Removal of Glyphosate in Agricultural Runoff Using Subsurface Constructed Wetlands in Monocultures and Polycultures of Tropical Plants

Glyphosate (GLY) is the most widely used herbicide in agriculture worldwide, posing a significant contamination risk to rivers, lakes, wetlands, and soils. Its ultimate fate represents a potential threat to the health of both terrestrial and aquatic ecosystems. This study evaluated the removal efficiency of glyphosate and conventional pollutants in mesocosm-scale horizontal subsurface flow-constructed wetlands planted with Canna indica, Heliconia psittacorum, and Alpinia purpurata in runoff water contaminated with glyphosate. Additionally, the study examined the performances of these species in monoculture and polyculture settings of tropical ornamental plants. Canna indica exhibited the highest growth (up to 160 cm) in both monoculture and polyculture conditions, as well as the highest removal efficiencies for total nitrogen (TN), total phosphorus (TP), and phosphate (PO43⁻), achieving a 91%, 93%, and 98% removal, respectively. Polyculture systems demonstrated a superior ammonium removal efficiency, reaching 94%. Alpinia purpurata (>5 ppm after 40 days) and Heliconia psittacorum (>5 ppm after 200 days) were the most effective species for glyphosate removal. Glyphosate can be effectively removed from aquatic environments through constructed wetlands planted with ornamental species, offering a sustainable approach to mitigating herbicide contamination in water bodies.