University of Minnesota Duluth
University of Minnesota Department of Chemistry and Biochemistry
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Friday, October 21, 2016; 3:00 p.m.; LSci 175


Department of Chemistry & Biochemistry Welcomes:

Dr. Joe Aldstadt

Associate Professor, Department of Chemistry & Biochemistry,
University of Wisconsin-Milwaukee

“Studies of Chemical Speciation in Surf & Turf: Arsenic in Green Bay Sediment & Lead in Civil War Battlefield Soil

Chemical speciation is of the utmost importance in understanding the transport, fate, and toxicity of pollutants in the environment. In the first project that will be described, arsenicals in the sediments of central Green Bay were chemically speciated by developing a novel method using solid-phase microextraction coupled to gas chromatography with pulsed flame photometric, electron capture, and mass spectrometric detection. Both inorganic and organic arsenicals were determined, the latter including an unusual organoarsine that apparently formed in situ. Using a radiochemical dating technique, depth profiles were constructed which closely correlated with the operation of an herbicide factory during the mid-20th century. In the second project, residual lead species in soil originating from the Second Battle of Bull Run (1862) near Manassas, VA were studied. A method based upon sequential extraction of soil core fractions followed by graphite furnace-atomic absorption spectroscopy was developed. Soil cores transecting the position of an infantry regiment were examined and compared to background samples to correct for other sources of lead compounds. Dating of the soil cores revealed the transport characteristics of lead species in the soil since the battle, with lead complexed to organic ligands being the most mobile. Finally, the design, fabrication, and testing of a novel long-pathlength absorbance spectrometer that has the potential to determine chemical speciation at ultra-trace levels will be briefly described.