Notable case, alto bacino del río San Jorge, Córdoba, Colombia
El Alacrán gold mine (upper San Jorge River basin)
Mina El Alacrán, cuenca alta del río San Jorge
El Alacrán, in the south of Córdoba department, is one of Colombia's most important sites of artisanal gold mining with mercury. The surrounding soils, used for farming, hold mercury, arsenic and lead, and it is one of the places in Latin America where mercury phytoremediation has been studied on site for longest.
At a glance
- Status
- Not addressed
- Media
- soil, surface water, air, living organisms
- Kind of site
- mining
- Area. No area in the sources consulted. The coordinates are those of the town of Puerto Libertador, a municipality in the upper San Jorge basin: the exact position of the mine needs checking.
Contaminants
Status
Not addressed
Artisanal mining continues and the contaminated soils are farmed. Remediation is at the research stage: surveys of wild plants and a pilot constructed wetland for effluents (University of Córdoba, 2016–2025).
Story
In the upper basin of the San Jorge River gold is extracted by small-scale miners who amalgamate it with mercury. In the farmed soils of the El Alacrán site total mercury ranges from 230 to 6,320 ng/g (Marrugo-Negrete et al. 2016). In soils from northern Colombia taken 0.6 km from active mines, 22.13 mg/kg of mercury, 1,997 mg/kg of lead and 37.52 mg/kg of arsenic were measured, with values falling at 3 and 20 km (Durante-Yánez et al. 2026).
Here gold lives alongside vegetable and rice growing: rice grown on mining soils from the basin exceeds the 20 µg/kg reference limit for mercury in grain in every treatment, even with compost added (Laza-Durante et al. 2026).
The University of Córdoba group has worked on the site for years: it surveyed the native plants growing on contaminated soil, tested a constructed wetland with the aquatic plant Limnocharis flava for mine effluent, and assessed the potential of tropical trees and shrubs for arsenic, cadmium and lead as well as mercury.
Timeline
- 2016The survey of 24 native species on the site's mercury-contaminated soils is published.
- 2017The pilot constructed-wetland trial with Limnocharis flava is published.
- 2019Study of genetic damage in the mining communities of the upper San Jorge.
Health
In 50 exposed people from mining communities of the upper San Jorge (19 of them from Mina El Alacrán), compared with 50 controls, blood mercury and arsenic were higher, and the comet and micronucleus assays showed DNA damage and cell death (Cruz-Esquivel et al. 2019).
Plants and fungi at this site
PhytoremediationField pilot
Limnocharis flava
Pilot-scale horizontal subsurface-flow constructed wetland with the anchored aquatic plant Limnocharis flava. The effluent came from the El Alacrán mining area (0.11 ± 0.03 µg/mL mercury) and was spiked with mercury nitrate to 1.50 µg/mL; 30-day test.
Outcome Mercury removal 9 times faster than in the unplanted control and a reduction of nearly 90% in the water concentration.
PhytoremediationField scale
Jatropha curcas
A field survey, not a remediation trial: 24 native species growing spontaneously on the contaminated farm soils of El Alacrán, analysed for mercury in roots, stems and leaves, with bioconcentration, translocation and accumulation factors.
Outcome Accumulation in the order roots > leaves > stems. Bioconcentration factor from 0.28 to 0.99, highest in Jatropha curcas; translocation factor from 0.33 to 1.73, of little use because most mercury in leaves comes from the air.
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
- Cannabis sativaIndustrial hempEvidence: field
- Eichhornia crassipesWater hyacinthEvidence: field
- Pteris vittataChinese brake fernEvidence: field
- Ricinus communisCastor beanEvidence: field
- Robinia pseudoacaciaBlack locustEvidence: field
- Agrostis capillarisCommon bentEvidence: field
Fungi
- Funneliformis mosseaeEvidence: greenhouse
- Paxillus involutusBrown roll-rimEvidence: greenhouse
- Aspergillus nigerBlack mouldEvidence: laboratory
- Mucor circinelloidesEvidence: laboratory
- Agaricus bisporusButton mushroomEvidence: laboratory
- Cunninghamella elegansEvidence: laboratory
The rest are on the contaminant pages.
Sources
- Marrugo-Negrete J. et al. Screening of native plant species for phytoremediation potential at a Hg-contaminated mining site. Science of the Total Environment, Elsevier, 2016
- Marrugo-Negrete J. et al. Removal of mercury from gold mine effluents using Limnocharis flava in constructed wetlands. Chemosphere, Elsevier, 2017
- Cruz-Esquivel Á., Marrugo-Negrete J., Calao-Ramos C. Genetic damage in human populations at mining sites in the upper basin of the San Jorge River, Colombia. Environmental Science and Pollution Research, Springer, 2019
- Durante-Yánez E.V. et al. Metal uptake in sweet peppers cultivated in soils contaminated by artisanal gold mining: implications for food safety. Environmental Geochemistry and Health, Springer, 2026
- Laza-Durante M. et al. Effects of Prior Thermal Exposure of a Soil-Compost System on Potentially Bioavailable Mercury and Its Accumulation in Rice Grown on Mining-Impacted Soils. Toxics, MDPI, 2026
- Puerto Libertador (coordinate), Wikipedia (es), 2026
Draft compiled from public sources, not yet reviewed.