How Does Uranium Move Around
in the Environment?
7:30 PM Friday
February 3, 2012
Uranium is mined for the nuclear industry and due to
decades of prospecting a lot is known about its natural occurrence. The
most notable association in near surface environments is with organic
matter. Uranium has two main oxidation states U(VI) and U(IV) and is
soluble as U(VI) and insoluble as U(IV). Due to the fact that
environments with abundant organic matter are also characterized by low
oxygen levels, there is a common assumption that uranium reduction is
responsible for its sequestration. We use synchrotron studies to
evaluate the oxidation state of the uranium associated with organic
matter and U-Pb dating of these samples to better understand the natural
processes that lead to uranium enrichment. Mining of uranium, as well as
processing of the ores, and the enrichment of 235U for the
nuclear industry, all lead to potential for environmental contamination.
Uranium is not only a health risk due to its radioactivity, it also can
cause kidney failure. Our results from a variety of natural settings go
against the paradigm that reduction of uranium is primarily responsible
for its immobilization. In fact,
results from organic bearing calcite demonstrate that oxidized uranium
can be immobilized by organic matter for hundreds of millions of years,
while results from near modern wetlands systems show that reduced
uranium is highly vulnerable to oxidizing fluids. Nuclear materials
stewardship demands that we understand the behavior of uranium and the
byproducts of the nuclear industry on millennial and longer timescales.
Natural systems offer exceptional insight into long-term storage issues.
Troy Rasbury is a sedimentary
geologist and isotope geochemist who has specialized in U-Pb dating of
sedimentary carbonates, and a more fundamental understanding of uranium
behavior in natural systems. She got her PhD at Stony Brook in 1998 and
has been a member of the Geosciences and IDPAS faculty since 1999.
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A Year after the Big Japan
Earthquake:
Implications for Earthquake Risk in
Japan and the United States"
7:30 PM Friday
March 2, 2012
As we approach the first anniversary of the great Tohoku
earthquake and tsunami in Japan it is time to reflect on what we have
learned from that event, as well as other earthquakes around the world.
In this presentation, Dan Davis of the Department of Geosciences will
explore what happened in last year’s earthquake, as well as what went
right (and horribly wrong) in preparation for it. In America, we have
good reason to want to learn the lessons from the disaster in Japan,
because there is reason to believe that our Pacific Northwest coast may
suffer a strikingly similar earthquake and tsunami in the coming
decades. Although the eastern US has a much lower overall seismic risk
than much of the west, large and damaging earthquakes have happened
here, and they will happen again. In this presentation, Dr. Davis will
also explore what aspects of earthquakes and tsunamis we do – and do not
– need to be concerned about here on Long Island.
Dan Davis has been a member of the Stony Brook faculty since 1986.
His primary area of research has focused on the tectonics of regions
where plates converge, causing great earthquakes and the construction of
mountain belts. Other areas of research include the application of
geophysics to nuclear arms control and to the study of the glacial and
post-glacial geology of Long Island. He is also co-author of Turn
Left at Orion, a guide to telescopic stargazing that has sold over
100,000 copies and has recently been released in a much-expanded 4th
edition.
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Rip Currents on Long Island Beaches
7:30 PM Friday
March 30, 2012
Rip currents are concentrated jets of water flowing out to sea from
the beach. Rip currents are also one of the most deadly hazards on
bathing beaches. They are responsible for 80% of all rescues and 100
deaths a year. There are several types but Long Island beaches are
dominated by "flash rips", rip currents that appear without warning.
They last only a few minutes before disappearing into the wave but they
can still be dangerous. This behavior makes forecasting particularly
difficult. They seem to be caused by a modulation of the incident waves
by long-period, infragavity, waves. The most persistent seem to be those
that impinge on irregular breaks in beach ridges and submerged sand
bars.
Prof. Bokuniewicz's research is concerned primarily with the
behavior of coastal sedimentary systems and coastal groundwater
hydrology. He and his students are working with the dynamics of coastal
processes, exploring, now, the role of infragravity waves and edge waves
in modulating coastal conditions especially the occurrence of rip
currents. They are involved with monitoring programs for ocean beaches
to investigate shoreline changes, beach dynamics and responses to
storms. Other research is being done on wakes of large ships moving
across shallow harbors. Field work also is undertaken to quantify the
seepage of groundwater across the sea floor especially around oceanic
islands as well as to investigate the global impact of coastal
groundwater seepage.
Much of this research is directly applicable to
problems of coastal zone management. He remains interested in applying
his research to practical problems of groundwater seepage at the sea
floor, shore erosion, the dispersion of contaminants, dredging and the
disposal of the dredged sediments and marine mining.
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Shining light on Earth Materials:
How modern synchrotron light sources help us understand the Earth.
Prof. Lars Ehm
7:30 PM Friday
April 13, 2012
The National Synchrotron Light Source has provided
very intense and bright light in the X-ray and infrared spectrum to
experiments used by the Earth Sciences community, since 1985. The
advances in experimental techniques, instrumentation, automation over
the last 22 years, have resulted in significant gains in our ability to
study the atomic structure, bonding, composition and properties of Earth
materials. We are able to create a variety of different environmental
conditions in the experiments and simultaneously study the atomic
structure, bonding and composition of the material. These capabilities
transformed our knowledge of the structure, evolution and processes in
the Earth.
In this talk we will explore the impact that
experiments at synchrotron radiation facilities have on our current
understanding of the structure and evolution of the Earth. Furthermore,
we will take a look at the future capabilities of the National
Synchrotron Light Source II and their potential impact on our insight
into processes in the Earth.
Lars Ehm is on the faculty of the Mineral Physics
Institute since 2007 and holds a joint appointment with the Photon
Science Directorate at Brookhaven National Laboratory. His research is
focused on understanding structure-property relationships in Earth
materials from experiments. As part of the staff at the Photon Sciences
Directorate at Brookhaven National Laboratory, he is deeply involved in
the development of new experimental techniques at the National
Synchrotron Light Source and the construction of the new National
Synchrotron Light Source II.
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