Measurements of concentration, fluorescence, and absorbance characteristics of DOC and stable hydrogen and oxygen isotope analysis of pore water from riparian wetlands in Denmark from September 2022 to October 2023

Wetlands play an important role in carbon retention, which is greatly dependent on hydrological conditions. Therefore, the interest in wetland hydrology has increased over recent decades. In wetland hydrology, stable water isotopes (δ2H, δ18O) have found increasing use, as laser-based instruments have become readily available and allow for faster analysis and lower costs. However, the use of laser-based determinations of stable hydrogen and oxygen isotopes in wetland pore waters might be challenging because of dissolved organic carbon (DOC), especially as wetland pore waters often contain elevated DOC concentrations. To study the potential interference of DOC on laser-based stable water isotopes determination, we determined concentration, fluorescence, and absorbance characteristics of DOC in pore waters collected from six restored and six near-natural riparian wetlands. The water samples’ δ2H and δ18O values were determined by a Picarro and a Los Gatos Research laser absorption spectrometer (LAS) and, for reference, in parallel by dual-inlet isotope-ratio mass spectrometry (DI-IRMS). The two LAS methods showed significant deviations from the DI-IRMS-determinations. Studies that investigate pore waters with high DOC aromaticity but where the DOC is not characterized, and which require a high accuracy of the δ2H-values for interpretation of the hydrological system, may be severely affected by DOC interference.

[
  "010:12"
]

[
  "geospatial"
]