Characterizing the impact of reservoir storage and discharge on nitrogen dynamics in an upstream wetland using a δ15N and δ18O dual-isotope approach

Kang, Pingping; Xu, Jie; Wang, Fuqiang; Zhang, Honglu; Zhao, Heng

doi:10.1016/j.scitotenv.2024.172923

Cited by 2 publications

(1 citation statement)

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“…The release of N nutrients from the sediment is limited (Figure 5) (Pan et al, 2008) due to the reduced mineralization, which is suppressed by the low temperature. Conversely, the transfer of DIN from the water column to the sediment is large (Figure 5c) due to the high water pressure (Kang et al, 2024). This shift, combined with the low potential for coupled nitrification-denitrification, controlled by the low TSS concentrations (Figure 2c), maintains relatively stable concentrations of DIN and ON in the overlying water.…”

Section: Hydrological Mechanisms Associated With N Cyclingmentioning

confidence: 99%

Nitrogen Cycling in Reservoir Drawdown Areas and the Impacts on Water Quality

Liu,

Chen,

Maavara

et al. 2024

Global Biogeochemical Cycles

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Reservoir drawdown areas (DAs) can be both important nitrogen (N) sources to river networks and hot spots for N removal from freshwater ecosystems. The net effect of DAs on the N availability in reservoirs within a full hydrological cycle remains unclear. In this paper, the N dynamics in the DA of the Three Gorges Reservoir, Yangtze River, China, are investigated through a combination of discrete and continuous in situ observations and sampling over a span of 2 years, complemented by numerical modeling. We show that the DA is a net source of N to the water column, and that about 30% of the total annual N load released from the DA is mitigated by the sediment through denitrification and capture. The annual net load of the total N from the DA to the reservoir is ca. 0.59 kg per meter along the river, which is on the same order of magnitude as the input load from the density current of the Yangtze River to its tributaries, generally considered to be the primary driver of eutrophication in tributaries. N release in the DA mainly occurs during the drying period, whereas denitrification in the sediment mostly takes place during the flooding period when the oxido‐reducing potential is low. Our findings quantify and therefore clarify the N source/sink dynamics from the DA to the reservoir, offering a new perspective on the importance of DA nutrient loading in decision‐making related to integrated management of inundated lands to alleviate reservoir eutrophication by river damming.

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Section: Hydrological Mechanisms Associated With N Cyclingmentioning

confidence: 99%