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Grantee Research Project Results

Grantee Research Project Results

Climatic Influence on Atmospheric Oxidant Concentrations and the Sulfur Cycle

EPA Grant Number: U915826
Title: Climatic Influence on Atmospheric Oxidant Concentrations and the Sulfur Cycle
Investigators: Alexander, Becky
Institution: University of California - San Diego
EPA Project Officer: Just, Theodore J.
Project Period: August 1, 2000 through August 1, 2003
Project Amount: $80,706
RFA: STAR Graduate Fellowships (2000)
Research Category: Academic Fellowships , Air Quality and Air Toxics , Fellowship - Atmospheric Sciences



The objective of this research project is to investigate changing oxidant concentrations throughout major climatic variations through multistable isotope analysis of sulfate preserved in ice cores from Vostok and Dome C, Antarctica.


The use of multiple stable oxygen isotope (16O, 17O, and 18O) analysis in the investigator's laboratory can provide a new, independent method to help resolve current and past atmospheric oxidant concentrations. The magnitude of the observed mass-independent isotopic composition in sulfate is directly related to atmospheric oxidant loading. A new technique has been developed in the laboratory for isotopic analysis of small amounts of sulfate. Ice core samples from Vostok and Dome C, Antarctica, were obtained in collaboration with the Laboratoire de Glaciologie in Grenoble, France, and cover the last interglacial through the Holocene. This offers a unique probe into oxidant variations in the past. Measurements of d17O and d18O of sulfate are complimented with sulfur (d34S) isotopic measurements to discern differing sources of sulfate and aid in interpretation. All five stable isotopes can be used together to not only identify the different sources of sulfate, but to study the oxidation state of ancient atmospheres and their changes because of climatic and anthropogenic variations. Future studies are planned around the Industrial Revolution from Greenland ice cores to discern the anthropogenic impact on the oxidizing capacity of the Earth's atmosphere. By using multiple stable oxygen isotope (16O, 17O, and 18O) analysis, a new independent method can be provided to help resolve current and past atmospheric oxidant concentrations.

Supplemental Keywords:

fellowship, atmospheric chemistry, global climate change, Antarctica, Greenland, sulfur cycle, oxidation capacity, paleoclimatology., RFA, Scientific Discipline, Air, Toxics, Geographic Area, Contaminant Candidate List, climate change, Analytical Chemistry, Atmospheric Sciences, International, environmental monitoring, Dome C, Antarctica, paleoclimatology, Antarctica, climatic influence, oxidation capacity, Greenland, atmospheric oxidant concentrations, sulfur cycle, Global Climate Change, Sulfate, Vostok

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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