Temporal and Spatial Distribution Characteristics and Pollution Assessment of Nutrients in Sediments of Daihai Lake.

In order to reveal the spatial and temporal distribution characteristics of nutrients in Daihai Lake sediments, 36 sediment samples were collected in spring, summer,autumn and winter of 2021, and the spatio-temporal distribution characteristics of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) were studied and analyzed,and the source of organic matter in sediments was judged according to the C:N atomic ratio, and the degree of pollution was evaluated by organic nitrogen, organic index and comprehensive pollution index. The results showed that the TN content was between 1.69 and 2.79 g/kg, and the average value was (2.10±0.28) g/kg; the TP content was between 159.84 and 306.91 mg/kg, and the average value was (213.73±33.95) mg/kg; the OM content was between 29.99 and 48.16 g/kg, and the average value was (38.63± 5.19) g/kg. Spatially, TN and OM spatial distribution are similar, the lake center area > the northwest > the east, the TP spatial distribution shows the western > the eastern > lake center area;in time, TN and TP are the highest in winter, the lowest in autumn and spring, and OM are the highest in summer and lowest in winter. The C:N atomic ratio in the sediments ranged from 8.30 to 13.53, with an average value of (11.24±1.35), indicating that the organic matter in Daihai Lake sediments was mainly contaminated endogenously, and zooplankton,phytoplankton and algae were the main sources of organic matter in the sediments. Organic nitrogen and organic index show that all points of sediment belong to the organic nitrogen pollution level, and the organic index is mainly clean; The comprehensive pollution index results show that the TN pollution index and comprehensive pollution index of all points of the sediment belong to the heavy pollution level, and the TP pollution index is mainly clean. Daihai Lake sediment nitrogen load is high,with potential endogenous nitrogen release risk. [ABSTRACT FROM AUTHOR]