Notable case, Aznalcóllar, Andalucía (Sevilla), Spain
Aznalcóllar spill and the Guadiamar Green Corridor
Aznalcóllar / Corredor Verde del Guadiamar
In 1998 the tailings dam of the Aznalcóllar pyrite mine failed and sent acid, metal-laden sludge down the Guadiamar river to the edge of Doñana National Park. The cleaned-up area became one of Europe's largest case studies of soil reclamation with amendments and plants.
At a glance
- Status
- Remediated
- Area
- 4,286 ha on land1
- Activity
- until 1998
- Media
- soil, surface water, sediment, living organisms
- Kind of site
- mining, accident
- Area. 4,286 ha covered by sludge, 59.7% of it farmland (Bernal et al. 2007); other sources give about 4,600 ha.
Contaminants
Status
Remediated
The sludge was removed in 1998–1999 and the river strip was afforested and protected from 2003. Metals and arsenic remain in patches in the soil, followed by twenty years of monitoring (Madejón et al. 2018). According to Wikipedia the mine was still closed in 2024, with a reopening project under discussion.
Story
The Los Frailes mine at Aznalcóllar extracted zinc, lead and copper sulphides and was run by Boliden Apirsa, the Spanish subsidiary of Sweden's Boliden. In the night of 25 April 1998 the wall of the tailings pond gave way: about 4 hm³ of acid water and 2 hm³ of pyrite sludge escaped and travelled down the Agrio and Guadiamar rivers for tens of kilometres.
The sludge carried arsenic, zinc, lead, copper, thallium and cadmium. About 37,400 kg of dead fish were collected. In 1998–1999 some 8 hm³ of sludge was removed together with 10–30 cm of topsoil; the farmland was expropriated, amended with sugar-beet lime and compost and planted with native Mediterranean species.
In 2003 the strip along the river was declared a protected landscape. The IRNAS-CSIC group in Seville has worked there ever since: it is the source of the data on trace-element transfer from soil to crops, herbs, shrubs and trees.
Timeline
- 199825 April: the tailings dam of the Los Frailes mine fails.
- 1999Mechanical removal of the sludge and topsoil is completed.
- 2003April: the Guadiamar Green Corridor Protected Landscape is declared.
- 2018The review of twenty years of soil-plant experiments and monitoring is published.
Remediation
- 1998excavationRemoval of about 8 hm³ of sludge and 10–30 cm of topsoil (1998–1999).
- 1999soil amendmentSugar-beet lime and biosolid compost to raise pH and lower metal availability.
Plants and fungi at this site
PhytoremediationField scale, 1999–2018
Ceratonia spp., Fraxinus spp., Populus spp.
Afforestation of the whole corridor with native Mediterranean trees and shrubs after amendments were added: landscape-scale phytostabilisation, followed for twenty years by IRNAS-CSIC. The RECARE site names the genera Ceratonia, Fraxinus and Populus as the most effective at lowering trace-element availability.
Outcome Sugar-beet lime cut the availability of Cd, Cu and Zn by 99%; compost doubled soil organic carbon. Soil pH under the trees ranged from 2.6 to 6.1, inversely related to metal availability (RECARE).
PhytoremediationField scale
Brassica juncea, Lupinus albus
CEBAS-CSIC experimental plots: phytoextraction with Indian mustard combined with organic amendments and limestone, and phytoimmobilisation with lupin, a legume that tolerates metals by excluding them at the root and suits acid soils.
PhytoremediationField scale, 1998–2005
Populus alba
After the sludge was removed the valley was amended and reforested with native woody species: phytomanagement on a large scale. Domínguez, Marañón, Murillo, Schulin and Robinson measured trace elements in soil and woody plants seven years after the spill.
Outcome Concentrations in the plants were on average within the normal range for higher plants, meaning that the elements do not move into the vegetation to any great extent. White poplar is the exception: it accumulated up to 3 mg/kg of cadmium and 410 mg/kg of zinc in its leaves.
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
- Noccaea caerulescensAlpine pennycressEvidence: field
- Populus albaWhite poplarEvidence: field
Fungi
- Funneliformis mosseaeEvidence: greenhouse
- Rhizophagus irregularisEvidence: 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
- Guadiamar, Spain (case study), RECARE project (EU FP7)
- Twenty years of environmental studies in the Guadiamar, IRNAS-CSIC, 2018
- The Los Frailes tailings dam failure (Aznalcóllar, Spain), WISE Uranium Project
- Doñana disaster, Wikipedia, 2026
Draft compiled from public sources, not yet reviewed.