ENVIRONMENTAL ISOTOPES IN THE HYDROLOGICAL CYCLE Principles and Applications Vol. 1 esources Programme r Water Water Atoms for Peace International atomic energy agency and united Nations educational, scientific and cAtomsultural for Peace organization (reprinted with minor corrections) Environmental Isotopes in the Hydrological Cycle Principles and Applications International Atomic Energy Agency and United Nations Educational, Scientific and Cultural Organization (reprinted with minor corrections) FOREWORD The increasing demand for water in many regions Member States and access to information. The of the world has been generally translated into IAEA has played a key role over the years in intensive and too often unsustainable, exploita- capacity building, especially with regard to con- tion of water resources. In many instances, natu- ducting individualized and group trainings on ral and man-made changes have profoundly af- how to use isotopes to improve water resources fected the local hydrological cycle. Under these management. circumstances, more detailed information is often This publication is a reprint of a six-volume joint required for a more precise assessment of wa- IAEA-UNESCO document released in 2001 as ter resources and for the adoption of sustainable part of the IHP-V International Hydrological management practices. Programme (Technical Documents in Hydrology, Environmental isotopes have been extensively No. 39). This document was originally edited by used during the last decades to address key as- W.G Mook and has been extensively used dur- pects of the water cycle, such as the study of ing the last decade in training courses, seminars the origin, dynamics and interconnections of for and workshops, by the IAEA and others, deal- example, groundwater, surface water and the at- ing with teaching the basic principles on the use mosphere. The use of environmental isotopes as of environmental isotopes in hydrology and re- tracers of the water molecule has been extend- lated fields. The publication has been a success- ed beyond the classical applications of Isotope ful technical reference as a training tool, and has Hydrology and today, a growing number of other been translated into French and Spanish. It has scientific disciplines, ranging from atmospheric been distributed as hard copy and electronic files circulation to palaeoclimatology or ecology have in training packages and through the IAEA web incorporated isotopes as powerful tracers to bet- page. Now it is made available in the form of ter characterize systems and processes. IAEA Training Course Series in a single volume. Expanding the use of isotope hydrology tools The IAEA officer responsible for this publication to conduct hydrological studies relies on the ad- is Pradeep Aggarwal of the Division of Physical equate training of scientists and technicians in and Chemical Sciences. PREFACE The availability of freshwater is one of the great Hydrology’ was realised in 1983 through the activ- issues facing mankind today — in some ways ity of the joint IAEA/UNESCO Working Group on the greatest, because problems associated with it Nuclear Techniques established within the frame- affect the lives of many millions of people. It has work of IHP, and it has been widely used as practi- consequently attracted a wide scale international cal guidance material in this specific field. attention of UN Agencies and related internation- In view of the fact that the IHP’s objectives in- al/regional governmental and non-governmental clude also a multi-disciplinary approach to the as- organisations. The rapid growth of population sessment and rational management of water re- coupled to steady increase in water requirements sources and taking note of the advances made in for agricultural and industrial development have isotope hydrology, the IAEA and UNESCO have imposed severe stress on the available freshwater initiated a joint activity in preparation of a series of resources in terms of both the quantity and qual- six up-to-date textbooks, covering the entire field ity, requiring consistent and careful assessment of hydrological applications of natural isotopes and management of water resources for their sus- (environmental isotopes) to the overall domain of tainable development. water resources and related environmental studies. More and better water can not be acquired with- The main aim of this series is to provide a com- out the continuation and extension of hydrologi- prehensive review of basic theoretical concepts cal research. In this respect has the development and principles of isotope hydrology methodolo- and practical implementation of isotope method- gies and their practical applications with some ologies in water resources assessment and man- illustrative examples. The volumes are designed agement been part of the IAEA’s programme in to be self-sufficient reference material for scien- nuclear applications over the last four decades. tists and engineers involved in research and/or Isotope studies applied to a wide spectrum of hy- practical applications of isotope hydrology as an drological problems related to both surface and integral part of the investigations related to wa- groundwater resources as well as environmental ter resources assessment, development and man- studies in hydro-ecological systems are presently agement. Furthermore, they are also expected to an established scientific discipline, often referred serve as ‘Teaching Material’ or text books to be to as ‘Isotope Hydrology’. The IAEA contributed used in universities and teaching institutions for to this development through direct support to re- incorporating the study of ‘isotopes in water’ in search and training, and to the verification of iso- general into the curriculum of the earth sciences. tope methodologies through field projects imple- Additionally the contents can fulfil the need for mented in Member States. basic knowledge in other disciplines of the Earth The world-wide programme of the International Sciences dealing with water in general. Hydrological Decade (1965–1974) and the sub- These six volumes have been prepared through sequent long-term International Hydrological efforts and contributions of a number of scien- Programme (IHP) of UNESCO have been an tists involved in this specific field as cited in each essential part of the well recognised interna- volume, under the guidance and co-ordination of tional frameworks for scientific research, edu- the main author/co-ordinating editor designated cation and training in the field of hydrology. for each volume. W. G. Mook (Netherlands), The International Atomic Energy Agency (IAEA) J. Gat (Israel), K. Rozanski (Poland), W. Stichler and UNESCO have established a close co-opera- (Germany), M.Geyh (Germany), K. P. Seiler tion within the framework of both the earlier IHD (Germany) and Y. Yurtsever (IAEA, Vienna) were and the ongoing IHP in the specific aspects of sci- involved as the main author/co-ordinating editors entific and methodological developments related in preparation of these six volumes, respectively. to water resources that are of mutual interest to Final editorial work on all volumes aiming to the programmes of both organisations. achieve consistency in the contents and layout The first benchmark publication on isotope hydrol- throughout the whole series was undertaken by ogy entitled ‘Guidebook on Nuclear Techniques in W. G. Mook (Netherlands). Mr.Y. Yurtsever, Staff Member of the umes and fully acknowledge the efforts and Isotope Hydrology Section of the IAEA; and achievements of the main authors and co-ordinat- Ms. A. Aureli, Programme Specialist, Division ing editors. of Water Sciences of UNESCO, were the Scientific It is hoped that these six volumes will contribute Officers in charge of co-ordination and provid- to wider scale applications of isotope methodolo- ing scientific secretariat to the various meetings gies for improved assessment and management and activities that were undertaken throughout of water resources, facilitate incorporation of iso- the preparation of these publications. tope hydrology into the curricula of teaching and The IAEA and UNESCO thank all those who education in water sciences and also foster fur- have contributed to the preparation of these vol- ther developments in this specific field. Paris / Vienna, March 2000 TABLE OF CONTENTS VOLUME I: INTRODUCTION — THEORY, METHODS, REVIEW THE GLOBAL CYCLE OF water ..................................................................................................... 1 ATOMIC SYSTEMATICS AND NUCLEAR STRUCTURE .............................................................. 19 ABUNDANCE AND fractionation OF staBLE isotopes ................................................. 23 ABUNDANCE VARIATIONS BY NATURAL PROCESSES ............................................................ 33 RADIONUCLIDE DECAY AND PRODUCTION .............................................................................. 43 EQUATIONS OF RADIOACTIVE DECAY AND GROWTH ............................................................ 49 naturaL ABUNDANCE OF the staBLE isotopes OF C, O AND H .................................... 55 NATURAL ABUNDANCE OF RADIOACTIVE ISOTOPES OF C AND H ..................................... 75 CHEMISTRY OF CARBONIC ACID IN WATER .............................................................................. 87 Water SAMPLING AND LABoratory treatment............................................................... 99 MEASURING TECHNIQUES ..........................................................................................................