Evaporation fractionation in a peatland drainage network affects stream water isotope composition

Matthias Sprenger, Doerthe Tetzlaff, Claire Tunaley, Jonathan Dick, Chris Soulsby

Research output: Contribution to journalArticle

33 Citations (Scopus)
5 Downloads (Pure)

Abstract

There is increasing interest in improving understanding of evaporation within a catchment for an enhanced representation of dominant processes in hydrological models. We used a dual-isotope approach within a nested experimental design in a boreal catchment in the Scottish Highlands (Bruntland Burn) to quantify the spatio-temporal dynamics of evaporation fractionation in a peatland drainage network and its effect on stream water isotopes. We conducted spatially distributed water sampling within the saturated peatland under different wetness conditions. We used the lc-excess – which describes the offset of a water sample from the local meteoric water line in the dual-isotope space - to understand the development of kinetic fractionation during runoff in a peatland network. The evaporation fractionation signal correlated positively with the potential evapotranspiration and negatively with the discharge. The variability of the isotopic enrichment within the peatland drainage network was higher with higher potential evapotranspiration and lower with higher discharge. We found an increased evaporation fractionation towards the center of the peatland, while groundwater seepage from minerogenic soils influenced the isotopic signal at the edge of the peatland. The evaporation signal was imprinted on the stream water, as the discharge from a peatland dominated sub-catchment showed a more intense deviation from the local meteoric water line than the discharge from the Bruntland Burn. The findings underline that evaporation fractionation within peatland drainage networks affects the isotopic signal of headwater catchments, which questions the common assumption in hydrological modelling that the isotopic composition of stream waters did not undergo fractionation processes. This article is protected by copyright.
Original languageEnglish
Pages (from-to)851-866
Number of pages16
JournalWater Resources Research
Volume53
Issue number1
Early online date15 Dec 2016
DOIs
Publication statusPublished - Jan 2017

Fingerprint

drainage network
peatland
fractionation
evaporation
isotope
catchment
water
potential evapotranspiration
meteoric water
shoreline
hydrological modeling
headwater
experimental design
seepage
isotopic composition
runoff
kinetics
groundwater
sampling

Keywords

  • Catchment
  • Wetlands
  • Evapotranspiration
  • Overland flow
  • Stable isotopes

Cite this

Evaporation fractionation in a peatland drainage network affects stream water isotope composition. / Sprenger, Matthias; Tetzlaff, Doerthe; Tunaley, Claire; Dick, Jonathan; Soulsby, Chris.

In: Water Resources Research, Vol. 53, No. 1, 01.2017, p. 851-866.

Research output: Contribution to journalArticle

@article{98c99cded5454acb8a02f69ba38a5b6f,
title = "Evaporation fractionation in a peatland drainage network affects stream water isotope composition",
abstract = "There is increasing interest in improving understanding of evaporation within a catchment for an enhanced representation of dominant processes in hydrological models. We used a dual-isotope approach within a nested experimental design in a boreal catchment in the Scottish Highlands (Bruntland Burn) to quantify the spatio-temporal dynamics of evaporation fractionation in a peatland drainage network and its effect on stream water isotopes. We conducted spatially distributed water sampling within the saturated peatland under different wetness conditions. We used the lc-excess – which describes the offset of a water sample from the local meteoric water line in the dual-isotope space - to understand the development of kinetic fractionation during runoff in a peatland network. The evaporation fractionation signal correlated positively with the potential evapotranspiration and negatively with the discharge. The variability of the isotopic enrichment within the peatland drainage network was higher with higher potential evapotranspiration and lower with higher discharge. We found an increased evaporation fractionation towards the center of the peatland, while groundwater seepage from minerogenic soils influenced the isotopic signal at the edge of the peatland. The evaporation signal was imprinted on the stream water, as the discharge from a peatland dominated sub-catchment showed a more intense deviation from the local meteoric water line than the discharge from the Bruntland Burn. The findings underline that evaporation fractionation within peatland drainage networks affects the isotopic signal of headwater catchments, which questions the common assumption in hydrological modelling that the isotopic composition of stream waters did not undergo fractionation processes. This article is protected by copyright.",
keywords = "Catchment, Wetlands, Evapotranspiration, Overland flow, Stable isotopes",
author = "Matthias Sprenger and Doerthe Tetzlaff and Claire Tunaley and Jonathan Dick and Chris Soulsby",
note = "We would like to thank the European Research Council (ERC, project GA 335910 VeWa) and Natural Environment Research Council NERC (project NE/K000268/1) for funding. We also want to thank Dr. Christian Birkel for the initial spatial distributed surveys of the tracers. The data is available from the corresponding author upon request. We thank the Associate editor and three anonymous reviewers for their feedback during the peer-review process.",
year = "2017",
month = "1",
doi = "10.1002/2016WR019258",
language = "English",
volume = "53",
pages = "851--866",
journal = "Water Resources Research",
issn = "0043-1397",
publisher = "American Geophysical Union",
number = "1",

}

TY - JOUR

T1 - Evaporation fractionation in a peatland drainage network affects stream water isotope composition

AU - Sprenger, Matthias

AU - Tetzlaff, Doerthe

AU - Tunaley, Claire

AU - Dick, Jonathan

AU - Soulsby, Chris

N1 - We would like to thank the European Research Council (ERC, project GA 335910 VeWa) and Natural Environment Research Council NERC (project NE/K000268/1) for funding. We also want to thank Dr. Christian Birkel for the initial spatial distributed surveys of the tracers. The data is available from the corresponding author upon request. We thank the Associate editor and three anonymous reviewers for their feedback during the peer-review process.

PY - 2017/1

Y1 - 2017/1

N2 - There is increasing interest in improving understanding of evaporation within a catchment for an enhanced representation of dominant processes in hydrological models. We used a dual-isotope approach within a nested experimental design in a boreal catchment in the Scottish Highlands (Bruntland Burn) to quantify the spatio-temporal dynamics of evaporation fractionation in a peatland drainage network and its effect on stream water isotopes. We conducted spatially distributed water sampling within the saturated peatland under different wetness conditions. We used the lc-excess – which describes the offset of a water sample from the local meteoric water line in the dual-isotope space - to understand the development of kinetic fractionation during runoff in a peatland network. The evaporation fractionation signal correlated positively with the potential evapotranspiration and negatively with the discharge. The variability of the isotopic enrichment within the peatland drainage network was higher with higher potential evapotranspiration and lower with higher discharge. We found an increased evaporation fractionation towards the center of the peatland, while groundwater seepage from minerogenic soils influenced the isotopic signal at the edge of the peatland. The evaporation signal was imprinted on the stream water, as the discharge from a peatland dominated sub-catchment showed a more intense deviation from the local meteoric water line than the discharge from the Bruntland Burn. The findings underline that evaporation fractionation within peatland drainage networks affects the isotopic signal of headwater catchments, which questions the common assumption in hydrological modelling that the isotopic composition of stream waters did not undergo fractionation processes. This article is protected by copyright.

AB - There is increasing interest in improving understanding of evaporation within a catchment for an enhanced representation of dominant processes in hydrological models. We used a dual-isotope approach within a nested experimental design in a boreal catchment in the Scottish Highlands (Bruntland Burn) to quantify the spatio-temporal dynamics of evaporation fractionation in a peatland drainage network and its effect on stream water isotopes. We conducted spatially distributed water sampling within the saturated peatland under different wetness conditions. We used the lc-excess – which describes the offset of a water sample from the local meteoric water line in the dual-isotope space - to understand the development of kinetic fractionation during runoff in a peatland network. The evaporation fractionation signal correlated positively with the potential evapotranspiration and negatively with the discharge. The variability of the isotopic enrichment within the peatland drainage network was higher with higher potential evapotranspiration and lower with higher discharge. We found an increased evaporation fractionation towards the center of the peatland, while groundwater seepage from minerogenic soils influenced the isotopic signal at the edge of the peatland. The evaporation signal was imprinted on the stream water, as the discharge from a peatland dominated sub-catchment showed a more intense deviation from the local meteoric water line than the discharge from the Bruntland Burn. The findings underline that evaporation fractionation within peatland drainage networks affects the isotopic signal of headwater catchments, which questions the common assumption in hydrological modelling that the isotopic composition of stream waters did not undergo fractionation processes. This article is protected by copyright.

KW - Catchment

KW - Wetlands

KW - Evapotranspiration

KW - Overland flow

KW - Stable isotopes

U2 - 10.1002/2016WR019258

DO - 10.1002/2016WR019258

M3 - Article

VL - 53

SP - 851

EP - 866

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

IS - 1

ER -