Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Dr. Solomon Bililign

Abstract

Plume intercepts from flights on the NSF-C-130 during the Wintertime Investigation of Transport, Emission and Reactivity (WINTER) campaign were used to estimate (1) the oxidation rates of Sulfur Dioxide (SO2) under wintertime conditions and the factors that determine SO2 removal; and (2) to examine the oxidation, lifetime and source apportionment of formaldehyde (HCHO). Observations suggest that OH governs the rate SO2 oxidation in the eastern United States during winter. The range of mean oxidation rates during the day from power plants were 0.22–0.71%/hr, producing SO2 lifetimes of 13–43 days, if SO2 consumption is assumed to occur during 10.5 hr of daylight in cloudless conditions. Though most nighttime rate measurements were zero within uncertainty, there is some evidence of nighttime removal. The fastest nighttime observed SO2 oxidation rate was 0.25±0.07%/hr, producing a combined day/night SO2 lifetime of 8.5–21 days. The upper limit of the oxidation rate (within the mean+1σ) is 16.5%/day, corresponding to a lifetime of 6.1 days. The analysis also quantifies the primary emission of sulfate from power plants. The median mole percentage of SO4 -2 from observed plumes was 1.7% and the mean percentage sulfate was 2.8% for intercepts within 1 hr of transit to power plants. Given its numerous sources, HCHO is one of the most abundant aldehydes in the lower troposphere, and has been extensively studied during the summer months. Despite this, attribution of anthropogenic primary and secondary HCHO production remains poorly constrained due to the dominance of primary and secondary biogenic sources of HCHO during the summer. Observations of co-generating power stations showed emissions to have a HCHO/CO of 0.017 – 0.018 with an upper limit of 8.48 ppbv HCHO emitted. Measurements of 2 urban area emissions of HCHO during the winter were correlated with known chemical tracers from vehicular emissions, urban heating, biomass burning, and other anthropogenic activities. Area sources during the night on average emitted 1.07 ± 0.27 × 1014 molecules/cm2 • hr or 1.31 ± 0.19 × 1014 molecules/cm2 •hr. A linear combination model strongly (r2 = 0.89) apportioned chemical species data (CO, CH4, SO2, NOy) with HCHO from the City of New York.

Download

Share

COinS