关键词: 水功能区, 水质评价, 总磷, 污染物入河量, 纳污限排, 长江干流

Abstract: Based on the water quality monitoring data of the Yangtze River in 2016, the water quality grades, standard-attainment situation, standard-exceeding characteristics and spatial water quality variation of the Yangtze River water function zone were first analyzed. Then, based on the related planning results of the Yangtze River water function zone, the current pollutant discharge, pollutant carrying capacity and discharge limitation of chemical oxygen demand and ammonia nitrogen were analyzed from the viewpoint of water resources zoning and water function area types. Finally, the main factors affecting the water quality of the Yangtze River water function area was discussed in this paper. The results showed that double indicators standard-attainment rate of the Yangtze River water function zone was close to 95%, while all indicators standard-attainment rate was less than 65%. The standard-exceeding water function zones mainly distributed in Chongqing, Hubei, Jiangsu and Shanghai reaches and were mainly the protection area, reserve area, drinking water zone and industrial water zone. In the main stream of the Yangtze River, the per unit length inflow pollutants was the largest in industrial water area and sewage discharge control area, where the pollution was the most serious. The pollutant carrying and discharge capacity limitation of the basin should comprehensively consider the natural environmental capacity of the water body and the demand of social and economic development. At present, total phosphorus is the key factor affecting the water quality of the Yangtze River water function zone, rather than chemical oxygen demand and ammonia nitrogen. It shows that total phosphorus is gradually increasing along the Yangtze River. It is imperative to promote the evaluation of total phosphorus in the Yangtze River water function zone, thereby forcing the reduction of total phosphorus pollutants.

Key words: water function zone, water quality evaluation, total phosphorus, inflow pollutants, pollutant carrying capacity and discharge limitation, main stream of Yangtze River;