Abstract: In an attempt to obtain the dynamic pollutant absorption capacity of East Dongting Lake in different hydrological and water quality conditions, a model of relationship among water level, area and volume was established according to MODIS remote sensing data in 2003-2016 and hydrological data. Some calculation parameters in the presence of different water levels, incoming flow rates, and incoming water quality indicators were acquired. According to the Code for calculation of water pollution absorption capacity, the coefficient of pollutant absorption capacity, together with the dynamic absorption capacity of COD and ammonia-nitrogen in different hydrological and water quality conditions was calculated. Authors insisted that the pollutant absorption capacity of East Dongting Lake varies with water level, discharge and water quality dynamically. The minimum absorption capacity of COD is 14 200 g/s, greater than the average emission intensity which is 1 837 g/s in 2016, brewing no risk of standard-exceeding; but the minimum absorption capacity of ammonia-nitrogen is 43 g/s, smaller than the average emission intensity which is 275 g/s in 2016, posing large risk of standard-exceeding of ammonia-nitrogen. Moreover, hydrology and water quality conditions which would result in the standard-exceeding of water quality were determined: when incoming concentration of ammonia-nitrogen stays below 0.95 mg/L, ammonia-nitrogen concentration in the Lake would not exceed standard. We concluded that (1) The established model provides support for the calculation of dynamic pollutant absorption capacity; (2) Pollutant emission could be rearranged reasonably according to the dynamic pollutant absorption capacity. (3) The incoming concentration of ammonia-nitrogen should be controlled under 0.95 mg/L in East Dongting Lake.

Key words: pollutant absorption capacity, East Dongting Lake, relationship among water level, area and volume, hydrology and water quality, ammonia-nitrogen