore sites than in the offshore sites. Results further reveal that in Thruston bay there are 13 fish species and Haplochromines dominate the fish catch in terms of numbers. Heavy metals including mercury resulting from artisanal and commercial gold mining in the Geita study site were also detected in the discharges into the lake. This paper also presents measures for the sustainable management of the lake environment, its quality and fisheries.

No abstract

A study was conducted in a sewage system at Kilombero Sugar Company to review its design, configuration, effectiveness and the quality of influent and effluent discharged into the Ruaha river (receiving body). The concern was that, the water in the river, after effluent has joined the river, is used as drinking water by villages located downstream of the river. Strategic sampling at the inlet of the oxidation pond, at the outlet and in the river before and after the effluent has joined the receiving body (river) was undertaken. Samples from each of these locations were taken three times, in the morning, noon and evening. The sample were then analysed in the laboratory using standard methods of water quality analysis. The results showed that the configuration and or the layout of the oxidation ponds (treatment plant) were not in accordance with the acceptable standards. Thus, the BOD5 of the effluent discharged into the receiving body (Ruaha River) was in the order of 41 mg/l and therefore not meeting several standards as set out both by Tanzanian and international water authorities. The Tanzanian water authorities, for example, requires that the BOD5 of the effluent discharged into receiving bodies be not more that 30 mg/l while the World Health Organization (WHO) requires that the effluent quality ranges between 10 – 30 mg/l. The paper concludes that proper design of treatment plants (oxidation ponds) is of outmost importance especially for factories, industries, camps etc located in rural developing countries where drinking water from receiving bodies like rivers and lakes is consumed without thorough treatment. The paper further pinpoint that both owners of treatment plants and water authorities should establish monitoring/management plan such that treatment plants (oxidation ponds) could be reviewed regarding the change on quantity of influent caused by population increase.