| Summary: | Thesis (Ph.D.)--University of Washington, 2013 The oxygen triple-isotopic composition (Δ 17 O) of sulfate or nitrate provides insight into the relative importance of the different pathways that lead to their formation in the atmosphere, with implications for their radiative impact, lifetime, and aerosol chemistry. Measurements of sulfate and nitrate Δ 17 O from ice cores provide constraints on long-term (up to 100 kyr) changes in the formation pathways of sulfate and nitrate and have the potential to constrain changes in the abundances of the oxidants responsible for their formation. Quantitatively connecting changes in the oxygen isotopes of sulfate and nitrate to changes in atmospheric conditions remains a key challenge in the application of these measurements to paleo-chemistry. In this work, a new ice core record of sulfate and nitrate isotopes from WAIS Divide, Antarctica is presented, and global chemical transport models and box models of sulfate and nitrate formation are used to quantitatively interpret ice core records of nitrate and sulfate Δ 17 O over a variety of time scales. In Ch. 2, a global chemical transport model is used to simulate preindustrial to present-day changes in tropospheric oxidants and the Δ 17 O of sulfate due to changing emissions only, constrained by previously published Greenland and Antarctic ice core records. The sulfate Δ 17 O record in Greenland demonstrates the increasing importance of metal-catalyzed sulfate production by O 2 due to increases in anthropogenic emissions of transition metals. Antarctic sulfate Δ 17 O indicates extratropical Southern Hemisphere increases in both H 2 O 2 and O 3 by 51% and 27%, respectively. This provides a constraint on the relative increases in the abundance of O 3 and H 2 O 2 in the remote Southern Hemisphere due to anthropogenic activity. In Ch. 3, a new ice core record of both nitrate and sulfate isotopes from the West Antarctic Ice Sheet (WAIS) Divide ice core spanning the past 2400 years is presented. There is a large (1.1‰) step ...
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