Carlsbad Caverns National Park Air Quality Study 2019

This data set includes fine particle and gas precursor measurements from Carlsbad Caverns National Park. The study was designed to examine the influence of regional sources, including urban emissions, oil and gas development, wildfires, and soil dust on air quality in the park. Field measurements of aerosols, trace gases and deposition were conducted from 25 July through 5 September 2019.Carlsbad Caverns National Park in southeastern New Mexico is adjacent to the Permian Basin, one of the most productive oil and gas regions in the country. The 2019 Carlsbad Caverns Air Quality Study (CarCavAQS) was designed to examine the influence of regional sources, including urban emissions, oil and gas development, wildfires, and soil dust on air quality in the park. Field measurements of aerosols, trace gases, and deposition were conducted from 25 July through 5 September 2019.This work was supported by the National Park Service Q5 [P20AC00679]

Meteorological and Back Trajectory Modeling for the Rocky Mountain Atmospheric Nitrogen and Sulfur Study II

The Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS II) study with field operations during November 2008 through November 2009 was designed to evaluate the composition and sources of reactive nitrogen in Rocky Mountain National Park, Colorado, USA. As part of RoMANS II, a mesoscale meteorological model was utilized to provide input for back trajectory and chemical transport models. Evaluation of the model's ability to capture important transport patterns in this region of complex terrain is discussed. Previous source-receptor studies of nitrogen in this region are also reviewed. Finally, results of several back trajectory analyses for RoMANS II are presented. The trajectory mass balance (TrMB) model, a receptor-based linear regression technique, was used to estimate mean source attributions of airborne ammonia concentrations during RoMANS II. Though ammonia concentrations are usually higher when there is transport from the east, the TrMB model estimates that, on average, areas to the west contribute a larger mean fraction of the ammonia. Possible reasons for this are discussed and include the greater frequency of westerly versus easterly winds, the possibility that ammonia is transported long distances as ammonium nitrate, and the difficulty of correctly modeling the transport winds in this area

UNCERTAINTY ASSOCIATED WITH ESTIMATING A SHORT-TERM (1–3 HR) PARTICULATE MATTER CONCENTRATION FROM A HUMAN-SIGHTED VISUAL RANGE

Several state air quality agencies have developed policies to issue air quality health index (AQI) warnings based on low values of visual range (Vr). Vr has been defined in the context of how far away a black object has to be such that it is just noticeable or visible. This distance at which a landscape feature can just be detected is referred to as the Vr. AQI warnings are based on the levels of particulates (PM2.5) resulting from fire smoke, often with less than 24-hr average concentrations. Because monitoring data are not available in all places where an AQI warning might potentially be given, human-observed visual conditions (i.e., sighting distant targets to determine Vr) have been used to estimate ambient fine particulate (PM2.5) concentrations. This procedure, originally developed in the arid West, may be particularly questionable when applied where higher humidity (especially in the humid Southeast) interacts with background sulfate and nitrate particulates and other aerosols from non-fire sources to reduce visibility. Human errors estimating Vr can be large. One result may be that the public is given an incorrect impression of air quality risks to their health and well-being; either the AQI or other indices are overestimates, causing undue public alarm, or underestimates from which the public, or at least sensitive sections of the public, undergo avoidable risks

Experimental Determination of Secondary Organic Aerosol Production from Biomass Combustion

This project, a collaboration between Colorado State University (CSU), Carnegie Mellon University (CMU), the University of Washington (UW), and the National Park Service (NPS), investigated the atmospheric aging of biomass burning plumes in order to examine changes in both primary particle emissions and the production of additional, secondary organic aerosol (SOA). Included in the project were chamber studies to directly study smoke aging as well as analyses of ambient samples to look for evidence of smoke aging and SOA formation in the ambient atmosphere. CMU conducted smog chamber studies to investigate the atmospheric evolution of fine particle and organic aerosol emissions in fire plumes. The experiments were conducted at the USDA/FS Fire Science Laboratory (FSL) in Missoula, MT as part of the FLAME-3 campaign organized by CSU and FSL; similar experiments were also conducted in the Air Quality Laboratory at CMU. The experiments investigated emissions from laboratory fires from fuels representing different regions in North America commonly impacted by prescribed burning and wildfires, including the Southeast (e.g., gallberry and pocosin), southern California (e.g., sagebrush and chamise) and forest regions of the western United States and Canada (e.g., ponderosa pine, lodgepole pine, and black spruce). The results from the chamber experiments are described in six papers published in peer-reviewed archival literature on the atmospheric stability of the primary smoke marker levoglucosan (Hennigan et al., 2010), the secondary organic aerosol formation and primary organic aerosol emissions processing biomass burning plumes (Hennigan et al., 2011); the formation and growth of new particles in biomass burning plumes (Hennigan et al. 2012); the evolution of cloud condensation nuclei in biomass burning plumes (Engelhart et al. 2012); the evolution of organic aerosol optical properties in biomass burning plumes (Saleh et al. 2013); and the gas-particle partitioning and volatility distribution of primary organic aerosol emissions from fires (May et al. 2013)

Relative contributions of fossil and contemporary carbon sources to PM2.5 aerosols at nine Interagency Monitoring for Protection of Visual Envirornments (IMPROVE) network sites

Particulate matter aerosols contribute to haze diminishing vistas and scenery at national parks and wilderness areas within the United States. To increase understanding of the sources of carbonaceous aerosols at these settings, the total carbon loading and 14C/C ratio of PM 2.5 aerosols at nine Interagency Monitoring for Protection of Visual Environments (IMPROVE) network sites were measured. Aerosols were collected weekly in the summer and winter at one rural site, two urban sites, five sites located in national parks and one site located in a wildlife preserve. The carbon measurements together with the absence of 14C in fossil carbon materials and known 14C/C levels in contemporary carbon materials were used to derive contemporary and fossil carbon contents of the particulate matter. Contemporary and fossil carbon aerosol loadings varied across the sites and suggest different percentages of carbon source inputs. The urban sites had the highest fossil carbon loadings that comprised around 50% of the total carbon aerosol loading. The wildlife preserve and national park sites together with the rural site had much lower fossil carbon loading components. At these sites, variations in the total carbon aerosol loading were dominated by nonfossil carbon sources. This suggests that reduction of anthropogenic sources of fossil carbon aerosols may result only in little decrease in carbonaceous aerosol loading at many national parks and rural areas. Examination of the major sources of uncertainty that might cause contemporary carbon contents to be artificially high indicates that potential errors and biases in the methodology do not change the fundamental conclusions of this study

Anomalous elevated radiocarbon measurements of PM2.5

Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 (14C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14C approximately 1.2 × 10-1214C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14C can skew the 14C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites

A Quantitative Method to Measure and Speciate Amines in Ambient Aerosol Samples

Ambient reactive nitrogen is a mix of nitrogen-containing organic and inorganic compounds. These various compounds are found in both aerosol- and gas-phases with oxidized and reduced forms of nitrogen. Aerosol-phase reduced nitrogen is predominately thought to include ammonium and amines. In ambient samples, the ammonium concentration is routinely determined, but the contribution of amines is not. We developed a method to discretely measure amines from ambient aerosol samples. It employs ion chromatography using a Thermo Scientific IonPac Dionex CS-19 column with conductivity detection and a three-step separation using a methanesulfonic acid eluent. This method allows for the quantification of 18 different amines, including the series of methylamines and the different isomers of butylamine. Almost all amines quantifiable by this technique were measured regularly when applying this method to ambient filter samples collected in Rocky Mountain National Park (RMNP) and Greeley, CO. The sum of the amines was ~0.02 µg m−3 at both sites. This increased to 0.04 and 0.09 µg m−3 at RMNP and Greeley, respectively, at the same time they were impacted by smoke. Analysis of separate, fresh biomass burning source samples, however, suggests that smoke is likely a minor emission source of amines in most environments

Relative contributions of fossil and contemporary carbon sources to PM2.5 aerosols at nine Interagency Monitoring for Protection of Visual Environments (IMPROVE) network sites,

Abstract Particulate matter aerosols contribute to haze diminishing vistas and scenery at National Parks and Wilderness Areas within the United States. To increase understanding of the sources of carbonaceous aerosols at these settings, the total carbon loading and 14 C/C ratio of PM 2.5 aerosols at nine IMPROVE (Interagency Monitoring for Protection Of Visual Environments) network sites were measured. Aerosols were collected weekly in the summer and winter at one rural site, two urban sites, five sites located in National Parks and one site located in a Wildlife Preserve. The carbon measurements together with the absence of 14 C in fossil carbon materials and the known 14 C/C levels in contemporary carbon materials were used to derive contemporary and fossil carbon contents of the particulate matter. Contemporary and fossil carbon aerosol loadings varied across the sites and suggest different percentages of carbon source inputs. The urban sites had the highest fossil carbon loadings that comprised around 50% of the total carbon aerosol loading. The Wildlife Preserve and National Park sites together with the rural site had much lower fossil carbon loading components. At these sites, variations in the total carbon aerosol loading were dominated by non-fossil carbon sources. This suggests that reduction of anthroprogenic sources of fossil carbon aerosols may result in little decrease in carbonaceous aerosol loading at many National Parks and rural areas

Model data associated with manuscript, "Source regions contributing to excess reactive nitrogen deposition in the greater Yellowstone area (GYA) of the United States"

We provide the CAMx simulation data related with the nitrogen deposition source apportionment results over the Greater Yellowstone Area.Research has shown that excess reactive nitrogen (Nr) deposition in the Greater Yellowstone Area (GYA) of the United States has passed critical load (CL) thresholds and is adversely affecting sensitive ecosystems in this area. To better understand the sources causing excess Nr deposition, the Comprehensive Air Quality Model with extensions (CAMx), using Western Air Quality Study (WAQS) emission and meteorology inputs, was used to simulate Nr deposition in the GYA. CAMx's Particulate Source Apportionment Technology (PSAT) was employed to estimate contributions from agriculture (AG), oil and gas (OG), fire (Fire), and other (Other) source sectors from 27 regions, including the model boundary conditions (BC) to the simulated Nr for 2011. The BC were outside the conterminous United States and thought to represent international anthropogenic and natural contributions. Emissions from the AG and Other source sectors are predominantly from reduced N and oxidized N compounds, respectively. The model evaluation revealed a systematic underestimation in ammonia (NH3) concentrations by 65% and overestimation in nitric acid concentrations by 108%. The measured inorganic N wet deposition at National Trend Network sites in the GYA was overestimated by 31–49%, due at least partially to an overestimation of precipitation. These uncertainties appear to result in an overestimation of distant source regions including California and BC and an underestimation of closer agricultural source regions including the Snake River valley. Due to these large uncertainties the relative contributions from the modelled sources and their general patterns are the most reliable results. Source apportionment results showed that the AG sector was the single largest contributor to the GYA total Nr deposition, contributing 34% on an annual basis. Seventy-four percent of the AG contributions originated from the Idaho Snake River valley, with Wyoming, California, and northern Utah contributing another 7%, 5%, and 4%, respectively. Contributions from the OG sector were small at about 1% over the GYA, except in the southern Wind River Mountain Range during winter where they accounted for more than 10%, with 46% of these contributions coming from OG activities in Wyoming. Wild and prescribed fires contributed 18% of the total Nr deposition, with fires within the GYA having the highest impact. The Other source category was the largest winter contributor (44%) with high contributions from California, Wyoming and northern Utah

A critical review of filter transmittance measurements for aerosol light absorption, and <i>de novo</i> calibration for a decade of monitoring on PTFE membranes

<p>The IMPROVE (Interagency Monitoring of PROtected Visual Environments) network monitors the attenuation of light by PM_2.5 samples (fine particulate matter, D_aero = 2.5 μm) routinely collected on polytetrafluoroethylene (PTFE) filters throughout the United States. The results of this measurement have long been reported as an indicator of absorption, with no rigorous calibration as such. Filter-based absorption measurements more conventionally employ optically thick quartz- or glass-fiber collection media, for which a substantial calibration literature offers algorithms to correct for particle scattering and filter loading effects. PTFE membranes are optically thinner and less homogeneous than the fiber media, but they avoid interference from adsorbed organic gases that is associated with quartz and glass fiber media. IMPROVE's measurement system is a hybrid of integrating sphere and integrating plate that records the light backscattered as well as transmitted by each filter. This article introduces and validates a theory-based model for calibration and data reduction that accounts for particle scattering effects as well as variations in filter optics. Tests based on historical analyses of field blanks and recent reanalyses of archived samples establish that the current system has operated with a stable calibration since 2003.</p> <p>The newly calibrated IMPROVE absorption values correlate strongly with the refractory carbon fraction reported by thermal-optical analysis as “elemental” (EC). EC is sometimes treated as the only significant light absorber in PM_2.5, but the general decline observed between 2005 and 2014 in IMPROVE EC was not accompanied by a comparable decline in IMPROVE absorption. Absorption also exhibits a distinct association with Fe concentrations, which at IMPROVE sites are attributable mainly to mineral dusts and have generally held steady or risen since 2003. An increased relative contribution by mineral dusts can explain some, but not all, of the observed difference between recent absorption and EC trends.</p