Abstract

To investigate the biogeochemical properties of nitrogen and phosphorus, to calculate the loads of these nutrients, and to evaluate their effects on water quality, surface sediment and water samples were taken from Daihai Lake. Total Phosphorus (TP), Total Nitrogen (TN), and various nitrogen forms in sediments were examined, as well as their regional distributions. TN and TP concentrations in surface sediments were found to range from 0.27 to 1.78 g/kg and from 558.31 to 891.29 mg/kg, respectively, according to the results. The C: N ratios ranged from 8.2 to 12.1, which showed that the majority of the nitrogen collected, came from terrestrial sources. All sampling sites had N: P ratios that were less than 10, indicating that N was the limiting nutrient for algae development in this lake. An impact of it was also determined what effects the environment has on the release of nitrogen and phosphorus in lake sediments; high pH levels may facilitate the release of nitrogen and phosphorus. To determine the trophic classification of the studied lake, modified Carlson’s Trophic State Index (TSIM) and Comprehensive Trophic State Index (TSIC) were used. The values of TSIM and TSIC ranged from 53.72 to 70.61 and from 47.73 to 53.67, respectively, indicating that the Daihai Lake was in the stage of hypereutropher.