Distribution and source analysis of nutrients in sediments of Huangda Lake

In order to study the source of nutrients in the sediments of Huangda Lake, the surface sediments and columnar sediments were collected from 13 points in Huangda Lake. Total nitrogen (TN), total phosphorus (TP) and organic matter (OM) contents were measured, the spatial and vertical distribution of nutrients in the sediments of Huangda Lake analyzed, and the sediment pollution degree assessed. The results showed that TN concentration of the surface sediments in Huangda Lake varied from 1 112 to 3 277 mg/kg with an average value of 2 016 mg/kg, TP concentration varied from 547.19 to 784.43 mg/kg with an average value of 651.84 mg/kg, and OM concentration varied from 5.21% to 11.21% with an average value of 8.6%. The spatial distribution of TN, TP and OM showed consistency, mainly in the northwest> southeast> middle of the lake center, and the vertical concentration of TN, TP and OM generally showed a decline with depth. The pollution caused by TN and OM was more serious than that of TP, and the spatial distribution of pollution degree was consistent with the spatial distribution of TN, TP and OM. Pearson correlation analysis showed that TN and OM were significantly positively correlated, indicating that they were homologous; TP and OM were not significantly correlated, suggesting that they were poorly homologous. The average C/N ratio of the sediment was 25.43, indicating that OM in the sediment mainly came from exogenous particulate organic matter. The increase of C/P ratio and N/P ratio in the upper 20 cm of the columnar sediments indicated that nutrients in the sediment were greatly affected by human activities surrounding Huangda Lake in recent years.