Plants for constructed wetlands as an ecological engineering alternative to road runoff desalination

Abstract

De-icing salt and snow pollution in urban and road areas is a growing threat seriously menacing the ecosystem goods and services provided by soils, rivers, wetlands, and lakes in the world. Up to 90 % of de-icing salt used for winter road maintenance (salt spreading and storage sites) can be transported, together with co-pollutants, e.g. metals, from tens to hundreds of metres from roads reaching soils, and both surface and ground water. Within ecological engineering, there are several strategies to reduce the impact of road de-icing salts once they are in the environment. Among them, constructed wetlands (CWs) have proved to be techno-economically feasible, energy efficient, and a green strategy. This chapter provides extensive information on the use of macrophytes in CWs for de-icing salt removal and presents: (a) an overview of phytoremediation in CWs and a summary of the full-scale facilities specifically conducted to road runoff treatment; (b) a compendium of studies focused on salt removal with macrophytes in greenhouses and those aimed at assessing macrophyte response to salinity in combination with other stressors (waterlogging, water depth, storm events, temperature, competitive interactions, nutrients, pollutants, and so on); and (c) a case study on treatment of runoff from an urban snow disposal site with Scirpus maritimus and Spartina pectinata.