Assessment of Heavy Metals and Microbial Contamination in Soil and Groundwater around Zomba Dumpsite, Malawi

The present study evaluated heavy metal and microbial contamination in soil and groundwater around a municipal solid waste dumpsite in Zomba, Malawi. It also examined the potential ecological and health risks to local communities. Samples were analyzed for heavy metals using an atomic absorption spectrophotometer (AAS) and for microbes using standard methods from the United States Environmental Protection Agency. Results showed that groundwater during the wet season had elevated levels of total coliforms (20900 cfu/100 mL), Escherichia coli (3,300 cfu/100 mL), Staphylococcus aureus (2,500 cfu/100 mL), and Vibrio cholerae (5,900 cfu/100 mL), all significantly above the permissible limits set by Malawi Standards (MS). Heavy metals such as Cr (0.011–0.14 mg/L) and Cd (07 – 041 mg/L) were also detected, raising concerns. In soil samples, lead (Pb) ranged from 0.16 to 224.05 mg/kg, copper (Cu) from 3.03 to 94.86 mg/kg, cadmium (Cd) from below detection limit (BDL) to 0.89 mg/kg, arsenic (As) from BDL to 1.88 mg/kg, and chromium (Cr) from 0.07 to 0.91 mg/kg. The cancer risk assessment showed all sampling points had CR levels exceeding 1 × 10^-3 for adults, with 40% of points indicating elevated CR levels for infants and children, emphasizing the cancer risk from Cd exposure, especially among vulnerable groups. These findings call for urgent intervention by the Ministry of Water Resources and Sanitation's groundwater division, in partnership with Zomba City Council, to provide safe water alternatives for nearby communities.