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Theme 22

Hydrogeochemistry and the Water Cycle

Ian Clark, Ottawa, Carleton,
Florent Barbecot, Paris-Sud,

Co-hosted sessions

SESSIONS

22a. Tracing groundwater variability

Co-convenors:
Florent Barbecot (Université de Paris-Sud) - florent.barbecotu-psud.fr
Rolf Kipfer (EAWAG) - rolf.kipfereawag.ch
Roland Purtschert (University of Bern) – purtschertclimate.unibe.ch

Geochemical parameters as water chemistry, isotopes and noble gases are can be used to describe and trace both the origin and geochemical processes that characterize a groundwater body. Very often, the interpretation of those geochemical signals is based on the (oversimplified) assumption that the investigated systems operate at steady state, i.e. the system dynamics remains constant and hence does not vary over time. However, recent changes on environmental (climate, land cover, abstraction, river flow…) parameters and their impact on hydrosystems may not be well depicted by such approaches, and part of information contained in tracer distribution is not restituted.

This session aims to cover recent assessment on tracing groundwater flows, particularly considering time and/or space distribution variability and on the investigation of water fluxes at interfaces (recharge and discharge) to reconstruct forcings related to recent climate and environmental changes.

Keynote speaker:
Kip Solomon (The University of Utah), kip.solomonutah.edu

22b. Chemistry and isotopes as biogeochemical tracers of water cycle in the critical zone

Co-convenors:
Lixin Jin (University of Texas at El Paso) – ljin2utep.edu
Katya Bazilevskaya (Penn State University) – eab204psu.edu

The Critical Zone (CZ) is a heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources. Water is an essential component of CZ processes and when water evolves from wet precipitation to soil solution, groundwater and eventually stream water, its interaction history within the critical zone is reflected in water solutes. The complex interplay between hydrology and biogeochemistry and the difficulty in modeling water and solute transport at the pedon, hillslope and catchment scales have been identified. We invite papers that utilize field observation and theoretical modeling to: (1) investigate water residence time and flowpaths in the critical zone using isotopes as biogeochemical tracers, (2) examine the dependence of water chemistry on watershed hydrology, (3) link soil porosity and permeability, bedrock fracturing to water transport dynamics. Cross-scale investigations across pedon, catena, catchment, or basin, are particularly welcome.

Keynote speakers:
Christopher J. Duffy (Penn State), cxd11psu.edu
Peter A. Troch (University of Arizona), patrochhwr.arizona.edu
Richard B. Wanty (USGS-Denver), rwantyusgs.gov

22c. Applications of emerging geochemical and isotopic analytical techniques for integrated water resource management and environmental monitoring

Co-convenors:
Jean Birks (Alberta Innovates/University of Waterloo) - jean.birksalbertainnovates.ca
Yi Yi (Alberta Innovates/University of Victoria, BC, Canada) - yiyiuvic.ca
Mike Moncur (Alberta Innovates/University of Waterloo) - mmoncuruwaterloo.ca
John Gibson (Alberta Innovates/University of Victoria) - jjgibsonuvic.ca

Recent advances in stable isotope measurements and mass spectrometry now provide unprecedented ability to obtain high-resolution information about the isotopic and geochemical labeling of water and solutes with many potential applications in integrated water resource management and environmental monitoring. The aim of this session is to explore emerging methods that can be used to provide better characterization of water and dissolved constituents in surface water and groundwater and to show how these new techniques can be used to provide insights into the sources of water and solutes, and hydrogeochemical processes. Investigations that use stable water isotopes, compound-specific isotope analyses, laser-assisted high resolution isotopic measurements, and ultrahigh resolution mass spectrometry techniques (including Orbitrap and Fourier Transform mass spectrometer) are particularly welcome.

22d. Geochemical and microbiological site characterization methods in low permeability and low porosity formations

(co-hosted by Themes 22, 9 and 16)

Co-convenors:
Niklaus Waber (University of Bern, Switzerland) - wabergeo.unibe.ch
Jennifer McKelvie (Nuclear Waste Management Organization, Canada) - jmckelvienwmo.ca
Sarah Hirschorn (Nuclear Waste Management Organization Canada) - shirschornnwmo.ca

Evaluation of geochemical and microbiological processes is a component of detailed site characterization studies in support of the development of deep geological repositories (DGR) for used nuclear fuel. Chemical and isotopic compositions of groundwaters and matrix porewaters provide information on the origin and evolution of groundwater systems and on groundwater fate over geologic time frames. Repository performance modelling routinely incorporates geochemical compositions and transport properties (e.g. diffusion and sorption measurements) when assessing solute transport processes of radionuclides. Because microbial processes play an important role in geochemical processes, assessment of microbial assemblages and their metabolic capabilities is also often included in site characterization activities. Given the typical low porosity and permeability of DGR host rock types, the development of methods for porewater and microbial extraction and analysis is an on-going research area for many nuclear waste management agencies. We invite contributions from academia, government, and industry researchers internationally, detailing novel, innovative advances in laboratory and field methods to characterize porewater composition and microbial communities in low permeability and low porosity rock formations.

22e. Assessing groundwater transport processes using natural geochemical tracers

Co-convenors:
Laura Kennell (Nuclear Waste Management Organization, Canada) – lkennellnmwo.ca
Monique Hobbs (Nuclear Waste Management Organization, Canada) – mhobbsnwmo.ca
Sébastien Savoye (CEA-France), sebastien.savoyecea.fr

Examination of natural tracer (conservative [e.g., δ¹⁸O, δ2H, Cl] and reactive) data is a key aspect of geochemical site characterization activities undertaken to assess site suitability for the development of deep geologic repositories (DGR) for low- to high-level radioactive waste. Chemical and isotopic compositions of groundwaters and porewaters provide information on the origin and evolution of the waters, and the examination of natural tracer profiles can allow assessments of fluid mixing processes. Combined with knowledge of the host rock composition (mineralogy), natural tracers can indicate the extent of 1) fluid-rock interaction, 2) mineral precipitation/dissolution, and 3) fluid-rock equilibrium. Natural tracer distributions, together with physical and hydrogeological properties, can be used to perform geochemical modelling to re-construct and/or predict the chemical evolution of groundwater-porewater systems. Repository performance modelling routinely incorporates geochemical compositions and transport properties (e.g., effective diffusion coefficients, hydraulic conductivities) when assessing the mechanisms governing solute (e.g., radionuclides) transport. We invite contributions from academia, government, and industry researchers in Canada and internationally, detailing applications of geochemical and isotopic tracers to evaluate groundwater transport and fate in low permeability crystalline or sedimentary rock formations.

Keynote speaker:
Martin Mazurek (University of Bern), mazurekgeo.unibe.ch

22f. Tracing fluid circulation and reconstruction of environmental conditions with noble gases: from basinal brines, freshwater to emerging aquatic systems

Co-convenors:
Daniele L. Pinti (GEOTOP-UQAM) – pinti.danieleuqam.ca
Rolf Kipfer (EAWAG) - rolf.kipfereawag.ch

Noble gases, inert and rare, are very good tracers of fluid circulation in the crust. Their isotopic signature is controlled by three potential sources: the crust, the atmosphere and the mantle. Atmospheric noble gases are very good continental paleoclimate recorders because the annual average temperature at the recharge controls their concentration in water. Crustal-produced radiogenic 4He is potentially a chronometer of the groundwater residence time, yet, to explain excesses often found in young freshwater requires, additional sources, either local or deeper, have to be called upon. Mantle helium is found in extensional, tectonics-dominated areas and its occurrence in aquifers or lakes can be helpful in tracing cross-formational fluid flow or limnic circulation.

Papers on noble gases in fresh and groundwater, basinal brines, pore water and other non-conventional aquatic systems are welcomed to this session. Particularly emphasized are studies which compare noble gas methods with more classical tracers (stable isotopes, CFC, major cations etc.) to reconstruct past environmental conditions and to analyze fluid dynamics and transport in hydrosphere and geosphere.

Keynote speaker:
Gisela Winckler (LDEO – Columbia University), wincklerldeo.columbia.edu

Co-hosted sessions:

Please note that for abstract submission purposes, the following sessions and their respective descriptions appear in their primary Theme assignments (numbers in red or before the title).

12g.-Contribution of submarine groundwater discharge to oceanic chemical cycles

Co-convenors: Aaron Beck/Virginia Institute of Marine Science and Richard Peterson/Coastal Carolina University
(co-hosted by Themes 12 and 22)

13c.- The atmosphere-continent-ocean linkage : the hydrologic cycle, weathering, and ocean-atmosphere exchange

Co-convenors : Yves Goddéris/CNRS, Toulouse, Louis A. Derry/Cornell and Yannick Donnadieu/CNRS-LSCE
(co-hosted by Themes 13 and 22)

16l.- Biogeochemistry of oxyanion-forming trace elements in the environment

Co-convenors: Karen Johannesson/Tulane, Saugata Datta/Kansas State, Rudolph Hon/Bonsto College and Annette Johnson/EAWAG
(co-hosted by Themes 16 and 22)

21a- Innovative approaches for improving water quality in mining environments

Co-convenors: L. Alakangas/Lulea, Sweden and M. Lindsay/UBritish Columbia
(co-hosted by Themes 21 and 22)

21c.- Smart materials for subsurface flow applications

Co-convenors: Amr Abde-Fattah/Los Alamos, Rex Hjelm/Los Alamos and David DiCarlo/UT at Austin
(co-hosted by Themes 21 and 22)

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