Groundwater Pollution in Koudougou, Burkina Faso: Chemical and Microbiological Assessment

Continued population growth in African cities has led to an increase in the demand for agricultural produce, with intensive use of inputs. The practice of market gardening in the vicinity of water bodies has an impact on groundwater quality. To make up for the lack of water, some people in the town of Koudougou resort to wells and boreholes. This study assessed the chemical and microbiological pollution of groundwater in the town of Koudougou, Burkina Faso. To this end, 40 water samples were taken from wells and boreholes near watercourses and in market garden production areas. Analyses were carried out using microwave plasma atomic emission spectrometry (MP-AES) and molecular absorption spectrophotometry. Principal component analysis was performed using XLSTAT software, and hydrochemical facies analysis was performed using Diagram software from the Laboratoire d'Hydrogéologie, Université d'Avignon. The extraction of pesticides from the water was adapted to the QuEchERS method proposed by Standard NF EN 15662 of 01/2009. Bacteria were also detected by filtration on cellulose membranes. The results of principal component analysis of the water samples revealed strong correlations between Ca2+ and Mg2+ (0.98), Al3+ and Fe2+ (0.96), Cl- and Na+ (0.93), NO3- (0.80). Thus, the origin of the chemical elements could be explained by direct infiltration of surface water and the influence of anthropogenic activities. Analysis of the hydrochemical facies reveals anthropogenic pollution. In addition, the high Al3+ content (0.31 mg/L) in some wells exceeds the WHO threshold value (0.2 mg/L), and is partly linked to rock weathering. In addition, pesticide residue levels have been found to exceed standards. The water is contaminated with faecal matter, with total coliform levels reaching 800 CFU/100 mL. All in all, well water as a whole and 80% of borehole water were found to be unfit for human consumption.