Abstract

Trace metal contamination of groundwater was assessed in Katuba and Kenya municipalities of Lubumbashi city in 2016 and 2017 to determine whether water was suitable or unsuitable for human consumption. Two hundred and four groundwater samples collected from twenty spade-sunk and four drilled wells in both municipalities were analyzed for their trace metal contents using a sector field inductively coupled plasma mass spectrometry Thermo Element II. Nineteen trace elements including strontium, molybdenum, cadmium, cesium, barium, tungsten, thallium, lead, bismuth, uranium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc and arsenic were recorded at varying concentrations in all samples. Arsenic, cadmium, lead, nickel and copper levels of groundwater exceeded the World Health Organization acceptable limits for drinking water, respectively in 14.44, 8.89, 6.67, 0 and 0%, of samples from Katuba and in 0, 16.67, 25, 16.67 and 16.67% of samples from Kenya municipality. In Katuba, 55.56% of the groundwater samples were acidic (pH 4.7-6.4) in dry season and 61.11% were very alkaline (pH 8.6-11.2) in rainy season. In Kenya municipality, 33.33% of the samples were acidic (pH 5.5-6.2) in rainy season. With such physicochemical and trace metal contamination status of the groundwater in both municipalities, water of many wells is unsuitable for human consumption and presents a health risk to people who use it to meet their drinking water needs.

Key words: Groundwater, pH, trace metals, Lubumbashi city.