U.S. project uses wetlands as massive water filters

摘要

Engineered wetlands, also called constructed or artificial wetlands, have long been used to treat municipal and low-grade industrial waste water as it passes through marshes in a controlled flow. Wetlands are a low-cost, low-maintenance technology relying on the passive role of sedimentation and biomass uptake of water-borne pollutants. Near agricultural areas, they are successful in removing excess nutrients, particularly nitrogen and phosphorus. They thus prevent eutrophication, or oxygen depletion which can lead to changes in vegetation, to fish die-off, and the eventual biological death of downstream water bodies.