Isotopes in the unsaturated zone: new opportunities and ... · 5/24/2019 · Isotopes in the...
Transcript of Isotopes in the unsaturated zone: new opportunities and ... · 5/24/2019 · Isotopes in the...
Isotopes in the unsaturated zone:new opportunities and challenges
Prof. Dr. Christine Stumpp
Institute for Soil Physics and Rural Water ManagementUniversity of Natural Resources and Life Sciences Vienna (BOKU)
International Symposium on Isotope Hydrology: Advancing the Understanding of Water Cycle Processes, Vienna, 20.05.-24.05.2019
Importance of unsaturated zone processes
• main part of critical zone
• water storage
• groundwater recharge
• ecosystem
• protection of aquifers
complex and heterogeneous
transient water flow and transport
water ages
(Lin, 2010, HESS)
Demographics of water in the critical zone
• wide range of different water ages
• strong influence of mixing at interfaces
• younger ages in soils and unsaturated zone
oxygen and hydrogen isotopes
tracer for age dating
hydrological processes
(Sprenger, Stumpp, Weiler et al, in press, Rev Geophys)
52 104 158 time [weeks]
δ18O
[‰]
-12
-
10
-8
-6
-4
precipitation
52 104 158 time [weeks]
δ18O
[‰]
-12
-
10
-8
-6
-4
precipitation
soil 1m
52 104 158 time [weeks]
δ18O
[‰]
-12
-
10
-8
-6
-4
precipitation
soil 1m
shallowgroundwater
Oxygen and hydrogen isotopes
• water fluxes and transit times• transport processes
analysis of isotopes in pore water extraction of water from variable saturated pores
Suction cups and lysimeter• apply „suction“
• matric potential controlled
• collect drainage
mobile water draining poresaccording waterretention function
mobile water
• interlaboratory comparison study• soils spiked with water of known isotopic composition
• 2 soils with different texture• 2 different water contents
compare different lab protocols best pratice
Cryogenic water extraction
(Orlowski et al. 2018, HESS)
• deviation from known isotope value• most pronounced for clayey loam and low water content
Cryogenic water extraction
(Orlowski et al. 2018, HESS)
all laboratories withdifferent results
procedure independent
development of protocols lab comparison test
Direct vapour equilibration method
• no extraction of pore water required
• measurement of isotopes in vapor phase
(Wassenaar et al. 2008, ES&T)
water – minutessoil – min. to days
Challenges of direct vapour equilibration method– Bag type and water loss
gree: crystal clear bagsblue: Ziploc bagsred: mylar bagsblack: black bagspurple: IsoPakspale blue: silver puches
(Hendry et al. 2015, HESS)
Challenges of direct vapour equilibration method– Bag type and water loss
gree: crystal clear bagsblue: Ziploc bigasred: mylar bagsblack: black bagspurple: IsoPakspale blue: silver puches
(Hendry et al. 2015, HESS)
Challenges of direct vapour equilibration method– Gas changes in bags
(Gralher et al., 2018, VZJ)
carrier gas changes need to be avoided correction of apparent evaporation effect
• build up of CO2 in bags
• bias of isotope readings
• different for oxygen and hydrogen
Challenges of direct vapour equilibration method– Gas changes in bags
(Gralher et al., 2018, VZJ)
carrier gas changes need to be avoided correction of apparent evaporation effect
• build up of CO2 in bags
• bias of isotope readings
• different for oxygen and hydrogen
Visit poster –Benjamin Gralher
In-situ equilibration techniques
(Rothfuss et al. 2013, WRR)
(Volkmann et al. 2014, HESS)
(Gaj et al. 2016, HESS)
(Volkmann et al. 2016, Plant Cell Environ)
• gas permeable tubings or other materials• pore water and xylem
high resolution sampling dynamic processes in soil hydrology and ecohydrology
polypropylen tubing
Examples - isotope depth profiles
(Chesnaux & Stumpp HSJ, 2018)
vegetationno vegetation
mathematical modelling for more detail information about flow and transport
• quantification of average recharge rates • identification of infiltation events
Mathematical modelling approaches
spatially explicit approach• Richards equation• convection-dispersion equation• e.g. HYDRUS
pro: - physically based- detailed information
con: - number of parameter- limitations for upscaling
spatially integrated approach• input – output relationship• unsaturated zone = black box
• transit time distribution functions• StorAge Selection funtions
pro: - reduction of complexity- upscaling
con: - reduction of complexity- uncertainty
isotopes increase informationcontent for inverse modelcalibration
isotopes are good tracer to testreliabilty of spatially integratedmodel approaches
Spatially explicit approach - inverse estimation of soil hydraulic and transport parameters
Optimization strategy
BOS1: θ + ψ
BOS2: ψ + δ
2SOS: θ + ψ; δ
MOS: θ + ψ + δ
(Groh et al. 2018, Vadose Zone J)
(picture: Pütz et al. 2018, VZJ)
• 6 lysimeter
• replicates
• HYDRUS-1D
flow and transport
informationcontent
optimizationstrategy
Spatially explicit approach - inverse estimation of soil hydraulic and transport parameters
Optimization strategy
BOS1: θ + ψ
BOS2: ψ + δ
2SOS: θ + ψ; δ
MOS: θ + ψ + δ
(Groh et al. 2018, Vadose Zone J)
• best optimization when water content, matric potential and isotopes are given
isotopes add information about water flow and transport
Application of lumped parameter modelapproach to describe transport in soils
( ) outoutiN
iieff
iiiinp
P
PNtC δδδα+−⋅
⋅⋅=
∑=1
)(
(Stumpp et al., 2009, J Hydro)• general pattern of flow and transport• not every precipitation event contributes to recharge
modify input function accounting for actual evapotranspiration
Application of lumped parameter modelapproach to describe transport in soils
(Stumpp et al., 2009c, J Hydro)(Stumpp and Maloszewski 2010, J Hydro)
PRO
BAB
ILIT
Y
• lumped model simultation similar to transient model• vegetation periods investigated separately transit time distributions are vegetation specific, tool for vulnerability assessment
Application of StoreAge selection functions todescribe transport
(Benettin, personal communication)
Application of StoreAge selection functions todescribe transport
(Benettin, personal communication)
Application of StoreAge selection functions todescribe transport in soils
(Asadollahi et al. submitted)
• 2 lysimeter
• artifical and environmental tracer
• SAS function
• HYDRUS-1D
model performance
variable mean transit times in Q and ET
Application of StoreAge selection functions todescribe transport in soils
(Asadollahi et al. submitted)• similar model performance• both lysimeter with similar SAS functions
fitting of SAS function providesphysically meaningful results
similar toADE withPe =10
Variable mean transit times and partioning ofprecipitation
(Asadollahi et al. submitted)
• similar mean transit times in drainage
Variable mean transit times and partioning ofprecipitation
(Asadollahi et al. submitted)
partioning of P in Q and ET
• similar mean transit times in drainage• different mean transit times in ET
• H1D: roots only in upper soil• SAS: entire water volume accessible
verification of ET not possible due tomissing tracer concentration
(Asadollahi et al. submitted)
transit times and partioning crucialfor ecohydrology and biogeochemistry
Current challenges
1) how can our methods for analysis of pore water isotopes getmore accurate?
• analysis of different pore water (mobile vs bulk)
• use of standard operating procedures
• reduce uncertainties
• awareness of uncertainties
(Gralher et al. 2018, VZJ)
development of protocols/SOPs lab comparison test
Current challenges
1) how can our methods for analysis of pore water isotopes getmore accurate?
2) how to upscale processes from the plot to the regional scale?
• choice of model complexity
• isotopes for model calibration and validation
mathematicl model development upscaling of uncertainties
(Asadollahi et al. submitted)
Current challenges
1) how can our methods for analysis of pore water isotopes getmore accurate?
2) how to upscale processes from the plot to the regional scale?
3) how to integrate time scales across compartments and at compartment interfaces?
• limitations of using stable isotopes for older ages
• high-resolution data
(Sprenger et al. in press, Rev Geophys)
multi-tracer approaches in-situ measurement of tracers
Future opportunities• which precipiation is really used by plants?
in-situ measurement of water isotopes in soilsand transpired water
partioning between evaporation and transpiration
improvement of root water uptake processes andsimulations
• how does climate impact hydrological, ecological andchemical processes in soils?
mutual feedback mechanisms
combination of isotopes approaches
combination of experiments and modelling
(Sprenger et al. in press, Rev Geophys) interdisiciplinary approaches and methodologies
Water ages in the hydrological cycleBlack Forest Autumn School
27.-31. October 2019Waldhotel Zollernblick, Freudenstadt, Germany
We will teach approaches, methods and models to determine water fractions, water ages and transit times throughout the hydrological cycle and we will foster inter-disciplinary discussions.
Course LecturerMarkus Weiler, University Freiburg, Germany
Christine Stumpp, BOKU Vienna, AustriaJames Kirchner, ETH Zürich, Switzerland
Matthias Sprenger, North Carolina State University, USAMarkus Hrachowitz, TU Delft, Netherlands
Paolo Benettin, EPFL Lausanne, Switzerland
Acknowledgement- Asadollahi, M., Stumpp, C., Rinaldo, A., and Benettin, P. (submitted) Transport and water age dynamics in soils: a comparative study of spatially integrated and spatially explicit
models. Water Resources Research
- Chesnaux, R., and Stumpp C. (2018) Advantages and challenges of using soil water isotopes for assessing groundwater recharge: Illustration with a field study located in Canada, Hydrological Sciences Journal 63, 679-695, doi: 10.1080/02626667.2018.1442577
- Gralher, B., Herbstritt, B., Weiler, M., Wassenaar, L.I., and Stumpp, C. (2018) Correcting for biogenic gas matrix effects on laser-based porewater-vapor stable isotope measurements. Vadose Zone Journal 17, 170157, doi:10.2136/vzj2017.08.0157
- Groh J., Stumpp C., Lücke A., Pütz T., Vanderborght J. & Vereecken H. (2018) Inverse Estimation of Soil Hydraulic and Transport Parameters of Layered Soils from Water Stable Isotope and Lysimeter Data. Vadose Zone Journal 17, 170168, DOI:10.2136/vzj2017.09.0168
- Orlowski, N., Breuer, L., Angeli, N., Boeckx, P., Brumbt, C., Cook, C. S., Dubbert, M., Dyckmans, J., Gallagher,B., Gralher, B., Herbstritt, B., Hervé-Fernández,P., Hissler, C., Koeniger, P., Legout, A., Macdonald, C. J., Oyarzún, C., Redelstein, R., Seidler, C., Siegwolf, R., Stumpp, C., Thomsen, S., Weiler, M., Werner, C. and McDonnell, J. J. (2018) Inter-laboratory comparison of cryogenic water extraction systems for stable isotope analysis of soil water. Hydrology and Earth System Sciences 22, 3619-3637, doi: 10.5194/hess-22-3619-2018
- Sprenger, M., Stumpp, C., Weiler, M., Aeschbach, W., Allen, S.T., Benettin, P., Dubbert, M., Hartmann, A., Hrachowitz, M., Kirchner, J.W., McDonnell, J.J., Orlowski, N., Penna, D., Pfahl, S., Rinderer, M., Rodriguez, N., Schmidt, M., and Werner, C. (in press) The demographics of water: A review of water ages in the critical zone. Reviews of Geophysics
- Stumpp C., Stichler W. & Maloszewski P. (2009) Application of the environmental isotope d18O to study water flow in unsaturated soils planted with different crops: Case study of a weighable lysimeter from the research field in Neuherberg, Germany. Journal of Hydrology, 368(1-4), 68-78
- Stumpp, C. and Maloszewski, P. (2010) Quantification of preferential flow and flow heterogeneities in an unsaturated soil planted with different crops using the environmental isotope d18O. Journal of Hydrology, 394, 407-415
References- Gaj, M., M. Beyer, P. Koeniger, H. Wanke, J. Hamutoko and T. Himmelsbach. 2016. In situ unsaturated zone water stable isotope (2H and 18O) measurements in semi-arid environments:
a soil water balance. Hydrol. Earth Syst. Sci. 20: 715-731. doi:10.5194/hess-20-715-2016.
- Hendry, M.J., E. Schmeling, L.I. Wassenaar, S.L. Barbour and D. Pratt. 2015. Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapour equilibration laser spectrometry method. Hydrology and Earth System Sciences 19: 4427-4440. doi:10.5194/hess-19-4427-2015.
- Lin, H. (2010) Earth’s Critical Zone and hydropedology: concepts, characteristics, and advances. HESS 14, 25-45
- Rothfuss, Y., H. Vereecken and N. Brueggemann. 2013. Monitoring water stable isotopic composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy. Water Resources Research 49: 3747-3755. doi:10.1002/wrcr.20311.
- Volkmann, T.H.M. and M. Weiler. 2014. Continual in situ monitoring of pore water stable isotopes in the subsurface. Hydrology and Earth System Sciences 18: 1819-1833. doi:10.5194/hess-18-1819-2014.
- Volkmann, T.H.M., K. Kühnhammer, B. Herbstritt, A. Gessler and M. Weiler. 2016. A method for in situ monitoring of the isotope composition of tree xylem water using laserspectroscopy. Plant, Cell & Environment 39: 2055-2063. doi:10.1111/pce.12725.
- Wassenaar, L.I., M.J. Hendry, V.L. Chostner and G.P. Lis. 2008. High resolution pore water d2H and d18O measurements by H2O(liquid)-H2O(vapor) equilibration laser spectroscopy. Environmental Science & Technology 42: 9262-9267.
Thank you….
Univ. Prof. Dr. Christine StumppInstitute for Soil Physics and
Rural Water Management (SoPhy)Univ. of Natural Resources and Life Sciences
Muthgasse 181190 Vienna, AUSTRIA
[email protected]: +43 1 47654/81511Fax: +43 1 47654/81509
….questions?