Impact of urbanization and land use on wetland water quality: A case study in Mengxi town

Wetlands provide critical ecological functions but are facing increasing threats from urbanization. This study assessed the impact of differentiated urban development approaches on wetland water quality in Mengxi town, Hangzhou, China. Water samples were collected from 48 locations in the Wuchang and Hemu wetlands from September 2021 to March 2022, covering different seasons. Parameters including COD, TN, TP, and NH4+-N were analyzed. The results showed the inlet water quality was heavily degraded, with NH4+-N concentrations up to 4.8 mg/L in January. The Hemu wetland showed improved water quality due to dilution effects after convergence of the two inlet rivers. However, NH4+-N and TN remained problematic, with average concentrations of 5.49 mg/L and 5.13 mg/L, exceeding the controlled standards. Statistical analysis identified paddy fields as the dominant contributor of TN (51%) and TP (41%) loads. The area contained 73.5% of total paddy fields obsereverd highest pollution levels. The results highlight the need for targeted agricultural runoff control and land use planning to conserve wetland ecological functions. This study provides important insights on differentiated impacts of urban development models on wetlands in southern China. The findings contribute to effective policy making for wetland water quality protection under rapid urbanization.