Owens (dry) Lake in California is one of the top PM10 dust producers in the United States.
Once a large freshwater lake, it has since been drained if its supply and source to feed the needs
of the metropolitan area of Las Angeles. PM10 dust (particulates smaller than 10 micrometers) is
small enough to enter the lungs and cause significant health problems. This mineral dust also has
large enough levels of arsenic to make Owens Lake one of the largest sources of airborne arsenic
in the United States. My research has been concerned with observing the speciation of arsenic in
Owens (dry) Lake dust using X-ray fluorescence mapping, micro-XANES, and micro-XRD at the
National Synchrotron Light Source.
In addition to my investigations of arsenic in Owens (dry) Lake, I have also been
studying the stability of amorphous calcium carbonate (ACC). Many invertebrate
organisms extract ions from ambient solutions (such as seawater) to form hard
functional skeletal materials, notably calcium carbonate and silica. These biogenic
forms are not always stable when removed from the organism. Additives such as
phosphate and magnesium have been documented as assisting in stabilization of
ACC, but it is not clear how. My investigation of this process will involve studying
the coordination of oxygen atoms around calcium using EXAFS, and how additives
and time affect its structure.
