GEOL 135
Water-rock interaction and Scotch whiskey
Fall 2007
Scotch, single-malt whiskey made in Scotland (but just called whiskey there), is a
national drink whose tastes and character are derived from a set of complex interactions
between source water (which is jealously guarded as the primary ingredient by
distilleries!), the rocks that water flows through, streams that water flows in on the
surface, and the barrel the whiskey is aged in (as well as the atmosphere that barrel sits in
for 10-50 years…). Today we will be learning how to properly taste scotch whiskey,
noting the subtle, and not so subtle, differences in flavor between different whiskeys
produced in different localities – and try to think about the chemical processes that affect
these characteristics.
Scientific projects require money, money to pay researchers, money for the equipment to
analyze and describe materials, and money to support the evaluation of hypotheses
proposed by a research team. The primary way in which projects are funded is by
submitting a proposal to a company, government funding agency, or private fund for
research. As part of your work for today, you will be coming up with a central
hypothesis concerning a hypothetical study investigating potential changes to scotch
whiskey source waters and final product quality as a result of global warming. Your will
craft a 1-page statement, in the form of a national science foundation proposal summary,
addressing this hypothesis, your plans to evaluate this hypothesis, and the impacts your
study results will have. Success rates for NSF today are lower than in recent times, often
less than 10%, but given our class size, we will evaluate and rank these proposals as
reviewers and a panel (which will meet next Tuesday). I will serve as program manager
to award the most highly ranked and strategically important proposal. I do not have the
resources of NSF, so your project itself won’t be funded, but the winning proposal will
receive a bottle of 10-12 year-old scotch whiskey. 2 NSF project summaries are included
with your lab material as examples.
Task 1: Learning how to taste scotch whiskey.
As with many other foods and drinks, the flavors of scotch can be subtle and expressed
differently depending on how you concentrate on their flavor. It is also a technique to
dilute it a little bit with water to bring out more of the subtleties (but not too much which
for different scotches can dilute it past the ability to determine this)
We will make notes on each scotch taste with 4 different tasting techniques:
1. Nose – smell the scotch, note any distinct aromas you can, compare to some other
common sensory input (for example, a scotch’s nose may be woody, smoky,
sweet, buttery, etc. - no description is wrong as long as what you smell can be
communicated as similar to something others may have also experienced to
communicate the idea)
2. Front pallatte – on taking a sip and before swallowing, the first thing you note
about the taste will often (not always) be located on the front part of your tongue
– sort of a first impression, again described as compared to some common sensory
input.
3. 3. Back pallatte – as and immediately after you swallow your whiskey (but before
exhaling over this), note the flavors you experience on the back part of your
tongue, note this again as compared to some common sensory input, and also how
it may differ from the initial flavor. Also indicate the smoothness of the scotch,
some will be harsh and harder to swallow (some will experience this as a measure
of pain…)
4. The ‘finish’ – similar to the aftertaste – after you swallow the sip and have
exhaled once, note the flavors lingering on your tongue (and how long they last,
the ‘finish’ of the scotch can last several minutes or a few seconds), again as
compared to some common sensory input, and also how it may differ from the
initial flavor.
We will each taste and make notes of each scotch on the table – write down your tasting
notes for each scotch type, and then we will concatenate the results on a table to gather
the aggregate experiences for everyone to see what common threads we have discerned
for each.
For more on tasting there are some wonderful online resources:
http://www.scotchwhisky.com/english/tasting/index.htm
Task 2: Water-rock interaction and Scotland bedrock geology
Using the following maps, one the generalized geologic map of Scotland and the other a
map of distilleries in Scotland, what units seem to be ‘preferred’ for distilleries and what
units seem to not be associated with production?
Are there any differences between scotches we tried that are not seemingly tied to the
bedrock geology very well? What else might affect the scotch besides bedrock geology
here based on the flavors you determined?
Task 3: Compounds in the starting water and their preservation through the distillation
process
Now that we have thought about the chemistry of the starting water, we need to think
about how scotch is produced and how the chemistry may change as the scotch is made
and aged.
Let’s look at the following web pages for a description of the production and distillation
process:
http://en.wikipedia.org/wiki/Single_malt_whisky
http://www.lochlomonddistillery.com/making-scotch.htm
Comment on what tastes you think may derive from the starting water and how they
would be affected at different points in the process:
For aging, the scotch is placed in used oak barrels (typically barrels that previously held
sherry, but also other fortified wines such as port and madeira) and aged for at least 10
years, during which time 1-2% of the total volume is lost per year (they call this the
‘angel’s share’) and the alcohol content goes up. Think about woody material and
describe why you think the used barrels may be important and why.
Also - what factors may affect the rate at which this water is lost in the angel’s share?
Task 4: The hypothesis and proposal
Now you are ready to formulate a hypothesis addressing how global warming may affect
the scotch industry. You may put this together and propose to use any combination of
field, lab, or theoretical work, but should address the chemistry of the process and how to
evaluate these potential changes at any point in the summary process – feel free to
concentrate on one aspect (focused proposals are welcome) or a wider approach, it is up
to you! As a scientist, remember the quality, clarity, and value of your idea must be
communicated clearly and efficiently …
These will be due next Monday in class, you peers will get 3 random copies to evaluate,
on Tuesday we will meet to evaluate, and rank the proposals (this is a panel).
Generalized Geologic map of Scotland
PROJECT SUMMARY
Collaborative Research:
Experimental determination of Fe isotope fractionations in sulfide minerals
Clark M. Johnson, Brian L. Beard
University of Wisconsin - Madison
Gregory K. Druschel
University of Vermont - Burlington
Martin A.A. Schoonen
Stony Brook University
A comprehensive experimental program is planned for determining the Fe isotope
fractionations among aqueous Fe-S species and sulfide minerals over the temperature range ~4 oC
to ~250 oC. The experimental program will explore isotopic fractionations in three systems:
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Fe(II)aq - Fe(III)Org - FeSaq - Mackinawite - Fe(OH)3 (~4-37 oC) [Task 1]
Mackinawite - Pyrite (~50-250 oC) [Task 2]
Pyrite - Chalcopyrite (~50-250 oC) [Task 3]
We will investigate both kinetic and equilibrium Fe isotope fractionations, including exploration
of different sulfide formation pathways and their associate isotopic exchange kinetics, issues that
may play a major role in determining the Fe isotope compositions of sulfide minerals. Inferring
equilibrium fractionations is a challenge, particularly at low temperatures, but are important to
provide a baseline for interpreting natural systems and to compare with theoretical predictions.
We will employ new approaches for inferring equilibrium fractionations through use of
isotopically distinct seed crystals, which will lower kinetic barriers to nucleation and allow
rigorous calculation of the isotopic compositions of newly formed minerals over time, as well as
their growth rates. In addition to temperature, we will explore the effects of pH and trace metal
substitution on Fe isotope fractionation and exchange kinetics.
Intellectual Merit:
The field of Fe isotope geochemistry has grown rapidly and the literature now contains
several thousand isotopic analyses in over 75 papers from two-dozen research groups in the
world. Most of this work has focused on natural systems, and only a handful of experimentally
determined kinetic and equilibrium fractionation factors and associated exchange kinetic data are
available for geologically relevant systems. The largest variations in Fe isotope compositions on
Earth are recorded in sulfides, where almost a 5 per mil (‰) range in 56Fe/54Fe ratios is found in
sedimentary pyrite and a 3 ‰ range in high-temperature hydrothermal sulfides, and yet aqueous
and mineral Fe-S systems remain the largest gap in our understanding of Fe isotope fractionation
mechanisms. The research team blends essential expertise in isotope and experimental
geochemistry from three institutions.
Broader Impacts:
Iron isotope geochemistry of sulfides has been used to investigate problems ranging from
the origin and evolution of life to the sources of metals in hydrothermal ore deposits, but these
interpretations are hindered by a paucity of information on fractionation mechanisms. In addition
to objectives specific to Fe isotopes and sulfides, the new experimental approaches that will be
employed are applicable to any experimental study of mineral synthesis. Integration of research
and teaching will be accomplished by involvement of graduate students and a post-doc from the
three institutions, including exchange of personnel. We have worked hard to involve underrepresented groups, and the work will form part of the Ph.D. thesis of a student from Ghana and
part of a post-doc for a woman scientist from Uruguay.
Project Summary: Evaluating the scale-dependence of microbial diversity through
investigating links between geochemical niches and microbial community structure
Intellectual Merit: We propose to conduct a biogeochemical study to address the
following questions: How much microbial diversity does a specific geochemical
environment support and what geochemical factors are microbial communities most
sensitive to? While the range of microbial diversity is known to be great in most areas of
the world, how much of that diversity reflects the sampling of distinct geochemical
microenvironments and how much is truly diversity in which specific organisms are
competing for common resources? By developing a database that carefully links
microbial communities with very specific geochemical environments, we may better
understand how physical and chemical heterogeneity affects microbial diversity, which
ultimately may be a factor in describing the role large-scale microbial populations play in
a variety of geological and environmental processes. We may also utilize this data to
derive what geochemical factors are most important in driving changes in microbial
ecology. In quantifying this sensitivity, we may provide greater insight as to how
microbes and the processes they catalyze respond to geochemical perturbation.
Our research goals are:
1. Map, in 3-dimensions, a number of physicochemical factors potentially affecting
microbial ecology in selected thermal springs at Yellowstone National Park (YNP)
2. Characterize microbial populations at concomitant scales
3. Gather redox and chemical information at a wide range of pools at YNP in
collaboration with others (see letters of support) to gather more geochemical and
microbial data
4. Using the physicochemical-microbial database generated from field characterizations,
design specific nonparametric algorithms that define and quantify geochemical
parameters most sensitive to microbial community structure
Broader impacts: This project is important to a range of topics in a number of
disciplines, principally because it seeks to address the underpinnings of how microbial
diversity may be correlated to physical and chemical heterogeneity and identify the most
sensitive parameters that impact microbial ecology. In effect, we seek to address the
controlling factors governing microbial population density and community structure (i.e.
who and how many are in what place at what time and why?). The educational impact of
this study is very broad as it seeks to bind analytical geochemistry, environmental
microbiology, and computational sciences together to address a basic scientific question.
We will bring together scientists from many fields and specifically train both students
and professionals to better work between disciplines in a truly collaborative fashion. As
part of these collaborations, this proposal will also provide complimentary data to other
NSF-funded research projects in Yellowstone National Park. We will draw on an
existing NSF sponsored undergraduate mentoring program that specifically targets underrepresented groups to develop cross-disciplinary research and scholarship involving
problem-oriented computational modeling and environmental biology.