No abstract

Pollution due to pesticide residues has been reported in the downstream of the Tano Basin in the rainy season and has been attributed to the anthropogenic activities upstream. However, data on the seasonal variations in pesticide residues in the upstream of Tano Basin are limited. Seasonal variations in 13 organochlorine pesticide residues, 8 organophosphorus pesticide residues, and 5 synthetic pesticide residues in water and sediment samples of River Tano upstream were assessed through extraction and Varian CP-3800 gas chromatography equipped with a CombiPAL Auto sampler set at ionization mode electron impact methods. Significantly higher pesticide residues were detected in water and sediment samples in the rainy season than the dry season. Permethrin (rainy: 0.007 ± 0.01 mg/kg; dry: 0.008 ± 0.02 mg/kg) and profenofos (rainy: 0.021 ± 0.02 mg/kg; dry: 0.026 ± 0.01 mg/kg) showed higher dry season concentrations in the sediment samples. Two isomers of lindane (δ-HCH = 0.059 ± 0.24 μg/L; γ-HCH = 0.002 ± 0.01 μg/L) were detected in the water in the rainy season, but 3 were detected in the sediment samples (δ-HCH = 0.004 ± 0.12 mg/kg; γ-HCH = 0.003 ± 0.01 mg/kg; aldrin = 0.001 ± 0.01 mg/kg) suggesting possible illegal use. The detected pesticide residual levels in both water and sediment samples were lower than the maximum residual levels in water and sediment. The Chemical Control and Management Centre of the Environmental Protection Agency should check possible faking and adulteration of banned organochlorine pesticides.

Increasing anthropogenic activities within the catchment of River Tano continues to threaten the river water quality but data is limited. Seasonal variations in some physicochemical and nutrients water quality parameters of River Tano were studied between November, 2016 and October, 2017 using electrometric and standard methods. The objective was to assess changes in physicochemical parameters and nutrient concentrations with the season and to generate useful information for water quality managers and policy makers to ameliorate the problem. The results showed significantly higher rainy season values for all the nutrients and the physicochemical parameters studied. The source of River Tano recorded pH levels lower than WHO minimum permissible level for both seasons but got corrected after 7.2 km from the source. The river was also challenged in terms of colour (61.0±4.6 NTU), total phosphorus content (0.376±0.3 mg/L), total suspended solids (69.7±24 mg/L), turbidity (96.2±21 mg/L) and electrical conductivity (252±33 µS/cm) since the levels of these parameters exceeded the permissible levels for WHO. Some physicochemical parameters and nutrients correlated strongly to indicate a possible common source to the water body. Cluster analysis extracted two clusters of the seasonal sampling sites for physicochemical parameters and three clusters for nutrients also confirming their respective possible common sources to the river. It is recommended that the buffer zone policy must be enforced to avert further deterioration of the river water quality. Industries must be compelled to treat their effluent before discharging into water bodies

Industrial effluents discharged into surface water body present a high percent of pollution in Ghanaian streams and rivers. The current study assessed the effects of industrial effluent on the quality of Onukpawahe stream which receives industrial effluents from the Tema Metropolis. Effluent samples were collected from six (6) selected industries and the water samples were collected from sixteen (16) different locations on the Onukpawahe stream. Various physico-chemical parameters such as BOD, TDS, Conductivity, COD, pH, TSS, Turbidity, Temperature, Colour, Sulphate, Phosphate, Ammonia and Nitrate were analysed during the current investigation. The average values of all the physico-chemical parameters (except pH and DO) were all above the EPA sector specific effluent guidelines. It was established in the study that the industries have polluted the stream and have grievously compromised the quality of the Onukpawahe stream. The surface water and industrial effluent must be monitored by the authorities in order to prevent further degradation of the river quality.