Hydrochemical characteristics of surface water and ecological risk assessment of sediments from settlements within the Birim River basin in Ghana

Abstract Background Geogenic and anthropogenic activities such as Artisanal and illegal gold mining continue to have negative impacts on the environment and river basins in China. This work studied the hydrogeochemical characteristics of surface water from the Birim River basin and assess the quality of water for human consumption and agricultural activities. In addition, the ecological risk assessment for Cd, Zn, Pb and As in sediment was evaluated using pollution indices. Results The results show that the turbidity, temperature, colour and iron concentration in the water samples were above the World Health Organization guidelines. Multivariate analysis explained five components that accounted for 98.15% of the overall hydrogeochemistry and affected by anthropogenic and geogenic impacts. The surface water was observed to range from neutral to mildly acidic, with the dominance of HCO3 −, Cl−, Ca2+, Mg2+, and Na+ in ionic strength. The Piper diagram reveals five major surface water types: Na–HCO3–Cl, Na–Cl–HCO3, Na–Ca–Mg–HCO3, Na–Ca–Mg–HCO3 and Ca–Na–Mg–HCO3. The Gibbs plot showed that the major ion chemistry of surface water was mostly influenced by atmospheric precipitation and the water quality index showed that the majority of the surface water from settlements within the Birim River basin were of poor quality for drinking and other domestic purposes. However, irrigation suitability calculations with reference to sodium adsorption ratio, residual sodium carbonate, and magnesium ratio values, together with Wilcox and USSL models indicated that the surface water within the area under study was suitable for agriculture. The potential ecological risk for single heavy metals pollution and potential toxicity response indices gave low to considerable ecological risks for the sediments, with greater contributions from Cd, Pb and As. Whilst geo-accumulation indices indicated that the sediments ranged from unpolluted to moderately polluted Modified degree of pollution and Nemerow pollution index calculations which incorporate multi-element effects, however, indicated no pollution. Conclusion There are some levels of both potential ecological risks and health hazards in the study area. Hence continuous monitoring should be undertaken by the relevant agencies and authorities so that various interventions could be put in place to prevent the situation from deteriorating further in order to protect the inhabitants of the settlements within the Birim River basin

HEALTH RISK ASSESSMENT OF SOME HEAVY METALS AND PHYSICO-CHEMICAL QUALITY OF SURFACE WATER IN BIBIANI A MINING ENCLAVE IN GHANA

The quality of water is a powerful environmental determinant of health, increased productivity and enhanced economic development. Levels of As, Fe, Pb, Zn, and Cu were determined in both water and sediment samples within ten communities in Bibiani and its environs using the Atomic Absorption Spectroscopy. The results for most of the physiochemical parameters determined were below the WHO permissible limits with the exception of colour and turbidity. Cd, Pb, and Zn in water were below detection whereas As were in the range of 0.006 to 0.047 mg/l and Fe below detection to 2.00 mg/l. Pamuso had the highest As the level of 0.480 mg/l whilst Pataboso recorded the least value of 0.006 mg/l. Fe in two communities were above the limit but Cu was within the WHO limit. The mean levels of heavy metals in sediment obtained were in the range of: As (1.451 to 4.220); Cd (below detection to 1.104 mg/kg); Cu (below detection to 3.951 mg/kg); Fe (46.215 to 549.450 mg/kg); Zn (0.351 to 2.350 mg/kg) whilst Pb was below detection. The HI results in six communities were above the guidance value of 1.0 for adults and in all samples for children which is likely to pose risk to human health. Moreover, the CRing for As was above the USEPA guidance value of 1 x 10-6 in all the communities which imply consumers are likely to be exposed to cancer risk. The concentrations of As, Cd, Cu and Zn in the sediments were lower than the corresponding effect range low (ERL) values in the sediment quality guidelines and could have no adverse effects on aquatic organisms