Abstract
Abstract. Natural gas production is associated with emissions of several trace gases, some of them classified as air toxics. While volatile organic compounds (VOCs) have received much attention, hydrogen sulfide (H2S) can also be of concern due to the known health impacts of exposure to this hazardous air pollutant. Here, we present quantitative, fast time-response measurements of H2S using proton-transfer-reaction mass-spectrometry (PTR-MS) instruments. An ultra-light-weight PTR-MS (ULW-PTR-MS) in a mobile laboratory was operated for measurements of VOCs and H2S in a gas and oil field during the Uintah Basin Winter Ozone Study (UBWOS) 2012 campaign. Measurements of VOCs and H2S by a PTR-MS were also made at the Horse Pool ground site in the Uintah Basin during UBWOS 2013. The H2S measurement by PTR-MS is strongly humidity dependent because the proton affinity of H2S is only slightly higher than that of water. The H2S sensitivity of PTR-MS ranged between 0.6–1.4 ncps ppbv−1 during UBWOS 2013. We compare the humidity dependence determined in the laboratory with in-field calibrations and determine the H2S mixing ratios for the mobile and ground measurements. The PTR-MS measurements at Horse Pool are evaluated by comparison with simultaneous H2S measurements using a PTR time-of-flight MS (PTR-ToF-MS) and a Picarro cavity ring down spectroscopy (CRDS) instrument for H2S / CH4. On average 0.6 ± 0.3 ppbv H2S was present at Horse Pool during UBWOS 2013. The correlation between H2S and methane enhancements suggests that the source of H2S is associated with oil and gas extraction in the basin. Significant H2S mixing ratios of up to 9 ppmv downwind of storage tanks were observed during the mobile measurements. This study suggests that H2S emissions associated with oil and gas production can lead to short-term high levels close to point sources, and elevated background levels away from those sources. In addition, our work has demonstrated that PTR-MS can make reliable measurements of H2S at levels below 1 ppbv.
Highlights
Hydrogen sulfide (H2S) is a flammable gas that is highly toxic at low concentrations; e.g., at 10–20 ppmv H2S starts causing eye irritation and at levels above 150 ppmv it is life threatening
In 2013, we further explored H2S detection by both protontransfer-reaction mass-spectrometry (PTR-MS) and PTR time-of-flight mass spectrometry (PTR-ToF-MS) (Graus et al, 2010) at the Horse Pool ground site
Assuming that the sensitivity of the ULW-PTR-MS for H2S was similar with the PTR-MS and in the same range as for formaldehyde, for which calibration was performed on PTR-MS, these occasionally high count rates suggested that H2S was in the ppmv range
Summary
Hydrogen sulfide (H2S) is a flammable gas that is highly toxic at low concentrations; e.g., at 10–20 ppmv H2S starts causing eye irritation and at levels above 150 ppmv it is life threatening. The primary emission sources of H2S to the atmosphere include volcanic eruptions, natural decomposition of sulfates and sulfur-containing organic compounds by anaerobic bacteria, and anthropogenic release from industrial processes. H2S is emitted from coal pits, landfills, livestock manure, thermal or polluted waters and septic systems (Environmental Protection Agency et al, 1993). Hydrogen sulfide is a major impurity in natural gas that needs to be removed prior to use. In oil and gas operations, H2S can be released routinely or accidentally at wellheads, piping, separation and storage tanks (Environmental Protection Agency et al, 1993; Tarver and Dasgupta, 1997). Previous H2S studies in oil fields indicated that hydrogen sulfide was the dominant reduced sulfur gas in all the sampled oil producing locations (Tarver and Dasgupta, 1997)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
