Msimbazi River Research Articles

English

The status of waste and its impact on macroinvertebrate assemblages along Msimbazi River was assessed between May 2014 and August 2014. The aim was to identify the type of waste, their potential sources, and the assemblage of macroinvertebrate taxa that have been affected by waste disposal in the river. The study involved field study and laboratory analysis. Results indicated that organic and inorganic waste are the main types of waste dumped into the river; industries and communities living adjacent and along the river are the main waste producers. Macroinvertebrates belonging to eight orders and 27 families were recorded. Macroinvertebrates of the Gastropoda and Diptera orders were the most dominant in occurrence of all macroinvertebrate taxa, contributing 27 and 21%, respectively of the total macroinvertebrates. Based on macroinvertebrates sensitivity, 21 taxa (77.77%) were identified as being highly tolerant to pollution, six taxa (22.23%) as moderately tolerant and none of the most sensitive taxa. Macroinvertebrate diversity indices yielded a slightly lower Shannon-Weiner diversity index (H’=0.42) and the Shannon Evenness Index (0.2050) amongst sites. These findings are indicative of disturbed systems whose severity seems to be driven by the on-going waste disposal within and along the river continuum. Key words: Benthic macrofauna, diversity indices, organic waste, inorganic waste, pollution, waste management.

Heavy Metal Pollution Assessment along Msimbazi River, Tanzania

Heavy Metal Pollution Assessment along Msimbazi River, Tanzania

The use of portable X-ray spectrometer in monitoring anthropogenic toxic metals pollution in soils and sediments of urban environment of Dar es Salaam Tanzania

The levels of toxic metals in sediments and soils along high traffic Sam Nujoma highway and in the densely populated Sinza area in Dar es Salaam Tanzania were determined using portable X-ray fluorescence spectrometer (pXRF) and atomic absorption spectrometer (AAS) in order to assess the levels of the metals in the sediments and soil and evaluate the use of pXRF in monitoring anthropogenic toxic metal pollution in the urban environment.Sediments from different areas in Sinza, especially those occurring near metal workshops, contained high toxic metal contents (e.g. Co, Zn, Pb and Ti) above the maximum permissible allowable limit by the Tanzania Bureau of Standards (TBS) for soils or sediments in an urban environment. This toxic metal content decreases sharply (~5m) away from workshops, and so reflecting pollution of the metals by workshop activities. Along Sam Nujoma highway, toxic metal contents of sediments and soils were lower than those of samples from Sinza, but also decreases as one moves from the road to the surroundings of the highway. Chromium and Zn contents in parts of Sam Nujoma highway were found, in places, to be above the maximum permissible allowable limit by the TBS for soils or sediments. As the geology of Dar es Salaam is mainly unconsolidated sands and clay and coral limestones, which are not likely natural source of the metals, then results of this study reflect anthropogenic addition of the metals to the Dar es Salaam environment.Similarity in concentration of Pb in sediments determined from previous study in the year 2009 along Sam Nujoma highway and those presented for this study suggests that Pb and most likely other metals as well, are not accumulating along or near the highway over time, but dispersed by water during wet season, when water table is high and most of roads and street are covered by surface runoff. Part of these contaminated surface runoff ends up in water, sediments and soils in downstream in the Msimbazi River, in which most of vegetables are grown and food sources like fish thrive, which highlights a potential risk of exposure of toxic metals in human food chain. Moreover, high levels of toxic metals in soils and sediments near workshops in Sinza pose high exposure risk to children and people leaving around the workshops.Successful application of pXRF in monitoring of anthropogenic toxic metals pollution in urban environment of Dar es Salaam open up possibility for similar applications in fast growing cities or artisanal miners’ sites that are frequently affected by anthropogenic pollution in the country and abroad.

Governance Deficits in Dealing with the Plight of Dwellers of Hazardous Land: The Case of the Msimbazi River Valley in Dar es Salaam, Tanzania

Hazardous land is given high profile in the Tanzanian National Land Policy 1995. Subsequent land laws provide for participatory procedures to declare land to be hazardous. Public authorities have over the years been concerned about the continued living on a flood-prone Msimbazi River Valley in the city of Dar es Salaam. Despite adopting carrot policies such as allocating alternative land, and stick policies including forced eviction and demolition, sections of the population have continued to live in the Valley. Research on the ways public authorities have dealt with flood-prone areas, established that legal procedures to declare Msimbazi River Valley to be hazardous or environmentally sensitive have never been taken, and are not well-known among officials. Moreover, focus has been placed on valley dwellers instead of addressing citywide flooding. Paternalism, dealing with market failure and exerting political authority are considered to be the drivers motivating the government to evict valley dwellers. It is concluded that the approach dealing with dwellers of floodprone areas should adhere to legal provisions by, in particular, being participatory; should utilize available technology to identify, declare and demarcate hazardous land, should put this land to the badly needed greening of the city; and should address citywide flooding as a part of managing the city instead of focusing on a few individuals in a particular hazardous area.

Comparative Analysis of Heavy Metals from Groundwater Sources Situated in Keko and Kigogo Residential Areas, Dar es Salaam

The study assessed in comparison the concentrations of heavy metals in water samples (n=12) collected from groundwater sources at Keko and Kigogo areas. Three trace elements; Copper, Zinc and Lead (Cu, Zn and Pb). Analysis was done once in dry season and once in rainy season at Ardhi University laboratory. The water samples were taken in 4oc equipment for transportation. Results show low concentrations of Cu and Zn for both seasons and study areas. Pb concentrations were detected beyond the WHO permissible level (min. 0.01mg/l and max. 0.35mg/l). This presence of high concentrations may be due to urban agriculture activities conducted around the areas surrounding Msimbazi river, and also presence and use of onsite facilities (septic tanks and pit latrines). Discharge and runoff collection from garages and industrial wastes is another reasons thought for this high amount of heavy metals. There is need of adopting cheap water treatment technology for domestic purposes so as to protect people from being affected by the use of untreated water directly.

Flood risk assessment for informal settlements

The urban informal settlements are particularly vulnerable to flooding events, due to both their generally poor quality of construction and high population density. An integrated approach to the analysis of flooding risk of informal settlements should take into account, and propagate, the many sources of uncertainty affecting the problem, ranging from the characterization of rainfall curve and flooding hazard to the characterization of the vulnerability of the portfolio of buildings. This paper proposes a probabilistic and modular approach for calculating the flooding risk in terms of the mean annual frequency of exceeding a specific limit state for each building within the informal settlement and the expected number of people affected (if the area is not evacuated). The flooding risk in this approach is calculated by the convolution of flooding hazard and flooding fragility for a specified limit state for each structure within the portfolio of buildings. This is achieved by employing the flooding height as an intermediate variable bridging over the fragility and hazard calculations. The focus of this paper is on an ultimate limit state where the life of slum dwellers is endangered by flooding. The fragility is calculated by using a logic tree procedure where several possible combinations of building features/construction details, and their eventual outcome in terms of the necessity to perform structural analysis or the application of nominal threshold flood heights, are taken into account. The logic tree branch probabilities are characterized based on both the orthophoto recognition and the sample in situ building survey. The application of the methodology is presented for Suna, a sub-ward of Dar es Salaam City (Tanzania) in the Msimbazi River basin having a high concentration of informal settlements.

Heavy metals accumulation in vegetables grown along the Msimbazi River in Dar es Salaam, Tanzania

Concentrations of cadmium, copper, chromium and lead was determined in four different edible vegetables namely Amaranthus blitum, A. gangeticus, Ipomea batata and Cucurbita maxima grown at four different sites along the contaminated Msimbazi River, Dar es Salaam, Tanzania. Analyses of these heavy metals were conducted using Atomic Absorption Spectrophotometry. Results obtained indicate that the concentrations of heavy metals range from below detection limit to 0.53, 0.14 to 29.08, 0.76 to 17.69, and below detection limit to 39.69 mg/100 g for cadmium, chromium, copper and lead, respectively. With exception to Ipomea batata, other vegetables contained at least two types of heavy metals with high concentrations beyond the permissible values recommended by FAO and WHO for human consumption. Concentrations of cadmium were within the acceptable limits for human consumption in all the vegetables investigated. This work, thus, seeks to provide information on levels of toxic heavy metals in leaves of edible vegetables irrigated with water contaminated by industrial and other anthropogenic effluents, and grown in contaminated soils along the Msimbazi River. The information can be used for monitoring processes to prevent excessive build-up in the food chain.

Heavy metal contamination in agricultural soils and water in Dar es Salaam city, Tanzania

Heavy metals in soil and water were determined at four points along Msimbazi River valley in Dar es Salaam city, which is popular for vegetable farming. Results indicated that the concentration of chromium in water ranged from (1.414±0.922) to 0.01 mg/L. Maximum and minimum lead concentrations of 0.113 and 0.083 mg/L were detected. The concentration of copper was generally low at all sites, ranging from (0.013±0.005) to (0.016±0.005) mg/L. The concentration of lead in water throughout the river exceeds the WHO (2004) drinking water limit of 0.01 mg/L, ranging from (0.113±0.104) to (0.083±0.059) mg/L. Cadmium concentration at all sampling points was below detection limit of 0.01 mg/L. Soil analysis indicated that the concentrations of heavy metals are highest at the top soil and decreased with depth. Lead had the highest concentration of (22.85±1.502) mg/kg; which did not exceed the TZS (2003) maximum limit of 200 mg/kg for soils. Chromium had maximum and minimum concentrations of (502.33±150.991) and (174.707±168.278) mg/kg, respectively, with most of samples exceeding the TZS (2003) permissible limit of 200 mg/kg. The maximum and minimum concentrations of copper were (21.073±2.881) and (4.513±1.713) mg/kg, respectively, lower than the TZS (2003) permissible limit of 100 mg/kg. Cadmium concentrations at all sampling points were lower than the permissible concentration of 100 mg/kg in soils (TZS, 2003). The presence of heavy metals in soil and water indicates the potential for pollution transfer from these media to the food chain, especially since this valley is popular for vegetable cultivation. Key words: Heavy metal, soil, water, pH, dissolved oxygen, Msimbazi River.

Pollution and Self-Cleansing of an Urban River in a Developing Country: A Case Study in Dar es Salaam, Tanzania

Pollution and self-purification trends of an urban river namely, Msimbazi River, in Dar es Salaam City, Tanzania, were investigated. Site investigations and water quality analyses were done. The river is polluted in terms of high organic and nutrient concentrations, low dissolved oxygen, and high counts of indicator organisms. Biochemical oxygen demand (BOD5) concentrations were 27-340 mg/L. Dissolved oxygen was found to be as low as 0.9 mg O2/L. Bacteriological pollution increased with distance downstream of the river, a trend attributable to an increase in the catchment of pollution sources, which are on-site sanitation systems. Although the river has an appreciable self-purification capacity, the capacity is strained by persistent pollution overloads. The pollution plight of the river is attributable to its being flanked by expanding human habitats and vibrant industrial, institutional, and socio-economic activities. Provision for pretreatment of discharges into the river is put forward as a remedial measure for the observed pollution. Matching non-technical and techno-social remedial measures are also recommended. These include sensitization of polluters on merits of environmental protection practices such as cleaner production and strict enforcement of environmental protection laws.

Evaluation of Pollution Loading Into Msimbazi River by Rapid Assessment and Direct Measurement Methods

Evaluation of Pollution Loading Into Msimbazi River by Rapid Assessment and Direct Measurement Methods

Sources and diagenetic alteration of organic matter in coastal waters at the vicinity of Dar es Salaam, Tanzania.

The stable isotope compositions of organic carbon (OC) and nitrogen, contents of OC and nitrogen, and C/N ratios for four short cores, which were recovered from Msansani Bay (WO 57), off Msimbazi River (WO 76) and Dar es Salaam harbour (WO 62 and WO 74), are used to document temporal variation in the sources and diagenetic alteration of organic matter (OM). The δ15N and δ13C values at sites WO 57, WO 62 and WO 74 show a trend of down-core decrease to the base of the core, and such a down-core trend could be related to diagenetic loss of compounds enriched in 13C and 15N. At site WO 76, the δ13C values show two zones that are depleted in 13C. These two zones correspond to black-greasy layers that were observed during sampling, and low δ13C values probably is an indication that the material was derived from the continent. Furthermore, these two zones have elevated values of OC, nitrogen and C/N ratios. The stable isotopes of OC and nitrogen show inter-sites differences with enrichment in 15N in the following order: WO 57 Tanzania Journal of Science Volume 27A (Special Issue) 2001, pp. 39-55

Metal pollution of river Msimbazi, Tanzania

Abstract The Msimbazi River in Dar es Salaam is polluted with industrial, urban and agricultural waste waters. A preliminary investigation on the extent of metal pollution (Hg, Cr, Cu, Zn, Fe, Ni, Cd, Mn, Al) was made from samples of sediments and biological indicators. The metal concentrations were in general low, but some of our results indicated industrial pollution.