About Me
Cirriculum
Vitae
Links
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Research
My research interests
are in
developing an understanding of
the interactions between humans and their environment.
Primarily
I am focused on
looking at climate
change that occurred thousands of years ago to understand how people
adapted to
changing temperature and precipitation patterns so that we can develop
strategies for allocating our own water resources.
I
am also interested in using
geology to help
solve archaeological puzzles.
This
includes looking at trace metal concentrations in the watershed to
assess
ancient metalworking techniques and their impact on the
environment.
Horseshoe Lake surface core near Cahokia Mounds, IL
Master's
Thesis
A
2500
Year Lake Sediment Record of Drought and Human
Activity From Southwestern China
The delivery of
precipitation to southwestern
China is largely through monsoon circulation which has evolved with
changing
insolation forcing during the Holocene and will likely continue
to change in
response to greenhouse gas increases. Additionally,
southwestern China has a long history of human activity including
mining,
metallurgy, agriculture, and pollution. Here,
high-resolution
sampling of a sediment core from Lake Xing Yun in
the Yunnan Province (24°10’N,
102°46’E), a drought sensitive lake that behaves
as a closed basin, provides a sub-decadal record of changing climate
and human
activity in the late Holocene.
We use
δ18O
and δ13C
measurements of authigenic carbonate precipitated from the
lake water and magnetic susceptibility values to document the timing,
direction, and magnitude of moisture changes associated with variations
in
monsoon strength.
We use δ13C
and δ15N
measurements on organic matter and carbon to nitrogen
ratios to assess the impact of human activity on the Xing Yun watershed
and
sediment trace metal concentrations in investigate regional mining and
smelting
intensity.
The
2,500 year record highlights several transition periods
related to both human and climate forcing. The rise of metallurgy and
intensive
mining practices occurs at 900 AD, much later than historical records
indicate.
A number of proxies
including
δ13C
values and C/N ratio show a marked shift at 1600 AD, the time in which
many Han
immigrants from the north settled and worked the land in the Yunnan
Province.
The most pronounced
feature
of the record is
a rapid transition to a substantially drier climate that took place
over 50
years and persisted from 1360-1880 AD as an expression of the Little
Ice Age
(LIA).
This project
demonstrates
that
complex human and climate interactions have been taking place for
thousands of
years and have the potential to illuminate discontinuities in Chinese
historical records and learn lessons that might apply to future climate
change. |
