Constructed Wetlands and the Ecology of Extreme Ecosystems

Constructed wetlands have been used for decades for the removal of organic pollutants. Organic contaminants are either degraded into air, gases or sequestered by aquatic vegetation. Inorganic elements need to be precipitated or adsorbed onto particulates, carried out of the water column, and stabilized in the sediments. Precipitation of these inorganic contaminants alters the hydrological conditions. This leads to plugging and hydrological changes with concomitant treatment failure, contrary to organic contaminants which are removed as gases or taken up by plant. Both processes are referred to as bioremediation, but the removal processes differ. Mine sites should be treated as extreme ecosystems, surrounded by intact, native ecosystems with their seed sources. This unconventional view of approaching ecosystem development in areas of ground or broken rocks, such as deserts, hot springs, salt lakes, high latitude and altitude systems requires an understanding of the blockages which limit further progression. Mostly, mine waste systems need to be balanced, as they are overwhelmingly oxidative and either acidic or alkaline. Their special biogeochemical challenges present their own complexity, and they need to be given time.