Total coliforms, arsenic and cadmium exposure through drinking water in the Western Region of Ghana: application of multivariate statistical technique to groundwater quality

• Published in: Environmental monitoring and assessment 2015-02, Vol.187 (2), p.1-23, Article 1
• Main Authors: Affum, Andrews Obeng, Osae, Shiloh Dede, Nyarko, Benjamin Jabez Botwe, Afful, Samuel, Fianko, Joseph Richmond, Akiti, Tetteh Thomas, Adomako, Dickson, Acquaah, Samuel Osafo, Dorleku, Micheal, Antoh, Emmanuel, Barnes, Felix, Affum, Enoch Acheampong
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Arsenic; Arsenic - analysis; Atmospheric Protection/Air Quality Control/Air Pollution; Cadmium; Cadmium - analysis; Cation exchange; Chemical contaminants; Cluster analysis; Coliforms; Contamination; Drinking water; Drinking Water - chemistry; Drinking Water - microbiology; E coli; Earth and Environmental Science; Ecology; Ecotoxicology; Enterobacter; Environment; Environmental Exposure - analysis; Environmental Exposure - statistics & numerical data; Environmental Management; Environmental Monitoring; Escherichia coli; Escherichia coli - growth & development; Geology; Ghana; Ground-water quality; Groundwater; Groundwater - chemistry; Groundwater - microbiology; Groundwater pollution; Hardness; Health risk assessment; Health risks; Human populations; Humans; Hydrology; Ions; Mercury; Mercury (metal); Microbial contamination; Monitoring/Environmental Analysis; Multivariate analysis; Nigeria; Physicochemical properties; Pollution sources; Population; Principal components analysis; Rainy season; Risk assessment; Salinity; Samples; Sanitation; Sodium; Sodium bicarbonate; Sodium carbonate; Sodium chloride; Statistical analysis; Statistical methods; Studies; Surface water; Sustainable development; Urban areas; Urban populations; Water analysis; Water Pollutants, Chemical - analysis; Water pollution; Water Pollution - statistics & numerical data; Water Quality; Water resources; Water sampling; Water supply; Water Supply - analysis
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-014-4167-x

In recent times, surface water resource in the Western Region of Ghana has been found to be inadequate in supply and polluted by various anthropogenic activities. As a result of these problems, the demand for groundwater by the human populations in the peri-urban communities for domestic, municipal and irrigation purposes has increased without prior knowledge of its water quality. Water samples were collected from 14 public hand-dug wells during the rainy season in 2013 and investigated for total coliforms, Escherichia coli , mercury (Hg), arsenic (As), cadmium (Cd) and physicochemical parameters. Multivariate statistical analysis of the dataset and a linear stoichiometric plot of major ions were applied to group the water samples and to identify the main factors and sources of contamination. Hierarchal cluster analysis revealed four clusters from the hydrochemical variables (R-mode) and three clusters in the case of water samples (Q-mode) after z score standardization. Principal component analysis after a varimax rotation of the dataset indicated that the four factors extracted explained 93.3 % of the total variance, which highlighted salinity, toxic elements and hardness pollution as the dominant factors affecting groundwater quality. Cation exchange, mineral dissolution and silicate weathering influenced groundwater quality. The ranking order of major ions was Na +  > Ca 2+  > K +  > Mg 2+ and Cl −  > SO 4 2−  > HCO 3 − . Based on piper plot and the hydrogeology of the study area, sodium chloride (86 %), sodium hydrogen carbonate and sodium carbonate (14 %) water types were identified. Although E. coli were absent in the water samples, 36 % of the wells contained total coliforms ( Enterobacter species ) which exceeded the WHO guidelines limit of zero colony-forming unit (CFU)/100 mL of drinking water. With the exception of Hg, the concentration of As and Cd in 79 and 43 % of the water samples exceeded the WHO guideline limits of 10 and 3 μg/L for drinking water, respectively. Reported values in some areas in Nigeria, Malaysia and USA indicated that the maximum concentration of Cd was low and As was high in this study. Health risk assessment of Cd, As and Hg based on average daily dose, hazard quotient and cancer risk was determined. In conclusion, multiple natural processes and anthropogenic activities from non-point sources contributed significantly to groundwater salinization, hardness, toxic element and microbiological contamination of the study area