Groundwater quality of Malawi : fluoride and nitrate of the Zomba-Phalombe plain

Abstract: Contamination of groundwater is a widespread issue around the globe and the water quality is highly dependent on the geology as well as anthropogenic interventions in the area. High (0.9 – 1.2 mg F-/L) fluoride levels in groundwater can give rise to dental fluorosis and have been reported in several areas of Malawi. Further studies of groundwater contamination apart from fluoride are limited. The aim of this study was to investigate the fluoride and nitrate concentrations of groundwater in boreholes around Lake Chilwa and the origin of the contaminants. The hypothesis was that elevated concentrations of fluoride and low nitrate concentrations would be found in the area. On average, most fluoride and nitrate values were non-measurable, however, on some sites elevated concentrations were measured. Around the village of Jali, levels ranging from 1.5 to 4.5 mg F-/L were found. The village of Nine miles had elevated levels of nitrate in the water with 48.5 mg NO3 -/L as the highest. The latter is an interesting result since levels greater than 50 mg NO3 -/L have been correlated with blue-baby syndrome, a condition lethal for bottle-fed infants. Due to these findings, further studies of the area are recommended along with implementation of nitrate-contamination prevention measurements.