Analysis of Nitrogen Change Characteristics of Chao Lake and Its Inflow Rivers
Based on the monitoring data of the surface water environmental quality monitoring network of Anhui Province,the characteristics of nitrogen change of the main inflow rivers and Chao Lake were studied from 2013 to 2022.The results showed that over the past ten years,the annual average values of total nitrogen in major inflow rivers and lake body were 2.93~6.52 mg/L and 1.18~1.72 mg/L respectively,and the annual average values of ammonia nitrogen were 0.49~4.98 mg/L and 0.10~0.44 mg/L respectively.The concentrations of total nitrogen and ammonia nitrogen in the inflow rivers were much higher than those in the lake.The nitrogen in the rivers and lake bodies showed similar annual,seasonal and monthly variation characteristics.The concentrations of total nitrogen and ammonia nitrogen in the lake and the inflow rivers were higher in winter and spring,and lower in summer and fall.The new and old pollution existed simultaneously in the rivers flowing into Chao Lake.The percentage of ammonia nitrogen in heavily polluted water bodies with the fifth grade and worse than the fifth grade was high,however it was lower in water bodies with better water quality.
Chao Lakeinflow riverstotal nitrogenammonia nitrogenthe ratio of total nitrogen to ammonia nitrogen