WATER & ENVIRONMENT NEWS WATER ENVIRONMENT · 2006-03-21 · WATER & ENVIRONMENT NEWS surface flow in catchment basins, and groundwater recharge. Under-standing these mechanisms also

Quarterly No. 5, October 1998 - Page 1

WATER & ENVIRONMENT NEWS

WATER &

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IAEA Scientific Forum 98Programme Review: Isotope Studies on Cli-mate ChangesIsotope Studies on the Caspian SeaCanadian Network for Isotopes in Precipita-tionIsotopic Composition of Past Precipitation

Pasterze glacier, southwestern Austria, see page 8

CONTENTS

Isotopes of Atmospheric Greenhouse GasesGroundwater DynamicsNuclear Techniques in Dam SafetyIsotope Hydrology Symposium 1999IHS on the InternetTechnical Review: Noble Gas Isotopes inHydrology and Climate Studies

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Issue No. 5, October 1998

Issued by the

Vienna, Austria

International Atomic Energy Agency

A Quarterly Newsletter of the IAEA Subprogramme on Development and Management of Water ResourcesNEWS

ISSN 1020–7120



• to assist, through inte-gration of isotope tech-niques in applied researchand practical applications,in solving practical prob-lems related to sustainableand efficient managementof water resources.

• to promote research andfield studies related toman-induced changes andhydro-climatic influenceson the water cycle and itsinteraction with other geo-spheric systems.

Human Impact on Wa-ter Resources (F4.01)

• to further develop andenhance applications of iso-tope methodologies in theassessment of adverse con-sequences of present waterutilization practices.

• to achieve improved wa-ter utilization policies thatwould minimize water qual-ity degradation caused byhuman activities.

Water Resources in Re-gions of Water Scarcity(F4.02)

• to contribute to and im-prove the assessment andprotection of water re-sources in regions of waterscarcity, in particular inarid and semi-arid areas.

• to assist Member Statesin such regions to incorpo-rate isotope methods intoroutine practices for thedetermination of hydrologi-cal parameters for optimumutilization of scarce waterresources.

Hydro-climatic Changesand Impact on Catch-ment and Surface WaterSystems (F4.03)

• to assess and demonstratethe applicability of isotopetechniques in selected stud-

ies of the hydrosphere andatmosphere related to naturaland man-induced environ-mental changes

• to enable better predictionof their future implications onwater resources.

• to enhance the contributionof isotope applications forimproved understanding offluvial processes and

• to minimize the adverse ef-fects of such fluvial processeson soil and water resources.

Analytical Services andQuality Assurance(F4.04)

• to provide assistance in thedetermination of the isotopeand chemical composition ofwater and other environmen-tal materials and to assureanalytical quality.

Support to Technical Co-operation Programmes(F4.05)

to provide technical supportto the Agency’s technical co-operation projects in MemberStates.

IAEA SUB-PROGRAMME ONDEVELOPMENT AND MANAGEMENT OF

WATER RESOURCES(1997-1998)

Contact Us

Isotope Hydrology SectionInternational Atomic Energy AgencyP.O. Box 100, Wagramer Strasse 5A-1400, ViennaAUSTRIA

Head of the Section:Mr. KlausFröhlichTel. +43-1-2600-21735/21736Fax: +43-1-26007e-mail: [email protected](Please note the new telephone & faxnumbers of the IAEA!)

Visit Us on theInternet

http://www.iaea.org/programmes/ripc/ih/index.html

These projects are beingimplemented by the IsotopeHydrology Section and theAgency’s Laboratories.



the IAEA General Conference,which was held last September.Isotope Hydrology once againshowed up in front of the delegatesfrom Member States attending theGeneral Conference.

We are grateful to our Swiss col-leagues F. Peeters and R. Kipfer,who have prepared a technical re-view paper on noble gas isotopesand applications, and to T. Edwardsfrom Canada for his report on theCanadian Network for Isotopes inPrecipitation.

This issue marks the second publi-cation year of Water & Environ-ment News. There is already somenoticeable progress to mentionhere: firstly, since September lastyear, we have published and dis-

his issue provides informa-tion on the Agency’s in-

volvement in a topical field, theapplication of isotope techniquesin climate change studies. In thelast quarter, a number of meet-ings related to this subject wereheld, including a consultantsmeeting on the study of waterlevel changes and water dynam-ics of the Caspian Sea; aPAGES/IAEA workshop on iso-topic composition of paleo-precipitation - ISOMAP. Re-cently, an IAEA Co-ordinatedResearch Project on atmo-spheric greenhouse gases wasconcluded.

Water Resources was chosen asthe topic of the first ScientificForum held in conjunction with

he Director General of theIAEA, in his opening remarks

to the Scientific Forum on“Nuclear Technology in Relation toWater Resources and the AquaticEnvironment”, said that “IsotopeHydrology is an integral techniquein scientific investigation of waterresources…”. The Scientific Fo-rum was held from 22 to 24September 1998, in conjunctionwith the IAEA annual General Con-ference at its Headquarters in Vi-enna.

The meeting recognized that avail-ability of freshwater, especially wa-ter supply for future demand due topopulation increase and associ-ated socio-economic develop-ment, protection of its quality, andimpact of climate change on waterresources are the most crucial is-sues of global concern. The meet-ing demonstrated, through presen-tations and discussions, theAgency’s potential in addressingthese problems with its pro-gramme components related toisotope hydrology.

from dams, identification of erosionregions within catchment basins,and hydraulic interrelationships be-tween surface water and groundwa-ter.

Scientific, methodological, and edu-cational aspects related to isotopehydrology were considered at thesession. From the methodologicalpoint of view, gradual widening ofthe spectrum of isotope hydrologyhas been achieved in the lastdecades from the use of radioiso-topes as tracers for local-scale ap-plications in the early stages, toapplications of various natural iso-tope species in dealing with hydro-logical processes and hydrologicalsystems on a much larger scale(both in terms of space and time) atthe present. Isotope hydrology hasalready had a significant impact on“Process Hydrology” such as evapo-ration, rainfall recycling, hill-slopehydrology through re-evaluation ofmechanisms and pathways of sub-

In the session of isotope hydrology,four keynote papers were given byinvited experts and discussionsheld. The titles of the presentationswere:

♦ Isotope Hydrology: Develop-ment and Challenges (J. Gat,Israel)

♦ Practical Applications of Iso-tope Hydrology

⇒ The Venezuelan experiencein isotope hydrology,achievements through IAEAtechnical co-operation (J.Lozada, Venezuela)

⇒ A case study from the MiddleEast (M. Geyh, Germany)

⇒ A case study from Pakistan(I. Sajjad, Pakistan)

In the presentations, an overviewon the historical evolution of“Isotope Hydrology” as a scientificdiscipline and its contribution to wa-ter sciences was made, which wasfollowed by case studies in differ-ent regions on selected topics, in-cluding assessment of groundwaterresources, water pollution, leakage General NewsGeneral News

tributed a total of five issues of ournewsletter to about 700 recipients;secondly, we have recently obtainedan official serial number (ISSN1020-7120) which is used globally inlibraries; thirdly, an on-line versionhas been produced and is now avail-able through the Internet with linksto our Section’s homepage. I wouldlike to take this opportunity to thankour readers for their interest in thenewsletter and for their kind supportin providing feedback to us whichhas helped to improve the quality ofthe newsletter ever since its incep-tion.

Klaus FröhlichHead, Isotope Hydrology Section



surface flow in catchment basins,and groundwater recharge. Under-standing these mechanisms alsolinks with residence (travel) time ofwater, the fate of pollutants andthe water quality issues in general.Isotope applications, particularlyfor water resources in arid regions,have distinct advantages and oftenthe information required cannot beobtained through conventionaltechniques.

It was concluded that isotopic com-position of precipitation, beingmonitored by the Agency throughthe Global Network for Isotopes inPrecipitation (GNIP) since 1960,should be enhanced and GNIPdata should be incorporated intolong-term hydrological/meteoro-logical monitoring at national lev-

gral part of the overall investigationsrelated to practical problems in wa-ter resources assessment, develop-ment and management. In this re-gard, the need for incorporation ofisotope hydrology into an integratedprogramme of fundamental educa-tion in hydrological sciences at uni-versities was also emphasized bythe meeting.

It was anticipated that the activityenvisaged by the IAEA to launch an“International Decade for Isotopes inthe Hydrological Cycle” would sub-stantially contribute to fulfilling theabove cited needs.

els. Such systematic monitoringshould not be limited to isotopecomposition of precipitation, butshould ideally also include isotopecomposition of rivers and outflowsto oceans, and should thus berelated to the overall hydrologicalcycle. The long-term data to beobtained will also contribute signifi-cantly towards differentiation of im-pacts of climate change on waterresources from those due to directanthropogenic effects. Compilationof all such global- scale data in acomputerized database for easy ac-cess and utilization by the scientificcommunity will be most desirable.

Furthermore, the meeting also rec-ognized the need for more effectiveutilization of the existing andproven methodologies as an inte-

Scientific Scope

Growing concern about the earth'senvironment - from issues ofglobal warming to air and waterpollution - has prompted importantnew research on how economicand industrial activities are chang-ing the world's ecosystem. In thisconnection, isotope techniqueshave shown specific potential instudying the human impact on theavailability and quality of waterresources. Moreover, it wasdemonstrated that the understand-ing of past and present climaticchanges can substantially be im-proved through isotope measure-ments in natural archives such asice cores, lake and sea sediments,palaeo-groundwater, cave de-posits and tree rings. Isotopeshave proved to be useful indicatorsof climate parameters such as airtemperature, and can be used todate past climatic events.

Recognizing the growing demandfor the utilization of isotopes instudies of hydroclimatic changes,the Agency increased over the lastfew years its efforts in this direc-tion. The activities planned for1999 and 2000 are grouped underthe theme: “Hydroclimatic changes

and impact on catchment and sur-face water systems”. The objectivesof these activities have been sum-marized as follows: “To asses andverify the application of isotopemethodologies in studying pro-cesses in the atmosphere and hy-drosphere related to natural andman-induced environmentalchanges and to permit improvedprediction of their possible futureimpact on water resources; and toenhance the contribution of isotopeapplications for improved assess-ment of fluvial transport processesand to minimize the adverse effectsof such processes on soil and waterresources.”

Surface and Ground Water Sys-tems Affected by HydroclimaticChanges

Groundwater resources are oftenexploited beyond their natural re-plenishment. To avoid such ground-water mining, it is essential to knowthe replenishment rate in the af-fected regions. Origin and replen-ishment of groundwater are prob-lems addressed by numerous IAEAtechnical co-operation projects cur-rently being implemented in Mem-ber States, especially in the coun-tries located in arid and semi-arid

regions. Prominent examples in thisregard are the two regional projectsin northern Africa (including Algeria,Egypt, Ethiopia, Mali, Morocco,Niger, Nigeria, Senegal and Sudan)and in the Middle East (includingIran, Jordan, Kuwait, Lebanon,Saudi Arabia, Syria, Turkey andUnited Arab Emirates). The spec-trum of problems to be tackled bythe combined use of conventional-hydrological and isotopic techniquesare also related to groundwater in-herited from previous climate peri-ods (palaeo-groundwater), artificialrecharge, mixing between ground-water and surface water, and groundwater pollution. In addition, theAgency contributes to palaeo-groundwater research through par-ticipation in two EU funded projects:“PALAEAUX-Management ofCoastal Aquifers in Europe” and“GASPAL-Continental Isotope Indi-cators of Palaeo-climate”. The latterproject is included in ISOMAP, aspecial programme under the IGBPcore-project PAGES (Past GlobalChanges). The ISOMAP programmeis introduced in a special contribu-tion to the present issue of Waterand Environment News.

Programme ReviewProgramme Review



Surface water systems are particu-larly vulnerable to anthropogenicimpact and climate change, asdemonstrated by the Caspian Sealevel fluctuations. The drastic sealevel rise starting in 1978 gave theimpetus to an isotope-based pro-ject of the IAEA with all ripariancountries. In view of the achieve-ments made so far (see specialreport on the Caspian Sea in thisissue), it was recommended tocontinue these efforts to furtherimprove the understanding of thewater circulation, especially thedeep water formation in theCaspian Sea.

Indicators of Past and CurrentHydroclimatic Changes

Continental records of past envi-ronmental changes are especiallyuseful in addressing these prob-lems because they reflect the‘baseline’ conditions against whichthe human impact on the environ-ment has to be gauged. A numberof current palaeo-climatologicalstudies are related to the climatechanges which occurred in theinter-tropical and tropical belts, twozones highly sensitive to externalforcing. In this connection, specialattention is paid to the Late GlacialMaximum period (LGM, dated at21 000 years BP), where ex-tremely rapid environmentalchanges occurred. Through theIAEA's recently completed coordi-nated research programme on theUse of Isotope Techniques inPalaeoclimatology Continental Iso-tope Indicators of Palaeoclimate,new data on this type of palaeo-climate reconstruction were pro-vided. It was, for example, foundthat during the LGM the mean airtemperature in the tropics was 5°Clower than today. Isotope studiesof lake sediments in Poland,Switzerland, France and China re-vealed that the transition periodfrom the Late Glacial to theHolocene was very short (about 70years) and was associated with achange in the mean surface airtemperature of about 6°C. Finally,isotope studies of the carbonatefraction of sediments from severallakes located in the Tibetan

national commitments on reducingthe release of greenhouse gases inthe future, as laid out in the 1997Kyoto Protocol. The involvement ofthe IAEA in these endeavors hasbeen considered essential with re-gard to (1) the co-ordination of thecollaboration among the specializedlaboratories, (2) the support in refin-ing the methods and assuring thequality of the measurements, and(3) the provision of reference mate-rials for stable isotope analysis.

The isotopic composition of atmo-spheric precipitation provides a fin-gerprint of atmospheric moisture cir-culation, reflects local atmosphericconditions, such as surface air tem-perature, and defines the isotopicinput to the majority of the naturalarchives used for palaeo-climate re-construction. No wonder that thescientific communities dealing withpalaeo-climate and global circula-tion modeling take increasingly re-course to the database of the IAEA/WMO Global Network for Isotopesin Precipitation. Several interna-tional programmes related topalaeo-climatology have com-mended the relevance of the GNIPdatabase as a primary reference forrecent isotope data and as a meansto validate palaeo-climatic recon-struction based on isotope records.In this regard, the ISOMAP Work-shop should be mentioned whichwas hosted by the IAEA in August ofthis year (see separate contributionincluded in this issue).

The previous issue of Water andEnvironment News extensively in-formed of the status and challengesof the GNIP and its database. In themeantime, the efforts towardsstrengthening the GNIP have beencontinued. The Memorandum of Un-derstanding (MoU) between theIAEA and the WMO on the GNIPand its database has been signed bythe Director General of the IAEAand sent to the Secretary General ofWMO for counter-signing. The MoUis paving the way for follow up activ-ities, among which is the preparationof an Isotope Climatology Confer-

plateau, China, provided evidenceof large scale changes in the inten-sification of the Indian monsoonduring the Holocene, with the peakof the monsoon circulation and as-sociated rainfall between 6,000 and10,000 years ago.

It is generally accepted that globalbudgeting of atmospheric carbon isa prerequisite for projections of fu-ture atmospheric levels and theirimpact on the Earth’s climate. Inthis connection, isotopes of the ele-ments constituting the atmospherictrace gases such as carbon dioxideand methane have become an es-sential tool in identifying thesources and sinks of these gases.Such studies require long-termmeasurements and high-accuracydata of the carbon isotopic compo-sition of these gases. To this end,the IAEA initiated a co-ordinatedresearch project (CRP) involvingthe world’s leading laboratories inthis field. The CRP is now in itssecond phase. The achievements,made so far, were discussed in aresearch co-ordination meeting re-cently held at the University ofGroningen, The Netherlands (seealso separate article in this issue).In particular, the comparability ofanalytical data between major labo-ratories was investigated in depthby the IAEA CLASSIC (Circulationof Laboratory Air Standards for Sta-ble Isotope Comparisons) labora-tory inter-calibration which includedthe preparation of high-pressurewhole-air standards for atmospherictrace gas analysis. The causes oflaboratory offsets could be identi-fied by the CLASSIC exercise andby accompanying inter-laboratorycomparisons. The participating lab-oratories demonstrated that the ex-ternal precision is now close to thetarget precision, necessary tomerge all data available from differ-ent observation programmes and toachieve a global coverage for com-parable data sets. For the first timeit was demonstrated during theCRP that the carbon budget, includ-ing source and sink terms, could becalculated on a regional scale. Thisimproved spatial resolution is anessential step towards assessinganthropogenic influences and pro-viding a tool for the verification of

Programme ReviewProgramme Review



ence to be held in May 1999 at theIAEA Headquarters in Vienna.

Future Outlook

Recognizing the importance ofstudies on climate changes, theIAEA has started a series of sym-posia devoted to the use of iso-topes in studying current and pastenvironmental changes in the at-mosphere and the hydrosphere.Two symposia in this series haveso far been organized, in 1993 and1997, respectively. Proceedingsof both symposia have been pub-lished by the IAEA. The next sym-posium of this series is planned tobe held in 2001. Further contribu-tions to studies on hydroclimaticchanges are included in the Iso-tope Hydrology Section’s pro-gramme for 1999 and beyond.These contributions include the fol-lowing CRPs: “Palaeo-water asdrinking water reserve and palaeo-climate archive”, “Processes con-trolling isotope composition of con-tinental indicators of present-dayclimate”, and “Isotopes in studying

changes: (1) Intensification of effortsto link isotope signatures of water inthe hydrological cycle to climatephenomena (including the WCRP-CLIVAR and other international pro-grammes on global changes of theEarth’s environment and climate,especially PAGES with its relevantprojects called PEP and ISOMAP);(2) Further strengthening of theIAEA/WMO Global Network for Iso-topes in Precipitation; (3) Productionand calibration of new isotope refer-ence materials relevant to investiga-tions of isotopes in the hydrologicalcycle.

Klaus Fröhlich

frequency and chronology of ex-treme flood events in connectionwith climatic changes”.

Recently, in connection with discus-sions on how to further enhance theuse of isotope techniques in climateresearch and to meet the growingdemand for an extensive use ofisotope hydrology in water re-sources management, it was sug-gested that an International Decadefor Isotopes in the Hydrological Cy-cle be launched. This initiativeshould be taken under the auspicesof the IAEA, jointly with other orga-nizations including the World Cli-mate Research Programme(WCRP). UNESCO could play akey role in this initiative through itsInternational Hydrological Pro-gramme (IHP). Scope, objectivesand framework for implementationof the Decade are presently dis-cussed by the concerned institu-tions and scientists. Among themain components of the Interna-tional Decade for Isotopes in theHydrological Cycle, the followingare relevant to hydroclimatic

he rapid rise of the water levelin the Caspian Sea (about

2.25 meters since 1978) has beena cause of great concern to theriparian countries (Azerbaijan,Iran, Kazakstan, Russia and Turk-menistan). To help improve theunderstanding of environmentalprocesses of the Caspian Sea, in-cluding sea level fluctuations andpossible contaminant movement,a regional IAEA technical co-operation project entitled"Preparatory Study of Caspian SeaWater Level Fluctuations" was im-plemented from 1995 to 1997 withthe riparian countries. The projectincluded studies of water balanceand water dynamics of the systemwhich were based on measure-ments of oceanographic parame-ters combined with determinationof the isotopic composition of wa-ter and sediments in the CaspianSea. A consultants meeting washeld in Vienna from 31 August to 2September 1998 to discuss theoutcome of the project and recom-

mend follow up activities. Thefollowing major results were high-lighted:

• The changes of the Caspian Sealevel are mainly caused by changesin the river input;

• During the recent sea level rise, thetotal inflow exceeded the evapora-tion by about 10%;

• The gathered data point to a ratherintense vertical water exchange inthe central and the southern basin ofthe Caspian Sea;

• The understanding of the deep waterformation in the two (deep) basins ofthe Caspian Sea has been improved.

The information obtained so farwas considered to be highly rele-vant to the Caspian Sea countriesin designing proper environmentalmanagement strategies, since itindicates that the Caspian Sea, aunique ecosystem, is vulnerable tothe impact of climatic changes andof contaminants into the sea, in-

cluding oil from oil spills. The partic-ipants of the consultants meetingagreed that the data availableshould be compiled in a report to bedistributed to the institutions andindividuals involved in the project.The need for continuation of thestudies was stressed. In particular,a hydrometeorological network ofselected stations around the seashould be established (possiblywithin the framework of a jointWMO-lAEA initiative) and furthercruises should be organized to mea-sure oceanographic parameters andcollect samples during the winterseason when deep water formationis expected to take place. To thisend, the participants suggested tosolicit finding from other donors(including oil companies). It is alsoenvisaged to produce a brochure onthe subject, to make the generalpublic and industrial companiesmore aware of the severe pollutionproblems in the Caspian Sea.



anada is a long-standing par-ticipant in the IAEA/WMO

Global Network for Isotopes in Pre-cipitation (GNIP) programme,aimed at documentation and un-derstanding of the distribution ofwater isotope tracers (stable 18Oand 2H, and radioactive 3H) inglobal precipitation. Such dataand knowledge about the naturalisotopic labeling that occurs as aresult of phase changes in thehydrologic cycle are playing in-creasingly important roles in waterand climate research, fostered inparticular by the incorporation ofisotope tracers into general circu-lation models (GCMs) used to in-vestigate global climate dynamics,and the need for new tools to sup-plement traditional hydrometricand hydro-meteorological tech-niques in water resources analysis.

Composite monthly samples havebeen collected at Ottawa, Ontario,for more than 30 years, providingone of the longest continuous time-series records in the world of δ18O,δ2H, and 3H in precipitation at onesite, making Ottawa a key NorthAmerican reference station [1].Collection at Ottawa has also beenjoined at intervals by samplingcampaigns at individual stations orover limited networks, generallyfor the purposes of specific re-search projects. Although many ofthese data are also incorporatedinto the GNIP data base, knowl-edge about the distribution of wa-ter isotopes in precipitation inCanada remains patchy in bothspace and time, and insufficient tosupport the needs of current andfuture water and climate research.

This situation was recognized andaddressed in a workshop in Winter1997 [2], leading to a cooperativeventure between university andgovernment researchers and theAtmospheric Environment Service(AES), Canada’s national meteoro-logical agency, to work towardsestablishment of a dedicatedCanadian Network for Isotopes inPrecipitation - CNIP. The firstinterim phase of CNIP was initi-

of Waterloo, which has had a longaffiliation with the GNIP programme.However, future plans call for shar-ing of analytical responsibilityamong a consortium of Canadianuniversity and government laborato-ries, under the scientific direction ofa special sub-committee of theCanadian Geophysical Union - Hy-drology Section.

Fig. 1. Map showing the current station configu-ration of the Canadian Network for Isotopes inPrecipitation (asterisks). Also indicated arethree stations collecting precipitation samples ona daily basis to examine the effects of the 1997-98 El Niño (crosses), and the Mackenzie Riverbasin, the focus of water balance studies usingisotope tracers within the Mackenzie BasinGEWEX Study (MAGS) of the Global Energyand Water Cycle Experiment.

References[1] Rozanski, K., Araguás-Araguás, L.,and Gonfiantini, R. 1993. Isotopic pat-terns in modern precipitation. Geophysi-cal Monograph 78, American Geophysi-cal Union.

[2] Workshop on Water and ClimateStudies in Canada using Isotopic Trac-ers: Past, Present, Future. University ofWaterloo, January 31-February 1,1997.

Thomas W. D. EdwardsDepartment of Earth SciencesUniversity of Waterloo, WaterlooON N2L 3G1 CANADA

ated in Spring 1997, through theadoption of precipitation samplingat selected stations from the Cana-dian Air and Precipitation Monitor-ing Network (CAPMoN), operatedby AES. These new stations, dis-tributed across southern Canada,were chosen to supplement Ottawaand an informal network of stationsin the North that had been operatingfor several years as a joint activitybetween researchers at CarletonUniversity and University of Water-loo, in collaboration with on-siteAES personnel.

CNIP (Phase I) currently comprises17 stations collecting monthly-composite samples, providing forthe first time reasonably well-distributed spatial coverage of theentire country (see Fig. 1). Thisinterim configuration is planned toexist for several years, permittingsufficient ongoing analysis of accu-mulating data to discern fundamen-tal linkages between the isotopiccomposition of precipitation andsynoptic climatology and to aid indesigning and optimizing a morepermanent future network.

An important feature of CNIP is itsfunction as an observational re-search network, producing data thatare readily accessible and of imme-diate value. It also provides aframework compatible with GNIP,within which other finer-resolutionnetworks and sampling campaignscan be nested to address particularregional and local questions. Pre-sent examples include extensiveisotopic observations of precipita-tion, atmospheric moisture, andsurface waters within the Macken-zie River Basin, as part of waterbalance studies within the GlobalEnergy and Water Cycle Experi-ment (GEWEX-MAGS), as well asdaily precipitation observations atthree sites in eastern Canadaaimed at capturing the isotopic ex-pression of the 1997-98 El Niño(also shown on Fig. 1).

At present, all analyses are beingconducted by the EnvironmentalIsotope Laboratory of the University



he distribution of stable iso-topes in precipitation provides

crucial quantitative informationabout the global water cycle. In-creasing use of the water isotopetracers 18O and 2H in the atmo-spheric general circulation modelsthat mimic the Earth's climate pro-cesses has especially highlightedthe need for better documentationand understanding of the distribu-tion of isotopes in both past andpresent precipitation.

The first PAGES/IAEA ISOMAPworkshop was held at the IAEAHeadquarters in Vienna, 24-26 Au-gust 1998, which gathered thirty-two participants. ISOMAP is thecentral element of PAGES Focus5 on Isotope Calibration (Activity 2,Task 1), and the primary goal ofthis inaugural workshop was toenunciate the transfer functionslinking the isotopic data recordedin a particular continental archiveto the precipitation from which itwas originally derived. This is anessential step in efforts to compileand manage isotopic data for data-model comparison, in order toclearly define the potential to esti-mate or constrain the isotopiccomposition of paleo-precipitation.

The discussions began by review-ing existing knowledge about thedistribution of isotopes in modernprecipitation, gained in large partfrom the IAEA/WMO Global Net-work for Isotopes in Precipitation(GNIP). This long-running pro-gram was recently strengthened bythe two agencies, including estab-lishment of formal PAGES repre-sentation on the GNIP ScientificSteering Committee. Althoughoriginally intended only to definewhat were thought to be essentiallystationary input functions for hy-drologic studies, the GNIPdatabase has proven to be a keysource of information about con-temporary global climate dynamicsand change. Other related activi-ties, especially the new scienceinitiative ISOHYC (Isotopes in theHydrologic Cycle) will build on the

permit ready retrieval of raw andinferred data for comparison andreinterpretation. This will be an im-portant goal of future ISOMAP activ-ities. Though the workshop was notfocused on the problems of datacompilation, the critical need formore paleo-data from low latitudeswas clearly recognized. Paradoxi-cally, low-latitude glaciers, whichconstitute one of the best sources ofpaleo-isotope data in regions suchas the Andes and Himalayas, areparticularly poorly represented by(or even invisible to) current GCMs(general circulation models).

Further information can be obtainedfrom: Thomas W. D. Edwards,project co-ordinator, Department ofEarth Sciences, University of Water-loo, Waterloo ON N2L 3G1CANADA.e-mail: [email protected]

GNIP foundation to forge more so-phisticated understanding ofisotope-climate linkages.

The remainder of the workshop wasdevoted to plenary presentations byfive previously established workinggroups and subsequent break-outsessions. The first presentationdealt with the current abilities ofgeneral circulation models to depictthe distribution of isotopes in globalprecipitation at different times, in-cluding the present. In spite of therelatively coarse (but continuallyimproving) spatial resolution of cur-rent model runs, it is clear that themajor features of the distribution ofisotopes globally can be reproducedwith some fidelity. The situation forthe past is less clear, in significantpart because of the sparse paleo-isotope data that are readily avail-able.

The other four working group pre-sentations focused on the majortypes of continental isotopicarchives, including glacier ice,groundwater and speleothems, lakesediments, and terrestrial organicarchives. For some archives, suchas glacier ice and groundwater, thelink to the original precipitation isvery direct, and can potentially pro-vide both δ18O and δ2H values, aswell as the d-excess parameter (d =δ2H - 8δ18O), whereas otherarchives, including carbonate lakesediments, for example, may onlysupport estimation of precipitationδ18O indirectly via isotopic transferfunctions linking both the archive tothe lake water and the lake water tolocal precipitation.

The presentations and discussionsdemonstrated that a high level ofsophistication already exists in thedevelopment of transfer functionsbetween measured parameters andprecipitation, as a result of the ex-tensive use of water isotope tracersin paleo-environmental investiga-tions, but a major challenge facingboth producers and users of paleo-isotope data is the effective man-agement of data and meta-data, to

Notes on the FrontCover Photo

asterze glacier (~2360 m.a.s.l.) in southwestern Aus-

tria is the largest glacier in theEastern Alps (19.7 km2 in 1969).The external ice stretches all theway for about 10 km from theGrossglockner (Big Clock) (3,798m.a.s.l.), Austria’s highest moun-tain, seen in the background of thephoto.

In the past, the ice extended muchfarther and reached much higherlevels of the slopes on both sidesof the valley, but in the last a fewdecades, it has receded remark-ably, as evidenced by glacier for-mations, probably due to recentclimate changes.



ecent attempts to balance theglobal budget of carbon diox-

ide in the atmosphere haveevolved towards determining thegeographical location of majorsources and sinks, as an essentialstep in predicting future atmo-spheric levels. Yet, until now theassessment has been limited to asemi-hemispheric scale. In gen-eral, these studies have not ex-ploited inter-calibration informationand have usually relied on atmo-spheric composition measure-ments from individual laboratoriesonly.

The IAEA has organized two con-secutive Co-ordinated ResearchProjects (CRPs) on Isotope-aidedStudies of Atmospheric CarbonDioxide and Other GreenhouseGases which have provided aninternational forum for inter-calibration between laboratoriesmeasuring the isotopic composi-tion of greenhouse gases world-wide. The final research co-ordination meeting of the secondCRP was held in Groningen, theNetherlands, from 8 to 11September 1998.

The meeting summarized theoverall achievements of the CRPs,and discussed the on-going interlaboratory comparison (CLASSIC),merging of data, need for a contin-uing technical forum, and CRPpublications.

Overall Achievements

1.Progress in the measurement ofisotopes in atmospheric CO2 hasbeen remarkable during the last 6years (2 CRP's). Some examplesare:

The discovery of different ion cor-rection assumptions in both com-mercial software and between lab-oratories.

Demonstration of many previouslyignored systematic effects in massspectrometers (memory/non-

forum for discussing the develop-ment of methods for determininglocal emissions of greenhousegases from continental (mainly Eu-ropean) regions. Here multi-speciesmethods have been pioneered toisolate fluxes (e. g. using 222Rn as atracer of atmospheric transport ofsoil emissions, or δ14C to identifyfossil emissions).

4. There is some overlap in scien-tific objectives and membership oftechnical committees between theIAEA CRP and the World Meteoro-logical CO2 Measurement ExpertsGroup. Previous technical meetingshave been jointly supported by bothWMO and IAEA. There are strongreasons for maintaining andstrengthening this interaction. TheWMO philosophy of "twinning" be-tween experienced and developinglaboratories also has possible rele-vance for the isotopic measurementcommunity (though this might beexpected to occur naturally underthe proposed CLASSIC II proposal).

The IAEA CLASSIC(Circulation ofLaboratory Air Standards for StableIsotope Comparisons) inter-calibration, mainly conducted by theCSIRO in Melbourne, Australia andthe first successful CO2 stable iso-tope inter-calibration between themajor global sampling networks, hasconfirmed suspected offsets, re-vealed possible non-linearity, andidentified inconsistencies in correc-tion algorithms. At the same time,the progress towards the CO2 andδ13C target inter-comparison preci-sion is encouraging.

The meeting agreed that a technicaldocument and technical guideshould be prepared and publishedby the IAEA to disseminate the out-come of the CRP.Proposed Future Activities

The 1997 Kyoto Protocol providesnew and urgent challenges to thescientific community:

With the formal acknowledgment ofmost governments that climatechange through anthropogenic mod-

linearity/scale contraction, N2O,H2O), flask storage effects (forδ18O) , and evidence of commonsystematic error arising from cryo-genic CO2 extraction, at a level withserious implications for global at-mosphere studies (e.g. with aver-aged δ13C precision targets of 0.01per mil or better).

The introduction of whole-air stan-dards by all major laboratories, toaddress these problems to a signifi-cant (if not yet entirely satisfactory)degree.

Demonstration (in several partici-pating laboratories) of external pre-cision at close to target precision(e.g. in seasonally averaged δ13Cfrom southern hemisphere stations,or in differences between laborato-ries with overlap sampling). In gen-eral, the IAEA CRPs have been theonly forum for close, critical com-parison of recent (unpublished) iso-tope data and methods.

The successful development(through IAEA technical contract) ofhigh pressure cylinder whole-airstandards with detailed calibrationand reporting protocols for CO2 sta-ble isotope calibration.

Parallel development of the com-plementary "operational" inter-comparison programme (ICP), alsocalled "flask air-sharing" calibrationstrategy. Confirmation of laboratoryoffsets with CLASSIC, consistentwith ICP and station records.

2. Progress with CH4 inter-calibration has included the devel-opment of the three pure CO2 gasreference materials by the NationalInstitute of Standards and Technol-ogy (NIST), USA (The mass spec-trometer non-linearity/memory ef-fects discussed for CO2 can also beserious for δ13CH4 due to referenceCO2 being much more positive thantypical sample values. There hasbeen some parallel progress in ad-dressing this).

3. The CRP has also been a key



ification of atmospheric composi-tion is a problem warranting inter-national action, the urgency has apolitical as well as scientific nature.

The measuring and monitoring ofgreenhouse emissions on a moreregional scale is an essential stepin distinguishing and moderatinganthropogenic influence. If, as webelieve, the tools that have beendeveloped for the global studiesare relevant to this task, now is thetime to demonstrate it.

An obvious first step from a mea-surement perspective is to havemore and better monitoring of spa-tial differences in atmosphericcomposition. This means that wemust overcome the inter-calibration problems which havepreviously prevented merging ofdata from different measuring net-works.

On the basis of information gained,CLASSIC II is proposed, in whichthe original CLASSIC strategy issignificantly enhanced by comple-mentary activities. The objective isworld-wide continuous high preci-sion inter-calibration, in a waywhich is accessible to both devel-oped and developing laboratories.Moderate internationally-coordinated funding is required toestablish and maintain the strat-egy. Co-ordinated IAEA and WMOinvolvement is seen as crucial infacilitating funding and in providingongoing technical forums for thepurpose of technology develop-ment and dissemination of results.

The responsible officer for thisCRP is Manfred Gröning.

The workshop provided a suitableforum for the transfer of know-howon the potential of isotope hydrol-ogy in Alpine environmental andhydrological investigations, and forthe incorporation of isotope studiesin relevant investigations carriedwith under EU support. Hydrologi-cal research is planned by the EUunder the key action “Sustainablemanagement and quality of water”which aims at developing knowl-edge and technologies needed forthe rational management of fresh-water resources.

The Workshop was attended byabout 60 participants, most ofthem from Austria and other EUcountries. It was structured in twoplenary sessions on “Water Regu-lations and Research Strategies ona European Scale” and “ResearchDeficits and Solutions in the AlpineEnvironment”, in which the state ofthe art in research in this field waspresented and research deficitsand demands were highlighted.

These sessions were followed bydiscussions of specific topics infive working groups:

(1) Present land use practices andassociated water problems;

(2) Water-related conflicts andsustainable water utilization;

(3) Research priorities in river wa-ter ecology;

(4) Integrative catchment and dis-aster management;

(5) Environmental monitoring andassessment. The results and rec-ommendations of the workinggroups were discussed in a con-cluding plenary session.

he EU-Workshop on “Waterrelated conflicts of interests in

the Alpine environment - researchdeficits, demands, solutions” wasorganized by the Austrian Networkfor Environmental Research andthe Austrian Federal Ministry ofScience and Transport, within theframework of the Austrian EU-presidency.

The workshop was administeredby the Joanneum Research, Insti-tute of Hydrology and Geother-mics, Graz, Austria, and held from28 September to 1 October 1998in Warmbad Villach, Austria.

A keynote paper on “Application ofisotope hydrology in Alpine re-gions” was presented by Mr. KlausFroehlich, Head of the IAEA-Isotope Hydrology Section. Thepaper summarized the principlesof isotope applications in Alpineregions and presented case stud-ies demonstrating the potential ofisotopes to-

(i) study the response of shallowAlpine aquifers to climaticchanges;

(ii) delineate recharge areas andprotection zones of springs andother aquifers used for drinkingwater supply;

(iii) determine the residence timeof water in (karst) aquifers and incatchment areas, and

(iv) estimate hydrological parame-ters of aquifers such as their stor-age capacity.

Mr. Froehlich also participated inthe working group 5 on environ-mental monitoring and assess-ment where he discussed and rec-ommended future activities re-lated to the integration of isotopetechniques in studying Alpine hy-drological systems and environ-ments.



he second co-ordination meet-ing of the Agency's CRP on

"Use of isotopes for analyses offlow and transport dynamics ingroundwater systems" was held atthe US Geological Survey, Reston,USA, from 18 to 22, May 1998.The meeting was attended byChief Scientific Investigators fromtwelve institutes involved in theCRP along with the interested re-lated staff of the host institute.

Overall Achievements

The meeting reviewed the overallprogress made by the participatinginstitutes in the development andfield verification of different con-ceptual model formulations relatedto the use of isotopes in groundwa-ter flow and transport simulation,through presentations made andsubsequent discussions held. Re-sults of applied field research inthis regard comprised of differentmodel formulations, i.e. lumpedparameter (transfer function) mod-els, compartment models (mixing-cell approach), distributed parame-ter numerical flow and transportmodeling, and geo-chemicallycoupled transport modeling. Re-sults obtained from field applica-tions of these formulations to spe-cific groundwater aquifer systemsof different hydrogeological set-tings and representing differentspatial scales were considered anddiscussed. The work done by someinstitutes also concerns PC soft-ware development for the abovecited different formulations. Thestatus of the software developedwas reviewed and discussed.USGS participants have also pro-vided valuable input to the meet-ing through presenting some oftheir ongoing work related to thesubject matter of the CRP, as wellas demonstrating recent softwaredeveloped by USGS on three- di-mensional numerical flow andtransport modeling in groundwatersystems.

The progress made and the results

tems, as limited knowledge abouttransient input concentrations willreduce this confidence (Figure 1).

Individual Presentations

• A combined interpretation of en-vironmental isotopes for analy-ses of flow and transport parame-ters by making use of thelumped-parameter approach. (A.Zuber)

• Application, calibration and vali-dation of the lumped-parametermodels for the interpretation oftransport and hydraulic parame-ters based on environmentaltracer data. (P. Maloszewski)

• Elaboration of advanced predic-tive and interpretive mathemati-cal models in isotope hydrology:isotope tracer movement de-scription in the aeration zone andgroundwater aquifers. (V. Du-binchuk)

• Underground mines as ana-logues for the hydrogeology ofnuclear waste repositories: mod-

obtained so far in the CRP havebeen very successful in develop-ment and field verification of differ-ent modeling formulations in whichisotopes could be used for con-straining the models, estimatingtime related parameters of thegroundwater flow (travel times andtheir distribution) and transport(dispersion parameters), providingquantitative information on the mix-ing patterns and ratios of differentcomponent flows (sources of water)in the groundwater system. As anexample, the study carried out byG. Harrington et. al. provides arelatively straight forward approachfor using environmental isotopesand other hydrochemical tracers toconstrain regional groundwater flowmodels. Application of the ap-proach to a transect in the OtwayBasin of southern Australia has en-abled rates of inter-aquifer leakageto be estimated with greater confi-dence than if only an hydraulicmodel had been used. The studyhas however highlighted a need forcaution when applying such an ap-proach to regional groundwater sys-

Figure 1 (a-d). (a-b) Modeled and observed aquifer head and confined aquifer carbon-14 distribu-tions obtained using the original MODFLOW model. (c-d) Modeled and observed distributions ob-tained using the re-calibrated MODFLOW model in which the choice of hydraulic conductivity wasconstrained by carbon-14 data.



eling surface-to-depth flow andmixing in crystalline rocks withenvironmental isotopes. (I.Clark)

• Use of environmental isotopes/tracers for demonstrating safetyof a waste disposal facility. (G.Moltyaner)

• Use of isotopes to constrainwater and solute models in theOtway Basin, Australia. (G.Harrington)

• Comparison of groundwaterflow modeling and environmen-tal isotope results in the GreatHungarian Plain. (J. Deak)

• Evaporation from phreaticaquifers in arid zones: apparentcontradiction between hydraulicand isotope data. (A.Coudrain-Ribstein)

• Use of isotopes (18O, 14C,87/86Sr) for analyses of ground-water flow and Cl transport overpast 10 000 years in BolivianAltiplano. (A. Coudrain-Ribstein)

• Use of isotopes and CFC's forthe analyses of groundwaterflow: Selected case studiesfrom Denmark. (K. Hinsby)

• Compartment-model simulationof groundwater flow systems.(M. Campana)

• Geochemical and isotopic con-straints on groundwater flow di-rections, mixing and rechargeat Yucca Mountain, Nevada. (E.Kwicklis)

• Mathematical modeling of largescale karstic springs system byusing environmental isotopes.(L. Tezcan)

• Coupled inverse modeling ofgroundwater flow and isotopegeochemical processes. (R.Kalin)

• Tracing and dating in ground-water in the Middle Rio GrandeBasin, New Mexico, USA. (L.Niel Plummer)

• Using environmental isotopedata to improve the USGSMODFLOW model of the Mid-dle Rio Grande Basin (W. San-ford)

• Age transport modeling in het-erogeneous media. Radontransport at the Mirror Lake,N.H. site. (D. Goode)

• Using environmental tracers to

2) A critical review and synthesis ofthe work done and results achievedby the CRP should be published in ascientific journal (i.e. Groundwater,Hydrogeology Journal, Journal ofHydrology) to facilitate the dissemi-nation of information to the scientificcommunity.

3) A practical manual should beprepared by the Agency in co-operation with the institutes involvedin the CRP, on the methods andprocedures of different modeling ap-proaches developed and verified inthe CRP, including the relevant PCsoftware. Such a manual shouldconsist of individual booklets oneach of the four main approachescited above and could be preparedduring 1999 based on the achieve-ments of the CRP.

The responsible officer for this CRPis Yuecel Yurtsever.

estimate matrix diffusion in frac-tured rock over distances of kilo-meters. (A. Shapiro)

• Stable isotopes as groundwatertracers on regional and localscales: Examples from Hawaiiand Oklahoma. (M. Scholl)

• 15N tracer experiment at the

Cape Cod site. Box modeling ofsulfate and nitrate in groundwa-ter. (J.K. Bohlke)

• Application of environmentalisotopes to the analysis of flowand transport in a thick clayaquitard system, Saskatchewan,Canada (J. Hendry)

• Some problems in the use ofenvironmental tracer methodsfor calibration and validation ofmathematical models of flowand transport in groundwatersystems. (A. Zuber)

Planned Follow-up Activities

In the final overall discussions, themeeting concluded that themethodologies developed for usingisotopes in the analysis of flow andtransport processes in groundwatersystems and dynamic simulation ofthe systems, even at the complexi-ties of the three-dimensional scale,are well developed, and the appliedfield research carried out within theCRP at different hydrogeologicalsettings and scales verifies theirapplicability. Assessment made inthis particular field through the re-search carried out and the com-puter software being developedwithin this CRP marks a valuablecontribution towards improved andmore effective use of isotopes. Fi-nal outcome of the CRP will bepublications to be realized for theirwider utilization in practice. In thiscontext, the meeting made the fol-lowing recommendations:

1) All the final reports to be pre-pared (in the format to be definedby the Agency) by the participatinginstitutes, should be submitted tothe Agency by the end of 1998,which is the scheduled completiondate of the CRP. These final docu-ments are recommended to becompiled by the Agency and pub-lished as a TECDOC during 1999.

General News: New programmefor the cycle 1999-2000

Programme Review: Geothermalresources development and man-agement

Technical Review: Isotopes ingeothermal investigations

News Updates on:1. Urban Hydrology-1st Research

Co-ordination Meeting, India2. Field manual on geothermal

exploration3. Workshop on geothermal en-

ergy, Mexico4. Water resources in Asia and

Pacific, Advisory Group Meet-ing, India

5. Reference materials, Consul-tants meeting in Groenigen

6. Groundwater renewal, Re-search Co-ordination Meeting,Tunisia

And more...



he technology transferred bythe IAEA to the Costa Rican

Institute of Electricity (ICE), in theframework of the ARCAL XVIIIprogramme on nuclear and relatedtechniques in dam and reservoirleakage studies (1994 - 1997), hasbeen incorporated as an additionaltool in their routine activities fordam safety monitoring, which hasprovided information needed tochoose the appropriate technicalsolutions to two safety problems onhydraulic works which occurredlast year.

In July 1997, a crack was noticedon one slope of the Arenal dam,where its structure is supported.After a few days this crack devel-oped into a land slide, the cause ofwhich appeared to be the presenceof excess water in the soil. Twodifferent hypotheses, requiring dif-ferent approaches to solve theproblem, were studied. If the waterwas originated in the reservoir, thedam structure should be rein-forced, a time consuming and ex-pensive solution. If the water camefrom elsewhere, the solutionshould be simply the stabilizationof the slope. In both cases, urgentaction was needed to avoid risks tothe stability of the dam. As the

nuclear and related techniques, itwas proven that this water camefrom a creek which infiltrated in ageological fault, more than one kilo-meter away. As this situation did notjeopardize the stability of the tunnel,instead of sealing the fault, the infil-trated water (an average 200 litersper second) will be allowed to flowinto the tunnel and into the streamdischarged from the reservoir, asthis will represent a slight increase inthe generation of electricity.

The usefulness of these techniqueshas been well recognized by theinstitution. In recent administrativeand functional reforms undertakenby the Government, the importanceof these techniques has been a keyaspect in justifying the existence ofthis technical group. Moreover, thisteam has attained a higher level inthe Organizational Chart as a conse-quence of their success in monitor-ing the stability of hydraulic struc-tures.

The responsible officer for theseprojects are Edmundo GarciaAgudo.

reservoir was completely full, theconsequences of a dam collapsewould be terrible. This hydroelectricpower station is responsible for 65%of the total electricity produced inthe country and provides 90% of theirrigation water to the Guanacasteprovince, which is a highly produc-tive agricultural area. The teamfrom ICE trained by the IAEA ondam leakage studies, using nuclearand conventional techniques ac-quired through the ARCAL XVIIIprogramme, demonstrated that thewater was an accumulation of infil-trated rain in the area. This informa-tion allowed immediate and appro-priate corrective action, which con-sisted of the installation of drainsystems and terraces to stabilizethe slope. The cost was approxi-mately US$ 700,000. If this problemhad not been identified and solvedin time, the result would have beena national catastrophe.

In a second case, during the con-struction of the Angostura hydro-electric power station, a tunnel witha diameter of 9.5 meters was drilledthrough the rock to feed the waterfrom the dam into the turbines. Dur-ing the construction of this tunnel, acrack in the rock was encountered,which flooded the tunnel. Using

ecognizing the need tostrengthen the collaboration

between Iranian institutes dealingwith karst hydrology and interna-tional organizations, an interna-tional symposium was organizedby the National Karst ResearchCentre, Ministry of Energy, Iran,and was held 4 - 6 July in Tehran.

The purpose of the Symposiumwas to gather national and interna-tional scientists dealing with differ-ent aspects of the karst, and todraw attention of national decisionmakers and the public to theuniqueness of karst ecosystems

and their exploration, managementand sustainable development. TheIAEA was one of the co-sponsoringorganizations.

The Symposium was attended byabout 500 national participants and25 representatives from other coun-tries and international organiza-tions. The 50 oral presentations and10 poster presentations were struc-tured in several sessions coveringthe following main topics: (i) hydrol-ogy, hydrogeology, geomorphology,tectonics, hydrochemistry and ex-ploration of karst systems; (ii)speleology; (iii) karst engineering;

(iv) karst water protection and envi-ronmental studies; and (v) modelingand management of karst systems.

A keynote paper entitled “IsotopeTechniques in the Study of KarstSystems” was presented by Mr.Klaus Froehlich, head of the IAEA-Isotope Hydrology Section. Themeeting emphasized the need forfurther research on the vulnerabilityof Karst systems to pollution andother issues related to Karst waterresources management.



Date: 10-14 May, 1999Venue: IAEA, Vienna, AustriaDeadline for submission of papers is 15 December1998.

General Information:

The Symposium is organized by the IAEA, andco-sponsored by the United Nations EducationalScientific and Cultural Organization (UNESCO), inco-operation with the International Committee onTracers (ICT) of the International Association ofHydrological Sciences (IAHS).

The Symposium will cover the whole spectrum ofresearch and applications of isotope techniques inwater resources development/management and re-lated environmental disciplines.

Contributions are invited on the themes listed below.They should have a new research-based develop-ment component or deal with significant refinementof isotope methods and/or open new fields of appli-cation to investigate/assess the impact of naturaland man-made environmental changes on waterresources. Papers submitted may also illustrate thecontribution and value of isotope techniques in pro-viding solutions to specific hydrological fieldsthrough new evaluation/interpretation tools of iso-tope data for improved management of water re-sources.

• Processes at the interface between atmosphereand hydrosphere

• Studies in surface waters• Studies in sedimentology• Studies in groundwater• Isotope data interpretation and evaluation method-

ologies in hydrological systems• Recent advances in analytical techniques for isotope

hydrology

Further information can be obtained from:

Meeting secretariat, IAEA-SM-361, International AtomicEnergy Agency, Vienna International Centre, P.O. Box100, Wagramer Strasse 5, A-1400 Vienna, Austria

Telefax: +43-1-2600 7E-mail: [email protected]

The Scientific Secretary of the Symposium is Mr. Y.Yurtsever, Isotope Hydrology Section, Division of Physi-cal and Chemical Sciences (telephone extension 21732,e-mail address: [email protected]).

Meeting organization is provided by Ms. R. Perricos,Conference Service Section, Division of External Rela-tions (telephone extension 21315 & 21311, e-mail ad-dress: [email protected]).

Information concerning the Symposium is also availablethrough the Internet at the following URL:

Welcome to theIsotope Hydrology Section

on the InternetThe IAEA Isotope Hydrology Section has re-cently opened a Website on the World WideWeb as a part of Worldatom, the Agency’s mainInternet service to the Member States and thegeneral public. The address (URL) of the Iso-tope Hydrology Section’s homepage is:

http://www.iaea.org/programmes/ripc/ih/ index.html

A major IAEA symposium held once every 4 years, don’t miss it !



Noble Gas Isotopes

Noble gas isotopes are very wellsuited to serve as tracers for physi-cal processes in the environmentbecause their concentrations arenot influenced by chemical or bio-logical transformations. The ele-mental abundance and isotopiccomposition of noble gases in wa-ter have been employed to studypaleo and recent temperaturechanges, to date ground water inthe time range from a few days toseveral million years and to quan-tify mixing in lakes and oceans.

The main reservoir of noble gaseson the Earth is the atmosphere,where their elemental abundanceis well known and seems to beconstant at least on times scalesup to a few million years. Theconcentrations of noble gases inwater are primarily controlled byair-water exchange. The solubilityof noble gases in surface watersdepends mainly on temperatureand pressure, but also to a minorextent on the chemical composi-tion of the water. Thus, noble gasconcentrations in the water provideinformation on temperature andpressure conditions prevailing dur-ing gas exchange.

Some noble gas isotopes (e.g.3He, 4He, 39Ar, 40Ar, 85Kr) are pro-duced by radioactive decay orother nuclear reactions. The accu-mulation of the stable isotopessuch as 3He, 4He and 40Ar, as wellas the decay of the radioactivenoble gas isotopes such as 39Ar(half life 270 yr) and 85Kr (half life10.5 yr), can be employed to datesurface and ground waters (seeTable 1). The dating methods pro-vide a means to estimate resi-dence times and flow velocities inaquifer systems and to quantifyvertical exchange in the deep partof surface water bodies.

In the following we first describehow recharge temperature can beestimated from atmospheric noblegas concentrations and then dis-cuss the use of helium isotopes for

Ne, Ar, Kr and Xe, which are mostlyof atmospheric origin, the methoddescribed above was applied to re-construct atmospheric cooling dur-ing the last ice age (e.g. Stute et al.1995 and Figure 1). Typically, theprecision of the noble-gas tempera-tures is in the order of 1°C.

A major limitation of the noble-gastemperature method lies in the com-position of the excess of noble-gases. In some ground waters theexcess air component seems to befractionated in favor of the heaviernoble gases. This effect is com-monly explained by partial de-gassing of excess air duringrecharge. However, neither the gen-eration of excess air nor the reasonfor the fractionation of noble gaseswithin the excess air component iswell understood. Thus, in groundwaters with strong fractionation ofthe excess noble gases, rechargetemperature derived from noble gasconcentrations is not well con-strained (Aeschbach-Hertig et al.1998).

Dating Using Helium Isotopes

3H-3He apparent water age3He is produced by radioactive de-cay of tritium 3H (half life 12.38 yr).As long as a water parcel is incontact with the atmosphere, 3Heproduced by tritium decay (3Hetri) israpidly removed from the water tothe atmosphere by gas exchange.Thus, the concentration of dissolved3He in the water parcel remains nearthe atmospheric equilibrium concen-

dating.

Temperature Estimation Basedon He, Ne, Ar, Kr, Xe

Reconstructing surface water tem-perature from noble gas concentra-tions assumes that at the time whenthe water was in contact with theatmosphere the concentrations inthe water were in equilibrium withthose in the atmosphere. Since theequilibrium concentrations dependon temperature T and pressure p,these parameters can directly beinferred from the observed noblegas concentrations. However, inmany cases and in particular inground waters, the measured con-centrations are significantly higherthan those expected for equilibriumconditions. This phenomenon iscommonly explained as caused bythe complete dissolution of air(excess air).

Temperature and the entrainmentof excess air have a different effecton the concentration of each of thenoble gases. Therefore, the simul-taneous measurement of the fivenoble gases allows to distinguishbetween excess air and the equilib-rium concentrations. Thus, the pa-rameters T and p, as well as theamount of excess air, can be ob-tained from the noble gas concen-trations. Note, that in many caseshelium cannot be directly includedin this calculation, because heliumconcentrations are often dominatedby non-atmospheric sources (seebelow). Based on the noble gases

Tracer Time scale Source Detection222Rn days to weeks 238U α counting37Ar months spallation (S) low level counting

(LLC)3H-3He months to

decadesS, nuclear bomb test-ing

mass spectrometry(MS)

85Kr months todecades

nuclear power plants LLC

39Ar 102 yr S LLC4Herad 103 - 108 yr U, Th MS40Arrad >105 yr 40K MS

Table 1. Time scales of dating methods by noble gas isotopes.



tration. As soon as the water parcelis isolated from the atmospherethe concentration of 3He in thewater increases because the pro-duced 3He can no longer escapeby gas exchange. The ratio be-tween 3Hetri and 3H is a measurefor the apparent water age which isthe time elapsed since the waterwas last in contact with the atmo-sphere. The 3H-3He apparent waterage is given by (Torgersen 1977)

(1)

where (= 0.05599 yr-1) is thedecay constant of 3H. To obtain3Hetri from the measured 3He con-centration, 3He of atmospheric ori-gin and 3He introduced from thegeological setting (terrigenic 3He)have to be subtracted. The 3He ofatmospheric origin is comprised oftwo components: 1) the 3He equi-librium concentration which can becalculated from the solubility ofhelium and the fractionation of 3Heand 4He during solution and 2) 3Heintroduced by excess air which canbe calculated from the Ne excess.The terrigenic 3He component canbe estimated from the 4He excessif the 3He/4He ratio of the terrigeniccomponent is known. Note that incontrast to the classical tritium dat-ing the calculation of 3H-3He ap-parent water age does not dependon the knowledge of the local inputfunction of tritium.

3H-3He dating can be applied ontime scales ranging from monthsto decades. It has successfullybeen used to date young groundwaters (e.g. Schlosser 1988) andto quantify deep-water mixing inlarge water bodies such as theCaspian Sea (Figure 2).

The major limitation of dating withthe 3H-3He apparent water age isthe terrigenic input of 3He. It musteither be small or well known that3Hetri can be calculated with suffi-cient precision.

Torgersen, T., Z. Top, W.B. Clarke, W.J. Jenkinsand W.S. Broecker, 1977. A new method forphysical limnology - tritium-helium-3 ages -results for Lakes Erie, Huron and Ontario.Limnol. Oceanogr. 22: 181-193.

F. Peeters and R. Kipfer, Dept. ofEnvironmental Physics, Swiss FederalInstitute of Technology (ETH) and SwissFederal Institute of Environmental Sci-ence and Technology (EAWAG), CH-8600 Dubendorf, Switzerland

4He dating4He is produced by -decayof isotopes within the ura-nium and thorium series.This 4He is released fromrock and minerals and accu-mulates in water saturatedregions. If the natural flux of4He into the ground water isknown the 4He concentra-tions are a direct measurefor the residence time of thewater.

Unfortunately, in manyground waters the accumula-tion rate of 4He is muchlarger than the in-situ 4Heproduction expected from theuranium and thorium con-centrations in the aquifer ma-trix. Because the additional4He flux often contributessignificantly to the overall4He concentration in theground water, 4He dating canonly be used as a qualitativeindicator of residence time.However, because 4He dat-ing covers residence timesfrom 103 up to 108 yrs, it isthe most reliable methodavailable to date very oldand stagnant ground waterssuch as those found in theGreat Artesian Basin in Aus-tralia.

τλ

= +

11

3

3lnHe

Htri

Figure 1. Recharge temperatures derived from the noblegases Ne, Ar, Kr and Xe at different locations along the flow pathin the Glatt Valley aquifer, Switzerland. The data suggests thatthe temperature prevailing at recharge of ground water was about4 to 5 °C lower during the last ice-age than it is today (Beyerle etal. 1998).

Figure 2. 3H-3He water age in the southern and central basin ofthe Caspian Sea. In 1995 and in 1996 the 3H-3He water age inthe central and southern basin is the same at equivalent depth.This suggest that the mixing rates must be similar in both basins.The time required to replace the deep water below 200 m bywater from above 200 m corresponds to the difference of themean water age in both regions. This time of internal mixing isabout 15 years which is significantly smaller than the refill time ofthe Caspian Sea (about 200 years) (Peeters et al. 1998).

References

Aeschbach-Hertig, W., F. Peeters, U. Beyerleand R. Kipfer, submitted 1998. Interpretationof dissolved atmospheric noble gases innatural waters. Water Resour. Res..

Beyerle, U., R. Purtschert, W. Aeschbach-Hertig, D.M. Imboden, H.H. Loosli, R. Wielerand R. Kipfer, in press 1998. Climate andgroundwater recharge during the last glacia-tion in an ice-covered region. Science.

Peeters, F., R. Kipfer, D. Achermann, M. Hofer,W. Aeschbach-Hertig, U. Beyerle, D.M. Im-boden, K. Rozanski and K. Fröhlich, submit-ted 1998. Analysis of deep-water exchangein the Caspian Sea based on environmentaltracers. Deep-Sea Res.

Schlosser, P., M. Stute, C. Dörr, C. Sonntagand K.O. Münnich, 1988. Tritium/ 3He-datingof shallow groundwater. Earth Planet. Sci.Lett. 89: 353-362.

Stute, M., M. Forster, H. Frischkorn, A. Serejo,J.F. Clark, P. Schlosser, W.S. Broecker andG. Bonani, 1995. Cooling of tropical Brazil (5°C) during the Last Glacial Maximum. Sci-ence. 269: 379-383.

Water and Environment News, Isotope Hydrology Section, International Atomic Energy Agency,Wagramer Strasse 5, P.O.Box 100, A-1400, Vienna, Austria. Printed by IAEA in Vienna

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