Spatial and temporal patterns of visibility in Las Vegas, July 2000--July 2001

The Clark County Department of Air Quality Management and the Nevada Department of Motor Vehicles funded a one-year study of visibility trends in Las Vegas. The Desert Research Institute conducted this study from July 2000 to July 2001. The monitoring sites for this study were chosen to represent three areas in Las Vegas, urban, suburban and background/transport. Strong diurnal patterns were found at the urban and suburban sites. The background site had low levels of air pollution, and most of the haze at this site was due to light scattering by particles. The suburban site followed a well-defined diurnal pattern during the cold season, and showed the influences of local activities (such as road construction) during the study. Overall, the urban site had the highest levels of visibility impairment, but during midday the visibility at this site improved and was comparable to that of the suburban site. This thesis presents the data from this study

Characterization of soluble bromide measurements and a case study of BrO observations during ARCTAS

A focus of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission was examination of bromine photochemistry in the spring time high latitude troposphere based on aircraft and satellite measurements of bromine oxide (BrO) and related species. The NASA DC-8 aircraft utilized a chemical ionization mass spectrometer (CIMS) to measure BrO and a mist chamber (MC) to measure soluble bromide. We have determined that the MC detection efficiency to molecular bromine (Br2), hypobromous acid (HOBr), bromine oxide (BrO), and hydrogen bromide (HBr) as soluble bromide (Br−) was 0.9±0.1, 1.06+0.30/−0.35, 0.4±0.1, and 0.95±0.1, respectively. These efficiency factors were used to estimate soluble bromide levels along the DC-8 flight track of 17 April 2008 from photochemical calculations constrained to in situ BrO measured by CIMS. During this flight, the highest levels of soluble bromide and BrO were observed and atmospheric conditions were ideal for the space-borne observation of BrO. The good agreement (R2 = 0.76; slope = 0.95; intercept = −3.4 pmol mol−1) between modeled and observed soluble bromide, when BrO was above detection limit (\u3e2 pmol mol−1) under unpolluted conditions (NOmol−1), indicates that the CIMS BrO measurements were consistent with the MC soluble bromide and that a well characterized MC can be used to derive mixing ratios of some reactive bromine compounds. Tropospheric BrO vertical column densities (BrOVCD) derived from CIMS BrO observations compare well with BrOTROPVCD from OMI on 17 April 2008

Comparison of the chemical evolution and characteristics of 495 biomass burning plumes intercepted by the NASA DC-8 aircraft during the ARCTAS/CARB-2008 field campaign

This paper compares measurements of gaseous and particulate emissions from a wide range of biomass-burning plumes intercepted by the NASA DC-8 research aircraft during the three phases of the ARCTAS-2008 experiment: ARCTAS-A, based out of Fairbanks, Alaska USA (3 April to 19 April 2008); ARCTAS-B based out of Cold Lake, Alberta, Canada (29 June to 13 July 2008); and ARCTAS-CARB, based out of Palmdale, California, USA (18 June to 24 June 2008). Extensive investigations of boreal fire plume evolution were undertaken during ARCTAS-B, where four distinct fire plumes that were intercepted by the aircraft over a range of down-wind distances (0.1 to 16 hr transport times) were studied in detail. Based on these analyses, there was no evidence for ozone production and a box model simulation of the data confirmed that net ozone production was slow (on average 1 ppbv h−1 in the first 3 h and much lower afterwards) due to limited NOx. Peroxyacetyl nitrate concentrations (PAN) increased with plume age and the box model estimated an average production rate of ~80 pptv h−1 in the first 3 h. Like ozone, there was also no evidence for net secondary inorganic or organic aerosol formation. There was no apparent increase in aerosol mass concentrations in the boreal fire plumes due to secondary organic aerosol (SOA) formation; however, there were indications of chemical processing of the organic aerosols. In addition to the detailed studies of boreal fire plume evolution, about 500 smoke plumes intercepted by the NASA DC-8 aircraft were segregated by fire source region. The normalized excess mixing ratios (i.e. ΔX/ΔCO) of gaseous (carbon dioxide, acetonitrile, hydrogen cyanide, toluene, benzene, methane, oxides of nitrogen (NOx), ozone, PAN) and fine aerosol particulate components (nitrate, sulfate, ammonium, chloride, organic aerosols and water soluble organic carbon) of these plumes were compared

Investigating water soluble organic aerosols: sources and evolution

An existing method for the measurement of atmospheric gaseous species was modified to collect data on aerosol concentrations. Data from biomass burning events in different regions (Canada, the Arctic and California) were collected during April to July, 2008 and the concentrations and evolution of secondary organic aerosols were discussed. And finally, data on the light absorbing properties of water soluble organic aerosols were collected in Atlanta, GA and compared with filter data for the same properties. The results presented in this thesis showed that a negative ion chemical ionization mass spectrometer (CIMS), can be modified by the addition of a thermally denuded inlet to measure aerosol phase sulfuric acid. This system can also be used to measure other aerosol phase organic acids. In the biomass burning plumes studied in the second part, no clear indication of formation of secondary aerosol or gaseous species was observed, except for peroxyacetyl nitrate (PAN). Filter data collected from FRM sites in the Southeastern U.S. showed that biomass burning is the most dominant source of water soluble light absorbing carbonaceous aerosol in this region. The data from a study in Atlanta, GA showed that the online PILS-LWCC-WSOC system might be used for measurements of light absorbing properties of aerosols and WSOC.Ph.D.Committee Chair: Dr. Rodney J. Weber; Committee Member: Dr. Athanasios Nenes; Committee Member: Dr. L. Gregory Huey; Committee Member: Dr. Michael Bergin; Committee Member: Dr. Paul H. Win

A practical framework for oil and gas operators to estimate methane emission duration using operational data

Methane management is a key greenhouse gas reduction focus within the oil and gas industry. While there are a variety of techniques for methane detection and measurement, aircraft-mounted sensors have become popular for both academic studies and operators in onshore regions in North America due to their ability to screen many sites in a relatively short amount of time. Many traditional leak detection and repair techniques, like optical gas imaging, and emerging approaches like aircraft-based or satellite-based screenings are periodic, which means that they can provide information about the presence of emissions and approximate rates during the observation period. Scaling periodic observations to annual emission estimates needed for regulatory and corporate reporting requires information on emission duration, which is not generally provided by the same screening techniques. In the literature to-date, there have been several statistical approaches proposed for annualization of basin-level methane observations, but these techniques may struggle to downscale to individual operators, across which methane emission intensities are expected to vary. This paper proposes a novel, conceptual framework for using other sources of data, such as records from operator inspections and parametric monitoring, to help define the duration of detected methane emissions. Such information may prove to be a useful input to measurement-informed methane emission protocols that are under development by multi-stakeholder groups, like GTI Energy Veritas, and Federal agencies in the United States

Dataset associated with "Effects of fuel moisture content on emissions from a rocket-elbow cookstove"

This dataset includes cookstove emissions data per energy delivered and per mass of fuel burned. Emissions data on a per-energy-delivered basis have units of grams per megajoule delivered. Emissions data on a per-mass-of-fuel-burned basis have units of grams per kilogram of fuel. These data were collected in a laboratory cookstoves testing facility at Colorado State University. The data file includes the following columns: 1. test_id - test ID (used internally to identify test replicates), 2. date - date on which the test replicate was conducted, 3. stove - name of the stove model tested, 4. fuel - name of the fuel, 5. fuel_shape - shape of the fuel, either "Milled" or "Split", 6. mc_level - moisture level of the fuel, either "Low", "Medium", or "High", 7. fuel_mc_dry - the moisture content of the fuel on a dry mass basis, in percent, 8. pollutant - name of the pollutant, 9. value - value of the emissions metric, 10. units - units associated with the emission metric, either "g_MJd" or "g_pol_kg_fuel".Exposure to air pollution from solid-fuel cookstoves is a leading risk factor for premature death; however, the effect of fuel moisture content on air pollutant emissions from solid-fuel cookstoves remains poorly constrained. The objective of this work was to characterize emissions from a rocket-elbow cookstove burning wood at three different moisture levels (5%, 15%, and 25% on a dry mass basis). Emissions of CO2, carbon monoxide (CO), methane, formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, xylenes, fine particulate matter (PM2.5), elemental carbon (EC), and organic carbon (OC) were measured. Emission factors (EFs; g·MJdelivered-1) for all pollutants, except CO2 and EC, increased with increasing fuel moisture content: CO EFs increased by 84%, benzene EFs increased by 82%, PM2.5 EFs increased by 149%, and formaldehyde EFs increased by 216%. Both modified combustion efficiency and the temperature at the combustion chamber exit decreased with increasing fuel moisture, suggesting that the energy required to vaporize water in the fuel led to lower temperatures in the combustion chamber and lower gas-phase oxidation rates. These results illustrate that changes in fuel equilibrium moisture content could cause EFs for pollutants such as PM2.5 and formaldehyde to vary by a factor of two or more across different geographic regions.This work was supported by grant ES023688 from the National Institute for Environmental Health Sciences.This work was supported by grant RD83543801 from the U.S. Environmental Protection Agency

Characterizing emissions from natural gas drilling and well completion operations in Garfield County, CO

This study was designed to characterize and quantify emission rates and dispersion of air toxics, ozone precursors, and greenhouse gases from unconventional natural gas well development activities in Garfield County, CO, located on top of a geological formation known as the Piceance Basin. Particular focus was placed on quantifying emissions of individual volatile organic compounds (VOCs) and methane during well drilling, hydraulic fracturing ("fracking"), and flowback. While some prior studies have measured VOC or methane concentrations near well development operations, ambient concentrations are strongly dependent not only on emission rates but also on sampling location and meteorological conditions, which greatly affect downwind dispersion and dilution. By characterizing emission rates directly, results from this study can be used to predict downwind concentration fields for any location of interest under a wide range of weather conditions. Emission rates were determined using a tracer ratio method (TRM). In this method, the rate of emission of a compound of interest (e.g., g s-1 of benzene) is determined as the product of a known tracer emission rate multiplied by the ratio of the background-corrected concentrations of the compound of interest and the tracer. Acetylene was selected as a tracer gas and its controlled release co-located with the main source of emissions on studied well pads. Real-time methane and acetylene concentrations and three minute integrated whole air sample canisters for VOC analysis were collected downwind of the release location. Meteorological data were collected at two heights (3 m and 10 m) near the well pad. Upwind acetylene, methane, and VOC concentrations were determined for background correction. The canisters were analyzed for a large suite of VOCs using gas chromatography with flame ionization detection. The study results provide novel information concerning emissions from natural gas drilling and completion activities in Garfield County, CO and are some of the first measurements of this type in any U.S. basin. Overall, 21 emission experiments were conducted from 2013-2015. Several sets of 2 to 5 canisters were collected at different times during each experiment, in addition to an upwind background sample per experiment. Using the TRM, each canister in the plume provides an independent measure of VOC emission rates. 28-48 VOCs are reported for each canister, along with real-time methane and acetylene data collected during each experiment. Using the TRM the emission rates of methane and individual VOCs are calculated and reported.The emission rates and field observations were used to conduct air dispersion (using the EPA's AERMOD model) simulations to: (1) evaluate AERMOD's accuracy in predicting observed, near-field dispersion of VOCs in Garfield County, CO and (2) predict concentration fields, as a function of emission rate, for dispersion of a hypothetical compound under a range of local meteorological conditions at a site with terrain similar to that observed in Garfield County. While not perfectly designed for prediction of the short-term concentration fields measured in the study, AERMOD did a reasonable job predicting the observed extent of dispersion across several field experiments. Moreover, emission rate ranges determined by activity type in this study can be used in a wide range of future simulations with AERMOD or other models to simulate downwind concentration fields relevant to understanding potential local health and air quality impacts associated with well development activities in Garfield County.Garfield County, CO.Encana Corporation.Ursa Resources Group.WPX Energy.Bill Barrett Corporation.Caerus Oil and Gas.Laramie Energy

Dataset associated with "Volatile organic compounds and ozone at four national parks in the southwestern United States"

Whole air canister samples were collected at four national parks in the southwestern United States. The parks are Carlsbad Caverns National Park (CAVE) in New Mexico, Grand Canyon National Park (GRCA) in Arizona, Great Basin National Park (GRBA) in Nevada, and Joshua Tree National Park (JOTR) in California. Sampling took place at each site from 4 April 2017 to 14 September 2017. In addition to these measurements, a short intensive study was conducted in and around CAVE in September 2017. This intensive included measurements from nearby Guadalupe Mountains National Park (GUMO) and Bitter Lake National Wildlife Refuge. Whole air samples were analyzed for 56 individual volatile organic compounds using a five-channel, three-GC (gas chromatograph) analytical system, which employed three flame ionization detectors (FIDs), one electron capture detector (ECD) and one mass spectrometer.This file contains the sample information and concentrations of data collected during a study to characterize volatile organic compounds at four national parks in the southwestern US. These data are associated with the manuscript: Benedict, K.B., Prenni, A.J. El-Sayed, M.M.H., Hecobian, A., Zhou, Y., Gebhart, K.A., Sive, B.C., Schichtel, B.A., Collett Jr, J.L., submitted. Volatile organic compounds and ozone at four national parks in the southwestern United States. Atmospheric Environment. The abstract from the submitted manuscript is as follows: The National Park Service is tasked with protecting the lands it oversees, including from impacts from air pollutants. While ozone is regularly monitored in many parks across the United States, precursors to ozone formation are not routinely measured. In this work we characterize volatile organic compounds (VOCs) at four national parks in the southwestern United States: Carlsbad Caverns (CAVE), Great Basin (GRBA), Grand Canyon (GRCA), and Joshua Tree (JOTR). Whole air samples were collected for VOC analysis for five months (mid-April through mid-September) in 2017. Samples were collected from 3 PM to 5 PM local time, corresponding approximately to the time of expected peak ozone concentrations, and were analyzed using gas chromatography for a variety of compounds including alkanes, alkenes, aromatics, biogenics, and alkyl nitrates. Among the four parks, the total measured VOC mixing ratio was greatest at CAVE, mostly due to an abundance of light alkanes (on average 94% of all VOCs measured) from oil and gas sources. VOC concentrations at the other three parks were similar to each other and approximately 7-10 times lower than at CAVE. While VOC sources varied across sites, VOC-OH reactivity was dominated by biogenic compounds at all sites except CAVE, which had similar contributions from biogenics and from light alkanes. To better characterize source influences, intensive measurements were conducted in and around CAVE for one week in September 2017. These measurements showed an oil and gas influence throughout the region and indicated that the whole air samples collected over the five-month study did not capture the full range of VOC mixing ratios present at other times of the day.This work was funded by the National Park Service. The CSU portion of the work was funded by Cooperative Agreement H2370094000, Task Agreement P13AC01187

North Front Range oil and gas air pollution emission and dispersion study

PI: Prof. Jeffrey L. Collett Jr.Improved unconventional oil and natural gas extraction methods have facilitated the development of these resources in several areas, including the northern Front Range of Colorado. Increased activity has spurred questions concerning possible air pollutant emissions. Processes associated with oil and gas extraction have been identified as emitting a variety of air pollutants, but observations of the rates and types of compounds emitted are limited. This is especially true for emissions during completion (hydraulic fracturing and flowback) of new wells, activities which have not been closely examined for emission of atmospheric pollutants, but additional information is also needed for oil and gas production sites which have long operational lifetimes. This study was designed to characterize and quantify emission rates and dispersion of air toxics, ozone precursors, and greenhouse gases from oil and gas operations in the Denver-Julesburg Basin on the northern Front Range of Colorado. Based on a review of critical knowledge gaps and input from a study Technical Advisory Panel, particular focus was placed on quantifying emissions of individual volatile organic compounds (VOCs), methane, and ethane from oil and gas production sites and from hydraulic fracturing ("fracking") and flowback, important steps in the completion of new wells. Four oil and gas production companies were recruited to participate in the study and provided access to field operations for emission measurements. While some prior studies have measured VOC, ethane, or methane concentrations near oil and gas operations, ambient concentrations are strongly dependent not only on emission rates but also on sampling location and meteorological conditions, which greatly affect downwind dispersion and dilution. By characterizing emission rates directly, results from this study can be used to predict downwind concentration fields for any location of interest under a wide range of weather conditions. By using a similar measurement approach, this study was designed to complement a parallel effort examining methane, ethane, and VOC emission rates from drilling and completion of natural gas wells in the Piceance Basin in Garfield County, Colorado. Emission rates were determined using a tracer ratio method (TRM). In this method, the emission rate of a compound of interest (e.g., g s-1 of benzene) is determined as the product of a known tracer emission rate multiplied by the ratio of the background-corrected concentrations of the compound of interest and the tracer. Acetylene was selected as a tracer gas and its controlled release co-located with the main source of emissions on study sites. Real-time methane and acetylene concentrations and three-minute integrated whole air sample canisters for VOC and ethane analysis were collected downwind of the release location. Meteorological data were collected at two heights (3 m and 10 m) near the activity under study. Upwind acetylene, methane, ethane, and VOC concentrations were determined for background correction. The canisters were analyzed for ethane and a large suite of VOCs using gas chromatography with flame ionization detection. The study results provide novel information concerning emissions from oil and natural gas production and completion activities in the northern Front Range of Colorado. Overall, 18 emission experiments were conducted from 2014-2016. Several sets of canisters were collected at different times during each experiment, in addition to upwind background samples. Using the TRM, each canister in the plume provides an independent measure of ethane and VOC emission rates. Ethane and 47 VOCs are reported for each canister, along with real-time methane and acetylene data collected during each experiment. Using the TRM, the emission rates of methane, ethane, and individual VOCs are calculated and reported. Methane, ethane, and propane were the most abundant constituents in measured emissions. Generally, higher rates of VOC, ethane, and methane emissions were observed during flowback operations, although a wide range of emissions was observed for each type of activity studied. Methane emission rates were examined as a percentage of produced natural gas at the diverse array of production sites included in the experiment. These included large and small sites (between 1 and 18 horizontal and/or vertical wells) with a variety of different separation schemes. A positive relationship was observed with gas production rate; median and mean methane emissions measured across all production sites were 0.23% and 0.37%, respectively, with the 95th percentile of emissions at 1.03%. The emission rates and field observations were used to conduct air dispersion simulations (using EPA's AERMOD model) to: (1) evaluate AERMOD's accuracy in predicting observed, near-field dispersion of ethane and VOCs in the Colorado Front Range and (2) predict concentration fields, as a function of emission rate, for dispersion of benzene under a range of local meteorological conditions at a site with terrain similar to that observed in the Front Range of Colorado. While not perfectly designed for prediction of the short-term concentration fields measured in this study, AERMOD did a reasonable job predicting the observed extent of dispersion across several field experiments. Moreover, emission rate ranges determined by activity type in this study can be used in a wide range of future simulations with AERMOD or other models to simulate downwind concentration fields relevant to understanding potential local health and air quality impacts associated with oil and gas well completion and production activities on the northern Front Range.This study was funded by CDPHE (Colorado Department of Public Health and Environment) and the City of Fort Collins

Chemical Composition and Emissions Factors for Cookstove Startup (Ignition) Materials

Air pollution from cookstoves creates a substantial human and environmental health burden. A disproportionate fraction of emissions can occur during stove ignition (startup) compared to main cooking, yet startup material emissions are poorly quantified. Laboratory tests were conducted to measure emissions from startups using kerosene, plastic bags, newspaper, fabric, food packaging, rubber tire tubes, kindling, footwear, and wood shims. Measured pollutants included: fine particulate matter mass (PM_2.5), PM_2.5 elemental and organic carbon, methane, carbon monoxide, carbon dioxide, benzene, and formaldehyde. Results demonstrate substantial variability in the measured emissions across materials on a per-startup basis. For example, kerosene emitted 496 mg PM_2.5 and 999 mg CO per startup, whereas plastic bags emitted 2 mg PM_2.5 and 30 mg CO. When considering emissions on a per-mass basis, the ordering of materials from highest-to-lowest emissions changes, emphasizing the importance of establishing how much material is needed to start a stove. The proportional contribution of startups to overall emissions varies depending on startup material type, stove type, and cooking event length; however, results demonstrate that startup materials can contribute substantially to a cookstove’s emissions. Startup material choice is especially important for cleaner stove-fuel combinations where the marginal benefits of reduced emissions are potentially greater