314 Geochemical rate models, by J. Donald Rimstidt

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Book reviews
Geochemical rate models, by J. Donald Rimstidt, 2014. Cambridge University Press, Cambridge, United Kingdom (order through http://www.cambridge.org/nl/academic/subjects/earth-and-environmental-science/geochemstry-and-environmental-chemistry/geochemical-rate-models-introduction-geochemical-kinetics). 239 pages. Hardcover: price
GBP 45.00, ISBN 978-1-107-02997-2; E-Book: price USD 60.00, ISBN 978-1-107-59643-6.
Deep insights into Earth systems have been
gained from the use of thermodynamic principles
in the modelling of geological processes. However,
although equilibrium thermodynamics allows to
reveal the end-point of a process, it does not predict
when this will happen and what is the exact course
of the reaction. Time is a fundamental variable in
kinetics, but not in thermodynamics. Geochemical
rate models concern the course of time of natural
processes and are the essentials of geochemical kinetics. Basically, geochemical rate models are based
on macroscopic observations; however, molecular
kinetics also provides insights into the subject. Kinetic theories and rate models concern all possible
Earth systems, starting from near-surface aqueous environments, through magma chambers, to
high-temperature and high-pressure solids in the
Earth’s interior. The present book discusses only
low-temperature processes in aqueous systems because these are commonly far removed from equilibrium and can be adequately modelled only with
tools delivered by geochemical kinetics.
The spatial and temporal patterns of natural
processes in Earth systems often are complex, and
even seem to be chaotic. The strategy to understand
such systems is to model simple processes, and then
to try to link them into larger fragments. The book
reviewed here provides tools for modelling and
interpreting such simple processes. Each chapter
contains theoretical background, where possible
shown as mathematical expressions, which is interwoven with examples from natural systems. These
examples are presented in ‘Example boxes’, which
are successive problems solved in an easy-to-follow
way, and frequently summarised by a more general
conclusion. Not only does the author emphasise the
meaning of a single model, he also warns against
overinterpretation of results of experiments and
shows possible pitfalls. Simple black-and-white illustrations make the text more comprehensive. A
large part of the examples is taken from the models worked out by the author himself, such as silica-water reactions, oxidation of pyrite and forsterite
dissolution. Undoubtedly, they do not include all
possible reactions that occur in near-surface environments. Rather, they were chosen as well-understood processes, studied in depth by the author.
Modelling tools are explained at the start, in
Chapter 2, and include regression models and numerical differentiation. Centre stage is for rate equations, which are expressed in several ways from the
time derivative of the number of moles of chemical
species formed or consumed, to the time derivative
of the extent of reaction, and presented for unopposed (one-way, forward) reactions and for various
types of opposed reactions. The coverage of the
book includes also the concept of ideal chemical
reactors as an introduction to experimental kinetics
(Chapter 4); molecular kinetics in the form of general physicochemical processes, and particularly the
conceptual basis of transition-state theory (Chapter
5); surface kinetics as a tool of understanding some
aspects of mineral dissolution and growth (Chapter 6); diffusion and advection and their influence
on chemical reaction rates (here, dimensionless
numbers are introduced to describe the two competing processes (Chapter 7)); quasi-kinetics assuming local equilibrium, as for reaction path models
(Chapter 8); accretion and transformation kinetics
describing multistep solid crystallisation from supersaturated solutions (Chapter 9). Additionally,
each chapter is supplemented by online resources,
Book reviews
freely available at www.cambridge.org/rimstidt,
consisting of problems to be solved and examples
of solutions in Excel sheets. The examples are not
trivial; they contain data from papers published in
Geochemica et Cosmochimica Acta.
The great achievement of the present book is its
clarity. Donald Rimstidt, currently Professor Emeritus of Geochemistry at Virginia Polytechnic Institute and State University, USA, has a wide experience in teaching geochemistry, and the effort of
making understood problems by explaining them
as best as possible underlies the entire volume. Successive topics are presented either as (relatively)
simple mathematical models, always accompanied
by examples of common, real-world processes, or
merely mentioned briefly with reference to relevant
textbooks or papers. Carefully chosen and up-todate references are another advantage. Since geochemical kinetics is anchored in chemical kinetics
and derives from the achievements of chemical
engineering, mineral processing, and soil sciences,
the reference list itself may be treated as a guide in
classic and modern texts in (geo)chemical kinetics.
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A distinguishable feature of the book is the importance placed on the use of consistent terminology and notation. This is clearly expressed in first
chapters but repeated in many places throughout
the text, so that none of readers are lost even if they
start reading from the middle of the book.
The subtitle, An introduction to geochemical kinetics, clearly indicates that not all aspects of geochemical kinetics are covered equally. Indeed, the book
is not voluminous, which encourages self study by
students interested in the subject.
In summary, this book is a must-read for students who are interested in the rates of geochemical
low-temperature processes and their quantitative
models, and who try to use this knowledge in designing experiments or for explaining experiment
observations. The book may be also useful for more
advanced researchers so as to ‘refresh their memories’, as a teaching aid, and to inspire future research.
Julita Biernacka
Adam Mickiewicz University, Poznań, Poland
julbier@amu.edu.pl