Date of Award

Spring 2-10-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Atmospheric & Oceanic Sciences

First Advisor

Joost A. de Gouw

Second Advisor

Darin W. Toohey

Third Advisor

Jimenez L. Jose

Fourth Advisor

Jana B. Milford

Fifth Advisor

Cora E. Randall

Abstract

Over the past decades, the rapid development of energy production in the U.S. has led to significant changes in atmospheric emissions and transformation of trace gas and particles, which are still very uncertain and poorly understood. Through laboratory, modeling and field experiments we hope to better understand the trace gas emission and their contribution to secondary organic aerosols (SOA) formation in the oil and natural gas (O&NG) operations.

A fast time-response Oxidation Flow Reactor (OFR) is used for the study of SOA formation from oil vapors. The radical chemistry and quantification of OH exposure (OHexp) in the reactor under various conditions were investigated using a photochemical kinetic model. An OHexp estimation equation derived from the model was shown to agree with measurements in several field campaigns. This work further establishes the usefulness of such reactors in atmospheric studies.

Motivated from the SOA observations of Gulf of Mexico oil spill, the SOA formation from organic compounds of different volatility in the oil vapors was studied in the laboratory using OFR. We use the evaporation time dependence on volatility of the precursors to quantify their contribution to total SOA formation. This study shows (1) organic compounds of intermediate volatility contribute the large majority of SOA mass formed, (2) the mass spectral signature of SOA shows good agreement with that of ambient SOA formed during oil spill. These results {Li, 2014 #970}In O&NG operations, the air toxic hydrogen sulfide (H2S) can be released at wellheads, separation and storage tanks. Here, quantitative, fast time-response measurements of H2S using Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) instruments in an O&NG field are presented. A laboratory calibration study was performed to measure the humidity dependent sensitivities of H2S. The close correlation between H2S and CH4 and significant H2S levels downwind of storage tanks suggest that H2S emissions associated with O&NG production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, this work has demonstrated that PTRMS can make reliable measurements of H2S at levels below 1 ppbv.

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