Chronic increasing nitrogen and endogenous phosphorus release from sediment threaten to the water quality in a semi-humid region reservoir

• Published in: The Science of the total environment Vol. 931; p. 172924
• Main Authors: Shou, Chen-Yang, Yue, Fu-Jun, Zhou, Bin, Fu, Xujin, Ma, Zhuo-Ni, Gong, Yao-Qi, Chen, Sai-Nan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.06.2024
• Subjects: Eutrophication; Sediment N and P; Spatial distribution; Yuqiao Reservoir; Spatial distribution; Sediment N and P; Eutrophication; Yuqiao Reservoir
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.172924

The water quality in the drinking water reservoir directly affects people's quality of life and health. When external pollution input is effectively controlled, endogenous release is considered the main cause of water quality deterioration. As the major nitrogen (N) and phosphorus (P) sources in reservoirs, sediment plays a vital role in affecting the water quality. To understand the spatial and temporal variation of N and P in the sediment, this study analyzed the current characteristics and cumulative effects of a semi-humid reservoir, Yuqiao Reservoir, in North China. The N and P concentrations in the reservoir sediment were decreased along the flow direction, while the minimum values were recorded at the central sediment profile. External input and algal deposition were the main factors leading to higher sediment concentrations in the east (Re-E) and west (Re-W) areas of reservoir sediment profiles. According to the long-term datasets, the peaks of both sediment total nitrogen content and deposition rate were observed in the 2010s, which has increased about three times and six times than in the1990s, respectively. Therefore, the increase in phosphorus concentration may be the main reason for eutrophication in water in recent years. The mineralization of organic matter has a significant promoting effect on releasing N and P from sediments, which will intensify eutrophication in water dominated by P and bring huge challenges to water environment management. This study highlights that the current imbalance in N and P inputs into reservoirs and the endogenous P release from sediment will have a significant impact on water quality. [Display omitted] •The N and P levels in studied reservoir sediment increased during the past 10 years.•River input and algae deposition regulated spatial variation of sediment nutrients.•OM content increase may promote the release of N and P from sediment.•High N concentration promoted the release of P in reservoir sediment.•P release will be enhanced when N and P imbalanced input to reservoir.