Browsing by Author "Muzuka, Alfred N. N."

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Assessment of sources and transformation of nitrate in groundwater on the slopes of Mount Meru, Tanzania
(Springer, 2015-09-21) Elisante, Eliapenda; Muzuka, Alfred N. N.
The stable isotope compositions of nitrogen-nitrate ( 15 N-NO 3 ) and oxygen-nitrate ( 18 O-NO 3 ), and concentration of nutrients (NO 3 - , NH 4 ? , NO 2 - , PO 43- ) for water samples collected from springs, shallow wells and boreholes during dry and wet seasons were used to inves- tigate sources and biogeochemical transformation of NO 3 - in groundwater along the slopes of Mount Meru. About 80 % of all water sources had nitrate concentration higher than background concentration of 10 mg/l during both seasons, while NH 4 ? and NO 2 - concentrations were very low probably due to nitrification. Concentrations of NO 3 - above 50 mg/l were observed in some water sources. Concentrations of PO 43- in all groundwater sources were very low during the two seasons owing to dilution and adsorption. The d 15 N-NO 3 - for boreholes waters averaged ?11.6 ± 2.1 and ?10.7 ± 2.1 % during dry and wet seasons, respectively. Similarly, the d 18 O-NO 3 - of bore- hole waters for the wet and dry seasons averaged ?5.2 ± 1.3 and ?4.6 ± 1.9 %, respectively. With regard to dug wells, the d 15 N-NO 3 - of well water averaged ?13.3 ± 2.5 and ?12.5 ± 2.3 % during dry and wet seasons, respectively, while the d 18 O-NO 3 - for the wet and dry seasons averaged ?7 ± 2.3 and ?6.4 ± 2.1 %, respectively. The d 15 N-NO 3 - , for springs averaged ?11.2 ± 2.2 % during dry season and ?11.7 ± 3.5 % during wet season whereas the d 18 O-NO 3 - for the wet and dry seasons averaged ?7.3 ± 3.6 and ?5.9 ± 2.6 %, respectively. The isotopic data suggested that the source of NO 3 - in the water sources are dominated by sewage and/or animal manure and to less extent, soil organic N. Few samples collected in close proximity of manure heaps and sanitary facilities had d 15 N values between 16 and 20 %suggesting occurrence of denitrification.
A review of the late pleistocene-holocene climatic and paleoecological records in Tanzania
(International Journal of Sciences: Basic and Applied Research (IJSBAR), 2019) Makoba, Edikafubeni; Muzuka, Alfred N. N.
Climate change is poorly addressed in the developing countries particularly in tropical East Africa such as Tanzania. This paper aimed to reconstruct the late Pleistocene to Holocene Tanzanian climate change using proxies from terrestrial and marine environment. Although data are limited, the inferred major events were found to have a link with global events. In late Pleistocene, during the Last Glacial Maximum (LGM), Tanzania experienced aridity as the other areas in the tropics. This was followed by the humid high precipitation period, highly pronounced between 9-6 ka. Proxies indicate that the humid period was interrupted by a brief dry Younger Dryas (YD) around 13.0-11.5 ka and a cool dry event at 8.2 ka. Other remarkable events are the cool event in the mid Holocene at 5.2 ka and the global dry event at 4.0 ka. There is a general decrease in precipitation from 5 ka to present with the aridity being pronounced between 3-2 ka and 1.2-0.5 ka. Despite of relatively low precipitation in Late Holocene, wet conditions are inferred between 1.7-1.2 ka (being interrupted by remarkable episodes of aridity) and the late periods of the 19 th and 20 th centuries. The 20 th century which is marked by increased temperature is likely to cause changes in hydrological circle leading to the increase in heavy rainfall and drought periods. Through this study, it is revealed that works are limited and concentrated in some specific areas within the country which exhibit different climatic condition. As a result, some proxies particularly from Eastern Arc Mountains show contradicting records and, in some places, interpretation is partial due to extrapolation of the proxies which are not widely distributed within a specific climate zone.