Based on the results of sample measurement of nutrient concentrations in the Yangtze River at Datong station in the year 1997 and 1998, combined with historical data of water quality, variations of nitrogen and phosphorus contents and the nutrient loads in the flood of 1998 were discussed. The mean concentration of total nitrogen (TN) were 1 6~2 2mg/L, and NO - 3 N accounted for 76 percent and the other forms mainly were dissolved orgunic nitrogen (DON) and particle nitrogen (PN); mean content of total...