Establishment techniques to using willow for phytoremediation on a former oil refinery in southern-Quebec: achievements and constraints

The remediation of former industrial sites using plants often requires a diversity of approaches to address different pollutants at different soil depths. Plant establishment is one of the most important phases in any phytoremediation project. In this article, we describe the results of two phytoremediation approaches corresponding to different sectors on the site of a former oil refinery in the Montreal region (Quebec, Canada). The first approach was conceived to remedy a deep, polluted plume contaminated mainly by organics, in the sector called EDC-VCM. The second dealt with decontamination of shallow soil (GERLED) polluted by a mixture of organics and heavy metals. The first approach showed a high mortality rate during establishment and resulted in failure. We attribute this to probable sensitivity of the plant roots to anoxia in deep soil. However, more research is needed on this topic. The establishment at the GERLED site was successful in terms of growth and survival. On this site, soil under willow plants showed a significantly lower concentration of both organic and heavy metal contaminants, which represents a very positive and encouraging result after a single growing season.