Evaluation of the IMPROVE Equation for estimating aerosol light extinction.

Unlabelled: The [revised] IMPROVE Equation for estimating light extinction from aerosol chemical composition was evaluated considering new measurements at U.S. national parks.

Characterization of PM2.5 and PM10 fugitive dust source profiles in the Athabasca Oil Sands Region.

Unlabelled: Geological samples were collected from 27 representative locations in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada. These samples were resuspended onto filter substrates for PM2.5 and PM10 size fractions.

Evaluation of assumptions for estimating chemical light extinction at U.S. national parks.

Unlabelled: Studies were conducted at Great Smoky Mountains National Park (NP) (GRSM), Tennessee, Mount Rainier NP (MORA), Washington, and Acadia NP (ACAD), Maine, to evaluate assumptions used to estimate aerosol light extinction from chemical composition. The revised IMPROVE equation calculates light scattering from concentrations of PM2.5 sulfates, nitrates, organic carbon mass (OM), and soil.

Comparison of water isotope-ratio determinations using two cavity ring-down instruments and classical mass spectrometry in continuous ice-core analysis.

We present a detailed comparison between subsequent versions of commercially available wavelength-scanned cavity ring-down water isotope analysers (L2120-i and L2130-i, Picarro Inc.). The analysers are used in parallel in a continuous mode by adaption of a low-volume flash evaporation module.

Toward Effective Source Apportionment Using Positive Matrix Factorization: Experiments with Simulated PM Data.

To elucidate the relationship between factors resolved by the positive matrix factorization (PMF) receptor model and actual emission sources and to refine the PMF modeling strategy, speciated PM (particulate matter with aerodynamic diameter <2.5 μm) data generated from a state-of-the-art chemical transport model for two rural sites in the eastern United States are subjected to PMF analysis. In addition to χ- and R used to infer the quality of fitting, the interpretability of PMF factors with respect to known primary and secondary sources is evaluated using a root mean square difference analysis.

Evaluation of Regional-Scale Receptor Modeling.

The ability of receptor models to estimate regional contributions to fine particulate matter (PM) was assessed with synthetic, speciated datasets at Brigantine National Wildlife Refuge (BRIG) in New Jersey and Great Smoky Mountains National Park (GRSM) in Tennessee. Synthetic PM chemical concentrations were generated for the summer of 2002 using the Community Multiscale Air Quality (CMAQ) model and chemically speciated PM source profiles from the U.S.

A Special Issue from the NARSTO Symposium on Tropospheric Aerosols.

This dedicated issue of the Journal of the Air & Waste Management Association contains nine peer-reviewed scientific papers that were presented at the NARSTO Symposium on Tropospheric Aerosols: Science and Decisions in an International Community, held October 24-26, 2000, in Querétaro, Mexico. Other peer-reviewed papers appear in a companion issue of Science of the Total Environment to be published in February 2002. More than 130 papers were presented in platform and poster sessions at the meeting.

The Impact of California Phase 2 Reformulated Gasoline on Real-World Vehicle Emissions.

In mid-1996, California implemented Phase 2 Reformulated Gasoline (RFG). The new fuel was designed to further decrease emissions of hydrocarbons (HC), oxides of nitrogen (NO), carbon monoxide (CO), sulfur dioxide (SO), and other toxic species. In addition, it was formulated to reduce the ozone-forming potential of the HCs emitted by vehicles.

Temporal Variations of PM, PM, and Gaseous Precursors during the 1995 Integrated Monitoring Study in Central California.

The spatial and temporal distributions of particle mass and its chemical constituents are essential for understanding the source-receptor relationships as well as the chemical, physical, and meteorological processes that result in elevated particulate concentrations in California's San Joaquin Valley (SJV). Fine particulate matter PM coarse particulate matter (PM), and aerosol precursor gases were sampled on a 3-hr time base at two urban (Bakersfield and Fresno) and two non-urban (Kern Wildlife Refuge and Chowchilla) core sites in the SJV during the winter of 1995-1996. Day-to-day variations of PM and PM and their chemical constituents were influenced by the synoptic-scale meteorology and were coherent among the four core sites.

Attribution of Particulate Sulfur in the Grand Canyon to Specific Point Sources Using Tracer-Aerosol Gradient Interpretive Technique (TAGIT).

Since aerosol particulate sulfur is generally a secondary airborne pollutant, most source attribution techniques require many assumptions about the transport and chemistry of sulfur dioxide (SO) emissions. Uncertainties in our understanding of these processes impair our ability to generate reliable attribution information that is necessary for designing cost-effective pollution control policies. A new attribution technique using artificial tracer is presented in hopes of reducing the uncertainty of secondary aerosol source attribution.

Middle- and Neighborhood-Scale Variations of PM10 Source Contributions in Las Vegas, Nevada.

The Las Vegas Valley PM10 Study was conducted during 1995 to determine the contributions to PM10 aerosol from fugitive dust, motor vehicle exhaust, residential wood combustion, and secondary aerosol sources. Twenty-four-hr PM10 samples were collected at two neighborhood-scale sites every sixth day for 13 months. Five week-long intensive studies were conducted over a middle-scale sub-region at 29 locations that contained many construction projects emitting fugitive dust.

Assessment of Nontailpipe Hydrocarbon Emissions from Motor Vehicles.

This report evaluates tailpipe and nontailpipe hydrocarbon (HC) emissions from light-duty spark-ignition (SI) vehicles. The sources of information were unpublished data sets, generated mainly from 1990 through 1994, on emissions from volunteer fleets of in-use vehicles in chassis dynamometer and sealed housing for evaporative determination tests, and published chemical mass balance (CMB) source apportionments of HC in roadway tunnels and in urban air. The nontailpipe emissions evaluated comprise running-loss, hot soak, diurnal emissions, and resting-loss emissions.

Long-Term Efficiencies of Dust Suppressants to Reduce PM Emissions from Unpaved Roads.

A 14-month study was undertaken to assess the long-term efficiencies of four dust suppressants (i.e., biocatalyst stabilizer, polymer emulsion, petroleum emulsion with polymer, and nonhazardous crude-oil-containing materials) to reduce the emission of PM from public unpaved roads.

Measurements of Dioxin and Furan Emission Factors from Heavy-Duty Diesel Vehicles.

This note describes the results of a study of the on-road emissions of dioxins and furans from mobile sources. This work was performed in response to the U.S.

Clean Air Corridors: A Geographic and.

Meteorological factors, pollutant emissions, and geographic regions related to transport of low optical extinction coefficient air to Grand Canyon National Park were examined. Back trajectories were generated by two models, the Atmospheric Transport and Dispersion Model (ATAD) and an approach using the Nested Grid Model output for a Lagrangian particle transport model (NGM/ CAPITA). Meteorological information along the trajectories was analyzed for its relationship to visibility at the Grand Canyon.

Identification of Candidate Clean Air Corridors for the Colorado Plateau.

The U.S. Clean Air Act, amended in 1990, mandated the establishment of the Grand Canyon Visibility Transport Commission (GCVTC).