A Review of the Late Pleistocene-Holocene Climatic and Paleoecological Records in Tanzania

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 19th and 20th centuries. The 20th 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

Evidence of climate change impacts on water, food and energy resources around Kilimanjaro, Tanzania

This research article published by Springer Nature Switzerland AG., 2019This review presents research evidence of climate change and anthropogenic impacts on the slopes of Mt. Kilimanjaro and its implications on water, food and energy production (WFE nexus). While there exist divided scholarly opinions on the impacts of climate change on the Mt. Kilimanjaro glacier, consistent decreases in precipitation amounts are evident throughout the existing literature. The 2050 projections indicate increases in the precipitation amounts by approximately 16–18%. However, it is also stated that there will be a concomitant increase in water deficit of about 71%, 27% and 1% in agriculture, hydropower and livestock production respectively. Despite a large number of researches on impacts of climate and anthropogenic pressure on WFE along Mt. Kilimanjaro slopes, there are still limited long-term, good-quality and high-resolution altitudinal precipitation, temperature records and observation network. Moreover, there is limited information on groundwater recharge areas and their stability under changing environment. It is not clear how the interdependence and interaction between climate change, irrigation, vegetation and river discharges affect groundwater recharge process. Also, there is scarce information on future land use/cover changes. Very limited studies focused on fog water deposition for Mt. Kilimanjaro forest and East Africa, despite its relevance as the water tower of the mountain streams. The review further highlights how both climate and anthropogenic impacts may affect ecosystem services in the region. There is a need for developing adaptive strategies for responding to climate change and anthropogenic impacts on the slopes of Mt. Kilimanjaro now and into the future

Seasonal water chemistry variability in the Pangani River basin, Tanzania

Research Article published by SpringerThe stable isotopes of δ18O, δ2H, and 87Sr/86Sr and dissolved major ions were used to assess spatial and seasonal water chemistry variability, chemical weathering, and hydrological cycle in the Pangani River Basin (PRB), Tanzania. Water in PRB was NaHCO3 type dominated by carbonate weathering with moderate total dissolved solids. Major ions varied greatly, increasing from upstream to downstream. In some stations, content of fluoride and sodium was higher than the recommended drinking water standards. Natural and anthropogenic factors contributed to the lowering rate of chemical weathering; the rate was lower than most of tropical rivers. The rate of weathering was higher in Precambrian than volcanic rocks. 87Sr/86Sr was lower than global average whereas concentration of strontium was higher than global average with mean annual flux of 0.13 × 106 mol year−1. Evaporation and altitude effects have caused enrichment of δ18O and δ2H in dry season and downstream of the river. Higher d-excess value than global average suggests that most of the stations were supplied by recycled moisture. Rainfall and groundwater were the major sources of surface flowing water in PRB; nevertheless, glacier from Mt. Kilimanjaro has insignificant contribution to the surface water.We recommend measures to be taken to reduce the level of fluoride and sodium before domestic use

Sanitation and Hygiene Practices in Small Towns in Tanzania: The Case of Babati District, Manyara Region.

Formative research findings from the fast-growing Babati town were used to assess the prevalence of sanitation and hygiene practices among individuals and institutions and associated factors. A cross-sectional study involving household surveys, spot-checks, focus group discussions, in-depth interviews, and structured observations of behaviors showed that 90% of households have sanitation facilities, but 68% have safely managed sanitation services. The most common types of household sanitation facilities were pit latrines with slab (42%) followed by flush/pour flush toilets (32%). Therefore, the management of wastewater depends entirely on onsite sanitation systems. The majority of households (70%) do not practice proper hygiene behaviors. Thirteen percent of the households had handwashing stations with soap and water, handwashing practice being more common to women (38%) than men (18%). The reported handwashing practices during the four critical moments (handwashing with soap before eating and feeding, after defecation, after cleaning child's bottom, and after touching any dirt/dust) differed from the actual/observed practices. Households connected to the town's piped water supply were more likely to practice handwashing than those not directly connected. Sanitation and hygiene behaviors of the people in the study area were seen to be influenced by sociodemographic, cultural, and economic factors. The conditions of sanitation and hygiene facilities in public places were unsatisfactory. There is an urgent need to ensure that the sanitation and hygiene services and behaviors along the value chain (from waste production/source to disposal/end point) are improved both at the household level and in public places through improved sanitation services and the promotion of effective hygiene behavior change programs integrated into ongoing government programs and planning

Assessment of sources and transformation of nitrate in groundwater on the slopes of Mount Meru, Tanzania

Research Article published by SpringerThe stable isotope compositions of nitrogen-nitrate (15N-NO3) and oxygen-nitrate (18O-NO3), and concentration of nutrients (NO3- NH4+, NO2 -, PO4 3- ) for water samples collected from springs, shallow wells and boreholes during dry and wet seasons were used to investigate sources and biogeochemical transformation of NO3- 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 NH4+ and NO2 - concentrations were very low probably due to nitrification. Concentrations of NO3- above 50 mg/l were observed in some water sources. Concentrations of PO43- in all groundwater sources were very low during the two seasons owing to dilution and adsorption. The δ15N-NO3- for boreholes waters averaged +11.6 ± 2.1 and +10.7 ± 2.1 0/00 during dry and wet seasons, respectively. Similarly, the δ18 O-NO3 - of bore-hole waters for the wet and dry season’s averaged +5.2 ± 1.3 and +4.6 ± 1.9 %, respectively. With regard to dug wells, the δ15 O-NO3 - of well water averaged +13.3 ± 2.5 and +12.5 ± 2.3 %0 during dry and wet seasons, respectively, while the δ18 O-NO3 m- for the wet and dry seasons averaged +7 ± 2.3 and +6.4 ± 2.1 %, respectively. The δ15 O-NO3 -, for +11.2 ± 2.2 % during dry season and +11.7 ± 3.5 %0 during wet season whereas the δ18 O-NO3 - for the wet and dry seasons averaged +7.3 ± 3.6 and ?5.9 ± 2.6 %0, respectively. The isotopic data suggested that the source of NO3 - 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 d15N values between 16 and 20 % suggesting occurrence of denitrification

Occurrence of nitrate in Tanzanian groundwater aquifers: A review

Research Article published by Springer OpenMore than 25 % of Tanzanian depends on groundwater as the main source of water for drinking, irrigation and industrial activities. The current trend of land use may lead to groundwater contamination and thus increasing risks associated with the usage of contaminated water. Nitrate is one of the contaminants resulting largely from anthropogenic activities that may find its way to the aquifers and thus threatening the quality of groundwater. Elevated levels of nitrate in groundwater may lead to human health and environmental problems. The current trend of land use in Tanzania associated with high population growth, poor sanitation facilities and fertilizer usage may lead to nitrate contamination of groundwater. This paper therefore aimed at providing an overview of to what extent human activities have altered the concentration of nitrate in groundwater aquifers in Tanzania. The concentration of nitrate in Tanzanian groundwater is variable with highest values observable in Dar es Salaam (up to 477.6 mg/l), Dodoma (up to 441.1 mg/l), Tanga (above 100 mg/l) and Manyara (180 mg/l). Such high values can be attributed to various human activities including onsite sanitation in urban centres and agricultural activities in rural areas. Furthermore, there are some signs of increasing concentration of nitrate in groundwater with time in some areas in response to increased human activities. However, reports on levels and trends of nitrate in groundwater in many regions of the country are lacking. For Tanzania to appropriately address the issue of groundwater contamination, a deliberate move to determine nitrate concentration in groundwater is required, as well as protection of recharge basins and improvement of onsite sanitation systems

Estimating groundwater recharge on the southern slope of Mount Kilimanjaro, Tanzania

This research article published by Springer Nature Switzerland AG., 2019This paper used three methods namely: water-table fluctuation (WTF), soil moisture balance (SMB), and chloride mass balance (CMB) to estimate groundwater recharge in a degraded Kahe catchment located on the southern slope of Mt. Kilimanjaro, Tanzania. Three methods yielded different groundwater recharge rates. Results of the WTF method showed that recharge in the catchment was about 248.4 million m3/year, whereas those of CMB and SMB methods were 156.0 and 132.1 million m3/year, respectively. The estimated recharge rates ranged between 132.1 and 248.4 million m3/year with an average of 191.34 ± 27.80 million m3/year. Differences in the estimated rates can be attributed to the scales of measurements, assumptions in each method, and the quality of the data used. Satellite images taken in between 2000 and 2017 were used to estimate the land-use changes and their impacts on groundwater recharge in the study catchment. Analyzed satellite images showed that over the 17-year period, natural forests and bushes and shrubs decreased by 3.6 and 4.1%, while agricultural land and built-up area increased by 12.8 and 0.8%, respectively. Using SMB method, we found that these land-use changes have contributed to a decrease in groundwater recharge of about 42% between 2000 and 2017 (i.e., from 227.8 to 132.1 million m3/year). The findings from this study are useful for assessing the potential impacts of land-use change on water resources in the catchment

Stable carbon and nitrogen isotope composition of organic matter in sediments of the Oman Margin

Stable isotopic compositions of carbon and nitrogen and organic carbon content of sediments ranging from the Pliocene to the Pleistocene-Holocene in age from the Oman Margin (ODP Sites 724 and 725) are reported. In general, the organic carbon content is greater than 2% at Site 724. Prior to the Pleistocene-Holocene at this site, sediments with higher content of organic matter were deposited owing to favorable preservation conditions and/or higher productivity. In the Pleistocene, lower amounts of organic matter have been preserved; this material generally has more enriched nitrogen isotopic compositions. This may indicate intensification of the Oxygen Minimum Zone and denitrification with the onset of the Pleistocene. A correlation of carbon isotope content of these sediments with oxygen isotope stages at Site 724 indicates an enrichment in 13C during glacial events. Based on the stable isotope evidence of both carbon and nitrogen, there does not appear to be major input of terrigenous-derived allochthonous material in this marine environment. The timing and extent of monsoon winds on the productivity of this region are not evident, but require further studies for collaborative interpretation of small-scale features in the isotopic and carbon content of this environment

Hydrogeochemical characteristics and spatial distribution of groundwater quality in Arusha well fields, Northern Tanzania

Abstract Arusha aquifers have been exploited intensively serving as the main source of domestic water supply in the city. But the quality of groundwater is not clearly documented for future planning and management. Hydrogeochemical assessment was carried out to establish groundwater quality and its spatial distribution with the aid of geostatistical techniques. Groundwater samples were collected and analyzed for major cations and anions using conventional methods of water analysis. Well lithology and geological map were considered for hydrogeological interpretation of the area. The results of piper diagram revealed Na–K–HCO3 water type with sodium and bicarbonate ions dominating in all samples. High fluoride concentrations and general groundwater chemistry are mainly controlled by aquifer lithology than anthropogenic activities. The levels of anthropogenic pollution indicators such as nitrate, chloride and sulfate in deep wells are generally low and most likely coming from natural sources. The geological sections indicate two potential aquifers (volcanic sediment and weathered/fractured formation) both yield water containing significant concentration of fluoride. Fluoride concentrations were higher than WHO guidelines (1.5 mg/l) and Tanzanian standards (4.0 mg/l) by 82 and 36% of the analyzed groundwater samples, respectively. The southern part of the study area yields groundwater of better quality for human consumption than northern zones which is at high elevation on the foot of Mt. Meru. With exception of fluoride, the quality of groundwater in the study area is generally suitable for drinking purpose and other socioeconomic uses