Comprehensive study of the occurrence and characteristics of organic matter, nitrogen, and phosphorus in sediments and riparian soils of a large drinking water reservoir

The contamination of nutrients has caused considerable worry about the environment, resource value, and ecological worth of drinking water reservoirs. Therefore, we comprehensively studied the abundance, sources, distribution, and environmental behavior of carbon, nitrogen, and phosphorus in Fengshuba Reservoir (FSBR) (a large drinking reservoir, China). A graded leaching technique (introduced in 2003), the European Standard, Measurement and Testing (SMT) protocol, and spectrometry combined with parallel factor analysis (EEMs-PARAFAC) were used to assess nitrogen, phosphorus forms, and spectra data in the sediment and soil phases, respectively. The study demonstrates that seasonal hydrological variation had no significant effect on the nutrient abundance and nutrient structure composition of the FSBR, while different environmental media (e.g., sediment and soil phase) exhibited considerable differences in nutrient abundance, composition, and environmental behavior. The abundance of colored dissolved organic matter (CDOM), as well as molecular weight, aromatization degree, and humification degree of dissolved organic matter (DOM) were all lower in sediments than in soils, whereas the authigenic component was greater than in soils. Microbial-derived humus (C1), terrestrial-derived humus (C2), and protein-like tryptophan (C3) were identified as the three primary fluorescence components. Principal component analysis indicated that three components were closely associated with phosphorus in the sediment phase, whereas nitrogen and phosphorus in the soil phase were mainly related to C1 and C2. In summary, soil media (drawdown area) must be carefully considered in the management and control of water environment nutrients in reservoirs.