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Stream 11a: Research and Development, New Technologies and Innovation – Phytoremediation
Agricultural-Enhanced and Nature-Based Remediation Techniques for Site Remediation
Christian Gosselin, Melissa Bacon, Guillaume Bastille
Golder Associates Ltd.
The objective of this presentation is to present some of the challenges associated with phytoremediation and illustrate how agricultural methods and other techniques can be used to overcome some of these challenges and improve overall performance.  
Abstract

Nature-based remediation methods aim to create balanced and thriving ecosystems within impacted soils to eliminate contaminants at a low cost, in a sustainable manner, and in some cases in a relatively short time frame. Dependant on the contaminant of concern and the project context, several different natural and agricultural processes can be leveraged to create an in-situ biological [BM1] ecosystem treatment. An efficient nature-based treatment can be implemented by integrating a combination of different bioremediation techniques (microbial degradation, phytoextraction, rhizodegradation, mycoremediation, etc.). Phytoextraction is based on the ability of plants to extract contaminants from the soil, transfer it and store it in the aerial parts of the plant such as stems, shoots and leaves. It is then possible to gradually reduce the mass of metal contained in the soil by regularly placing aboveground biomass.

Rhizodegradation is the degradation of contaminants in the area of soil surrounding the roots of the plants (the rhizosphere) by means of microbial activity which is enhanced by the presence of plant roots. These roots release natural carbon-containing substances such as sugar, alcohols, and acid, providing the microorganisms with additional nutrients which stimulate their activity.

Mycoremediation is another promising field in which the enzymatic degradation from different types of fungi can break down or degrade recalcitrant contaminants. This treatment method biomimics the remarkable ability of fungi in nature to degrade complex molecules such as lignin.

To increase the efficiency of these remediation techniques, agricultural methods can be used to enhance and control soil conditions and improve the quality of the microbiota. By selecting plants on their ability to grow at different rates, depth and in various soil conditions we are able to quickly develop a dense and deep root system and increase the soil porosity and permeability. For years, agronomists have been using variations of these techniques to enhance agricultural production. Today, we are using proven soil structure enhancement plants such as buckwheat, rye, oat, mustard, radish and others to create a sustainable, natural treatment system for contaminated soils.

Nature-based remediation processes have the advantages of limiting dust dispersion, volatilization into the atmosphere, or infiltration into the groundwater of the contaminants. It also offers a natural appearance which is popular with the general public, helping gain community acceptance of the work.

In this presentation, we will present multiple examples of nature-based remediation projects at various stages of advancement. These examples will present some of the challenges associated with these techniques and illustrate how agricultural methods can be used to overcome some of these challenges and improve overall performance.

Christian Gosselin earned his bachelor's degree in Rural Engineering at McGill University in 1989 then completed a master’s degree in Geotechnical Engineering, also at McGill University. Mr. Gosselin worked for environmental consultants between 1991 and 1999 as the head of various site characterization studies and remedial work using soil leaching, bioreactor, in-situ bioventing and air injection techniques as well as others. In 1999, he joined Golder in Montréal where he is responsible for characterization and site restoration projects. He is also involved in wastewater treatment projects.

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