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| Woods Hole Isotope Camp, 1986: Brian Fry, Marilyn, Bob Michener front row center 2nd row: Marion O'Leary (center) next to Chuck Douthitt, then Ron Benner (2nd from right) 3rd Row: Kate Lajtha, Terry Chapin (left), Tom Jordan, Brad Tebo (right) |
When you’re a kid, if you’re lucky, your parents might send
you to camp in the summer to learn new skills or just have fun. My children
attended nature camps, art camp, horseback riding camp, and sports camps, as
well as a “just be silly and have fun” camp. My childhood friend Franny Stein
(Kasen) excelled at doing camp first as a camper, then a counselor in training,
and eventually a counselor. She held court every summer at overnight camps that
lasted months. The friends she met there sustained her throughout the rest of
the year. And in fact, she met her husband at camp when she was a lifeguard at
the Jewish Community Center day camp in South Jersey. Good things can and do
happen at camp. Similarly, students interested in the field of stable isotope
biogeochemistry meet peers and network at what is becoming very popular—isotope
training camps.
To learn the “Ins and Outs” of stable isotopes these days,
graduate students and postdoctoral scholars often attend Isocamps—week(s)-long training sessions with lectures by experts
(Isopopes) and laboratories led by the technically savvy (Isocopes). The first
workshop that I organized for students to learn about stable isotopes was in
1982 on the more general topic of “Biogeochemistry.” Sponsored by the American
Geophysical Union (AGU), about 25 young scientists came to the Geophysical
Laboratory for 2 days of lectures from microbiologist Ken Nealson, organic
geochemists John Zumberge and Bernie Simoneit, my Geophysical Lab colleagues Tom
Hoering, Ed Hare, Steve Macko, Michael Engel, and me. We were educating a new group of people who
wanted to think outside of their disciplinary boxes. Some of the students who
attended that workshop went on to become leaders in biogeochemistry. We didn’t
include a laboratory component, but I learned how to bring senior scientists on
board, show enthusiasm to people outside my field, and develop lecture skills.
I learned enough from this experience to do a much better
job for the isotope “camp” I organized in 1986 with my colleague Brian Fry,
then a scientist at Woods Hole Marine Biology Lab in Massachusetts. Brian Fry
and I had worked together as graduate students at the University of Texas
Marine Science Lab in Port Aransas. Essentially, we’d “grown up” together going
from being “Isodopes”, learning our way to becoming young “Isopopes”. We
planned our workshop with lectures in the mornings and evenings with
laboratories in the afternoons. For the lectures, we brought in some big names
at the time—John Hayes, Marion O’Leary, and Leo Sternberg. Each of us had a
full day to give our lectures that concentrated on the basics in the morning
followed by more specific examples in the evening.
Brian and I worked with his lab manager Bob Michener to set
up six glass vacuum lines for processing samples for isotope analysis. This was
a feat that required much planning and thought. Each vacuum line needed its own
vacuum pump, metal support frame, liquid nitrogen flasks, clamps, and sample
bulbs. Fortunately, we were able to make a simple design that worked well and
purchased six lines from a local glassblower. Our students worked three to a
vacuum line so that they became intimately familiar with how they worked.
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| Isotope camp students and lecturers, Patagonia, 2013 |
Each group of students designed a simple research project on
Monday, collected samples, prepared them, and analyzed them by Thursday. They
presented their results on Friday. Bob needed to make sure all the fragile vacuum
lines held a vacuum and didn’t break. He also needed to make sure the isotope
ratio mass spectrometer was in tip-top condition so he could finish all the
analyses by Thursday night. Nothing was automated at that time, so each and
every sample required hands on careful attention to details.
The class was a raging success!! It was a great sense of
accomplishment for me to carry this off, including showcasing my abilities to
important Isopopes like John Hayes, a decided leader of stable isotope
biogeochemistry. Brian, Bob Michener, and I really enjoyed working together.
Even today, I believe the shared experience from holding this workshop almost
35 years ago remains a fond memory for the three of us. Many of the students
from this class went on to use stable isotopes to solve scientific problems in
their specific disciplines.
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| Brian Fry's cartoon on isotopes-masterpiece! |
Brian Fry used this experience to write the first textbook
on Stable Isotope Ecology, a somewhat
folksy rendition of an otherwise serious subject. I’ve used parts of this book
for teaching Isocamps and full on classes during my career. Brian made up
cartoons of people with their hands, body, head, and feet as stable isotopes.
He drew an illustration of “light” and “heavy” isotopes paddling a canoe with
the heavy isotope’s figure tilting the canoe dangerously. Brian’s cartoons of
isotopes are classics in our field of isotope scientists and convey to even the
most chemically-adverse student the basic rules of stable isotope chemistry and
physics.
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| From Brian Fry's book, Stable Isotope Ecology |
Chemistry and physics—two subjects that strike fear and
loathing in the hearts of many who eschewed science and studied the liberal
arts. In fact, even science majors have a certain dread about taking organic
chemistry classes. To get a deeper
understanding of the stories in Brian’s book, bear with me and consider a
couple basic rules first articulated by Marion O’Leary, a physical chemist who
was very influential in the 1970s and 1980s.
Recall—atoms are made up of protons (P), neutrons (N), and
electrons.
Rule #1: Lighter isotopes go through chemical reactions faster than
heavier ones.
This makes sense to just about everyone. For example,
thinner, lighter people typically can run up hills faster than thicker, heavier
people like me.
The lighter isotopes
that have one or two less neutrons like 12C (carbon atoms with 6P:6N),
14N (nitrogen atoms with 7P:7N), 16O (oxygen atoms with 8P:8N),
and 1H (hydrogen atoms with just 1P), form chemical bonds easier and
faster than the heavier isotopes: 13C (6P:7N), 15N (7P;
8P), 18O (8P; 10N), and 2H (1P;1N) that have an extra
neutron or two.
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| From: Brian Fry's Stable Isotope Ecology book |
Rule #2: Heavier isotopes form stronger chemical bonds than lighter
ones.
This concept is harder to grasp, but let’s work through it. Chemical
bonds hold together important molecules like sugars in which hydrogen and
oxygen atoms are bound to carbon atoms.
The heavier isotopes stick to other atoms more strongly. While
the lighter isotopes will form chemical bonds more easily according to Rule #1,
they also break apart more quickly later on. The heavier isotopes need more
energy to form a bond initially and they require more energy later to break
these bonds.
Rule #3: Beware of over interpreting small isotope differences or
patterns.
Although we can break the chemistry and physics down into a
couple of simple rules, the natural world is much more complicated than that! A
living organism carries out thousands of biochemical reactions every second.
Comprehending the shuffling of stable isotopes at that scale is impossible! We
rely on knowing which reactions are the most important and understanding those
in greater detail. Even geological reactions, which can take place over
millions of years and at extreme temperatures, take some time to understand
fully.
Rule #4: You are what you eat—plus or minus a little bit.
The isotopes we eat—yes, we eat them folks—are in our food
and end up in our tissues. You shouldn’t be surprised.
When we analyze animal tissues we do this to figure out what
animals have been eating when no one is watching. Imagine trying to determine
what a whale is eating as it cruises 100 meters below the surface of the ocean.
Our work measuring stable isotopes in Australia on extinct species allowed us
to figure out what animals now long gone ate! This approach enabled us to understand
prehistoric ecosystems.
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| Baja Mexico--Isotope camp 2012 |
After a week of in-depth isotope camp, we expect students to
fully grasp Rules #1 and #2, to see the utility of Rule #4 and to come to appreciate
Rule #3.
Every year Isocamps are held in Salt Lake City, New Mexico, Michigan,
Germany, Italy, and Chile or somewhere else in the world. Jim Ehleringer and
Thure Cerling at the University of Utah held one of the most popular and
longest running Isocamps for over twenty years. They branded the name “IsoCamp”,
attracted a worldwide student population, and provided lecturers from around
the globe the opportunity to spread their knowledge to a diverse audience.
I worked with my colleague Seth Newsome holding isotope
ecology short courses in Argentina (2009 and 2013) and Baja Mexico (2012). When
we held our first isotope camp in Argentina in 2009, there was only one isotope
mass spectrometer in the entire country. Because there was no available mass
spectrometer for us to use, we trained students in how to design ecosystem
level isotope studies and how to formulate laboratory experiments to understand
more complex species level isotope questions. When serious isotope ecologists
like me look at a landscape, we see isotope patterns in the plants, the soil,
and in the tissues of animals. It’s a talent akin to how a naturalist might
examine an ecosystem identifying plant communities, stream flow, tallying
species diversity, and listening for the sounds of birds and insects. It takes years to get good at imagining and
speculating about the isotope patterns in an ecosystem, but with many of my
postdocs, Seth and Matt Wooller for example, we have “mass spectrometer” eyes
that assess a plant’s photosynthesis pathways, the influence of climate and
water availability, water sources, and potential prey items.
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| Luciana, Marilyn, and Seth, 2009 |
In 2009, Seth and I flew to Argentina to work with Argentinian
grad student Luciana Ricciardelli on presenting our first Isocamp. Earlier she
had visited the Geophysical Lab to analyze samples of dolphins and porpoises
found stranded on the coast of southern Patagonia. Seth and I landed in Buenos
Aires with duffle bags filled with sample gear and technical books. After a
short stay in Buenos Aires, we drove south along the La Plata River with Luciana
to the city La Plata where we conducted our short course at the University de
la Plata, a sizeable university of more than 30,000 students.
In general, Argentinians of a certain age aren’t fans of
Americans. During their Dirty War in the mid 1970s to early 1980s, the CIA
tacitly ignored what was happening in Argentina. In the US, we rarely learn the
history of countries outside of Europe, so I was almost completely ignorant of
what happened at that time. I became educated by staring in shock at the photos
of “missing” students, who would have been my age (18-22) at that time. It’s
now well known that dissident students were rounded up by the fascist
government, murdered, then dumped off shore. It was a horrible time for
Argentina. Seth and I worked hard to engender good relationships, and I think
it worked.
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| Seth giving informal lecture, 2009 |
On the first day of the camp thirty eager students arrived.
My Spanish is rudimentary to non-existent. Fortunately most students knew some
English so that lectures could be conducted in English as were our question and
answer periods. Argentinians drink coffee in the evening, but prefer yerba matte,
a hot drink with lots of caffeine, throughout the day. Matte bowls were passed
around the room during the long lecture periods. Students used a shared special
metal straw to take a hit off the strong brew. In the evenings, we went out for
pizza, steaks, and ice cream often meeting up with a few students in the class.
Seth and I worked nearly round the clock preparing lectures,
lab practicums, and interacting with students who were thirsting for knowledge.
By the time it was over we invited several of the most promising students to
come to the United States as interns, and we were able to provide modest
support for them.
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| Students working on sample strategies, 2009 |
This year, Seth and his colleagues at University of New
Mexico will take over the next phase of IsoCamp as Jim and Thure have passed
the torch. There are 60 applicants to fill 25-30 available slots. Clearly we
had created a unique and powerful way of educating the next generation of
stable isotope scientists. Working on these camps was one of the most
satisfying educational opportunities of my career and a strong testament to the
power of using isotopes as important tool in scientific research.
For this year’s IsoCamp in Albuquerque, New Mexico, I have
been asked to give an evening lecture on a topic of my choice, not the nuts and
bolts lectures that others will cover. I’ve got plenty of stories to tell—many
of them good, all of them educational.
People want to learn about stable isotopes! I hope that this
memoir reaches an even greater audience and when you hear the word “isotope”
you’ll think of all the cool things about them.
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| Marilyn (foreground) teaching isotopes, 2013 |
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