Treatment of Salted Road Runoffs Using Typha latifolia, Spergularia canadensis, and Atriplex patula: A Comparison of Their Salt Removal Potential

摘要

De-icing salts are used all around the world to improve driving security. Their impacts on the environment are a major concern, especially due to the production of salted road runoffs that induce rising of salinity of freshwater ecosystems. Some plants tolerate high salt concentrations and are able to accumulate large amounts of salt in their tissues. To protect freshwater ecosystems, constructed wetland incorporating this kind of plant could be used to treat salted road runoffs before they reached natural ecosystems. Lake Saint-Augustin, located near Quebec City (Quebec, Canada) is used as an experimental watershed area. Typha latifolia, Atriplex patula, and Spergularia canadensis have been selected and assessed for their ability to survive and grow in salted waters by accumulating salt in their tissues. Germination (20 days) experiments, recovery experiments (20 days), and chloride accumulation experiments (2 months) have been performed in a controlled environment. The three species showed no germination inhibition for salt concentrations found in the field (0, 150, 1500 mg NaCI/L). Accumulation of chloride has been found significant for all species. Typha latifolia showed the best accumulation of chloride (63 mgCl~-/g of dry mass) which corresponds to a standing stock up to 230,000 mgCl·m~2. This result is promising and supports the decision for upgrading the process to a constructed wetland.