Distribution of nitrogen and phosphorus in water and eutrophication assessment of Dongping Lake.

Distribution of nitrogen and phosphorus in water of Dongping Lake were measured.Eutrophic status of the Lake was also assessed by integrated index.Results showed that concentration of total nitrogen ranged from 0.86 to 2.34,1.63 to 4.75 and 0.26 to 2.53mg/L for spring,summer and autumn respectively.Higher TN concentration in summer than that in autumn indicated that non-point pollution played an important role for TN in the Lake.No significant differences could be found for total phosphorus concentrations in the Lake among different seasons,with average concentration of 0.05mg/L.Result of integrated index indicated that the Lake was under the moderate eutrophication status.Ratio of nitrogen and phosphorus were higher than 7,indicating the phosphorus was the limited factor for eutrophication of the Lake.