Seasonal Surficial Distribution of Water Quality Parameters at Lake Nyamagoma, Western Tanzania
Charles Buteta Athuman

Abstract
This paper discusses the seasonal surficial distribution of water quality parameters at Lake Nyamagoma in Western Tanzania during dry and wet seasons. Standard methods and gears were used to determine levels of the water quality parameters such as turbidity, DO, PO43-, NO3- and Cl-. The study reveals that the water quality parameters vary significantly seasonally along the four sampling sites consequent to processes including nitrification, fixation, evaporation-crystallization, adsorption, photosynthesis, mixing and dilution effect. Higher surficial distribution data were recorded at Chagu compared to other sampling sites in both seasons. The data show elevated levels during the wet season compared to the dry season as shown by turbidity and PO43- (5 - 13.28 NTU and 3 - 13.11 NTU along with 12 - 17.03 mg/L and 3 - 9.04 mg/L) in the wet and dry seasons respectively. These observations could be attributed to catchment anthropogenic activities disturbance such as agriculture using fertilizers along with cattle grazing and artisanal mining. The contour map clearly show the increasing trend of chloride from downstream to the upstream sites and has its sources in the Moyowosi River, whilst turbidity originates from Igombe River and near Mfumu landing site. The noted variation alters the water quality of the lake and in turn setting up health risks to the riparian community. However, most of these data are still within the WHO and TBS standards making it possible for use. The monitoring of the pollution influx from both point and diffused sources is recommendable by engaging both the riparian villagers and all the stakeholders of this precious and peculiar ecosystem.

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