Quantification of micropollutants in some water sources in northern Tanzania

The loading of micropollutants in freshwater ecosystems to levels exceeding their waste assimilative capacity is a threat to both ecology of the ecosystems and health of the resource users. Some chemical species are of much concern due to their persistence, bioaccumulative and toxicity nature, even at trace levels, while others are of concern due to their contribution to eutrophication, oxygen depletion and other disruptive changes. Despite contamination threats from human activities around catchment areas in Tanzania, specific extent of the impacts are rather not well investigated. In this work, we quantified concentration levels of some major elements, trace elements, dissolved inorganic ions, nutrients and organochlorine pesticide residues in river water and sediments from northern Tanzania. Information on land use practices in the area, which represents potential sources of contamination, was gathered. Samples were collected from pre-selected stations in two different seasons and characterized for physico-chemical parameters. Preparation and instrumental analysis of samples was done by standard analytical protocols. Obtained results indicated contamination by some micropollutants, including some dissolved ionic species in water: Na+ (> 200 mg/l), K+ (> 25 mg/l), Mg2+ (> 50 mg/l) and NO3– –N (> 80 mg/l). High concentrations of some toxic metals were also measured in sediment samples, including V (325 mg/kg), Cr (270 mg/kg), Cu (114 mg/kg), Ni (85 mg/l) and Zn (355 mg/kg). Low levels of organochlorine pesticide residues were measured. Concentration levels were compared to water and sediment quality guidelines to establish their ecotoxicological risk implications.Keywords: Micropollutants; Surface water; Sediments; Contamination; Tanzani

Physicochemical and Bacteriological Water Quality Parameters in Relation to Land-use Practices at a Rural Catchment, Mbinga District, Tanzania

Data on physicochemical water quality parameters and contamination levels is crucial for protection and sustainable utilization of water resources. This study assessed the physicochemical water quality parameters, faecal coliform bacteria and nutrient loads in water at a catchment used for municipal supply in Mbinga District, Tanzania. Samples were seasonally collected from three areas characterized by distinct geographical features, settlement patterns and land-use practices, and analyzed using standard analytical protocols. Data were subjected to paired-sampled t-test and cluster analysis. The parameters varied as follows: pH (4.75–6.83); temperature (16.4–26.2 ºC); electrical conductivity (14.6–121.1 µS/cm); total dissolved solids (7.0–23.2 mg/L); total suspended solids (BDL–35.5 mg/L); dissolved oxygen (8.6–23.8 mg/L); turbidity (0.1–68.1 NTU); faecal coliform (<1–76 FC/100 mL); nitrite (BDL–0.09 mg/L); nitrate and sulphate were not detected. Spatial variations were associated with land-use disparities. Comparison to risk-based regulatory thresholds for drinking water revealed the levels to be within the acceptable limits, with a few exceptions. Observed seasonal trends indicated an overall decrease in water quality during the wet season. Generally, results showed that water quality at the catchments satisfies requirements for domestic uses. However, the potential contamination risks from human activities call for regular monitoring. Keywords:   Physicochemical parameters; faecal contamination; water quality; surface water; Mbinga Distric

Pesticide residues in four rivers running through an intensive agricultural area, Kilimanjaro, Tanzania

Organochlorine pesticide (OCP) residues were determined in water and bottom- sediments from four rivers running through sugarcane plantations in Kilimanjaro Tanzania. The aim was to assess the levels of pesticide contamination as the rivers are important sources of domestic water in the area. Water samples were extracted by liquid\u2013liquid extraction method, and ultrasonic-assisted liquid-solid extraction coupled with gel permeation chromatography was employed in sediment preparation, before analysis by GC-ECD and GC-MS. Blank and spiked recovery tests were used to validate the analytical procedure. Data were assessed by using descriptive statistics and multivariate analysis to study correlations between different parameters, evaluate the contamination patterns and describe their spatial and seasonal trends. The percentage recoveries ranged from 75.0 \ub1 2.4 to 89.8 \ub1 1.5 in water, and 70.5 \ub1 1.7 to 86.2 \ub1 2.3 in sediments, which are within the acceptable ranges. The OCP concentrations ranged from trace (endrin) to 120 ng/l (p,p\u2019-DDD) in water, and from trace (aldrin) to 132 ng/g-dry weight (p,p\u2019-DDD) in sediments, and were higher during the dry season. A notable water contamination that exceeded the European Union maximum acceptable concentration for the protection of human health was detected in river Kikavu

Use of physicochemical parameters and metal concentrations in assessing anthropogenic influences on coastal rivers in Dar es Salaam, Tanzania

Spatio-temporal variations in water quality of three rivers along the Indian Ocean coast in Dar es Salaam, Tanzania, were investigated based on physicochemical parameters and metal concentrations. A compliance analysis was performed based on the Tanzania Bureau of Standards (TBS) and World Health Organization (WHO) limits to examine the suitability of water for domestic use. The dataset was subjected to statistical analysis to determine differences and similarities amongst the rivers. Levels of pH (6.83-11.41), total dissolved solids (203–34,333 mg/L), electrical conductivity (9,408-68,014 μS/cm), turbidity (10.0-45.0 NTU), chloride (108-14,248 mg/L), sulphate (35-766 mg/L) and ammonium (40-5,468 μg/L) complied with neither TBS nor WHO limits. Dissolved oxygen (1.4-6.6 mg/L), chemical oxygen demand (91-1,863 mg/L), total suspended solids (11.9-50.7 mg/L), alkalinity (200-2,658 mg/L), total hardness (362-12,1312 mg/L), salinity (0.19-29.35 ppt) and phosphate (<method detection limit-3.01 μg/L) indicated polluted water in parts of the rivers. Pb (0.7-24.0 μg/L) exceeded both the TBS and WHO limits, whereas Cr, Cu, Fe, Zn and Cd were below limits. Water quality was poorer during the wet season. The results indicate that water from the rivers is unsafe for human consumption and the poor water quality probably also affects the ecology of the rivers. Strategic measures to protect the rivers from further contamination are suggested

Mineralogical and Physicomechanical Characterization of Kaolinitic Clay from Moshi, Northern Tanzania for Potential Ceramic Utilization

Kaolin clay from Moshi, northern Tanzania has been characterized for potential ceramics productions. Clay samples taken from three different levels of the deposit were analysed by XRD and XRF. Firing experiments were carried out on experimental briquettes at a maximum temperature of 1300 °C at the rate of 100 °C/hour. The results revealed dominance of kaolinite and illite in the raw clay. The samples were composed majorly by silica (36.88–41.62%), alumina (30.83–32.40%) and hematite (9.29–12.70%). Granulometric analysis showed that the amount of clay decreased with deposit depth. The physicomechanical properties of the clay fired at the optimal temperature of 1300 °C included shrinkage (22.06–30.72%), water absorption (18.23–20.15%), bulk density (1.834–2.182 g/cm3) and modulus of rupture (2.957–6.313 MPa). Mullite was the key component responsible for mechanical strength. Clay sample from the top level showed the best properties. The parameters were of satisfactory quality and comparable to other ceramically suitable clays. High levels of Fe2O3 (> 9%) could adversely affect the translucency of whitewares. These findings indicate that the investigated kaolin has potential of being used in the ceramic industry for making materials such as non-vitreous tiles, bricks and various high-temperature products that do not require high brightness specifications. Keywords: Clay mineralogy, firing temperature, microstructure characterization, ceramic properties, Tanzanian kaolin

Pesticide residues in four rivers running through an intensive agricultural area, Kilimanjaro, Tanzania

Organochlorine pesticide (OCP) residues were determined in water and bottom- sediments from four rivers running through sugarcane plantations in Kilimanjaro Tanzania. The aim was to assess the levels of pesticide contamination as the rivers are important sources of domestic water in the area. Water samples were extracted by liquid–liquid extraction method, and ultrasonic-assisted liquid-solid extraction coupled with gel permeation chromatography was employed in sediment preparation, before analysis by GC-ECD and GC-MS. Blank and spiked recovery tests were used to validate the analytical procedure. Data were assessed by using descriptive statistics and multivariate analysis to study correlations between different parameters, evaluate the contamination patterns and describe their spatial and seasonal trends. The percentage recoveries ranged from 75.0 ± 2.4 to 89.8 ± 1.5 in water, and 70.5 ± 1.7 to 86.2 ± 2.3 in sediments, which are within the acceptable ranges. The OCP concentrations ranged from trace (endrin) to 120 ng/l (p,p’-DDD) in water, and from trace (aldrin) to 132 ng/g-dry weight (p,p’-DDD) in sediments, and were higher during the dry season. A notable water contamination that exceeded the European Union maximum acceptable concentration for the protection of human health was detected in river Kikavu