climate and Earth processes
biogeochemistry Simon Brassell, Erika Elswick, Lisa Pratt, Ed Ripley, Peter Sauer, Juergen Schieber, Arndt Schimmelmann,
Laura Wasylenki, Chen Zhu
SIMON BRASSELL Professor of Geological Sciences
Simon’s research activities continue to be fo-
cused on the use of the molecular and isotopic
compositions of sediments to elucidate paleo-
climates and paleoenvironments, and to study
the fate of organic matter in the geosphere.
Recent investigations by Devon Colcord as part
of her M.S. and Ph.D. studies have included as-
sessment of climate records in lake sediments
from Greenland, studying cores collected by
the GetGamm program led by Lisa Pratt. Two
publications in Organic Geochemistry have
verified that the distributions of molecules
biosynthesized by bacteria known as branched GDGTs (glyc-
erol dialkyl glycerol tetraethers) include contributions from
autochthonous sources within lakes augmenting their origin
from surrounding soils, and confirmed this conclusion by the
first direct measurement of the carbon isotope composition
of these molecules in collaboration with Professor Ann Pear-
son at Harvard University. Another recent publication in Or-
ganic Geochemistry reports the results from the M.S. thesis
of Amishi Kumar, who elucidated the separate contributions
of polycyclic aromatic hydrocarbons originating from both
natural and anthropogenic sources of both petrogenic and py-
rolytic compounds within sediments from the Santa Barbara
Basin, offshore California.
Over the past couple of years, investigations led by
Ph.D. students Devon Colcord and Andi Shilling are elu-
cidating changes in climate recorded by biogeochem-
ical indices in a series of early Pleistocene lacustrine
sediment cores recovered from Olduvai Gorge. This
research is part of a larger collaborative project led by
Jackson Njau, Nick Toth, and Kathy Schick that aims
to explore environmental change during critical inter-
vals of hominin evolution established at Olduvai. The
laminated sediment sequence from ~1.8 Ma provides
an extraordinary opportunity to determine short-term
changes in climate that triggered responses in the lake
phytoplankton and surrounding vegetation at a time of
high hominin diversity.
Simon continues to work on profiling ancient climates
and is a co-author of a recent paper focused on a com-
prehensive collation of temperature records for the
Cretaceous, which has been published in Earth Science
Reviews. He is also collaborating with Arndt Schim-
melmann and Maria Mastalerz in analysis to better un-
derstanding the specific nature of catalytic processes
transforming organic matter during diagenesis in the
New Albany and other shales.
Simon teaches both a fully online introductory ocean-
ography course that utilizes web-based resources in
student exercises exploring a wide range of oceano-
graphic phenomena and a College critical approaches
class on records of global climate change.
ERIKA ELSWICK Senior Lecturer and Director, Analytical Chemistry Laboratory
News From the Analytical Geochemistry Laboratory
Erika R. Elswick - Director
Fall 2017 has brought a lot of additional activity to the Analytical Geochemistry Laboratory with a full class
in Methods in Analytical Geochemistry (G444/G544). In the spring we acquired a new ion chromatograph
for the analysis of anions in water samples. The new Thermo/Dionex instrument replaces a much older
unit, and is very student friendly. We continue to analyze aqueous solutions and solids for departmental
members, as well as colleagues in other departments and units across campus.
During the summer of 2017 I embarked on a new project with a colleague to begin to instrument a wetland
located in the National Forest land above the IU Field Station associated with the late 19th and early 20th
Century mining activities. We ultimately hope to shed some light on this dynamic setting to develop mod-
els for remediation at higher altitudes.
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ARNDT SCHIMMELMANN Senior Scientist | Organic Geochemistry and Chemical Oceanography
Arndt Schimmelmann’s international team of sci-
entists from Vietnam, Germany, and Indiana Uni-
versity identified subterranean microbes in caves
to voraciously consume the strong greenhouse
trace gas methane from air. Cave air typically ex-
changes with the atmosphere on short time scales.
Methane depletion in cave air on several conti-
nents indicates that the subterranean microbial
sink for methane is substantial enough to warrant
inclusion in global greenhouse gas modeling. In
contrast, laboratory experiments at Indiana Uni-
versity with strong radiation from radon isotopes
excluded the possibility that elevated natural ra-
dioactivity in caves can significantly contribute to
oxidation of methane in air.
Furthermore, Schimmelmann’s team continues
to develop remediation strategies to mitigate
radiation geohazards in mud-built homes in de-
veloping countries (see website: http://eosvnu.
net/projects/mud-built-homes/). Outreach ac-
tivities in mountain villages established person-
al contacts and reliable logistic support for our
research. As a third collaborative research project with
Vietnam National University in Hanoi, the lam-
inated sediment from a volcanic maar lake in
central Vietnam near Pleiku is being explored as a geological ar-
chive for prehistorical monsoon strength. The record of distinct
flood layers of the past can be radiocarbon-dated and may offer a
reliable statistical basis to judge the effects of climate change on
modern precipitation patterns in central Vietnam.
Two images from sediment coring activities in a central Vietnamese maar lake. The image
on the left shows our mobile coring platform where inner tubes from trucks provide flota-
tion. The entire platform with anchors cost only about $150 and worked extremely well.
We pulled 20 wonderful sediment cores from up to 21 m water depth with penetration
into sediment of up to 3.5 meter. At one time we needed a special heavy-duty core catcher.
On the right, a local machine shop in Pleiku lathed a core catcher for us from an old rusty
artillery shell at a few hours notice. In Vietnam everything is possible if you know your
way around. Our Vietnamese colleagues are experts in improvising.
LAURA WASYLENK I Associate Professor of Geological Sciences | Biogeochemistry of Metals
Laura Wasylenki was on sabbatical in 2016-17,
spending seven months at Stanford Universi-
ty and three months at École Polytechnique
Fédérale de Lausanne in Switzerland. She is in-
vestigating mineral-fluid reactions that attenuate
the migration of toxic heavy metals in soils and
near-surface groundwater. At the Stanford Syn-
chrotron Radiation Lightsource, she shone bright
beams of X-rays onto samples of iron and manga-
nese oxyhydroxide particles that she had loaded
with small amounts of tungsten, a likely carcino-
gen that has been widely introduced to the envi-
ronment during weapons production and testing.
She is studying the molecular-scale mechanisms
by which adsorption to common soil particles
can immobilize this toxic metal. She plans to
test some of the new knowledge derived in the
laboratory on a tungsten-contaminated field site
in SW Indiana with new graduate student Coley
Smith. In Switzerland, Wasylenki began a
collaboration with an environmental micro-
biology group interested in molecular-scale mechanisms
of uranium immobilization. While in Switzerland, she also
made time to observe with great joy plenty of steeply dip-
ping Jurassic carbonates adorned with Late Holocene gla-
ciers and was joined on one occasion by former student
Michael Haluska, M.S. ’15.
Wasylenki in the Lauterbrunnen
Valley with Jungfrau in the center
and Eiger on the left.
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