Contamination of water and food crops by trace elements in the African Copperbelt: A collaborative cross-border study in Zambia and the Democratic Republic of Congo

Muimba-Kankolongo, Ambayeba Banza Lubaba Nkulu, Célestin Mwitwa, Jacob Kampemba, Florence M. Mulele Nabuyanda, Misery Haufroid, Vincent [UCL] Smolders, Erik Nemery, Benoit et al.[show all]

BACKGROUND. Environmental pollution by trace metals is of concern in the African Copperbelt, a region of intense mining situated on either side of the border between the Democratic Republic of Congo (DRC) and Zambia. Scientists from both countries undertook a collaborative study using the same sampling and analytical methodologies to assess metal contamination of water and food in both countries. Methods. In six mining areas (Lubumbashi, Likasi, Kipushi in DRC; Chingola, Kitwe, Luanshya in Zambia) samples of water (surface, boreholes, taps) and various crops were collected in two residential sites near mining operations, and in rural villages farther away (controls). Nine elements (Mn, Co, Ni, Cu, Zn, As, Cd, Pb, U) were measured by ICP-MS or ICP-OES. RESULTS. In drinking water obtained close to mining, the median concentrations (µg/L) of all trace elements, except Zn, were substantially higher in DRC (n=20) than Zambia (n=18), this being most pronounced for Pb (27 vs 0.08), Cd (0.7 vs <0.015) and Co (65 vs 1.3). In plants, most of which were leafy vegetables, the concentrations of all trace elements, except Mn, were consistently higher in DRC (n=145) than Zambia (n=128). Compared to control sites, crops obtained near mining exhibited significantly higher concentrations of Zn and Pb in Zambia, and of Co, Cu, As, Cd, Pb and U in DRC. Cd and Pb exceeded international standards in most DRC crop samples. CONCLUSION. This unique cross-border study documented metal contamination of drinking water and locally grown vegetables near mining activities in Zambia and DRC, with the contamination being worse in DRC. The higher pollution observed in DRC compared to Zambia must largely be attributed to differences in environmental governance between the two countries. Efforts are needed to enforce regulations and to mitigate the negative impacts of mining and smelting operations on the environment, population health, and food security in the African Copperbelt.