Browsing by Author "Maswe, Ezrael Josephat"

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    Modeling processes governing transformations and transport of nitrogen compounds and heavy metals in Geita Wetland: The case of Mtakuja and Mabubi rivers
    (University of Dar es salaam, 2019) Maswe, Ezrael Josephat
    Geita wetland suffers heavy metals pollution loads due to mining activities in the upstream and nitrogen nutrient loads due to agricultural practices in the area. In this research the processes governing transformations and transport of nitrogen compounds (NO3-N and NH4-N) and heavy metals (Hg, Ni and Cu) through Geita wetland were studied. The Mtakuja and Mabubi rivers which pass through the wetland were used as case studies. The hydrologic and water quality models SWAT and DUFLOW were applied to model transport of the nitrogen compounds and heavy metals, respectively. The results of modelling and the measured water quality data from the monitoring stations in the Mabubi and Mtakuja Rivers document higher concentration levels of the studied pollutants above the WHO recommended surface water quality standards for aquatic life. The results of study showed that the main processes governing transformations of nitrogen compound are mineralization, nitrification and denitrification. It was also revealed that adsorption and accumulation in the sediment are the major processes that determine the fate and transport of heavy metals. The models results and field measurements demonstrated that about 40% of the studied annual heavy metals and 70% of the studied nitrogen compounds loadings which would otherwise reach the lake Victoria is retained in the wetland. Therefore, the study results advocate for retention, conservation and rehabilitation of wetland ecosystem especially around areas where agricultural and mining activities take place. The models can therefore be used to hlp future water quality monitoring efforts in the Geita wetland and other wetlands with similar problems around the world.