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Quantification of micropollutants in some water sources in northern Tanzania
HELLAR-KIHAMPA, HARIETH
Abstract
The loading of micro pollutants 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, bio
accumulative 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 micro
pollutants, 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.© JASEM
Keywords
Micropollutants; Surface water; Sediments; Contamination; Tanzania
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