Assessment of Trace Metal Levels of Groundwater in Lubumbashi, Kampemba and Kamalondo Communes of Lubumbashi City, Democratic Republic of Congo

Trace metal levels of groundwater in Lubumbashi, Kampemba and Kamalondo communes of Lubumbashi city were assessed from October 2016 to February 2017. Two hundred forty water samples collected from twenty-two spade-sunk wells and twelve drilled wells in these three communes of Lubumbashi city were analyzed for their metal contents using ICP-SF-MS (Inductively Coupled Plasma-Sector Field Mass Spectrometry). Twenty trace elements including strontium, molybdenum, cadmium, cesium, barium, tungsten, thallium, lead, bismuth, uranium, aluminum, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc and arsenic were recorded at varying concentrations in all the water samples and were compared with the WHO (World Health Organization), US EPA (Environmental Protection Agency) and EU (European Union) drinking water MCLs (Maximum Concentration Limits) for cadmium, barium, thallium, lead, uranium, aluminum, chromium, manganese, iron, nickel, copper, zinc and arsenic. Mean cadmium, lead, aluminum, manganese, iron, nickel, zinc and arsenic levels respectively exceeded the WHO, US EPA and EU drinking water MCLs in 6.66%, 3.38%, 26.67%, 5.02%, 30.03%, 3.38%, 1.64% and 5.02% of the samples with the highest mean levels of 116.89 µg/L for cadmium, 38.162 µg/L for lead, 2,712.5 µg/L for aluminum, 1,242.68 µg/L for manganese, 17,325.98 µg/L for iron, 64.647 µg/L for nickel, 9,900.72 µg/L for zinc and 65.458 µg/L for arsenic. Mean water pH values ranged from 4.7 to 11.1 with 19.17% of the groundwater samples having mean pH values outside the WHO drinking water pH optimum range values of 6.5-8.5, including 5.02% of the water samples which were acidic (mean pH values ranging from 4.7 to 6.4) and 14.15% which were alkaline (mean pH values ranging from 8.6 to 11.1). With such physicochemical and trace metal contamination status of groundwater in the three communes of Lubumbashi city, there is a high risk to the health of people who use that water to meet their drinking water needs.