Cold Temperature Effects on Long-Term Nitrogen Transformation Pathway in a Tidal Flow Constructed Wetland

摘要

The present study investigated long-term treatment performance and nitrogen transformation mechanisms in tidal flow constructed wetlands (TFCWs) under 4, 8, and 12 ℃ temperature regimes. High and stable ammonium (NH_4~+-N) removal efficiency (93-9696) was achieved in our TFCWs, whereas nitrate (NO_3~--N) was accumulated at different levels under different temperatures. Quantitative response relationships showed anammox/amoA, (narG +napA)/amoA, and (narG+napA)/bacteria were the respective key functional gene groups determining 4, 8, and 12 ℃ NO_3~--N reduction. Pathway analysis revealed the contribution of these functional gene groups along a depth gradient In addition, denitrification process increased, while anammox process decreased consistent with a rise in temperature from 4 to 12 ℃. Furthermore, cold temperatures exhibited different effects on anammox and denttrification and their long-term acclimatization capacities changed with temperature.