Assessing the Relative Contribution of Biogenic and Fossil Processes to Visibility-Scattering Aerosols Found in Remote Areas: Near-Term Organic Research Program

Abstract

Organic carbon has been found to be a significant component of aerosols that impair visibility in remote areas across the country. Organic aerosols are particularly important in western areas of the United States and contribute roughly equally with sulfate aerosols and dust in the total extinction budget. Potential visibility enhancement resulting from various future energy management options that reduce volatile organic carbon and particulate material emissions from fossil-energy-related processes hinges on the relative contribution of the fossil-fuel-derived organic component to the extinction budget. Thus, additional studies are needed to quantify the partitioning of organic carbon between biogenic and fossil sources. Relative humidity (RH) also plays an important role in visibility impairment. It is well known that water soluble aerosol species, such as sulfate and nitrate, can increase light-scattering efficiencies of fine particles by more than an order of magnitude as RH is increased from 20-30% to 90-95%. Organic carbon aerosol has been found to be a mixture of more soluble and less soluble components, but few studies have been performed to evaluate the RH response function of aerosols composed of these components, either separately or in combination, especially at high relative humidities. The purpose of this paper is to describe some experiments that could address the major uncertainties of biogenic and fossil carbon contributions to the fine particle extinction budget and visibility impairment.     

Studies on the drug resistance profile of Enterococcus faecium distributed from poultry retailers to hospitals

The multidrug resistant Enterococcus faecium (MEF) strains originating from farm animals are proliferating at a substantial pace to impact downstream food chains and could reach hospitals. This study was conducted to elucidate the drug susceptibility profile of MEF strains collected from poultry products in Ann Arbor, MI area and clinical settings from Michigan State Lab and Moffitt Cancer Center (MCC) in Florida. Presumptive positive Enterococcus isolates at species level were identified by Matrix Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) analysis. The antibiotic susceptibility profile for both poultry and clinical strains was determined by the Thermo Scientific's Sensititre conform to the National Committee for Clinical Laboratory Standards (NCCLS) and validated via quantitative real-time PCR (qPCR) methods. Out of 50 poultry samples (Turkey: n = 30; Chicken: n = 20), 36 samples were positive for Enterococcus species from which 20.83% were identified as E. faecium. All the E. faecium isolates were multidrug resistant and displayed resistance to the last alternative drug, quinupristin/dalfopristin (QD) used to treat vancomycin resistant E. faecium (VRE) in hospitals. Results indicate the presence of MEF strains in food animals and clinical settings that are also resistant to QD.     

Bioaerosol Generation at Large-Scale Green Waste Composting Plants

Abstract

Bioaerosol release from composting plants is a cause of concern because of the potential health impacts on site workers and local residents. A one-year monitoring was undertaken in a typical composting plant treating green wastes by windrowing in the open. Aspergillus fumigatus spores and mesophilic bacteria were used as monitoring parameters and were collected in a six-stage Andersen sampler impactor from the air at different locations and during different operational activities. Background concentrations of both microorganisms were generally below 1000 colony-forming units m^?3 when no vigorous activity was taking place. Shredding of fresh green wastes, pile turning, and screening of mature compost were identified as the activities generating the highest amounts of both bioaerosols 40 m downwind of the composting pad. These air concentrations were ～2 log units higher than background levels. Screening of mature compost generated lower amounts of A. fumigatus than the other two activities (an average of 1 log unit higher than background levels). Workers were identified as the main potential receptors of high bioaerosol concentrations in areas close to the composting pad, whereas no major risk for local residents was expected because the concentrations recorded at distances of 200 and 300 m downwind of the operational area were not significantly different from background levels.     

Linking fine-scale sub-arctic vegetation distribution in complex topography with surface-air-temperature modelled at 50-m resolution

Recent studies have shown that the complexities of the surface features in mountainous terrain require a re-assessment of climate impacts at the local level. We explored the importance of surface-air-temperature based on a recently published 50-m-gridded dataset, versus soil variables for explaining vegetation distribution in Swedish Lapland using generalised linear models (GLMs). The results demonstrated that the current distribution of the birch forest and snowbed community strongly relied on the surface-air-temperature. However, temperature alone is a poor predictor of many plant communities (wetland, meadow). Because of diminishing sample representation with increasing altitude, the snowbed community was under-sampled at higher altitudes. This results in underestimation of the current distribution of the snowbed community around the mountain summits. The analysis suggests that caution is warranted when applying GLMs at the local level.     

Conditioning of Fly Ash with Ammonia

This paper presents the results of an investigation of the conditioning of fly ash with ammonia in electrostatic pre-cipitators of power plants operated by the Tennessee Valley Authority. It focuses attention primarily on the mechanisms of conditioning encountered under the particular circumstances available for study. No effect of ammonia on the electrical resistivity of fly ash was evident. Instead, the effect of ammonia appeared to be an enhancement pf the space-charge component of the electric field used for charging and precipitating particles of fly ash. In addition, a second effect appeared to be an increase in the cohesiveness of precipitated ash and a reduction in the quantity of ash reentrained during electrode rapping. Data demonstrating the value of ammonia conditioning for lowering the emission pf fly ash during three precipitator studies are presented. Reasons for the ineffectiveness of ammonia conditioning during a fourth precipitator study are discussed. In conclusion, comments are made about the effects to be expected from ammonia conditioning under circumr stances different from those investigated experimentally, particularly with ammonia as a conditioning agent for fly ash from low sulfur western coal.     

Fabric Filtration for Fly Ash Control

Economic projections and the growing experience with more diverse baghouse applications indicate that fabric filtration will become an even more popular type of control technology. While the fabric filter market shows signs of great promise now, an especially significant upturn is predicted within the next half dozen years when dry scrubbing becomes the primary process for combined S0₂ and par-ticulate control. In the interim, with more and more utility and industrial boilers gaining experience with baghouses, this control method can be expected to develop as an even more acceptable technique, especially on low S coal burning units. Nevertheless, the users stress the need for conservative planning and designing, giving extra care to start-up and maintenance procedures.     

Estimates of 1973–1982 Annual Sulfur Oxide Emissions from Electric Utilities

Estimates of 1973–1982 annual SO₂ emissions from electric utility plants are presented in this paper. Results are based on analyses of plant level data collected by the U.S. Department of Energy on consumption and quality of fuels burned. Emissions are estimated from known information about fuel consumption, sulfur content, ash content, and control equipment. Results show that electric utility emissions decreased 16% from 1973 to 1982 and that these reductions were due to the use of lower sulfur coals and to the operation of flue gas desulfurization equipment.     

Performance Audits of EPA Protocol Gases and Inspection and Maintenance Calibration Gases

Air pollution abatement policies must be based on quantitative information on current and future emissions of pollutants. As emission projections uncertainties are inevitable and traditional statistical treatments of uncertainty are highly time/resources consuming, a simplified methodology for nonstatistical uncertainty estimation based on sensitivity analysis is presented in this work. The methodology was applied to the “with measures” scenario for Spain, concretely over the 12 highest emitting sectors regarding greenhouse gas and air pollutants emissions. Examples of methodology application for two important sectors (power plants, and agriculture and livestock) are shown and explained in depth. Uncertainty bands were obtained up to 2020 by modifying the driving factors of the 12 selected sectors and the methodology was tested against a recomputed emission trend in a low economic-growth perspective and official figures for 2010, showing a very good performance.

Implications:?A solid understanding and quantification of uncertainties related to atmospheric emission inventories and projections provide useful information for policy negotiations. However, as many of those uncertainties are irreducible, there is an interest on how they could be managed in order to derive robust policy conclusions. Taking this into account, a method developed to use sensitivity analysis as a source of information to derive nonstatistical uncertainty bands for emission projections is presented and applied to Spain. This method simplifies uncertainty assessment and allows other countries to take advantage of their sensitivity analyses.     

Remedial Options for Leaking Underground Storage Tanks

Remedial options for leaking underground storage tanks were investigated in a joint project of the Electric Power Research Institute and the Underground Storage Tank Committee of the Utility Solid Waste Activities Group. Both existing and emerging technologies were examined. Thirteen remedial techniques were identified and initially characterized as in situ or non-in situ. In situ methods include volatilization, biodegradation, leaching and chemical reaction, vitrification, passive remediation, and isolation or containment. Non-in situ techniques include land treatment, thermal treatment, asphalt incorporation, solidification and stabilization, groundwater extraction and treatment, chemical extraction, and excavation. Soil and groundwater remediation problems have many site-specific considerations which must be considered in choosing an appropriate remedial option; these include cleanup goals, site and contaminant characteristics, cost, exposure pathways, and others. Appropriate remedial techniques are chosen by assessing technical, implementational, environmental and economic considerations of each available option to achieve the desired cleanup goal at the specified site.