Abstract
We monitored stable water isotopes in liquid precipitation and atmospheric water vapour (δv) using in situ cavity ring-down spectroscopy (CRDS) over a 2 month period in an urban green space area in Berlin, Germany. Our aim was to better understand the origins of atmospheric moisture and its link to water partitioning under contrasting urban vegetation. δv was monitored at multiple heights (0.15, 2 and 10 m) in grassland and forest plots. The isotopic composition of δv above both land uses was highly dynamic and positively correlated with that of rainfall indicating the changing sources of atmospheric moisture. Further, the isotopic composition of δv was similar across most heights of the 10 m profiles and between the two plots indicating high aerodynamic mixing. Only at the surface at ~0.15 m height above the grassland δv showed significant differences, with more enrichment in heavy isotopes indicative of evaporative fractionation especially after rainfall events. Further, disequilibrium between δv and precipitation composition was evident during and right after rainfall events with more positive values (i.e., values of vapour higher than precipitation) in summer and negative values in winter, which probably results from higher evapotranspiration and more convective precipitation events in summer. Our work showed that it is technically feasible to produce continuous, longer-term data on δv isotope composition in urban areas from in situ monitoring using CRDS, providing new insights into water cycling and partitioning across the critical zone of an urban green space in Central Europe. Such data have the potential to better constrain the isotopic interface between the atmosphere and the land surface and to thus, improve ecohydrological models that can resolve evapotranspiration fluxes.
| Original language | English |
|---|---|
| Article number | e14989 |
| Number of pages | 17 |
| Journal | Hydrological Processes |
| Volume | 37 |
| Issue number | 9 |
| Early online date | 14 Sept 2023 |
| DOIs | |
| Publication status | Published - Sept 2023 |
Bibliographical note
Funding Information:This study was funded through the German Research Foundation (DFG) as part of the Research Training Group ‘Urban Water Interfaces’ (UWI; GRK2032/2) and the Einstein Foundation as part of the ‘Modelling surface and groundwater with isotopes in urban catchments’ (MOSAIC) project. Funding for Dörthe Tetzlaff was also received through the Einstein Research Unit ‘Climate and Water under Change’ from the Einstein Foundation Berlin and Berlin University Alliance (grant no. ERU‐2020‐609) and the project BiNatur (BMBF No. 16LW0156). We also acknowledge the BMBF (funding code 033W034A), which supported the stable isotope laboratory and in situ laser analyser. Contributions from Chris Soulsby have also been supported by the Leverhulme Trust through the ISO‐LAND project (grant no. RPG 2018 375). We thank all colleagues involved in the ecohydrological monitoring and daily precipitation and groundwater sampling, but in particular are grateful to Jan Christopher, Jonas Freymüller and Jessica Landgraf. Open Access funding enabled and organized by Projekt DEAL.
Publisher Copyright:
© 2023 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.Keywords
- atmospheric vapour isotopes
- cities
- ecohydrology
- equilibrium assumption
- in situ monitoring
- urban green spaces
Access to Document
- Ring_etal_HP_High-Resolution_VOR
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