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- Title
Effect of Thermal Stratification on Nitrogen and Phosphorus Release from Sediments in Daye Reservoir.
- Authors
WANG Xingju; YU Wenqing; ZHAO Huaqing; ZHAO Ranhang; ZHAO Ying; LYU Jing
- Abstract
The stratification of water temperature in the reservoir in summer and autumn has an effect on the vertical water exchange and water-sediment interface environments. In order to study the effect of stratification in summer and autumn on the release of nitrogen and phosphorus from sediments in Daye Reservoir, Jinan City, field monitoring of the reservoir was conducted, and water samples and sediments were collected from June to October 2022. The characteristics of water temperature, dissolved oxygen (DO) stratification, and the distribution of nitrogen and phosphorus nutrients were analyzed. The effects of an anoxic environment caused by thermal stratification on the release rate, migration, and transformation of nitrogen and phosphorus in sediments were studied through simulation experiments in the laboratory. The results showed that there was obvious thermal stratification in the Reservoir from June to September. In October, the stratification disappears. And the maximum water temperature difference between the surface and bottom of the reservoir is 15.6 °C. The concentration of dissolved oxygen in water appears to be stratified vertically with the formation of a thermal stratification structure. From June to August, there were hypoxic and even anaerobic phenomena in the bottom water of the reservoir. In July, the concentration of dissolved oxygen was as low as 0.84 mg/L. The content of nitrogen and phosphorus in the bottom water is significantly higher than that in the surface and middle water bodies, and the content of total nitrogen (TN) and total phosphorus (TP) in the bottom water is about 1.5 times that in the surface water and 4 times that in the middle water. Dissolved oxygen is an important driver of nitrogen and phosphorus releases from sediments. The results of simulation experiments in the laboratory showed that the release rate of total nitrogen and total phosphorus in an anaerobic environment was about 1.5 times that in an aerobic environment. Nitrogen release in sediments is mainly in the form of ammonia nitrogen (NH4+-N), and Fe-Al-binding phosphorus (Fe/Al-P) is a potential phosphorus source. Endogenous pollution in the Reservoir poses a serious risk to the water quality. This study can provide some references for reservoir water quality management and endogenous pollution risk avoidance.
- Subjects
PHOSPHORUS in water; WATER quality management; PHOSPHORUS; WATER pollution; DISSOLVED oxygen in water; BOTTOM water (Oceanography); NITROGEN; ANOXIC zones
- Publication
Environmental Science & Technology (10036504), 2023, Vol 46, Issue 10, p42
- ISSN
1003-6504
- Publication type
Article
- DOI
10.19672/j.cnki.1003-6504.0885.23.338