Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1002/hyp.70383 |
Licence  |
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| Title (Primary) | Effects of a perennial drought on nitrate fate in an agriculturally dominated mesoscale catchment as constrained by stable isotope investigations |
| Author | Mueller, C.; Krieg, R.; Merz, R.; Knöller, K. |
| Source Titel | Hydrological Processes |
| Year | 2026 |
| Department | CATHYD |
| Volume | 40 |
| Issue | 1 |
| Page From | e70383 |
| Language | englisch |
| Topic | T5 Future Landscapes T4 Coastal System |
| Keywords | climate; drought; extremes; hydrology; nitrate; stable isotopes |
| Abstract |
Especially in the years 2018 to 2020, a severe drought
was observed in central Germany. To explore the potential impact of this
drought on the catchment-scale nitrogen cycling, we investigated the
ground- and surface-water compartments of the Holtemme watershed, a
mesoscale river catchment in the Harz Mountains, Germany. Analysis of
nitrate concentrations and corresponding isotope signatures for
groundwater and surface water samples was conducted throughout the
drought period and continued until discharge conditions returned to the
long-term mean in early 2021. The study revealed a pronounced decline in
nitrate concentrations in both compartments during the drought, with
groundwater showing an average reduction of ~60%, and surface water
exhibiting a wide range of changes from +32% to −59% (mid- and
downstream decreasing from 19.4 to 2.3 mg L−1). In the post-drought period, surface-water nitrate concentrations increased sharply, reaching values up to 18.3 mg L−1.
Isotope investigations allowed us to distinguish between different
nitrate sources and microbial turnover processes. Time series analysis
of δ15N–NO3 showed regular oscillations within the
year ranging from 2‰ to 20‰ (AIR), illustrating a periodic organic
fertiliser applications. Corresponding δ18O–NO3
signatures showed higher, seasonally independent variations, with a mean
of 6‰ (VSMOW), which can be explained by the expected isotope
variability of the ambient water during nitrification. However, flow
paths for nitrate mobilisation into the surface water appear to be
unaffected by the drought, as the contributions of each nitrate source
decreased equally during the dry period. Nitrate concentrations
increased markedly after the drought, regardless of the recent nitrate
supply, reaching values of up to 20 mg L−1 in 2022. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=31858 |
| Mueller, C., Krieg, R., Merz, R., Knöller, K. (2026): Effects of a perennial drought on nitrate fate in an agriculturally dominated mesoscale catchment as constrained by stable isotope investigations Hydrol. Process. 40 (1), e70383 10.1002/hyp.70383 |
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