Distribution patterns of spontaneous vegetation and pollution at a former decantation basin in southern Québec, Canada

• Revegetation pattern in contaminated sites may reflect spatial distribution of soil pollution.
• Partial redundancy analysis was used to investigate spatial distribution of vegetation and pollutants in a former decantation basin.
• We found that up to 61% of spontaneous plant distribution was explained by pollutant distribution on the study site.
• These findings provide important guidelines for design of site-specific and community-based remediation strategy.

After industrial activities shut down, the brownfields remaining on abandoned sites are often left to revegetate naturally, a process that reflects the site's biotic and abiotic characteristics, including spatial pollutant distribution. The soil of a former decantation basin in Varennes (southern Québec, Canada) was systematically sampled and described in terms of concentration of PAHs (polycyclic aromatic hydrocarbons), PHs (petroleum hydrocarbons C10–C50), various trace metals as well as ruderal plant abundance and diversity. Partial redundancy analysis was used to investigate the effect of heterogeneous pollution on the plant community's spatial distribution. Up to 61% of variance in spontaneous plant distribution was explained by the pollutant dispersion pattern on the study site. These findings provide guidelines for the design of site-specific and within-site remediation or rehabilitation promoting natural processes that are already in progress. They also suggest using local vegetation and a greater diversity of plant species when conditions are conducive as this may have many associated benefits. The resulting design, which promotes development of the local plant community, can be a more cost effective and environmentally sustainable alternative to traditional plant-based remediation approaches.