Harvest of typical cold season submerged plant Potamogeton crispus regulating water purification capacity in wetland

Potamogeton crispus plays a key role in wetland water purification during low temperatures, but plant aging affects the water purification capacity and seasonal plant decay periodically deteriorates water quality. However, harvest strategies to mitigate this issue remain unclear. This study aims to evaluate the effects of harvest intensity and frequency on P. crispus growth and water purification performance. Results showed that plant harvest promoted biomass accumulation. With the most significant plant height observed under low-intensity (25 %) and low-frequency (1 time) plant harvest enhanced complete or partial recovery. This plant harvest mode also enhanced pollutant removal, achieving COD, NH₄⁺-N, TN, and TP removal of 54.70 %, 69.60 %, 47.20 %, and 67.30 %, respectively. In contrast, medium-high intensity (50 % and 75 %) and frequency (2 and 4 times) of plant harvest reduced water purification efficiency. Pearson correlation analysis indicated a strong link between P. crispus growth and water purification. Therefore, plant harvest 1–2 times with low harvest intensity of 25 % was recommended to enhance plant recovery and pollutant removal.