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Quarterly No. 6, January 1999 -

WATER & ENVIRONMENT NEWS

WATER &

ENVIRONMENT

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A geothermal well in the Philippines

CONTENTS

IAEA Sub-programme on WaterResources (1999-2000)

IAEA and WMO Sign MoU

Programme Review: IsotopeInvestigations of GeothermalSystems

Interlab Calibration of ChemicalAnalysis

Geothermal Database

Selected Geothermal Fieldsfrom IAEA Projects

Technical Review: Whole Sys-tem Chemical geothermometry

Improved Reservoir Manage-ment in Los Humeros

Sustaining Geothermal Devel-opment

Reference Materials and Qual-ity Assurance

New CRP on Long-term Ex-ploitation

Training on Analytical QualityManagement

How to Order Reference Mate-rials from IAEA

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Issue No. 6, January 1999

Issued by the

Vienna, Austria

International Atomic Energy

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

NEWS

ISSN 1020–7120



OBJECTIVES

• to assist in the wider useof isotope techniques in ap-plied research and practicalfield applications related tosustainable developmentand optimum managementof water resources;

• to provide support for ef-fective integration of iso-tope methods into nationalactivities in this field; and topromote research and fieldstudies related to humaninduced changes and theirhydroclimatic impact on thewater cycle and. its inter-action with other environ-mental systems.

PROJECTS

Human Impact on WaterResources (F4.01)

• to further improve and,enhance isotope methodolo-gies applied to a wide spec-trum of hydrological prob-lems encountered as a re-sult of water utilizationpractices that induce ad-verse effects on availablewater resources; and

• to attain improved watermanagement practices thatwould minimize water qual-ity degradation due to hu-man activities.

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

• to contribute and improvethe quantitative assessmentand protection of water re-sources in regions of waterscarcity, in particular in aridand semi-arid areas; and

• to assist and. provide sup-port to Member States inregions for effective incor-poration of isotope methodsinto routine practices forestimation and verificationof hydrological field param-eters for optimum manage-ment of scarce water re-sources.

Hydro-climatic Changesand Impact on Catchmentand Surface Water Sys-tems (F4.03)

• to assess and verify theapplication of isotope method-ologies in studying processesin the atmosphere and hydro-sphere related to natural andhuman induced environmentalchanges and

• to permit improved predic-tion of their possible futureimpact on water resources;and

• to enhance the contributionof isotope applications for im-proved assessment of fluvialtransport processes and tominimize the adverse effectsof such processes on soil andwater resources.

Analytical Services andQuality Assurance(F4.04)

• to provide assistance and.support in the determinationof the isotope and chemicalcomposition of water andother environmental materialsand to assure analytical qual-ity.

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(1999-2000)

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

Head of the Section:Mr. Klaus FroehlichTel. +43-1-2600-21735/21736Fax: +43-1-26007e-mail: [email protected]

Visit Us on theInternet

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

The projects are being imple-mented by the Isotope Hydrology

Section and the Agency’s



The headline of the current issue isdevoted to the signing of the Memo-randum of Understanding (MoU) onGlobal Network for Isotopes in Pre-cipitation (GNIP) by WMO andIAEA. The MoU is aimed at strength-ening this programme, which hasbeen jointly operated by the twoorganizations for more than threedecades.

The theme of the current issue hasbeen chosen to be “Isotope Investi-gations of Geothermal Systems”,which is an important component ofour sub-programme and representsabout 20% of our current TC activi-ties as well as a share of our re-search programme. As was done inprevious issues, a programme re-

This is the first issue of Water& Environment News in 1999,

the first year of the new pro-gramme cycle. The official formu-lation of the sub-programme(1999-2000) can be found on theinside front-cover of this issue,from which one will realize thatthe new programme is a consoli-dation of the previous one.

Eight new CRPs have beenplanned to be implemented in thenew cycle. Three regional TC pro-jects (one in Africa, one in Asiaand Pacific, and one in WestAsia) have been included togetherwith 28 national projects whichwere selected from the proposalsmade by individual MemberStates.

EDITORIAL

Amemorandum of understanding(MoU) has been signed recently

by the Director-General of IAEA andthe Secretary-General of WMO onthe long-term joint programme -“Global Network for Isotopes in Pre-cipitation (GNIP)”.

For the last more than 35 years,institutions in IAEA and WMOMember States have made theirprecipitation samples from meteoro-logical stations available to theIAEA for isotope analysis. Manyinstitutions have provided their owndata of the isotopic composition ofprecipitation to the IAEA for inclu-sion in the GNIP Database. Theprogramme is known as the GlobalNetwork for Isotopes in Precipitation(GNIP) (See Water & EnvironmentNews Issue-4 for details of the pro-gramme).

Recently, in realization of expectedchanges in the water cycle and inclimate, the IAEA and WMO have

tific purposes by national institu-tions;

⇒ national networks operated by na-tional authorities which providedata to the GNIP database;

⇒ the GNIP database to be operatedand maintained by the IAEA;

⇒ the Steering Committee, in chargeof the implementation of the Pro-gramme.

In a preparatory meeting for the GNIPScientific Steering Committee held inlast July in Vienna, strategies andpractical measures were discussedto implement the MoU.

Information on the GNIP and itsdatabase is also available on theInternet Website of the Isotope Hy-drology Section (See address on in-side front-cover of this issue).

initiated the necessary steps tostrengthen the GNIP programme de-voted to monitoring parameters inprecipitation including isotopesindicative of those changes.

As stated in the MoU by the twoorganizations, further efforts will bemade to create a new framework forco-operation in this area. The majorelements included in the renewedGNIP Programme are:

⇒ the global network of referencestations; i.e. a set of key sta-tions with global coverage provid-ing long-term isotope data andwhose operation will be monitoredby the IAEA and WMO.

⇒ the stations which, from time totime, may co-operate with theIAEA, input from special mea-surements, stations or networksresulting from individual researchprojects, short-period stationsthat are set up for various scien-

IAEA AND WMO SIGN MEMORANDUM ON GNIP

G e n e r a l N e w sG e n e r a l N e w s

view and a technical review will sup-plement the reports on recent eventswithin relevant projects in geother-mics. Technical support of the IAEAover the last two decades has madea remarkable impact on geothermaldevelopment in developing MemberStates. A collection of photos fromselected geothermal fields will high-light some of the aspects in thisregard.

Laboratory activities on reference ma-terials and quality assurance havealso been included in this issue.

Klaus FroehlichHead, Isotope Hydrology Section



Scientific Scope

The hydrology of deep geother-mal systems is closely linked

to the shallow and cold hydrologicalsystem. The complexity resultingfrom the interplay of different fluidsand their origins made nuclear tech-niques using 18O, 2H, 3H, 34S, 13C,3He, and 131I among others, indis-pensable tools in geothermal inves-tigations. The occurrence, therefore,of geothermal energy resources,and the essential techniques re-quired to define its hydrological andgeochemical characteristics providea strong link to water resourcesdevelopment and management. Thisled to the integration of the geother-mal energy-related projects to theIAEA Sub-Programme on WaterResources Development and Man-agement.

Stable isotopes are the sole indica-tors of possible recharge areas.Isotopic and chemical study of wellfluids during geothermal develop-ment indicate the subsurface flowpaths and the locations of zones ofupflow, outflow, and marginal areasof mixing with cooler waters. Asexploitation proceeds, changes inpressure and fluid isotopic andchemical composition can give anindication of field capacity and themode of response to fluid produc-tion.

IAEA Support forGeothermal Develop-

ment in Member States

Technical Assistance on De-velopment Projects

The assistance of IAEA to MemberStates in geothermal developmentbegan in 1976 by its cooperationwith India through the United Na-tions. Since 1980, the IAEA hasawarded technical assistancethrough its technical co-operationprogramme to various countries forthe application of isotope tech-

plemented from 1997-2000. The CRPwill bring an understanding of thegenesis of acidic fluids in geothermalsystems which will provide sufficientinput to management of the resourceas well as to decision-making formonitoring and development ofgeothermal areas. It will also developthe methodology for using the SO4-H2O pair for estimating temperaturesof fluid.

Manpower Development

Efforts have been made to developmanpower capabilities in MemberStates to apply isotope methodolo-gies in geothermal investigationsthrough fellowship and training pro-grammes (Table 2). Training haveprogressed from the basic aspects toadvanced methods of geochemicalmodeling where isotopes are inte-grated. The basic aspects of isotopeand geochemical methodologies areessentially provided by locally devel-oped resources through the years ofIAEA assistance. However, ad-vanced methods are shared acrossregional boundaries, through collabo-rative efforts to exchange experi-ences and expertise on various as-pects of geothermal development.The most recent is the creation of acollaborating group for geothermalgenerating countries in the Circum-Pacific area.

Establishment of Laboratories

Various laboratories have also beenestablished under geothermal pro-jects, initially focusing on applica-tions to geothermal but eventuallycatering to the requirements of thewater resources sector (Table 3).

The isotope laboratory in El Salvador(Figure 2) created under a modelgeothermal project established thecapability for oxygen-18 and deu-terium measurements. This isotopelaboratory is a candidate regional

niques to explore geothermal areas,to define the hydrology during ex-ploitation and to manage the reser-voir particularly in identifying areasfor reinjecting wastewater.

Countries endowed with geothermalresources, particularly those in ac-tive volcanic and tectonic zones haveembarked on development pro-grammes. This is reflected in theincrease of number of geothermalprojects in the last years (Table 1and Figure 1). Currently the IAEAhas operational technical co-operation projects in 14 MemberStates covering at least 17 majorgeothermal systems in the CircumPacific region. All these projects,one of which is a regional project inAsia, constitute about 20% of theIAEA Technical Cooperation projectson isotope hydrology.

Support to Research Projects

The IAEA supplements field applica-tions with research programmesdealing with problems associatedwith geothermal exploitation andwhere isotope techniques could pro-vide for a better understanding of thecomplex behavior of geothermal sys-tems. Two Coordinated ResearchProjects (CRP) to support the re-search needs associated withgeothermal exploration have beencompleted. One was in 1990 forLatin America involving Argentina,Bolivia, Colombia, Costa Rica,Ecuador, Guatemala, Mexico,Nicaragua, Peru and Venezuela; andthe second in 1993, for Asia involv-ing China, India, Indonesia, Pak-istan, Philippines, Turkey, Vietnam,Iceland, Italy and New Zealand.Through these efforts, the use ofisotopes has progressed consider-ably for the understanding of thehydrology and origin of different fluidtypes in various areas and stages ofgeothermal development.

A Coordinated Research Project(CRP) on “The use of isotope tech-niques in problems associated withgeothermal exploitation" is being im-

ISOTOPE INVESTIGATIONS OF GEOTHERMAL SYSTEMS

P r o g r a m m e R e v i e wP r o g r a m m e R e v i e w



laboratory to serve the Latin Ameri-can countries. The isotope labora-tory in the Philippines was upgradedenabling the operation of a massspectrometer now devoted to mea-suring isotopes of geothermal watersamples. The isotope laboratory inIndonesia while able to measure 18Oand 2H is also capable of measuringisotopes in dissolved sulfate.

Dissemination of Information

Two TECDOCs on geothermal en-ergy which have been published bythe Agency reflect the different lev-

Table 1. IAEA Technical Cooperation Projects onGeothermal Energy

Duration Topic and geothermal areas Country1991-95 Isotope ratios in geothermal exploration: Indonesia

Kamojang1991-96 Isotope techniques in geothermal hydrology: Philippines

Palinpinon, Leyte, Bacon-Manito, Mt. Apo1991-present Isotope studies in geothermal fields Guatemala

Zunil, Totonicapan, San Marcos1993-95 Exploration of geothermal resources China

South Eastern China1993-present Isotope study of geothermal fluids in the Ethiopia

Rift Valley: Langano, Northern Afar, Dallol1993-present Hydrological model for Momotombo Nicaragua1995-1997 Geothermal exploration in Aegina, Methana Greece

and Soussaki1995-present Isotope hydrology and geochemistry- El Salvador

model project: Berlin and Ahuachapan1995-present Studies on injection including regional Mexico

hydrology: Los Azufres, Cerro Prieto,Los Humeros

1997-present Regional project (RAS/8/075) in Asia China,Indonesia, Philippines, Thailand

1997-present Rational exploitation of Miravalles-model project Costa Rica

1999- Geochemical and isotope characterization of Ecuadorgeothermal areas

1999- Study of the geothermal potential of So.Altiplano Peru

Figure 1. Countries (in red) involve in IAEA research and technical co-operation projects on the application of isotope geochemistry and hydrology to geothermaldevelopment (since 1976) (Note: former USSR is considered as one recipient country in this map for simplicity).

Table 2. IAEA Seminars/Work-shops/Training Courses in geother-

mal geochemistry and hydrology

-Latin America 1984-Middle East,

Asia and Pacific 1989-Philippines 1992-Indonesia 1992-El Salvador 1996-Philippines 1997-China

1998-Thailand 1998



els of isotope integration into geo-chemistry and hydrology for theexploration of various systems inLatin America and Asia. Thesedemonstrated the techniques for in-vestigating and interpreting data indifferent countries (Table 4).

The continuing efforts of the IAEA todisseminate the methodology is re-flected in the current effort to publisha manual on isotopic and chemicaltechniques in geothermal investiga-tions. This will address the expand-ing applications of isotope tech-niques in geothermal operations,continuing IAEA technical co-operation on geothermal energy de-velopment as well as the increasingawareness for geothermal energypotential. The manual can guideexploration and monitoring activities

ment.

As geothermal development pro-gresses, there will be a need forcollaboration across regions. Vastgeothermal energy resources in thePacific area exists as a result of nearsurface heat emanating from the vol-canic activity in the Circum-PacificBelt. Since the development ofgeothermal energy has led to thematuration of isotopic and geochemi-cal techniques, each geothermal gen-erating country within the Circum-Pacific area has developed its ownunique expertise to investigate spe-cific problems inherent in theirgeothermal system. The differentstrategies and decisions taken forsimilar reservoir problems provide thevaried experiences which will be mu-tually beneficial and could acceleratedevelopment if shared to othersthrough a collaborative effort. Thiscould proceed towards developingprediction models to enable the simu-lation of the movement of fluids be-tween the deep hot geothermal sys-tem and cold groundwater.

Geothermal development will alsolook into low enthalpy resources bothfor electrical and non-electrical appli-cations. Like high enthalpy deep

by the use of geochemical toolsincluding isotopes in geothermal in-vestigations in geothermal projectsas well as investigations for waterresources

Future OutlookIsotope techniques have been estab-lished for exploration and monitoringof the reservoir. The Member Stateshave developed its own pool of localscientists to sustain, and even pur-sue further applications of the tech-nique to various hydrological prob-lems. Isotope laboratories exist ei-ther in the different regions to sup-port analytical requirements.

The focus of geochemical and hydro-logical investigations in geothermalsystems is expected towards inves-tigations dealing with impacts ofgeothermal development to water re-sources within the geothermal area.A comprehensive understanding ofthe connection between the deepergeothermal reservoir and the shallowgroundwater resources will besought to improve exploitation strate-gies and management of the environ-

Figure 2. An isotope Hydrology laboratory was established in El Salvador with technical assistance from

Table 4. IAEA Publications inGeothermics

• TECDOC 641- (1992) Geo-thermal investigations withisotope and geochemicaltechniques in Latin America

• TECDOC 988 - (1995) Iso-tope and geochemical tech-niques applied to geothermalinvestigations in Asia and the

Table 3. Laboratories es-tablished or upgraded

with IAEA support

A. Isotope laboratories-El Salvador-Philippines-Indonesia-China-Mexico

B. Water or gas chemistry laboratories-El Salvador-Guatemala-Costa Rica-Mexico-Nicaragua-Ethiopia



An Inter-laboratory calibration ac-tivity was organized recently by

IAEA for the Asia and Pacific re-gion.

This led to the improvement of thetechniques in the participating labo-ratories, increased awareness forthe importance of good analyticalresults and to a certain extent modi-fication and change of laboratoryinstruments by the institutes.

The results were evaluated by theIAEA Isotope Hydrology Sectionconsidering both statistical analysisas well as most probable or truevalues from reference labs - theIAEA Isotope Hydrology Laboratoryand INRA (France).

The efforts made by the participat-ing laboratories to improve their pro-cedures and replace minor equip-ment that may have caused theerrors clearly denote that the labora-tories pay serious attention to theaccuracy of their analytical results.

Below is a list of problems encoun-tered and solutions suggested bythe participating labs:

1 The back titration method byGiggenbach and Goguel (1980)can be adopted for HCO3 analy-

ways be within the range of cali-bration standards.

d Preserved natural standards maybe used as control sample perbatch analysis.

e Cation/anion balance should bewithin 0.95-1.05 for neutralsprings.

f For samples from the samesource, the trends in chemistry isan indicator that results are ofconsistent quality.

g A regular preventive maintenanceservice for all precision lab instru-ments should be ensured.

Further steps will be taken by individ-ual countries to sustain the achievedquality assurance procedures.

A second inter-comparison of chemi-cal results will be conducted in 1999.This will include more elements likeboron.

The responsible officer for this projectis Jane Gerardo-Abaya

sis.2 Titrants should be standardized

(e.g., NaOH, AgNO3) and theirtrue normality should be used incalculations.

3 The Mohr method is not recom-mended for analysis of low Cl.Other methods like IC, ISE andcolorimetric method (using mer-curic thiocyanate) need to beapplied.

4 Samples with high SiO2 concen-trations have to be digested withNaOH and analyzed using theyellow molybdate method byUV-Visible spectrophotometry.The method is also described inGiggenbach and Goguel, 1980.

5 It is necessary to always opti-mize the AAS operating parame-ters (burner angle and height,fuel/air ratio, lamp current, etc.).

6 Dilution factors used should bechecked.

It has been realized by the participat-ing labs that the following procedurescan sustain the quality of results:

a Standard calibration curves forAAS and colorimetric methodsof analysis should have goodlinearity (r2> or = 0.999).

b A batch analysis is always nec-essary.

c Sample concentration should al-

INTERLAB CALIBRATION OF CHEMICAL ANALYSIS

The Regional Database onGeothermal Surface Manifesta-

tions (RDGSM) has been developedby East China Geological Institute(ECGI) in the framework of IAEAregional geothermal project for Asiaand the Pacific (RAS/075).

The training for the operation of theRDGSM which was held China in1998 (see issue-4) enabled the ini-tial modification to the programme.The programme is currently beingtested and revised as well as modi-fied also to facilitate the exchangeof data with ISOHIS, a database of

all isotope data currently being devel-oped by the IAEA.

It is expected that the regionaldatabase system will provide chemi-cal and stable isotope data ongeothermal manifestations for use byresearchers and possible investorsin the region.

The requirement in RDGSM cat-alyzed the collection and manage-ment of existing data in China, In-donesia, Philippines and Thailand. Itis viewed as a useful database sys-tem since that is solely dedicated to

isotope hydrology and related data.

The database could eventually be anavenue to establish a co-operationon the exchange of geothermal infor-mation among the Asian-Pacificcountries and support such activitiesas the preparation of a digital geother-mal map for the region.

The responsible officer for this projectis Jane Gerardo-Abaya.

GEOTHERMAL DATABASE FOR ASIA AND PACIFIC



Bottom: Steam andwater sampling forisotope and chemicalmeasurements from ageothermal well inPalinpinon geothermalfield (192 MWe), Ne-gros Oriental, Philip-pines.

SELECTED GEOTHERMAL FIELDS FROM IAEA PROJECTS

Top: A pilot geothermal powerplant to gener-ate 7.5 MWe in Aluto Langano geothermalfield, Ethiopia. Wells with temperatures ofabout 280-300 °C will supply steam to theplant.

Middle left: A high temperature geothermalwell in Mamotombo geothermal field,Nicaragua. The power generated from thisfiled has decreased from 15 MWe due toeffects of exploitation.

Middle right: Extensive surface thermalmanifestations of a geothermal prospect withhigh potential for development in Costa Rica.



Bottom: A geothermal wellready to produce steam forpower generation in Zunil,Guatemala, where tempera-tures up to 300 °C are en-countered and field capacityis estimated at 24 MWe.

Note: Photos displayed onpages 8 and 9 were takenby Jane Gerardo-Abaya of

SELECTED GEOTHERMAL FIELDS FROM IAEA PROJECTS

Top: Steam separators and a geothermalwell in Kizildere geothermal field, Turkey.

Middle left: Demonstration of gas sam-pling in the fumarole in Salak Volcano,Indonesia.

Middle right: Sampling hot water from ageothermal well near Zhangzhou geother-mal field, Fujian, China (Photo credit:Roberto Gonfiantini / Italy).



Whole-System Chemical

GeothermometryThe geothermometry method first proposed by Reed andSycher (1984) is referred to as theoretical chemicalgeothermometry or whole system chemical geothermome-try. The theoretical basis of thisgeothermometry method ischemical thermodynamic calcu-

Introduction

Chemical and isotopic geothermometers are equa-tions or models based on temperature-dependent

chemical reactions or isotope equilibrium fractionationrelations from which equilibrium temperatures ofthese reactions can be calculated.

Conventional chemical geothermometers based onsolutes (Silica Geothermometers, Cation Geother-mometers) and gases (Gas Geothermometers) aswell as on the atoms in water molecules and dis-solved substances (Isotope Geothermometers) ingeothermal discharges have been used in the lastthree decades to predict the temperature at depth ofgeothermal systems (reservoir temperature). This is akey parameter in geothermal resources assessment.The major drawback of all the conventional geother-mometry methods lies in their incapability in makinga judgment on the equilibrium status of the studiedsystems.

This review will focus on two recent approaches in thisfield. Zhangzhou Geothermal Field in SE China will beused as an example to demonstrate the applications.

Na-K-Mg GeoindicatorThe combination of Na-K and Mg-K geothermometerequations allows the construction of Na-K-Mg ternarydiagram or the so-called Na-K-Mg Geoindicator cre-ated by Giggenbach (1988), which provides the possi-bility in distinguishing equilibrium status in thegeothermal systems by the Na-K-Mg inter-relations.

The advantage of this diagram is remarkable. It allowsthe effect of Mg on the Na-K geothermometers to beassessed more easily. The unique graphical presen-tation of geothermometry results makes it convenientto compare different samples and to identify possiblemixing relations among them. However, the methodis still based on the empirical geothermometry equa-tions and discrepancy for different cation geother-mometers still exists. In fact, the location the curve of“full equilibrium” curve is different if a different Na-Kgeothermometry equation is used. The difference ispronounced for temperatures lower than about 220 °C(Figure 1).

Equilibrium situation is indicated and maximum reser-voir temperature of about 150 °C is obtained based onthe geothermometry equation by Fournier (1979),partial equilibrium by Giggenbach (1988), and super-saturation by Arnorsson (1983). The reservoir temper-ature was confirmed by the SO4-H2O pair Oxygen-18geothermometer (Figure 2).

WHOLE SYSTEM CHEMICAL GEOTHERMOMETRY

Figure 1. Na-K-Mg Geoindicator with samples from Zhangzhou geothermalfield. The three different curves for “full equilibrium” are based on Na-Kgeothermometry equations by the indicated respective authors (from Pang,1996).

Figure 2. Oxygen isotope geothermometer based on the SO4-H2O pair. Filledcircles are samples of geothermal water from Zhangzhou geothermal filed,China. The iso-temperature lines are based on Lloyd, 1968 (from Pang et al.,

T e c h n i c a l R e v i e wT e c h n i c a l R e v i e w



Q/K graph to eliminate problems with water analyseslacking Al or with erroneous analyses of Al. This is madepossible by forcing the water to be at equilibrium with aselected Al-bearing mineral, such as microcline. In aFixAl graph, a modified Q/K value is plotted againsttemperature for Al-bearing minerals. Saturation indices ofnonaluminous minerals are plotted in the same way as inan ordinary Q/K graph (Figure 3).

In addition to Al concentration errors, degassing of CO2,and dilution of reservoir water interfere with computedequilibrium geothermometry. These effects can be distin-guished in a Q/K graph by comparing curves for non-aluminous minerals to those of aluminous minerals thencorrecting for CO2, loss and dilution by a trial and errormethod.

Example geothermal waters from China, Iceland, and theUSA that are used to demonstrate the methods show thaterrors in Al concentrations are common, and some aresevere. The FixAl approach has proved useful for chemi-cal geothermometry for geothermal waters lacking Alanalysis and for waters with anincorrect Al analysis. Theequilibrium temperatures esti-mated by the FixAl approach

lations of multi-component equilibria involving mineral,water and gas phases. The result of the thermody-namic calculations allows:

• to evaluate the equilibrium status of the system;• to obtain equilibrium temperature if an equilibrium

for a mineral assemblage does exist;• to acquire information as to whether a dilution or

degassing process has taken place.

Differing from the conventional geothermometers, thismethod for the first time provide the possibility to judgethe equilibrium status of the studied systems beforemaking a temperature estimate.

However, this geothermometry method with soundtheoretical basis did not receive immediate wide appli-cation due to the fact that in reality there exist manyfactors that would blanket the equilibrium fingerprint.

A recent refinement of the theoretical geothermometrywas achieved by the FixAl method (Pang & Reed,1998) which provides the possibility to identify andsolve problems such as an erroneous analytical valueof Aluminum, and influence of processes such asdilution and degassing, and therefore makes it possi-ble to reconstruct most of the lost equilibrium”.

Errors in Al analyses impose strong effect on theoreti-cal chemical geothermometry based on multi-component chemical equilibrium calculations of min-eral equilibria. The FixAl method employs a modified

Figure 3. A comparison of a normal Log(Q/K) graph (a) with a FixAl graph(b), where the Aluminum-bearing minerals show different curves whilenon-Aluminum minerals remain unchanged. The equilibrium temperatureindicated by the convergence of curves is the same (from Pang and Reed, T e c h n i c a l R e v i e wT e c h n i c a l R e v i e w

Figure 4. FixAl result of a geothermal water sample from Zhangzhou geother-mal field, China showing (a) original log(Q/K)graph; (b) the same graph but with100% CO2 added back; (c) FixAl graph showing the reconstructed equilibrium

Log

(Q/K

)

Log

(Q/K

)



agree well with quartz, or chalcedony, and isotopicgeothermometers. Figure 4 is the example ofZhangzhou geothermal system, which shows the recon-structed equilibrium after both effects of Al and CO2 areremoved.

The best choice of mineral for forced equilibrium de-pends on pH. For most neutral pH waters, microclineand albite work well; for more acidic waters, kaolinite orillite are good choices. Measured pH plays a criticalrole in computed equilibria, and we find that the best pHto use is the one to which the reported carbonate alsoapplies. Commonly this is the laboratory pH instead offield pH, but the field pH is still necessary to constrainCO2 degassing.

The use of chemical or isotopic composition of geother-mal fluids (water & gas) to estimate subsurface temper-ature (reservoir temperature) has been a routine practicein any geothermal project. The development and applica-tion of chemical and isotopic geothermometers haveevolved from empirically calibrated equations based onindividual components or minerals (gases) to the model-ing of the equilibrium scenario of the whole water-gas-mineral geochemical interaction system in the geother-mal environment as briefly discussed in this review.

Furthermore, as isotopes are being incorporated into thechemical reaction models (Bethke, 1996), it can beexpected that isotopic geothermometry methods whichdo not rely merely on individual isotope exchangerelations but on whole system isotope equilibrium willprobably also be available in the future for geothermal

investigations.References

Arnorsson, S., 1983, Chemical equilibrium in Icelandic geother-mal systems: implications for chemical geothermometry investi-gations, Geothermics, 12, 119-128.

Bethke, C.M., 1996, Geochemical Reaction Modeling, OxfordUniversity Press, pp.397, ISBN 0-19-509475-1.

Fournier, R.O., 1979, A revised equation for the Na-K geother-mometer, Geotherm. Res. Council Transactions, 3, 221-224.

Giggenbach, W., 1988, Geothermal solute equilibrium, derivationof the Na-K-Mg Geoindicator, Geochim. Cosmochim. Acta, 45,939-410.

Lloyd, R. M., 1968, Oxygen isotope behavior in the sulphate-watersystem, J. Geophys. Res., 73:6099-6110.

Pang, Z. H., 1996, FixAl method applied to Zhangzhou geothermalsystem, 144-153, in: Advances in Solid Earth Sciences, Pang Z.H. et al. (eds), Science Press, Beijing, pp.209, ISBN 7-03-005532-2/P•938.

Pang, Z. H. and Reed, M. H., 1998, Theoretical chemical geother-mometry on geothermal waters: Problems and Methods,Geochim. Cosmochim. Acta, 62 (6), 1083-1091.

Pang, Z. H., Wang J. Y., Michelot, J. L., 1995, Reservoir tempera-tures of geothermal fields and residence time of thermal watersderived from isotope data on dissolved sulphate, 215-218, in:Water-Rock Interaction, Kharaka & Chudaev (eds,), Balkema,Rotterdam, pp.911, ISBN 9054105496.

Reed, M. H. and Spycher, N., 1984, Calculation of pH and mineralequilibria in hydrothermal waters with application to geother-mometry and studies of boiling and dilution, Geochim. Cos-mochim. Acta, 48, 1479-1492.

PANG ZhongheIsotope Hydrology Section, IAEAand:Institute of Geology

IMPROVED RESERVOIR MANAGEMENT IN LOS HUMEROS

Hydrology of the Los Humerosgeothermal system is com-

plex because of very high tempera-ture (>300oC) and acidic geothermalfluids. It was concluded, that thegeothermal reservoir is a closedsystem where there is no naturalrecharge to or discharge from thereservoir, implying that re-injectionof spent brine is essential for sus-tainable exploitation of the reservoir.

This has been achieved by the IAEATC project entitled "Regional hydrol-ogy of Los Humeros", which hasprovided vital technical assistancein developing the understanding ofthe regional hydrological model ofthe geothermal system, through theintegration of chemical and isotopictechniques including 87Sr/86Sr.

Based on the improved understand-ing of the system, the ComisionFederal de Electricidad (CFE) hasprogrammed to increase electricitygeneration capacity from 35 to 85MWe with installation of two unitseach of 25 MWe before year 2000.

In the implementation of the project,accomplishments were alsoachieved in terms of manpower de-velopment through fellowships andexpert services ensuring sustainablegeothermal development.

The quality for the measurements of18O and 2H isotope were assessedduring the project to ensure the qual-ity of analytical results. Similarly,

the analysis of alcohol in water sam-ples was implemented in the CFE labat Los Humeros for developing alco-hol as a tracer in vapor-dominatedgeothermal systems. A thermal sta-bility study of organic material likealcohol which was conducted throughthis project, showed that the alcoholis good tracer for geothermal reservoirof temperature up to 300oC.

The responsible officer of this projectis Jane Gerardo-Abaya.



Vast geothermal energy re-sources in the Pacific area ex-

ists as a result of near surface heatemanating from the volcanic activityin the Circum-Pacific Belt (Figure1).

The support of IAEA forgeothermal energy de-velopment has institu-tionalized the integra-tion of isotope methodsin geothermal reservoirmanagement. This en-abled a significant im-provement to the under-standing of the geother-mal reservoirs andaided decision-makingwith sound scientific in-formation.

Since the developmentof geothermal energyhas led to the matura-tion of isotopic and geo-chemical techniques, each geother-mal generating country within theCircum-Pacificarea has devel-oped its ownunique expertiseto investigatespecific prob-lems inherent intheir geothermalsystem.

The “Workshopon GeothermalUtilization” heldin Los AzufresG e o t h e r m a lField, Mexicolast November16-20 1998 andparticipated by24 mid manage-ment and seniorscientific staff ofthe 9 countries(Figure 2) in the Circum Pacificrealized that the experiences in dif-ferent countries are varied despitethe commonality of topics, e.g.,geothermal development, geochem-istry and applications of isotopes

through which transfer of technologyunder the concept of TCDC (technicalco-operation between developingcountries) can be facilitated. Thisexpertise should be extended to Cen-

tral America under the col-laborative activity.

The collaboration aims toensure the sustainability ofgeothermal resources forelectrical and non-electrical generation andthe protection of the envi-ronment amidst the utiliza-tion the natural resourcesin the Circum -Pacific area.

The collaboration will in-volve the following activi-ties:

a) exchange of results ofinvestigations among par-ticipating countries;

b) regular round-table discussion toassess results and follow-up activi-

ties;

c) field visits todemonstrate fieldtechnologies anddiscuss strategiesfor reservoir man-agement.

The TCDC amonggeothermal gener-ating countries inboth Asia and LatinAmerica will en-sure the sustain-ability of geother-mal developmentfor electrical andnon-electrical gen-eration as well asthe protection ofthe environmentamidst the utiliza-

tion the natural resources in the Cir-cum -Pacific area.

The responsible officer for this projectis Jane Gerardo-Abaya

and the presence of hydrologicalproblems related to reservoir man-agement. The different strategiesand decisions taken for similar reser-voir problems provide the varied ex-

periences which will be mutuallybeneficial and could accelerate de-

velopment if shared to others througha collaborative effort.

A mechanism through the RAS/8/075 regional project which startedsince 1997 developed a core group

SUSTAINING GEOTHERMAL DEVELOPMENT: A NEW STRATEGY

Figure 2. Participants of the “Workshop on Geothermal Utilization” held in Los Azufres, Mexico

Figure 1. Distribution of major geothermal activities (in red) in the “Circum-Pacific



Consultants’ Meeting, Groningen ,Netherlands, 14 to 16 September1998

This Consultants’ Meeting is the7th in a series of meetings

organized by the IAEA on the sametopic. It assessed the current statusin the production of reference mate-rials for stable isotope measure-ments of light elements and maderecommendations for future activi-ties of the IAEA in this field.

The meeting was hosted by theCentruum voor Isotopen Onderzoek(Centre for Isotope Research) of theUniversity of Groningen in theNetherlands.

The meeting was attended by 4consultants from Canada, China,Poland and USA and 14 observersfrom 7 countries including the hostinstitute. Also present were tworepresentatives from two major pro-ducers of reference materials,namely the National Institute forStandards and Technology (NIST),Gaithersburg, USA, and the Insti-tute for Reference Materials andMeasurements (IRMM) of the Euro-pean Commission in Geel, Belgium.

All together 19 presentations were

ing inorganic carbon reference materi-als was discussed using new ap-proaches which could minimize ef-fects of cross contamination andmemory effects of mass spectrome-ters. After intense discussion a cali-bration exercise was initiated for 1999involving a few selected laboratories.It is aimed to improve the accuracy ofthe recommended isotope values forthe existing reference materials andtherefore to improve the comparabilityof carbon stable isotope measure-ments world-wide.

A manual on isotope data acquisitionand quality control in Isotope Hydrol-ogy laboratories is under preparation.The first three parts covering generallaboratory practice and analysis ofhydrogen and oxygen stable isotopesare expected to be ready for distribu-tion in 1999. It is planned to extend itin future covering carbon stable iso-topes, tritium and 14C analysis andlater on nitrogen and sulphur stableisotopes.

The responsible officer for this projectis Manfred Groening

given during the meeting. Discus-sions were held in four workinggroups on the following topics re-spectively:

• Reference Materials and Calibra-tion Strategies;

• The Sulfur Reference Material Cal-ibration Exercise;

• Guidelines for Isotope HydrologyLaboratories.

Special attention was paid to anongoing calibration of existing sul-phur stable isotope reference materi-als on the recently established com-mon VCDT scale. Noticeably threeindependent approaches using SF6

gas for sulfur isotope analysis resultin remarkable good agreement witheach other for the analyzed referencematerials, while large discrepanciesexists among laboratories measuringsulfur isotopes using SO2 gas. In thiscontext, further SF6 laboratories arecalled up to participate and to ana-lyze the six examined reference ma-terials for confirmation of the resultsobtained so far by the SF6 method.

The status of the production of asuccessor material for VSMOW bythe IAEA Isotope Hydrology Labora-tory was presented.

A possible re-calibration of the exist-

REFERENCE MATERIALS AND QUALITY ASSURANCE

RESPONSE IN GROUNDWATER DUE TO EXPLOITATION

Anew Co-ordinated ResearchProject (CRP) on the above

topic is expected to start this year.

The overall objective of the CRPis to make an assessment of poten-tial utilization of long-term isotoperesponses of hydrological systems,particularly groundwater aquifers inarid and semi-arid regions, in thequantitative understanding of hydro-dynamic changes induced by ex-ploitation.

Hydrological systems for which ba-sic hydrogeological and isotope datafrom earlier studies conducted a fewdecades ago are available will beincluded in the CRP.

A new set of data to be obtainedfrom these systems during the CRPwill reveal the long-term isotopic re-sponse of these systems to exploita-tion. Applied field research in se-lected bench-mark systems with dif-ferent hydrogeological settings andspatial scales will enable more reli-

able predictions to be made of futurebehavior of the systems under differ-ent exploitation scenarios.

The responsible officer for this CRP isY. Yurtsevertelephone:+43-1-2600-21732;fax:+43-1-26007;e-mail:[email protected]

Those who are interested in participa-tion may wish to contact him directlyfor further details ofthe project.

C R P N e w sC R P N e w s



Regional TrainingCourse for Africa, Vi-enna, 27 October to6 November 1998

The training coursewas attended by 28participants from 19different Africancountries and com-plemented a similarinterregional trainingcourse on qualityassurance held inApril 1998 Three ex-ternal lecturers fromGermany, NewZealand and USA aswell as six staffmembers from theIAEA Laboratoriesdelivered lectures atthe training course.

The programme of the course fo-cused on the presentation of thestate-of-the-art of analytical tech-niques used for isotope analysesrelevant for investigations in environ-mental sciences, including stableisotope mass spectrometry, deter-mination of environmental tritiumand 14C radioactivity and of waterchemistry. The main part of thecourse was dedicated to introduce

electronic data processing systemcan considerably improve the dataconsistency, as well as facilitate thenecessary calculations from raw datato final results and may serve asdatabase for a laboratory.

The director of the training coursewas Manfred Groening.

and discuss the importance of qual-ity assurance for these analyses inthe daily laboratory practice and toprovide information on its practicalimplementation by examples fromexperienced isotope hydrology labo-ratories. A computer based labora-tory information management sys-tem (LIMS, available from the UnitedStates Geological Survey) was intro-duced in detail. The use of such an

TRAINING ON ANALYTICAL QUALITY MANAGEMENT

As part of the IAEA Analytical Qual-ity Control Services (AQCS), theIsotope Hydrology Laboratory is re-sponsible for production and distri-bution of reference materials for as-sessment of stable isotope ratios oflight elements at environmentallevel.

In 1998, five new reference materialsproduced by collaborating instituteswere issued by the IAEA, increas-ing the total number of availablereference materials to 38. In thesame year, more than 800 units ofthese reference materials were dis-tributed to laboratories world-wide

upon their request, the highest num-ber ever reached.

Because reference materials are es-sential for the calibration and for thecomparability of results from isotopehydrology laboratories, this repre-sents an important contribution ofthe Laboratory’s analytical qualityassurance activities in isotope hy-drology.

The IAEA AQCS catalogue 1998/99covering all existing 105 IAEA refer-ence and inter-comparison materials(radionuclides, stable isotopes, traceand minor elements, organic con-

The stable isotope reference mate-rials and the 14C quality assurancematerials can be ordered using the or-der form in the AQCS catalogue or bysending a fax or email to the followingaddress:

Mr. M. GroeningIAEA-Isotope Hydrology SectionP.O.Box 100, A-1400 Vienna, AUSTRIAFax:+43-1-2600-7email: [email protected]

All other materials can be orderedfrom the following address:

IAEA-Analytical Quality Control ServicesAgency’s Laboratories Seibersdorf

HOW TO ORDER REFERENCE MATERIALS FROM THE IAEA

Figure 1. Participants of the regional training course on analytical quality management of isotope hydrology laboratories (Photo



1999IAEA MEETINGS AND TRAINING

April

AGM - Interagency meeting on moreeffective collaboration among UNAgencies in the water sector forisotope hydrology applications(jointly with UNESCO, WHO, WMO,UNEP, FAO), Vienna, Austria

RCM on Isotope techniques for theassessment of slow moving deepgroundwater and their potential ap-plication for the assessment ofwaste disposal sitesBern, Switzerland

May

10-14, International Symposiumon Isotope Techniques in Water Re-sources Development and

RCM on “Isotope-based Assess-ment of Groundwater Resources”Mexico City, Mexico

Final assessment meeting of theTC project on “Geothermal EnergyResources and Environment Man-agement”, Indonesia (RAS/8/075)

IAEA Meeting CategoriesAGM: Advisory Group MeetingRCM: Research Co-ordinationMeetingCS: Consultants ServiceCM: Consultants MeetingSYM: International Symposium

ManagementVienna, Austria

AGM - Prepare a technical documenton the state of the art in GC/CF-IRMSVienna, Austria

October

RCM on “Radionuclide Transport Dy-namics in Freshwater Resources”.

CM on IAEA/UNESCO Teaching ma-terial in Isotope Hydrology.

4-8, RCM on “Isotope Techniques toStudy Soil Erosion and Sedimenta-tion in Lakes and Reservoirs, PhaseII”Barcelona, Spain

November

RCM on “Isotope response to dy-namic changes due to long-term ex-ploitation in groundwater systems”

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

ISOTOPE HYDROLOGY CALENDAR

Staff Changes in the Isotope Hydrology Section and Isotope Hydrology Labora-

Arrivals:Arrivals:

Cheikh B. Gaye joined the Sectionin January 1999. He is from Senegal,Ph.D. in Hydrogeology and IsotopeHydrology. He will be especially in-volved in activities related to theapplication of isotope hydrology inarid and semi-arid regions and fossilgroundwaters as archives for Paleo-climate.

He can be contacted at:Telephone: +43-1-2600-21733E-Mail:[email protected]

Marina Dargie joined the IsotopeHydrology Laboratory in February1999 as the successor of ChristineSchueszler. She is from Croatia, M.Sc. in Analytical Chemistry and hasalready worked for several years atthe IAEA Laboratories in Seibersdorf.She will be mainly responsible for theanalysis of water samples for chemi-cal composition (major, minor andtrace constituents) and for the train-ing of fellows.

She can be contacted at:Telephone: +43-1-2600-21764E-Mail: [email protected]

Johanna Lippmann joined the Iso-tope Hydrology Laboratory in Novem-ber 1998 as a temporary assistant.She is from Germany, Ph. D. in

Physics (Isotope Hydrology) andworks on the implementation of anoble gas analysis line for watersamples and on updating informa-tion sheets for the existing IAEAstable isotope reference materials.

She can be contacted at:Telephone: +43-1-2600-21766E-Mail: [email protected]

Departure:Departure:

Christine Schueszler retired andleft the Agency in the end of De-cember 1998 after nearly threedecades of service with the IAEAIsotope Hydrology Laboratory forthe sub-programme on the develop-ment and management of water

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