Attending the 12th International Conference on Mine Closure

Last September, the 12th International Conference on Mine Closure was celebrated in Leipzig (Germany). This conference, organized by the Technical University Bergakademie Freiberg, is one of the world`s reference events among the mine closure professionals. The main conference topics that were discussed and that have been found as the main issues were:  establishing integrated life of mine planning, design sustainable land uses from the social and environmental perspective, increasing the post-mining assets value, and establishing  stable and self-regenerating ecosystems, among others.

Due to the urgent necessity of improving reclamation of mining areas, abandoned and/ or in transition to close, researchers from IRNAS-CSIC, University of Seville, University of Reading and Haute École Condorcet have collaborated to present a paper and an oral communication in this conference.

Gil-Martínez M, Domínguez MT, Navarro-Fernández CM, Crompot H, Tibbett M , Marañón T (2018). Long-term effects of trace elements contamination on soil microbial biomass and enzyme activities, in C Drebenstedt, F von Bismarck, A Fourie & M Tibbett (eds), Proceedings of the 12th International Conference on Mine Closure, Technical University Bergakademie Freiberg, Germany, pp. 633-644.

Results from the applied strategy of phytostabilisation on mining areas contaminated by heavy metals were presented. In our study area known as Guadiamar Green Corridor, where phytostabilisation have happened over 19 years, forestation has been found to improve soil fertility and microbial biomass, which is an indicator of improved soil quality. Moreover, different tree species have been found to affect soil chemistry and biology in different ways. White poplar was found to increase soil pH and to recover nutrients levels. However, stone pine was found to acidify the soil, increasing heavy metal availability and reducing microbial communities. In conclusion, previous to forestation is recommended to select the most suitable species for the specific conditions of the mining area to reclaim.

In this conference, Marta Gil-Martínez, predoctoral researcher from IRNAS-CSIC, had the opportunity to visit the Wismut Uranium Tailings Remediation Project , which started back in 1991 and currently clean-up, re-contouring and implementation of covers tasks are still in place. Last cover consists in revegetation to establish some forest and pastures areas, in order to maximize biodiversity.


Presentation in the Iberian Congress of Soil Science

“The soil as sustainable resource for the bioeconomy” was the theme for the VIII Iberian Congress of Soil Sciences, held at San Sebastián/Donosti, during 20-22 June 2018.

Researchers of the projects RECARE and RESTECO contributed to the 3rd session, devoted to “Protection and restoration of soils”, with the comunication titled “Soil restoration strategies in the Guadiamar River Valley. Evaluation of 20 year of monitoring after the Aznalcóllar mining accident”.

This work is a review of the 20-year monitoring of contaminated and remediated soils, after the Aznalcóllar mine-spill. The application of soil amendments (sugarbeet lime and biosolid compost) was evaluated and results of 14-year changes of pH and organic carbon were shown.

At a large scale, in a soil survey along the Agrio and Guadiamar rivers, high level of Cd and Zn were detected in certain spots of channel and river banks.

A copy of the presented poster can be downloaded from Digital CSIC.

Measures to remediate contaminated soils: the Guadiamar case study

Soil pollution is one of the main environmental problems at a global scale. Within the European RECARE project, several threats of soil degradation are investigated, and measures and solutions to remediate degraded soils are proposed.

A research team from the IRNAS, CSIC participating in the RECARE project has contributed with the evaluation of remediation measures for contaminated soils in the case study of the Guadiamar Green Corridor (Seville, Spain). The implementation of a phytoremediation process in three stages was proposed: amendments addition, planting of trees and monitoring of the system.

1) Firstly, results were presented showing a long-term study (from 2002 to 2016) where two types of amendments (sugarbeet lime and biosolid compost) were applied to a contaminated soil. The treatment effectiveness was evaluated by measuring the produced plant biomass and the trace element (TE) concentration in plants, as well as the transfer of TE from soil to plants. The lime-rich inorganic amendments were very effective increasing soil pH and therefore reducing TE availability (mobility); while the organic amendments were effective compensating the organic matter loss in the soil.

2) Secondly, the soil remediation effects of seven tree species (Populus alba, Celtis australis, Fraxinus angustifolia, Quercus ilex, Olea europaea, Ceratonia siliqua and Pinus pinea) planted in the contaminated area were investigated. Concentration of TE in leaves and roots of trees, and in the soil underneath was measured in 2014 (about 15-year-old trees). The capacity to phytostabilize soil TE by different tree species was evaluated based on the retention of TE in roots and the low translocation of TE from roots to leaves.

3) Thirdly, in this phytoremediation process of contaminated soils is crucial the long-term monitoring of soil availability of TE and their concentration in the living organisms (plants and animals) composing the trophic network. The continuous evaluation of those results will modify the following remediation measures within an adaptive management cycle.

This work has been published in the special issue of the journal CATENA, entitled “Testing Soil Conservation”, compiling the results of the different case studies within the European RECARE project.

Madejón P., Domínguez M.T., Gil-Martínez M., Navarro-Fernández C.M., Montiel-Rozas M.M., Madejón E., Murillo J.M., Cabrera F., Marañón T. (2018) Evaluation of amendment addition and tree planting as measures to remediate contaminated soils: The Guadiamar case study (SW Spain). Catena 166: 34-43.

Evaluation of measures to remediate contaminated soils: European meeting

The RECARE project is focused on preventing and remediating degradation of soils in Europe.

A Plenary Meeting has been held at Hella (Iceland), from May 29th to June 2nd 2017. Each of the 17 study sites participating in the project presented their results.

Photo: Erik van den Elsen

The Group SOIL-PLANT, from the IRNAS, CSIC, presented their results about two measures applied for the remediation of contaminated soils at the Guadiamar Green Corridor: a) amendment addition and b) tree plantation.

Those results are part of a joint work by the projects RECARE and RESTECO.

Copies of the presentation and poster can be consulted at the repository Digital CSIC.