SUITMA 2005 Cairo - Effectiveness and environmental impact of a soil reconstitution process on a degraded site
SUITMA 2005 Cairo
| This abstract is about one of the papers of the Consumed mining and military areas theme of the SUITMA 2005 symposium. |
| Geoffroy Séré,i,ii | Stéphanie Ouvrard,i |
| Christophe Schwartz,i | Cécile Payet,ii |
| Jean-Christophe Renat,ii | Jean-Louis Morel.i |
- i - Laboratoire sols et environnement (LSE), ENSAIA, Université de Lorraine - INRA, Nancy, France
The population growth and simultaneous higher demand in resources supplied by human enterprises lead to an increasing alteration of the major biogeochemical cycles and to the degradation of soil quality. Approximately 6 % of Earth’s surface has already sustained very severe human-induced degradation due to intensive agriculture, deforestation, urbanism or industry. As a consequence, wider areas of degraded sites, that need to be reclaimed, are formed as for example industrial brownfields, ski runs, landfills or roadsides. From an ecological point of view, these sites are severely disturbed zones presenting an ecosystem balance that needs to be restored. The main challenges of degraded sites reclamation include the re-initiation of carbon and nutrient cycling, the establishment of a sustainable plant cover, and the limitation of pollutant transfer to the environment and the possibility of a new land-use. The compulsory restoration of derelict land is a major problem for site-managers. It usually requires the use of large amounts of natural arable earth material, which is both economically and environmentally expensive. Therefore, the use of organic products, like urban wastes and/or industrial by-products can be an attractive alternative solution to both municipalities and industries. This work presents an innovative process for degraded sites reclamation using compost, paper industry by-product and treated industrial soil. The process is based on the use of these wastes to rebuild a new soil over in situ derelict substrates. These materials are associated and stacked in layers to form new horizons and reproduce various soil functions: water cycling, fauna and flora growth. Our objectives are (i) to evaluate the effectiveness of the process, through measurements such as the sustainability of the vegetation cover, the water balance or the soil properties, (ii) to determine the environmental impacts of the reconstituted soil, through ecotoxicological tests and pollutant analysis in all matrixes (solid materials, leachates, vegetation). This project combines both in situ pilot scale experiments and lab-scale measurements and experiments. Three types of material associations called “modalities” are tested. Modality I represents a classic reclamation practice, consisting of a single layer of treated industrial soil directly deposited on the local substrate. Modalities II and III represent two options of reconstituted soil profiles associating compost, paper sludge and treated industrial soil. Results illustrate the differences between the three modalities, in terms of agronomic properties, vegetation development, soil characteristics and water fluxes. Both heavy metals balance and ecotoxicological tests of leachates on the in situ experiment help assessing the environmental impacts of the process. Soil reconstitution is then an innovative way of recycling organic and industrial wastes, an efficient process to reclaim degraded sites and an alternative mode for organic carbon storage in soils. This process has no major ecotoxicological impact on the compartments of the ecosystem.
