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Hydrospheric Tracers and Proxies (HydroTraP)

Grundwasserprobennahme

The hydrosphere encompasses water on earth in its entirety and thus permeates all compartments of the environment. The hydrological cycle is a central part of the global climate system and replenishes vital freshwater resources in lakes, rivers and aquifers. In addition, water and ice store information on the climate of the past.

The HydroTraP group uses various trace elements, compounds and isotopes (tracers) contained in liquid water as well as in ice for age dating, to obtain information on the chronology of archives and the dynamics of surface and subsurface waters as well as glaciers. Atmospheric noble gases and water isotopes additionally serve as proxies for environmental conditions during the formation of water and ice masses, such as past temperatures and other climate parameters. HydroTraP uses these methods to contribute to water resources management as well as for paleoclimate reconstruction.

Research

Grundwasserprobennahme bei Rennes, Frankreich

The HydroTraP group deals with the experimental development, methodical improvement and practical application of tracer and proxy methods in the hydrosphere (groundwater, lakes, and oceans) as well as in climate archives (speleothems, glaciers, and aquifers). Our central tools are stable and radioactive isotopes of the noble gases (3He, 4He, main isotopes of Ne, Ar, Kr, Xe sowie 39Ar, 81Kr, 85Kr, 222Rn). Often we use the noble gases in combination with classical methods of isotope hydrology (2H, 18O, 3H and 14C) or with transient environmental tracers (SF6, CFCs).

Information on many of our current and completed research projects can be found on the pages of DFG (GEPRIS Project Details on W. Aeschbach). Many projects are connected to thte innovative development of Dating by Atom Trap Trace Analysis (ATTA). Additional links to individual projects:

Current research projects

  • The Arctic Ocean 2020 - Ventilation timescales, anthropogenic carbon and variability in a changing environment
    DFG project page
     
  • Novel age determination of alpine glaciers by 39Ar-ATTA (ArTTA-ICE)
    DFG project page
     

Currently available positions

Grundwasserprobennahme in Jordanien

Completed research projects

 

Seewasserbeprobung am Willersinn Weiher, Ludwigshafen

Methods

Our experimental methods encompass two compartments: tracers and proxies. Samples are analyzed in different laboratories, partly also on commission. For data analysis and interpretation, different kinds of software have been developed and can be downloaded for free.

Tracers and Proxies

The following tracers are applied. Further information can be found on our methods page.

  • Dating Tracers (3H, 3He, 4He, 14C, 39Ar, 81Kr, 85Kr, 222Rn, SF6, CFCs)
  • Proxies for environmental conditions(2H, 18O, main isotopes of Ne, Ar, Kr, Xe)
     

Edelgasmassenspektrometer

Laboratories

The different tracers and proxies are analyzed in specialized laboratories:

  • Noble gas mass spectrometry laboratory (3H, 3He, 4He, main isotopes of Ne, Ar, Kr, Xe)
  • ATTA extraction laboratory (39Ar, 81Kr, 85Kr, analysis at KIP)
  • Gas chromatography laboratory (SF6, FCKWs)
  • 14C extraction and graphitization (14C, analysis at the Klaus-Tschira-Labor, Mannheim)
  • Radon monitors (222Rn)
  • Analysis of stable isotopes (2H, 18O)

The laboratories are also part of the Heidelberg Environmental Analytics Platform (HEAP) of the Heidelberg Center for the Environment (HCE). More information can be found here

Analytics

Probennahmeequipment

Analysis of noble gases and tritium can be done on commission. For more information please contact Florian.Freundt@iup.uni-heidelberg.de or Werner.Aeschbach@iup.uni-heidelberg.de. Sampling instructions can be found on our methods page.

Software

PANGA-Software

HydroTraP has developed a number of programs for the data analysis of tracers and proxies. Those software tools are available for download.

Modeling noble gas concentrations in (ground)water:

Inverse determination of model parameters by weighted least squares fitting. There are three programs available: A simple MS EXCEL workbook, a more sophisticated MATLAB routine, and finally the very versatile, stand-alone program PANGA. The old, simpler EXCEL workbook developed by myself is available here: Noblebook. The MATLAB routine developed by Frank Peeters is available at EAWAG: Noble gas fitter. There is new version available (since Dec. 2003), and an updated manual.

The new software PANGA developed by Michael Jung is available here: PANGA page.
 

Modeling age tracer data in young (ground)water:

Box-model approaches to interpret 3H(-3He), CFC, and 85Kr data. The software "Boxmodel V3"  is a MICROSOFT EXCEL workbook, designed for educational purposes. It has originally been developped by Kai Zoellmann, and later been expanded by myself and used for a UNESCO-workshop by Urs Beyerle. Workbook and documentation are provided here for free download.

Boxmodel_V3 workbook (0.5 MB MS-Excel file)
Boxmodel documentation (1 MB pdf-file).

 

People

Arbeitsgruppenfoto 2019

Name Postition Email (@iup.uni-heidelberg.de) Phone (+49 6221 54)
Name Funktion Email-Benutzername (@iup.uni-heidelberg.de) Telefon (+49 6221 54)
Werner Aeschbach Group leader (Prof.) Aeschbach 6331
Yannis Arck PhD student Yannis.Arck 6315
Kathrin Foshag Post-Doc Kathrin.Leutz 6313
Florian Freundt Post-Doc Florian.Freundt 6316
Johannes Garrecht Bachelor student Johannes.Garrecht  
Bertram Graf von Reventlow Bachelor student Bertram.Reventlow  
Emmy Hieronimus HiWi Emmy.Hieronimus  
Hannah Janecke HiWi Hannah.Janecke  
Ann-Kristin Kunz Hiwi Ann-Kristin.Kunz  
Shaoheng Li Guest PhD student    
Florian Meienburg Master student Florian.Meienburg  
Sophie Negele PhD student Sophie.Negele  
Sven Riedner Master student sven.riedner  
Stefan Schäfer Technician Stefan.Schaefer 6387
Kerstin Urbach Hiwi Kerstin.Urbach  
David Wachs PhD student David.Wachs  

 

Alumnis

See the list of completed theses.

 

Teaching

Prof. W. Aeschbach hält eine Vorlesung

Lectures

The following environmental physics lectures are offered by HydroTraP:

  • Co-operation of the master’s core course „Environmental Physics“ (MKEP4)
     
  • Annual master’s specialization lecture „Physics of Aquatic Systems“ (MVEnv3)
     
  • Master’s specialization lectures „Isotope Hydrology“, „Groundwater Science“ and other topics
     
  • Supervision of the experiment “Limnology” in the Advanced Physics lab for Physicists

More information on lectures and seminars can be found here.

Graduate theses

HydroTrap offers all types of graduate theses. Completed theses are listed in the following.

PhD theses

  • Schmidt, M., 2021. Investigations of Lake Kivu with 39Ar Argon Trap Trace Analysis. PhD thesis, Universität Heidelberg, 102 pages. pdf (7 MB)
     
  • Leutz, K., 2019. Klimawandel an öffentlichen Plätzen der Stadt Heidelberg. Transdisziplinäre Herausforderungen urbaner Räume. PhD thesis, Universität Heidelberg, 277 pages. pdf (23 MB)
     
  • Kersting, A., 2018. Dating of groundwater and ocean samples with noble gas radioisotopes – sample preparation and field applications. PhD thesis, Universität Heidelberg, 161 pages. pdf (30 MB)
     
  • Freundt, F., 2017. Application of Helium Isotopes in Shallow Groundwaters for Geothermal Energy Exploration in the Upper Rhine Graben. PhD thesis, Universität Heidelberg, 184 pages. pdf (48 MB)
     
  • Mayer, S., 2017. Dynamics of reactive and inert gases in soil air and groundwater in the context of noble gases as environmental tracers. PhD thesis, Universität Heidelberg, 266 pages. pdf (14 MB)
     
  • Hoffmann, H. M., 2016. Micro radiocarbon dating of the particulate organic carbon fraction in Alpine glacier ice: method refinement, critical evaluation and dating applications. PhD thesis, Universität Heidelberg, 156 pages. pdf (34 MB)
     
  • Schneider, T., 2014. Eine Paläoklimastudie an einem Grundwasseraquifersystem in der Nordchinesischen Ebene. PhD thesis, Universität Heidelberg, 227 pages. pdf (6.8 MB)
     
  • Jung, M., 2014. Dissolved Noble Gases in Groundwater: Properties of the Closed-System Equilibration Model and Review of Data Sets from the Literature. PhD thesis, Universität Heidelberg, 106 pages. pdf (4.4 MB)
     
  • Kaudse, T., 2014. Noble gases in groundwater of the Azraq Oasis, Jordan, and along the central Dead Sea Transform - Two case studies. PhD thesis, Universität Heidelberg, 228 pages. pdf (6 MB)
     
  • Reichel, T., 2013. Groundwater Degassing and Separation of Argon from Air for 39Ar Dating with ATTA. PhD thesis, Universität Heidelberg, 142 pages. pdf (3.3 MB)
     
  • Wieser, M., 2011. Imprints of climatic and environmental change in a regional aquifer system in an arid part of India using noble gases and other environmental tracers. PhD thesis, Universität Heidelberg, 208 pages. pdf (6.8 MB)
     
  • Kluge, T., 2008. Fluid inclusions in speleothems as a new archive for the noble gas palaeothermometer. PhD thesis, Universität Heidelberg, 191 pages. pdf (4.3 MB)
     
  • Friedrich, R., 2007. Grundwassercharakterisierung mit Umwelttracern: Erkundung des Grundwassers der Odenwald-Region sowie Implementierung eines neuen Edelgas-Massenspektrometersystems. PhD thesis, Universität Heidelberg, 271 pages. pdf (14.7 MB)
     
  • Kreuzer, A., 2007. Paläotemperaturstudie mit Edelgasen im Grundwasser der Nordchinesischen Tiefebene. PhD thesis, Universität Heidelberg, 146 pages. pdf (3.3 MB)
     
  • El-Gamal, H., 2005. Environmental tracers in groundwater as tools to study hydrological questions in arid regions. PhD thesis, Universität Heidelberg, 146 pages. pdf (3.5 MB) link in HeiDoK
     

Master's and Diploma theses

  • Schwenk, C., 2021. Creating high Temperature Noble Gas Solubility Functions to analyze missing Noble Gases in Lake Kivu’s deep Water. Master thesis, Universität Heidelberg, 67 pages.
     
  • Dischl, S. R., 2021. Multi-Tracer Studies for Groundwater Dating in Estonia. Master thesis, Universität Heidelberg, 94 pages.
     
  • Metz, T., 2021. Multi-Tracer Study of Groundwater in the Netherlands. Master thesis, Universität Heidelberg, 120 pages.
     
  • Negele, S., 2020. Enhancing Noble Gas Data Evaluation based on high precision Solubilities from Literature. Master thesis, Universität Heidelberg, 62 pages.
     
  • Wachs, D., 2020. Multi-Tracer Studies for Groundwater Dating and Paleotemperature Reconstruction in Denmark and Germany. Master thesis, Universität Heidelberg, 110 pages.
     
  • Arck, Y., 2019. Development of a Krypton Separation Setup for Dating with Atom Trap Trace Analysis. Master thesis, Universität Heidelberg, 134 pages.
     
  • Rädle, V., 2019. Multi-tracer study for groundwater dating in Southern Oman. Master thesis, Universität Heidelberg, 143 pages.
     
  • Rosendahl, C., 2018. Novel one-step pressure reduction for OmniStar GE-MIMS. Master thesis, Universität Heidelberg, 95 pages.
     
  • Speicher, R., 2018. Refining the Sampling and Extraction for Groundwater Dating with Radiocarbon. Master thesis, Universität Heidelberg, 89 pages.
     
  • Weber, U. W., 2018. Continuous Gas Measurements to Analyse Air-Water Exchange and Fracking. Masterthesis, Universität Heidelberg, 52 pages.
     
  • Jenner, F., 2017. Modeling seasonal variations of subsurface gas dynamics and soil gas compositions in the context of inert gas transfer applications. Master thesis, Universität Heidelberg, 124 pages.
     
  • Beyersdorfer, S., 2016. Argon extraction from glacier ice and ocean water for dating with 39Ar - ATTA. Master thesis, Universität Heidelberg, 99 pages.
     
  • Horstmann, E., 2016. Development of a mobile membrane inlet system for the analysis of dissolved gas concentrations. Master thesis, Universität Heidelberg, 109 pages.
     
  • Mathouchanh, E., 2015. Krypton separation from argon for Atom Trap Trace Analysis of 85Kr and 81Kr. Master’s internship report, Universität Heidelberg and Université Paris-Sud, 52 pages.
     
  • Beck, B., 2014. Lokalisierung von aktiven geologischen Störungszonen im Oberrheingraben durch Messung von 3He/4He-Verhältnissen in der Bodenluft. Diploma thesis, Universität Heidelberg, 161 pages.
     
  • Weißbach, T., 2014. Noble gases in palaeogroundwater of glacial origin in the Cambrian-Vendian aquifer, Estonia. Master thesis, Universität Heidelberg, 129 pages.
     
  • Tsur, N., 2013. Noble gas isotopic signatures in thermal waters of the Dead Sea Transform, Israel. Master thesis, Universität Heidelberg, 109 pages.
     
  • Kersting, A., 2013. A new method of krypton purication for groundwater dating with atom trap trace analysis. Diploma thesis, Universität Heidelberg, 76 pages.
     
  • Walser, A., 2013. Characterization of a New Quadrupole Mass Spectrometer for Precise Noble Gas Analysis. Diploma thesis, Universität Heidelberg, 139 pages.
     
  • Klose, S., 2013. Modeling of Noble Gas Concentrations in Soil Air and the Effect on Concentrations in Groundwater. Master thesis, Universität Heidelberg, 113 pages.
     
  • Götz, W., 2013. Energiespeicherung: Szenarienbasierte Analyse der Kapazität und Auslastung von Kurzzeit- und Langzeitspeicher in der Region Europa. Diploma thesis, Universität Heidelberg, 60 pages.
     
  • Mayer, S., 2012. Analyzing short-term fluctuations of noble gas concentrations in soil air and groundwater. Master thesis, Universität Heidelberg, 155 pages.
     
  • Sander, T., 2012. Investigation of the reproducibility and accuracy of noble gas measurements on small water samples. Diploma thesis, Universität Heidelberg, 78 pages.
     
  • Görger, S. M., 2012. Noble gas studies on the origin of deep anoxic hyper-saline brines in the Eastern Mediterranean Sea: Methods and interpretation. Diploma thesis, Universität Heidelberg, 137 pages.
     
  • Schwefel, R., 2012. Methoden zur Probenaufbereitung von Eis- und Grundwasserproben zur 39Ar-Datierung mittels "atom trap trace analysis". Diploma thesis, Universität Heidelberg, 107 pages.
     
  • Bröder, L., 2011. A Paleoclimate Record from Groundwater of the Great Artesian Basin in Australia. Diploma thesis, Universität Heidelberg, 100 pages.
     
  • Freundt, F., 2011. Measuring annual variation of soil atmosphere composition focusing on the effect of oxygen depletion on noble gas partial pressures. Diploma thesis, Universität Heidelberg, 119 pages.
     
  • Herb, C., 2011. Paleoclimate study based on noble gases and other environmental tracers in groundwater in Dhofar (Southern Oman). Diploma thesis, Universität Heidelberg, 197 pages.
     
  • Sorger, S., 2010. Bestimmung der SF6-Konzentration von Wasserproben mit Kupferzylindern als Probenahmegefaßen. Diploma thesis, Universität Heidelberg, 85 pages.
     
  • Jung, M., 2009. Aufbau eines Systems zur Gasanalyse von Fluideinschlüssen in Speläothemen. Diploma thesis, Universität Heidelberg, 64 pages.
     
  • Reichel, T., 2009. Optimierung eines Verfahrens zur Radonmessung in Wasser. Diploma thesis, Universität Heidelberg, 69 pages.
     
  • Schneider, T., 2009. Einfluss von Sauerstoffzehrung auf Edelgaspartialdrücke in Bodenluft. Diploma thesis, Universität Heidelberg, 97 pages
     
  • Marx, T., 2008. Weiterentwicklung des Mess- und Extraktionssystems zur Bestimmung von Edelgastemperaturen aus Spelaothemen. Diploma thesis, Universität Heidelberg, 81 pages.
     
  • von Oehsen, A., 2008. Parameter Estimation and Model Validation for Models of dissolved Noble Gas Concentrations in Groundwater. Diploma thesis, Universität Heidelberg, 100 pages.
     
  • Wonneberger, A., 2008. Novel Methods of Water Sample Preparation for 39Ar Analysis. Diploma thesis, Universität Heidelberg, 75 pages.
     
  • Gölzhäuser, T., 2008. Laborexperimente zur diffusiven Ausgasung von Helium aus polarem Eis. Diploma thesis, Universität Heidelberg, 96 pages.
     
  • Beyersdorff, E., 2007. Analytik und Interpretation von Edelgasdaten aus Grundwasser und Anwendung auf eine Paläoklimastudie in Algerien. Diploma thesis, Universität Heidelberg, 123 pages.
     
  • Ebert, C., 2007. Untersuchung neuer Verfahren zur Radonextraktion aus Wasser. Diploma thesis, Universität Heidelberg, 66 pages.
     
  • Kopf, M., 2007. Labor- und Feldexperimente zur Bildung von Excess Air im Grundwasser. Diploma thesis, Universität Heidelberg, 221 pages.
     
  • Wieser, M., 2006. Entwicklung und Anwendung von Diffusionssamplern zur Beprobung gelöster Edelgase in Wasser. Diploma thesis, Universität Heidelberg, 154 pages.
     
  • Kluge, T., 2005. Radon als Tracer in aquatischen Systemen. Diploma thesis, Universität Heidelberg, 91 pages.
     
  • Träumner, K., 2005. Inbetriebnahme, Tests und erste Anwendung einer neuen Anlage zur massenspektrometrischen Messung von Edelgasen aus Grundwasser- und Stalagmitproben. Diploma thesis, Universität Heidelberg, 113 pages.
     
  • Klement, R., 2005. Optimierung von SF6-Grundwasserprobenahme-Methoden. Diploma thesis, Universität Heidelberg, 91 pages.
     
  • Rice, S., 2004. The development of a method for the extraction and measurement of noble gases from fluid inclusions in samples of calcium carbonate. Master thesis, Universität Heidelberg, 65 pages.
     
  • Friedrich, R., 2003. Helium in polaren Eisschilden. Diploma thesis, Universität Heidelberg, 98 pages.
     

Bachelor's theses

  • Hieronimus, E. G. E., 2022. Estimation of the subsurface production rate of 39Ar in soil using a permafrost sample analysed by Atom Trap Trace Analysis. Bachelor thesis, Universität Heidelberg, 37 pages.
     
  • Janecke, H. F., 2022. Groundwater Study in Schwetzinger Hardt: Multi-Tracer Approach to Age Dating. Bachelor thesis, Universität Heidelberg, 35 pages.
     
  • Lucas, L. L. F., 2022. Investigation of water samples from the Central Arctic Ocean using dissolved 39Ar, CFC-12 and SF6 - An approach to a better understanding of ocean dynamics in the Arctic. Bachelor thesis, Universität Heidelberg, 40 pages.
     
  • Krastel, J., 2022. Laborexperimente zur diffusiven Ausgasung von Helium und Neon in Gletschereis und Datierung des Jamtalferners mit Hilfe der Argon Trap Trace Analyse. Bachelor thesis, Universität Heidelberg, 32 pages.
     
  • Kunz, A., 2021. Models for Noble Gas Enrichment in Groundwater of Glacial Origin in Estonia. Bachelor thesis, Universität Heidelberg, 65 pages.
     
  • Kolar, J., 2021. Reevaluation of Noble Gas Data in Groundwater from an Arid Region in Western India. Bachelor thesis, Universität Heidelberg, 30 pages.
     
  • Breunig, E., 2020. Constructing and testing an experimental setup for determining the partial pressures of CO2 and CH4 in Lake Kivu. Bachelor thesis, Universität Heidelberg, 75 pages.
     
  • Elfes, J., 2020. Recommissioning of the mass spectrometer MM3000 for measuring 3He/4He ratios from water samples. Bachelor thesis, Universität Heidelberg, 31 pages.
     
  • Richter, T., 2020. Kalibrierung und Inbetriebnahme eines Gaschromatographen zur Messung von Wasserproben. Bachelor thesis, Universität Heidelberg, 48 pages.
     
  • Kaiser, A. V., 2020. Combining the Purification of Argon from Water Samples with the Analysis of Chlorofluorocarbons, Sulfur Hexafluoride and Noble Gases. Bachelor thesis, Universität Heidelberg, 47 pages.
     
  • Schliffka, M. J., 2019. Gaschromatographische Messmethodik zur Bestimmung von SF6- und FCKW-Konzentrationen. Bachelor thesis, Universität Heidelberg, 55 pages.
     
  • Meienburg, F., 2019. Characterization of a new degassing setup for 39Ar ocean sampling. Bachelor thesis, Universität Heidelberg, 45 pages.
     
  • Stezura, S., 2017. Noble gas measurements and the dating of young groundwater with the 3H-3He method in Russia at Gatchina and Kirovsk . Bachelor thesis, Universität Heidelberg, 34 pages.
     
  • Bange, L., 2017. Untersuchung anthropogener Spurengase in der südlichen Hemisphäre anhand atmosphärischer Luftproben aus der Antarktis. Bachelor thesis, Universität Heidelberg, 38 pages.
     
  • Arck, Y., 2017. Noble Gas measurements on groundwater samples from Mount Etna. Bachelor thesis, Universität Heidelberg, 70 pages.
     
  • Baghumian, N., 2017. Untersuchung und Verbesserung eines mobilen Membraneinlasssystems zur Analyse von Konzentrationen in Wasser gelöster Gase. Bachelor thesis, Universität Heidelberg, 75 pages.
     
  • Hopkins, P., 2015. Überprüfung der Reproduzierbarkeit von Grundwasserdatierungen mit Hilfe von SF6 und FCKWs. Bachelor thesis, Universität Heidelberg.
     
  • Jenner, F., 2014. Untersuchung kurzzeitiger SF6- und FCKW-Variationen in der Bodenluft im Kontext der Datierung jungen Grundwassers. Bachelor thesis, Universität Heidelberg.
     
  • Zimmerer, K., 2014. SF6-Datierung junger Grundwässer in Heidelberg und Umgebung. Bachelor thesis, Universität Heidelberg.
     
  • Schüler, J. W. O., 2014. Kalibrierung eines auf einem Quadrupolmassenspektrometer basierenden Gasanalysesystems und erste Feldmessungen. Bachelor thesis, Universität Heidelberg.
     
  • Batvinyeu, K., 2012. Entwicklung einer neuen Methode zur Messung von SF5CF3. Bachelor thesis, Universität Heidelberg, 32 pages.
     
  • Kalt, J., 2012. Auswirkung von CO2 auf den Strahlungshaushalt in einem Modellversuch. Bachelor thesis, Universität Heidelberg, 54 pages.
     
  • Schenke, J., 2012. Untersuchung des Äquilibrierungsprozesses von Air Equilibrated Water (AEW). Bachelor thesis, Universität Heidelberg, 47 pages.
     
  • Kollefrath, A., 2011. Test einer Entgasungsanlage. Bachelor thesis, Universität Heidelberg, 65 pages.
     
  • Kreyenberg, P., 2011. Test einer Radonentgasungsanlage. Bachelor thesis, Universität Heidelberg, 57 pages.
     
  • Mayer, S., 2010. Untersuchung der Eignung von Meereswellen zur Elektrizitätserzeugung. Bachelor thesis, Universität Heidelberg, 58 pages.
     
  • Sonntag, P., 2010. Radon Exchange Processes in the Lake Sediment Pore Water of Lake Willersinnweiher. Bachelor thesis, Universität Heidelberg, 51 pages.
     

State examination theses

  • Bauer, A., 2016. 14C-Messungen an DOC aus Grundwasser: Charakterisierung einer Extraktionsanlage und erste Pilotstudie. State examination thesis, Universität Heidelberg, 60 pages.
     
  • Engelhardt, L., 2015. Bestimmung von Bodenparametern im Raum Heddesheim im Kontext der Untersuchung von Transportprozessen in der ungesättigten Bodenzone. State examination thesis, Universität Heidelberg, 110 pages.
     
  • Engel, J., 2011. Tests und Weiterentwicklung der Messprozedur fur Gase aus Stalagmiten. State examination thesis, Universität Heidelberg, 61 pages.
     
  • Feißt, C. R., 2009. Klimarekonstruktion mit Edelgastemperaturen aus Grundwasser in Dänemark. State examination thesis, Universität Heidelberg, 48 pages.
     
  • Lorenz, S., 2008. Entwicklung eines Praktikumsversuches zum Themenbereich Limnophysik. State examination thesis, Universität Heidelberg, 134 pages.
     
  • Osusko, D., 2007. Kalibrierung eines Gaschromatographen zur Messung von Schwefelhexafluorid . State examination thesis, Universität Heidelberg, 56 pages.
     

Publications

Papers in peer-reviewed scientific journals

  • Rädle, V., A. Kersting, M. Schmidt, L. Ringena, J. Robertz, W. Aeschbach, M. Oberthaler, and T. Müller, 2022. Multi-Tracer groundwater dating in Southern Oman using Bayesian modelling. Water Resour. Res. 58, e2021WR031776, doi:10.1029/2021WR031776.
     
  • Schwenk, C., S. Negele, C. M. Balagizi, W. Aeschbach, and B. Boehrer, 2022. High temperature noble gas thermometry in Lake Kivu. East Africa. Sci. Total Environ. 837: 155859, doi:10.1016/j.scitotenv.2022.155859.
     
  • Schwenk, C., F. Freundt, W. Aeschbach, and B. Boehrer, 2022. Extending Noble Gas Solubilities in Water to Higher Temperatures for Environmental Application. J. Chem. Eng. Data 67, 1164–1173. doi:10.1021/acs.jced.2c00009.
     
  • Broers, H. P., J. Sültenfuß, W. Aeschbach, A. Kersting, A. Menkovich, J. de Weert, and J. Castelijns, 2021. Paleoclimate signals and groundwater age distributions from 39 public water works in the Netherlands; insights from noble gases and carbon, hydrogen and oxygen isotope tracers. Water Resources Research 57, e2020WR029058, doi:10.1029/2020WR029058.
     
  • Walraevens, K., A. Fernández-Lagunas, P. Blaser, W. Aeschbach, A. Vandenbohede, M. Van Camp, 2021. Understanding the mechanisms of groundwater recharge and flow in periglacial environments: New insights from the Ledo-Paniselian aquifer in Belgium. J. Contam. Hydrol. 241, 103819, doi:10.1016/j.jconhyd.2021.103819.
     
  • Vaikmäe, R., J. Pärn, V. Raidla, J. Ivask, E. Kaup, W. Aeschbach, C. Gerber, J.-M. Lemieux, R. Purtschert, A. Sterckx, T. Martma, and L. Vallner, 2021. Late Pleistocene and Holocene groundwater flow history in the Baltic Artesian Basin: a synthesis of numerical models and hydrogeochemical data. Estonian Journal of Earth Sciences 70: 152–164. doi:10.3176/earth.2021.11.
     
  • Seltzer, A. M., J. Ng, W. Aeschbach, R. Kipfer, J. T. Kulongoski, J. P. Severinghaus, and M. Stute, 2021. Widespread six degrees Celsius cooling on land during the Last Glacial Maximum. Nature 593: 228–232, doi:10.1038/s41586-021-03467-6.
     
  • Foshag, K., N. Aeschbach, B. Höfle, R. Winkler, A. Siegmund, W. Aeschbach, 2020. Viability of public spaces in cities under increasing heat: A transdisciplinary approach. Sustainable Cities and Society 59: 102215, doi:10.1016/j.scs.2020.102215.
     
  • Walraevens, K., P. Blaser, W. Aeschbach, M. Van Camp, 2020. A palaeoclimatic record from the Ledo-Panselian Aquifer in Belgium - indications for groundwater recharge and flow in a periglacial environment. Quat. Int., 547: 127–144, doi:10.1016/j.quaint.2019.06.003.
     
  • Sprenger, M., C. Stumpp, M. Weiler, W. Aeschbach, S. T. Allen, P. Benettin, M. Dubbert, A. Hartmann, M. Hrachowitz, J. W. Kirchner, J. J. McDonnell, N. Orlowski, D. Penna, S. Pfahl, M. Rinderer, N. Rodriguez, M. Schmidt, C. Werner, 2019. The demographics of water: A review of water ages in the critical zone. Rev. Geophys., 57: 800–834, doi:10.1029/2018RG000633.<
     
  • Feng, Z., P. Bohleber, S. Ebser, L. Ringena, M. Schmidt, A .Kersting, P. Hopkins, H. Hoffmann, A. Fischer, W. Aeschbach, M. K. Oberthaler, 2019. Dating glacier ice of the last millennium by quantum technology. Proc. Natl. Acad. Sci. USA, 116: 8781–8786, doi:10.1073/pnas.1816468116.
     
  • Raidla, V., J. Pärn, W. Aeschbach, S. Schloemer, G. Czuppon, J. Ivask, A. Marandi, H. Sepp, R. Vaikmäe, K. Kirsimäe, 2019. Origin and formation of methane in groundwater of glacial origin from the Cambrian-Vendian aquifer system in Estonia. Geochim. Cosmochim. Acta 251: 247–264, doi:10.1016/j.gca.2019.02.029.
     
  • Pärn, J., K. Walraevens, M. van Camp, V. Raidla, W. Aeschbach, R. Friedrich, J. Ivask, E. Kaup, T. Martma, J. Mažeika, R. Mokrik, T. Weissbach, R. Vaikmäe, 2019. Dating of glacial palaeogroundwater in the Ordovician-Cambrian aquifer system, northern Baltic Artesian Basin. Appl. Geochem. 102: 64–76, doi:10.1016/j.apgeochem.2019.01.004.
     
  • Raidla, V., J. Pärn, W. Aeschbach, G. Czuppon, J. Ivask, M. Kiisk, R. Mokrik, V. Samalavičius, S. Suursoo, S. Tarros, T. Weissbach, 2019. Intrusion of Saline Water into a Coastal Aquifer Containing Palaeogroundwater in the Viimsi Peninsula in Estonia. Geosciences 9: 47, doi:10.3390/geosciences9010047.
     
  • Ebser, S., A. Kersting, T. Stöven, Z. Feng, L. Ringena, M.Schmidt, T. Tanhua, W. Aeschbach, M. K. Oberthaler, 2018. 39Ar dating with small samples provides new key constraints on ocean ventilation. Nat. Commun. 9: 5046, doi:10.1038/s41467-018-07465-7.
     
  • Jung, M., W. Aeschbach, 2018. A new software tool for the analysis of noble gas data sets from (ground)water. Environ. Modell. Software 103: 120–130, doi:10.1016/j.envsoft.2018.02.004.
     
  • Gerber, C., R. Vaikmäe, W. Aeschbach, A. Babre, W. Jiang, M. Leuenberger, Z.-T. Lu, R. Mokrik, P. Müller, V. Raidla, T. Saks, H. N. Waber, T. Weißbach, J. C. Zappala, R. Purtschert, 2017. Using 81Kr and noble gases to characterize and date groundwater and brines in the Baltic Artesian Basin on the one-million-year timescale. Geochim. Cosmochim. Acta 205: 187–210, doi:10.1016/j.gca.2017.01.033.
     
  • Müller, T., Osenbrueck, K., Strauch, G., Pavetich, S., Al-Mashaikhi, K.-S., Herb, C., Merchel, S., Rugel, G., Aeschbach, W., Sanford, W., 2016. Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman, Appl. Geochem. 74: 67-83.
     
  • Aeschbach, W. 2016. New perspectives for noble gases in oceanography, J. Geophys. Res. Oceans, 121, 6550–6554, doi: 10.1002/2016JC012133.
     
  • Kaudse, T., R. Bani-Khalaf, R. Tuffaha, F. Freundt, W. Aeschbach-Hertig, 2016. Noble gases reveal the complex groundwater mixing pattern and origin of salinization in the Azraq Oasis, Jordan. Appl. Geochem. 66: 114-128.
     
  • Wei W., W. Aeschbach-Hertig, Z. Chen, 2015. Identification of He sources and estimation of He ages in groundwater of the North China Plain. Appl. Geochem. 63: 182-189.
     
  • Visser A., E. Fourre, F. Barbecot, L. Aquilina, T. Labasque, V. Vergnaud, B. K. Esse, Contributors from participating laboratories, 2014. Intercomparison of tritium and noble gases analyses, 3H/3He ages and derived parameters excess air and recharge temperature. Appl. Geochem. 50: 130-141.
     
  • Labasque T., L. Aquilina, V. Vergnaud, F. Barbecot, Contributors from participating laboratories, 2014. Inter-laboratory comparison of the analyses of sulphur hexafluoride (SF6) and three chlorofluorocarbons (CFC-11, -12 and -113) in groundwater and an air standard. Appl. Geochem. 50: 118-129.
     
  • Ritterbusch, F., S. Ebser, J. Welte, T. Reichel, A. Kersting, R. Purtschert, W. Aeschbach-Hertig, M. K. Oberthaler, 2014. Groundwater dating with Atom Trap Trace Analysis of 39Ar. Geophys. Res. Lett., doi: 10.1002/2014GL061120.
     
  • Aeschbach-Hertig, W., 2014. Radiokrypton dating finally takes off. Proc. Natl. Acad. Sci. 111: 6856-6857.
     
  • Kluge, T., T. Marx, W. Aeschbach-Hertig, C. Spotl, D.K. Richter, 2014. Noble gas concentrations in fluid inclusions as tracer for the origin of coarse-crystalline cryogenic cave carbonates. Chem. Geol. 368: 54-62.
     
  • Sander, T., T. Marx, J. Engel, W. Aeschbach-Hertig, 2014. Reproducibility and accuracy of noble gas measurements on water samples in the microlitre range. Rapid Commun. Mass Spectrom. 28: 42-48.
     
  • Friedrich, R., G. Vero, C. von Rohden, B. Lessmann, R. Kipfer, and W. Aeschbach-Hertig, 2013. Factors controlling terrigenic SF6 in young groundwater of the Odenwald region (Germany). Appl. Geochem. 33: 318?329.
     
  • Aeschbach-Hertig, W. and D.K. Solomon, 2013. Noble gas thermometry in groundwater hydrology, in: Burnard, P. (Ed.), The noble gases as geochemical tracers. Advances in Isotope Geochemistry. Springer Verlag, pp. 81-122. Preprint
     
  • Utting, N., B. Lauriol, N. Mochnacz, W. Aeschbach-Hertig, I. Clark, 2013. Noble gas and isotope geochemistry in western Canadian Arctic watersheds: tracing groundwater recharge in permafrost terrain. Hydrogeol. Hydrogeol. J., 21: 79-91 .
     
  • Kluge, T., H. P. Affek, T. Marx, W. Aeschbach-Hertig, D. F. C. Riechelmann, D. Scholz, S. Riechelmann, A. Immenhauser, D. K. Richter, J. Fohlmeister, A. Wackerbarth, A. Mangini, and C. Spotl, 2013. Reconstruction of drip-water δ 18O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany). Clim. Past 9: 377-391.
     
  • Freundt, F., T. Schneider and W. Aeschbach-Hertig, 2013. Response of noble gas partial pressures in soil air to oxygen depletion, Chem. Geol. 339: 283-290.
     
  • Jung, M., M. Wieser, A. von Oehsen and W. Aeschbach-Hertig, 2013. Properties of the closed-system equilibration model for dissolved noble gases in groundwater, Chem. Geol., 339: 291-300.
     
  • Aeschbach-Hertig, W., and T. Gleeson, 2012. Regional strategies for the accelerating global problem of groundwater depletion. Nature Geoscience, 5: 853-861.
     
  • Kluge, T., C. von Rohden, P. Sonntag, S. Lorenz, M. Wieser, W. Aeschbach-Hertig and J. Ilmberger, 2012. Localising and quantifying groundwater inflow into lakes using high-precision 222Rn profiles. J. of Hydrology, 450-451: 70-81.
     
  • Tröndle, T., U. Platt, W. Aeschbach-Hertig, K. Pfeilsticker, 2012. Erneuerbare Energie fur Europa. Phys. Unserer Zeit, Vol. 43(6): 300-306.
     
  • Utting, N., I. Clark, B. Lauriol, M. Wieser and W. Aeschbach-Hertig, 2012. Origin and flow dynamics of perennial groundwater in continuous permafrost terrain using isotopes and noble gases: Case study of the Fishing Branch River, Northern Yukon, Canada. Permafrost Periglac., 23 Vol. 2: 91-106.
     
  • Sanford, W. E., W. Aeschbach-Hertig, A. Herczeg, 2011. Preface: Insights from environmental tracers in groundwater systems. Hydrogeol. J., 19: 1-3.
     
  • Welte, J., F. Ritterbusch, I. Steinke, M. Henrich, W. Aeschbach-Hertig, and M. K. Oberthaler, 2010. Towards the realization of atom trap trace analysis for 39Ar. New J. Phys. 12, 065031(14pp).
     
  • Newman, B. D.; K. Osenbruck; W. Aeschbach-Hertig; D. K. Solomon; P. Cook; K. Rozanski; R. Kipfer, 2010. Dating of 'young' groundwaters using environmental tracers: advantages, applications, and research needs. Isotopes in Environ. and Health Studies, 46(3): 259- 278.
     
  • Kluge, T., D.F.C. Riechelmann, M. Wieser, C. Spotl, J. Sultenfuß, A. Schroder-Ritzrau, S. Niggemann, W. Aeschbach-Hertig, 2010. Dating cave drip water by tritium. J. of Hydrology, 394: 396-406.
     
  • Von Rohden, C., A. Kreuzer, Z. Chen, and W. Aeschbach-Hertig, 2010. Accumulation of natural SF6 in the sedimentary aquifers of the North China Plain as a restriction on groundwater dating. Isotopes in Environ. and Health Studies, 46(3): 279-290.
     
  • Kluge,T., M. Wieser, and W. Aeschbach-Hertig, 2010. Assessing the use of 3H-3He dating to determine the subsurface transit time of cave drip waters. Isotopes in Environ. and Health Studies, 46(3): 299- 311.
     
  • Blaser, P.C., R. Kipfer, H.H. Loosli, K. Walraevens, M. van Camp, and W. Aeschbach-Hertig, 2010. A 40 ka record of temperature and permafrost conditions in northwestern Europe from noble gases in the Ledo-Paniselian Aquifer (Belgium). J. Quaternary Sci, 25:1038-1044.
     
  • Von Rohden, C., A. Kreuzer, Z. Y. Chen, R. Kipfer, and W. Aeschbach-Hertig, 2010. Characterizing the recharge regime of the strongly exploited aquifers of the North China Plain by environmental tracers. Water Resour. Res., 46, W05511,doi:10.1029/2008WR007660
     
  • Blaser, P.C., M. Coetsiers, W. Aeschbach-Hertig, R. Kipfer, M. Van Camp, H.H. Loosli, and K. Walraevens, 2010. A new groundwater radiocarbon correction approach accounting for palaeoclimate conditions during recharge and hydrochemical evolution: The Ledo-Paniselian Aquifer, Belgium. Appl. Geochem., 25: 437- 455.
     
  • Shotyk, W., M. Krachler, W. Aeschbach-Hertig, S. Hillier, and J. C. Zheng, 2010. Trace elements in recent groundwater of an artesian flow system and comparison with snow: enrichments, depletions, and chemical evolution of the water. J. Environ. Monit. 12: 208- 217.
     
  • Holzner, C. P., W. Aeschbach-Hertig, M. Simona, M. Veronesi, D. M. Imboden, and R. Kipfer, 2009. Exceptional mixing events in meromictic Lake Lugano (Switzerland/Italy), studied using environmental tracers. Limnol. Oceanogr. 54: 1113-1124.
     
  • Kreuzer, A. M., C. von Rohden, R. Friedrich, Z. Chen, J. Shi, I. Hajdas, R. Kipfer, and W. Aeschbach-Hertig, 2009. A record of temperature and monsoon over the past 40 kyr from groundwater in the North China Plain. Chem. Geol., 259: 168-180.
     
  • Aeschbach-Hertig, W., 2009. Clean coal and sparkling water. Nature 458: 583-584. pdf
     
  • von Rohden, C., J. Ilmberger and B. Boehrer, 2009. Assessing groundwater coupling and vertical exchange in a meromictic mining lake with an SF6-tracer experiment. J. Hydrol., 372: 102-108.
     
  • Corcho Alvarado, J. A., F. Barbecot, R. Purtschert, M. Gillon, W. Aeschbach-Hertig, and R. Kipfer, 2009. European climate variations over the past half-millennium reconstructed from groundwater. Geophys. Res. Lett., 36, L15703, doi:10.1029/2009GL038826.
     
  • Welte, J., I. Steinke, M. Henrich, F. Ritterbusch, M. K. Oberthaler, W. Aeschbach-Hertig, W. H. Schwarz, and M. Trieloff, 2009. Hyperfine spectroscopy of the 1s5-2p9 transition of 39Ar. Rev. Sci. Instrum. 80, 113109, doi:10.1063/1.3257691.
     
  • Aeschbach-Hertig, W., H. El-Gamal, M. Wieser, and L. Palcsu, 2008. Modeling excess air and degassing in groundwater by equilibrium partitioning with a gas phase. Water Resour. Res. 44, W08449, doi:10.1029/2007WR006454.
     
  • Kluge, T., T. Marx, D. Scholz, S. Niggemann, A. Mangini, and W. Aeschbach-Hertig, 2008. A new tool for palaeoclimate reconstruction: Noble gas temperatures from fluid inclusions in speleothems. Earth Planet. Sci. Lett., 269: 407-414.
     
  • Kluge, T., J. Ilmberger, C. von Rohden, W. Aeschbach-Hertig, 2007. Tracing and quantifying groundwater inflow into lakes using radon-222. Hydrol. Earth Syst. Sci. 11: 1621-1631.
     
  • Corcho Alvarado, J. A., R. Purtschert, F. Barbecot, C. Chabault, J. Rüedi, V. Schneider, W. Aeschbach-Hertig, R. Kipfer, and H.H. Loosli, 2007. Constraining the age distribution of highly mixed groundwater using 39Ar: a multiple environmental tracer (3H/3He, 85Kr, 39Ar and 14C) study in the semi-confined Fontainebleau Sands aquifer (France). Water Resour. Res. 43, W03427, doi:10.1029/2006WR005096.
     
  • Aeschbach-Hertig, W., C. P. Holzner, M. Hofer, M. Simona, A. Barbieri, and R. Kipfer, 2007. A time series of environmental tracer data from deep meromictic Lake Lugano, Switzerland. Limnol. Oceanogr. 52: 257-273. 
     
  • von Rohden, C., K. Wunderle, and J. Ilmberger, 2007. Parameterisation of the vertical transport in a small thermally stratified lake. Aquat. Sci. 69: 129-137.
     
  • Wollschlager, U., J. Ilmberger, M. Isenbeck-Schroter, A. M. Kreuzer, C. von Rohden, K. Roth, and W. Schäfer, 2007. Coupling of groundwater and surface water at Lake Willersinnweiher: Groundwater modeling and tracer studies. Aquat. Sci. 69: 138-152.
     
  • Aeschbach-Hertig, W., 2007. Rebuttal of "On global forces of nature driving the Earth's climate. Are humans involved?" by L. F. Khilyuk and G. V. Chilingar. Env. Geol. DOI 10.1007/s00254-006-0519-3.
     
  • Edmunds, W. M., J. Z. Ma, W. Aeschbach-Hertig, R. Kipfer, and D. P. F. Darbyshire, 2006. Groundwater recharge history and hydrogeochemical evolution in the Minqin Basin, North West China. Appl. Geochem. 21: 2148-2170.
     
  • Aeschbach-Hertig, W., 2005. A comment on "Helium sources in passive margin aquifers - new evidence for a significant mantle 3He source in aquifers with unexpectedly low in situ 3He/ 4He production" by M. C. Castro [Earth Planet. Sci. Lett. 222 (2004) 897-913], Earth Planet. Sci. Lett. 240: 827-829. pdf
     
  • Corcho Alvarado, J. A., R. Purtschert, K. Hinsby, L. Troldborg, M. Hofer, R. Kipfer, W. Aeschbach-Hertig, and H.-A. Synal, 2005. 36Cl in modern groundwater dated by a multi tracer approach (3H/3He, SF6, CFC-12 and 85Kr): A case study in quaternary sand aquifers in the Odense Pilot River Basin, Denmark. Appl. Geochem. 20: 599-609. pdf
     
  • Peeters, F., U. Beyerle, W. Aeschbach-Hertig, M. S. Brennwald, and R. Kipfer, 2004. Response to the comment by G. Favreau, A. Guero, and J. Seidel on "Improving noble gas based paleoclimate reconstruction and groundwater dating using 20Ne/22Ne ratios" (2003) Geochim. Cosmochim. Acta, 67, 587-600. Geochim. Cosmochim. Acta 68: 1437-1438. pdf
     
  • Beyerle, U., J. Rüedi, M. Leuenberger, W. Aeschbach-Hertig, F. Peeters, R. Kipfer, and A. Dodo, 2003. Evidence for periods of wetter and cooler climate in the Sahel between 6 and 40 kyr BP derived from groundwater. Geophys. Res. Lett. 30, DOI 10.1029/2002GL016310. pdf
     
  • Brennwald, M. S., M. Hofer, F. Peeters, W. Aeschbach-Hertig, K. Strassmann, R. Kipfer, and D. M. Imboden, 2003. Analysis of dissolved noble gases in the porewater of lacustrine sediments. Limnol. Oceanogr.: Methods 1: 51-62. pdf 
     
  • Holocher, J., F. Peeters, W. Aeschbach-Hertig, W. Kinzelbach, and R. Kipfer, 2003. Kinetic model of gas bubble dissolution in groundwater and its implications for the dissolved gas composition. Environ. Sci. Technol. 37: 1337-1343. pdf  supporting material
     
  • Lehmann, B. E., A. Love, R. Purtschert, P. Collon, H. H. Loosli, W. Kutschera, U. Beyerle, W. Aeschbach-Hertig, R. Kipfer, S. K. Frape, A. Herczeg, J. Moran, I. Tolstikhin, and M. Gröning, 2003. A comparison of groundwater dating with 81Kr, 36Cl and 4He in four wells of the Great Artesian Basin, Australia. Earth Planet. Sci. Lett. 211: 237-250. pdf
     
  • Peeters, F., U. Beyerle, W. Aeschbach-Hertig, J. Holocher, M. S. Brennwald, and R. Kipfer, 2003. Improving noble gas based paleoclimate reconstruction and groundwater dating using 20Ne/22Ne ratios. Geochim. Cosmochim. Acta 67: 587-600. pdf
     

Other publications

Extended Abstracts

  • Schmidt, G., S. Al Najem, M. Isenbeck-Schröter, F. Freundt, M. Kraml, W. Aeschbach, 2017.  87Sr/86Sr ratios in shallow and deep aquifers from the southern Upper Rhine Graben, Germany. Procedia Earth Planet. Sci. 17: 626-629.
     
  • Schmidt, G., S. Al Najem, M. Isenbeck-Schröter, F. Freundt, M. Kraml, W. Aeschbach, 2017. 87Sr/86Sr ratios in thermal water from the southern Upper Rhine Graben, Germany. Procedia Earth Planet. Sci. 17: 364-367.
     
  • Schmidt, G., S. Al Najem, M. Isenbeck-Schröter, F. Freundt, M. Kraml, R. Eichstädter, W. Aeschbach, 2017. 87Sr/86Sr ratios in shallow and deep aquifers and thermal water from the Eastern Boundary Fault of the northern Upper Rhine Graben at the Heidelberg Basin, Germany. Procedia Earth Planet. Sci. 17: 108-111.
     
  • Schmidt, G., S. Al Najem, M. Isenbeck-Schröter, F. Freundt, M. Kraml, R. Eichstädter, W. Aeschbach, 2017. Ascending deep fluids into shallow aquifer at hydraulically active segments of the Western Boundary Fault of the Rhine Graben, Germany: Constraints from 87Sr/86Sr ratios. Procedia Earth Planet. Sci. 17: 81-84.
     
  • Wieser, M., W. Aeschbach-Hertig, T. Schneider, R. D. Deshpande, S. K. Gupta, 2011. A temperature and monsoon record derived from environmental tracers in groundwater of Northwest India. In: Proceedings of the International Symposium on Isotopes in Hydrology, Marine Ecosystems, and Climate Change Studies, IAEA, Monaco, 2011. IAEA-CN-186-029, Vol. 1: 7–14.
     
  • Aeschbach-Hertig, W., H. El-Gamal, K. Dahab, R. Friedrich, R. Kipfer, I. Hajdas, 2007. Identifying and dating the origin of groundwater resources in reclamation areas of Egypt. In: Advances in Isotope Hydrology and its Role in Sustainable Water Resources Management (HIS-2007), Proceedings of a Symposium, Vienna, 21-25 May 2007. IAEA, Vienna, STI/PUB/1310, Vol. 2: 395–403.
     
  • Kreuzer, A. M., C. Zongyu, R. Kipfer, and W. Aeschbach-Hertig, 2006. Environmental Tracers in Groundwater of the North China Plain. In: Isotopes in Environmental Studies - Aquatic Forum 2004. IAEA, Vienna, C&S Papers Series 26/P: 136-139. pdf