Notable case, Lubumbashi, Haut-Katanga, Congo - Kinshasa
Lubumbashi and the Katangan Copperbelt
Lubumbashi (Penga Penga / Cité Gécamines), Copperbelt katangais
More than a century of copper and cobalt mining and smelting in the south-east of the Democratic Republic of the Congo has contaminated soils, rivers and the food chain; residents have the highest urinary cobalt levels ever measured in a general population. It is also the home of the Katangan copper flora, some 600 metallophytes, used at Lubumbashi in phytostabilisation trials.
At a glance
- Status
- Not addressed
- Media
- soil, air, surface water, living organisms
- Kind of site
- mining, smelter
- Area. No official perimeter. The fallout footprint of the Lubumbashi smelter extends for about 30 km in the direction of the prevailing winds (Langunu et al. 2023, citing earlier studies).
Contaminants
Status
Not addressed
No overall clean-up. In the Penga Penga district, downwind of the Gécamines copper smelter, phytostabilisation trials by the University of Lubumbashi with Belgian universities have run for about fifteen years, but unplanned urbanisation stands in the way of a large-scale programme (Langunu et al. 2023).
Story
The outcrops of south-eastern Congo are among the largest copper and cobalt orebodies in the world. Lubumbashi was founded in 1910 on a spot chosen for its proximity to the Étoile du Congo mine and to the copper smelting furnace that the Union Minière du Haut Katanga had installed on the Lubumbashi river (Wikipedia). Mining grew throughout the twentieth century; today more than half the world's mined cobalt comes from here, and an estimated 15–20% of it is dug by artisanal miners (Banza Lubaba Nkulu et al. 2018).
The oldest and best documented case in the city is Penga Penga, the district downwind of the Gécamines smelter. The fumes deposited metal-rich particles and acidified the soils: 42,500 mg/kg of total copper was measured in bare soil, against 220 mg/kg in a remote forest (Shutcha et al. 2015). The original open forest was replaced by short, sparse vegetation with large patches of bare ground, now occupied by housing: only 6.5% of plots (44 of 674) have at least one tree.
The same outcrops carry a unique vegetation, with nearly 600 metallophytes including rare and endemic species, threatened by mining (Boisson et al. 2018). This flora is the source of the grasses used in the Lubumbashi phytostabilisation trials.
Timeline
- 1910Élisabethville (now Lubumbashi) is founded next to the Union Minière copper smelter (Wikipedia).
- 2009First biomonitoring study: unprecedented cobalt exposure in the general population.
- 2010The first phytostabilisation trial with native grasses in Katanga is published.
- 2015Three years of phytostabilisation trials on the bare soils of Penga Penga are published.
- 2018The Kolwezi study on artisanal cobalt mining and children's exposure.
Health
In the first biomonitoring study (351 people; Banza et al. 2009), those living within 3 km of mines or smelters had urinary cadmium, cobalt, lead and uranium at 4, 43, 5 and 4 times the background values of the US population; cobalt exceeded 15 µg/g creatinine in 53% of subjects and in 87% of children. The main pathway is the diet (vegetables, cereals, fish, water), with dust ingestion important in children (Cheyns et al. 2014). At Kolwezi, children in a neighbourhood turned into an artisanal cobalt mine showed evidence of exposure-related oxidative DNA damage (Banza Lubaba Nkulu et al. 2018).
Plants and fungi at this site
PhytoremediationField scale
Microchloa altera, Monocymbium ceresiiforme, Cynodon dactylon
Experimental plots in Katanga artificially contaminated with 2,500 mg/kg of copper, planted with three grasses (Microchloa altera, under the synonym Rendlia altera in the paper, Monocymbium ceresiiforme and Cynodon dactylon) with compost or lime, and followed for two years.
Outcome M. altera was the best candidate, with the highest survival without amendments; C. dactylon survived only with lime. Lime increased reproduction and lowered leaf copper more than compost did.
PhytoremediationField scale
Microchloa altera
Three years of trials on the bare, acid soil of Cité Gécamines/Penga Penga (42,500 mg/kg total copper), comparing spontaneous colonisation with assisted phytostabilisation: planting of M. altera with lime and compost.
Outcome According to the abstract, promising results for reclaiming contaminated bare soil in a tropical climate; Boisson et al. (2018) describe the technique as successfully implemented near Lubumbashi with M. altera. We could not read the full text: the measured values should be checked against the paper.
PhytoremediationField scale
Microchloa altera
Trial near Lubumbashi on using the M. altera cover as a nurse plant to establish four other herbaceous species of the copper flora (two annuals and two perennials), with the aim of combining phytostabilisation and conservation of endemics.
Outcome The M. altera cover affected the emergence and survival of the sown species and reduced their growth.
PhytoremediationField scale
Mangifera indica, Syzygium guineense
Survey of trees planted by Penga Penga residents in former household dumps or with amendments (including termite-mound soil), compared with the unpolluted district of Kalebuka.
Outcome Bioconcentration factors below 1, but 47% of fruit and leaf samples from Penga Penga exceeded FAO/WHO thresholds (18.5% at Kalebuka).
From the literature
Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.
Plants
- Agrostis capillarisCommon bentEvidence: field
- Arabidopsis halleriHaller's rockcressEvidence: field
- Cannabis sativaIndustrial hempEvidence: field
- Festuca rubraRed fescueEvidence: field
- Helianthus annuusSunflowerUraniumEvidence: field
- Noccaea caerulescensAlpine pennycressEvidence: field
Fungi
- Funneliformis mosseaeUraniumEvidence: greenhouse
- Rhizophagus irregularisUraniumEvidence: greenhouse
- Paxillus involutusBrown roll-rimEvidence: greenhouse
- Aspergillus nigerBlack mouldEvidence: laboratory
- Mucor circinelloidesEvidence: laboratory
- Suillus luteusSlippery jackEvidence: laboratory
The rest are on the contaminant pages.
Nearby
Sources
- Banza C.L.N. et al. High human exposure to cobalt and other metals in Katanga, a mining area of the Democratic Republic of Congo. Environmental Research 109(6), Environmental Research, 2009
- Cheyns K. et al. Pathways of human exposure to cobalt in Katanga, a mining area of the D.R. Congo. Science of the Total Environment 490, Science of the Total Environment, 2014
- Banza Lubaba Nkulu C. et al. Sustainability of artisanal mining of cobalt in DR Congo. Nature Sustainability 1, Nature Sustainability, 2018
- Langunu S. et al. Accumulation of Trace Metals in Fruits from Mango and Syzygium guineense… (introduction on Penga Penga), Toxics (MDPI), 2023
- Shutcha M.N. et al. Three years of phytostabilisation experiment… (abstract, AGRIS record), FAO AGRIS / Ecological Engineering, 2015
- Lubumbashi (coordinates, founding), Wikipedia, 2026
Draft compiled from public sources, not yet reviewed.