Gentle Remediation Options (GRO): A Literature Review (Part 1/2)

Report, 2021

Soils are a non-renewable resource and comprise a key component of the world's stock of natural capital. Due to industrialisation, urbanisation and other patterns of unsustainable development, widespread land degradation in the form of contamination, soil sealing, compaction, etc. has impaired the capacity of soils to perform their essential functions and provide humans with vital ecosystem services. Brownfields are typically urban or peri-urban sites that have been affected by the former uses of the site, are or are perceived to be contaminated, and require intervention to bring them back to beneficial use. They also constitute an important and underutilised land and soil resource to provide ecosystem services in urban areas as an element of green infrastructure through the use of nature-based solutions such as gentle remediation options (GRO). Within the scope of the Ph.D. project " Enhancing ecosystem services by innovative remediation using gentle remediation options (ECO-GRO)", an in-depth but inexhaustive literature review has been carried out to build a theoretical understanding of GRO for the overall research project. This literature review report (part 1 of 2) will present a compilation of the main findings by beginning with A) core concepts of GRO including the background of their usage and development as well as key physiological mechanisms and processes; then B) mechanisms for the gentle remediation of organic (i.e. degradation and volatilisation) and inorganic contaminants (i.e. extraction and stabilisation) are reviewed, including the various strategies for implementation, practical aspects, key limitations, the possibilities to enhance effectiveness by combining with soil amendments and compilations of field studies demonstrating successful application. GRO mechanisms that are more specific in use like rhizofiltration and phytohydraulics are also briefly discussed as well as other remediation techniques included under the GRO umbrella such as bioremediation, mycoremediation and vermiremediation; C) the development in the field towards applying GRO to both manage risks and provide wider economic, social and environmental benefits, i.e. phytomanagement, is discussed at some length while considering its broader implications; and finally D) suitable plants for the various GRO mechanisms are discussed throughout the report but a specific section is set aside to discuss methods for selecting the most suitable plants as well as summarising the most applied plants.