Effectiveness of various wetland vegetation species on mitigating water pollution from highway runoff.

Abstract

This study selected and tested five submerged aquatic vegetation-based (SAV) wetlands to improve highway runoff treatment in best management practices. The removal efficiencies of suspended solid (SS), chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen ( ), and total phosphorus (TP) in the five SAV wetlands were analyzed. Furthermore, the lead (Pb) and zinc (Zn) accumulation capabilities of five submerged macrophytes were determined. The obtained results show that Ceratophyllum demersum wetlands achieved the highest nutrient removal and had the heavy metal accumulation property. Vallisneria natans showed the highest bioaccumulation of Pb among all tested species. Ceratophyllum demersum wetlands showed the highest average removal efficiencies of SS (82.97%), COD (62.08%), TN (77.63%), (76.24%), TP (77.55%), Pb (96.24%), and Zn (91.23%). The tendencies of contaminant removal showed seasonal variation, and SAV wetlands performed better in summer than in spring and autumn. Consequently, SAV wetlands showed selectivity for contaminant removal. PRACTITIONER POINTS: Chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in highway runoff were removed by submerged aquatic vegetation (SAV). Ceratophyllum demersum and Myriophyllum spicatum wetlands performed well on heavy metal removing. Ceratophyllum demersum showed the highest removal efficiencies of TSS, COD, TN, , and TP. The SAV wetlands performed better in summer than in other seasons.