Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.1029/2022WR032329
Lizenz creative commons licence
Titel (primär) Disentangling in-stream nitrate uptake pathways based on two-station high-frequency monitoring in high-order streams
Autor Zhang, X.; Yang, X.; Hensley, R.; Lorke, A.; Rode, M.
Quelle Water Resources Research
Erscheinungsjahr 2023
Department ASAM
Band/Volume 59
Heft 3
Seite von e2022WR032329
Sprache englisch
Topic T5 Future Landscapes
Keywords high-order streams; nitrate uptake pathways; high-frequency measurements; two-station approach; diel patterns
Abstract In-stream nitrate (NO3-) uptake in rivers involves complex autotrophic and heterotrophic pathways, which often vary spatiotemporally due to biotic and abiotic drivers. High-frequency monitoring of NO3- mass balance between upstream and downstream measurement sites can quantitatively disentangle multi-path NO3- uptake dynamics at the reach scale. However, this approach remains limited to a few river types and has not been fully explored for higher-order streams with varying hydro-morphological and biogeochemical conditions. We conducted two-station 15-min monitoring in five high-order stream reaches in central Germany, calculating the NO3--N mass balance and whole-stream metabolism based on time series of NO3--N and dissolved oxygen, respectively. With thorough considerations of lateral inputs, the calculated net NO3--N uptake rates (UNET) differed substantially among campaigns (ranging from -151.1 to 357.6 mg N m2 d-1, with cases of negative values representing net NO3--N release), and exhibited higher UNET during the post-wet season than during the dry season. Subtracting autotrophic assimilation (UA, stoichiometrically coupled to stream metabolism) from UNET, UD represented the net balance of heterotrophic NO3--N uptake (UD > 0, the dominance of denitrification and heterotrophic assimilation) and NO3--N release (UD < 0, the dominance of nitrification/mineralization). This rarely reported uptake pathway contributed substantially to UNET patterns, especially during post-wet seasons; moreover, it appeared to exhibit various diel patterns, and for UD > 0, diel minima occurred during the daytime. These findings advance our understanding of complex reach-scale N-retention processes and can help develop future modeling concepts at the river-network scale.
dauerhafte UFZ-Verlinkung
Zhang, X., Yang, X., Hensley, R., Lorke, A., Rode, M. (2023):
Disentangling in-stream nitrate uptake pathways based on two-station high-frequency monitoring in high-order streams
Water Resour. Res. 59 (3), e2022WR032329 10.1029/2022WR032329