Nature-Based Solutions (NSB) are defined by European Commission as “solutions that are inspired and supported by nature, which are cost-effective, simultaneously provide environmental, social and economic benefits and help build resilience. Such solutions bring more, and more diverse, nature and natural features and processes into cities, landscapes and seascapes, through locally adapted, resource-efficient and systemic interventions".
Within the SPIRE project, NBS phytoremediation techniques use plants to clean up contaminated land and remove Heavy Metals from the soil. On the one hand, it constitutes a cost-effective and ecological alternative to more common physical remediation methods; on the other hand, it requires more time, being a slower solution. Thanks to this green technology, former urban contaminated land (5 pilot sites) can be restored and re-inserted into the ecosystems that service to the city, providing healed land for the future of the urban system.
Phytoremediation technology for soil is classified into the following categories: phytoextraction, phytostabilization, rhizofiltration, phytodegradation, and phytovolatilization. Not all plants are suitable or equally efficient for phytoremediation. The ability of the plant to account for the decrease in soil metal concentrations as a function of metal uptake and biomass production plays a vital role in achieving regulatory acceptance. Depending on heavy metal concentration in the contaminated soil and the target values sought for in the remediated soil, phytoextraction may involve repeated cropping of the plant until the metal concentration drops to acceptable levels (SPIRE - Technical Report D.6.2.11). An important consideration in this matter is the tree and plant selection. Existing plant species that currently perform phytoremediation at the pilot sites are integrated into the landscaping plan because of their optimal adaptation to the local conditions.
Fig. 2/3/4/5/6: Phytoremediation technics. Source: Celaya Alvarez, Amaia - based on Naturvårdsverket och Boverket (2006) Förorenade områden och fysisk planering. Rapport 5608: ISBN1/5600/91-620- 5608-5/.