Rapidly evolving ultrafine and fine mode biomass smoke physical properties: Comparing laboratory and field results

Combining field and laboratory results, we present biomass smoke physical properties. We report sub-0.56 µm diameter (Dp) particle sizing (fast mobility particle sizer, FMPS) plus light absorption and scattering at 870nm (photoacoustic extinctiometer). For Dp\u3c200 \u3enm, the FMPS characterized sizing within ±20% compared to standards. As compared to the traditional scanning mobility particle sizer, the FMPS responded most accurately to single-mode polydispersions with mean Dp\u3c200 \u3enm, which characterized the smoke sampled here. Smoke was measured from laboratory fresh emissions (seconds to hours old), the High Park Fire (hours to\u3c1 \u3eday), and from regional biomass burning (several days). During a High Park Fire episode, light extinction rapidly reached a maximum of σep = 569 ± 21Mm-1 (10 min) with aerosol single scattering albedo peaking at ω= 0.955 ± 0.004. Concurrently, number concentration and size peaked with maximum Dp = 126nm and a unimodal distribution with σg = 1.5. Long-range transported smoke was substantially diluted (Ntot factor of 7 lower) and shifted larger (maximum Dp = 143) and wider (σg = 2.2). We compared ambient data to laboratory burns with representative western U.S. forest fuels (coniferous species Ponderosa pine and Alaska black spruce). Smoldering pine produced an aerosol dominated by larger, more strongly light scattering particles (Dp\u3e100 nm), while flaming combustion produced very high number concentrations of smaller (Dp ~ 50 nm) absorbing particles. Due to smoldering and particle growth processes, Dp approached 100nm within 3 h after emission. Increased particle cross-sectional area and Mie scattering efficiency shifted the relative importance of light absorption (flaming maximum) and light scattering (smoldering maximum), increasing ω over time. Measurements showed a consistent picture of smoke properties from emission to aging

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

Cork : properties, capabilities and applications

Cork is a natural, renewable, sustainable raw material that has been used for many centuries. As a result of this very long term interest, the scientific literature on cork is extensive. The present review focuses on the chemical composition, physical and mechanical properties of cork and on its products and sub-products. The substantial efforts to fully characterise cork, as well as new developments and evolving research, are reviewed, beginning with its histology, growth and morphology (at macro- and microscales). The chemical structure is analysed in detail, covering both the materials that form the wall structure and the low molecular weight, extractable components. The unique properties of cork are discussed and correlated with current knowledge on morphology and chemical structure. Finally, the important industrial applications of cork are reviewed, in the context of research to provide cork with novel, high added-value applications

Direct Aerosol Radiative Forcing Based on Optical Measurements at Contrasting, Climatically Important Sites

189 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2000.To characterize direct aerosol radiative forcing of climate ( DARF), aerosol optical properties were measured at two contrasting locations, a clean marine Southern Hemisphere site (Cape Grim Tasmania) and an anthropogenically perturbed Northern Hemisphere site (Sagres, Portugal). Total light scattering and backscattering coefficients by particles (sigma sp and sigmabsp, respectively) and their dependence upon controlled relative humidity (RH), particle diameter ( Dp) size cut, and wavelength of light were measured using a controlled RH nephelometer system. Results from Cape Grim demonstrated the predominate influence of sea-salt aerosol in regard to all aerosol optical properties and for both sub- and super-micrometer Dp size cuts. At Sagres, polluted aerosol predominated and even during times of "clean" air masses of a marine origin, evidence of an anthropogenic: influence was observed. As such, much greater magnitude and wavelength dependence of aerosol light scattering resulted at Sagres. Whereas the marine aerosol at Cape Grim was virtually a purely light scattering aerosol, the perturbed aerosol at Sagres had a significant light absorbing component though too was dominated by light scattering. Furthermore, aerosol hygroscopic growth was smaller in magnitude and monotonic at Sagres in comparison to the deliquescent marine aerosol at Cape Grim. At Sagres, evidence of hysteresis in growth in sigmasp as a function of RH (different pathways for increasing and decreasing controlled RH) was greatest at RH = 65% with enhanced growth of ∼20% during "clean" and ∼10% during "polluted periods." Based on laboratory and field measurements from Sagres, hysteresis effects are presumed to be greater at Cape Grim as individual humidograms from marine aerosol at Sagres demonstrated increases up to 67%. Using these measurements and literature data, at Cape Grim DARF is estimated as ∼0 while DARF at Sagres = --3.3 Wm--2 with an estimated uncertainty +/-1.2 Wm--2. DARF at Sagres is ∼50% larger in magnitude but opposite in sign (i.e. causing a net cooling) to global and annual mean greenhouse gas radiative forcing. However, instantaneous DARF varied substantially in time, and at Sagres was as significant as 40 Wm--2 for broadband calculations. These results are available as inputs to global climate models to enhance prediction of aerosol-climate effects.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Direct Aerosol Radiative Forcing Based on Optical Measurements at Contrasting, Climatically Important Sites

189 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2000.To characterize direct aerosol radiative forcing of climate ( DARF), aerosol optical properties were measured at two contrasting locations, a clean marine Southern Hemisphere site (Cape Grim Tasmania) and an anthropogenically perturbed Northern Hemisphere site (Sagres, Portugal). Total light scattering and backscattering coefficients by particles (sigma sp and sigmabsp, respectively) and their dependence upon controlled relative humidity (RH), particle diameter ( Dp) size cut, and wavelength of light were measured using a controlled RH nephelometer system. Results from Cape Grim demonstrated the predominate influence of sea-salt aerosol in regard to all aerosol optical properties and for both sub- and super-micrometer Dp size cuts. At Sagres, polluted aerosol predominated and even during times of "clean" air masses of a marine origin, evidence of an anthropogenic: influence was observed. As such, much greater magnitude and wavelength dependence of aerosol light scattering resulted at Sagres. Whereas the marine aerosol at Cape Grim was virtually a purely light scattering aerosol, the perturbed aerosol at Sagres had a significant light absorbing component though too was dominated by light scattering. Furthermore, aerosol hygroscopic growth was smaller in magnitude and monotonic at Sagres in comparison to the deliquescent marine aerosol at Cape Grim. At Sagres, evidence of hysteresis in growth in sigmasp as a function of RH (different pathways for increasing and decreasing controlled RH) was greatest at RH = 65% with enhanced growth of ∼20% during "clean" and ∼10% during "polluted periods." Based on laboratory and field measurements from Sagres, hysteresis effects are presumed to be greater at Cape Grim as individual humidograms from marine aerosol at Sagres demonstrated increases up to 67%. Using these measurements and literature data, at Cape Grim DARF is estimated as ∼0 while DARF at Sagres = --3.3 Wm--2 with an estimated uncertainty +/-1.2 Wm--2. DARF at Sagres is ∼50% larger in magnitude but opposite in sign (i.e. causing a net cooling) to global and annual mean greenhouse gas radiative forcing. However, instantaneous DARF varied substantially in time, and at Sagres was as significant as 40 Wm--2 for broadband calculations. These results are available as inputs to global climate models to enhance prediction of aerosol-climate effects.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Impacts of a Prescribed Fire on Air Quality in Central New Mexico

A short-duration but high-impact air quality event occurred on 28 November 2018 along the Rio Grande Valley of New Mexico. This fire occurred outside the typical wildfire season, and greatly impacted the air quality in Socorro, NM, and the surroundings. Measurements were taken during the event using an aerosol light scattering technique (integrating nephelometer) and a particulate mass concentration monitor (DustTrak PM optical monitor). The instruments sampled the ambient air during the event on the campus of the New Mexico Institute of Mining and Technology in Socorro, New Mexico. The peak values on a 5-min basis of light scattering and the PM mass concentration reached 470 Mm−1 and 270 µg/m3, respectively. We examined the meteorological context of the event using local meteorological data and back trajectories using the NOAA HYSPLIT model to determine atmospheric transport and possible sources. Several fires, both prescribed and wildfires, occurred in the region including a prescribed burn at Bosque del Apache National Wildlife Refuge (17 km south-southeast of the receptor site). The data suggest that the prescribed burn at Bosque del Apache was the dominant contributor due to transport evidence and the event’s narrow spatiotemporal extent. The increasing importance of restoring ecosystem function using prescribed fire in wildland fire management will likely lead to more frequent air quality impacts and sets up policy tradeoffs that require a balance between these public goals. This study examines the evidence of the effects of a prescribed fire in a protected wildland area impacting the air quality in a nearby populated area

Running with Scissors: a Systematic Review of Substance Use and the Pre-exposure Prophylaxis Care Continuum Among Sexual Minority Men

Patterns of sexualized drug use, including stimulants (e.g., methamphetamine) and chemsex drugs, are key drivers of HIV incidence among sexual minority men (SMM). Although pre-exposure prophylaxis (PrEP) mitigates HIV risk, there is no consensus regarding the associations of substance use with the PrEP care continuum. SMM who use substances are as likely or more likely to use PrEP. Although SMM who use stimulants experience greater difficulties with daily oral PrEP adherence, some evidence shows that SMM who use stimulants or chemsex drugs may achieve better adherence in the context of recent condomless anal sex. Finally, SMM who use substances may experience greater difficulties with PrEP persistence (including retention in PrEP care). SMM who use stimulants and other substances would benefit from more comprehensive efforts to support PrEP re-uptake, adherence, and persistence, including delivering behavioral interventions, considering event-based dosing, and providing injectable PrEP

The importance of carbon and mineral dust to seasonal aerosol properties in the Nepal Himalaya

Though recent studies suggest that aerosols may influence the Asian monsoons, limited knowledge exists regarding aerosol impacts on regional climate and air quality. To improve understanding of aerosols in the Himalaya, mass concentrations (PM10 and PM2.5), chemical composition, and wavelength dependent aerosol optical depth (δλ) were measured from December 1998 through October 2000 at sites on the edge of the Kathmandu valley (Nagarkot) and in the remote Himalaya (Langtang). Though highly variable, aerosol concentrations peaked in February to May with average PM2.5=59±61 μg/m3 and aerosol optical depth at Nagarkot. With arrival of southerly flow and monsoon rains, PM2.5 dropped to 8±7 μg/m3 in June through September. With the cessation of summer rains, aerosol concentrations began steadily increasing with average PM2.5=25±14 μg/m3 during October to January. During all seasons, a large PM2.5/PM10 ratio (0.77±0.21), the predominance of particulate organic material (48±28% of PM2.5), and an ionic composition dominated by SO42−, NH4+, and NO3− (16±14% of PM2.5) all implicated combustion sources. Nonetheless, a large fraction of the aerosol was insoluble and non-carbonaceous (33±27%), particularly during the peak season when it reached 45%. Elemental analysis of a filter subset showed large concentrations of Ca, Si, Al, and Fe, indicating that dust was responsible for much of the remaining material. Though an influence of the Kathmandu valley was likely, evidence supported long-range transport of desert dust to the Himalaya from arid regions ranging from India and the Middle East to perhaps as far as the Sahara

Randomized Controlled Trial of Motivational Enhancement Interventions to Increase Pre-Exposure Prophylaxis Use in Sexual Minority Men Who Use Stimulants

Although pre-exposure prophylaxis (PrEP) could substantially mitigate HIV risk, sexual minority men (SMM) who use stimulants commonly experience difficulties with engaging in PrEP clinical services. Motivational interviewing (MI) and contingency management (CM) reduce substance use and condomless anal sex in this population, but these motivational enhancement interventions require adaptation to promote engagement along the PrEP care continuum. PRISM is a pilot sequential multiple assignment randomized trial (SMART) testing the feasibility, acceptability, and preliminary effectiveness of distinct combinations of telehealth MI and CM in 70 cisgender SMM who use stimulants that are not currently taking PrEP. A national sample was recruited via social networking applications to complete a baseline assessment and mail-in HIV testing. Those with non-reactive HIV results are randomized to receive either: 1) a 2-session MI intervention focusing on PrEP use (session 1) and concomitant stimulant use or condomless anal sex (session 2); or 2) a CM intervention with financial incentives for documented evidence of PrEP clinical evaluation by a medical provider ($50) and filling a PrEP prescription ($50). At the 3-month follow-up assessment, participants who report they have not filled a prescription for PrEP are randomized a second time to either: 1) Switch to a second-stage intervention (i.e., MI + CM or CM + MI); or 2) Continue with assessments only. Outcomes for both responders and non-responders are reassessed at a 6-month follow-up. The primary outcome is documented evidence of filling a PrEP prescription. Self-reported, secondary outcomes include PrEP clinical evaluation by a medical provider, stimulant use, and condomless anal sex. Qualitative exit interviews are conducted with a sub-group of responders and non-responders to characterize their experiences with the MI and CM interventions. Implementation of this pilot SMART underscores the challenges in reaching SMM who use stimulants to optimize HIV prevention efforts such that approximately one in ten (104/1,060) eligible participants enrolled. However, 85% (70/82) of enrolled participants with non-reactive HIV results were randomized. Further research is needed to determine the effectiveness of telehealth MI and CM for supporting PrEP use in SMM who use stimulants. This protocol was registered on clinicaltrials.gov (NCT04205487) on December 19, 2019