a critical review of the Effect of Air Pollution Control Regulations on Land use Planning

A study of the potential effectiveness of several strategies for reducing pollutant emissions from aircraft at a busy metropolitan airport has been carried out. This work is based on a model of emission-producing activities at the Hartsfield Atlanta International Airport and emissions from additional sources in the region surrounding the airport. A steady-state Gaussian plume dispersion model, developed previously,^1-4 was used to determine pollutant concentrations at selected receptor sites. The model of the Atlanta airport was assembled to evaluate the results of a field test of one of the strategies (engine shutdown during taxiing) performed there in late 1973. The results of that field test are reported elsewhere.^5,6 A full discussion of the interpretation of the comparison between modeled and monitored pollutant concentrations during the field test and the examination of alternative strategies noted, here are contained in the final report of this project.⁷     

Review of Statistics of Extreme Values with Applications to Air Quality Data Part I. Review

In the field of air pollution control, the rare event is often of more significance than the common event. This is evidenced by the content of air quality standards which define acceptable upper limits of air pollution concentrations and acceptable frequencies with which such concentrations can be exceeded. The principles of extreme value statistics provide important tools for analyzing air quality data in an appropriately significant context.

The purpose of this paper is twofold. First the principles of extreme value statistics are reviewed. The presentation is decidedly utilitarian; no attempt is made to derive more than the simplest propositions. The underlying assumptions of the theory are carefully pointed out and discussed. Particular emphasis is placed on the second largest value and its relation to the largest value. Exact probability distributions, and approximations to them, are derived in terms of the total population probability function. The more familiar and useful asymptotic distributions and their uses are presented and discussed. Part II of the paper will present applications of the theory to air quality data.     

Review of Statistics of Extreme Values with Applications to Air Quality Data

In the field of air pollution control, the rare event is often of more significance than the common event. This is evidenced by the content of air quality standards which define acceptable upper limits of air pollution concentrations and acceptable frequencies with which such concentrations can be exceeded. The principles of extreme value statistics provide important tools for analyzing air quality data in an appropriately significant context.

Part II of the paper presents applications of the theory to air quality data. First, application is made to decisions regarding the length of air monitoring experiments and the length of data records for dis-person analyses. The theory is then applied to the analysis of long term air pollution data collected by the South Coast Air Pollution Control District. The interrelations between extremes from monthly and annual samples are noted and are shown to be consistent with theory.     

Assessing and monitoring semi-arid shrublands using object-based image analysis and multiple endmember spectral mixture analysis

Arid and semi-arid shrublands have significant biological and economical values and have been experiencing dramatic changes due to human activities. In California, California sage scrub (CSS) is one of the most endangered plant communities in the US and requires close monitoring in order to conserve this important biological resource. We investigate the utility of remote-sensing approaches—object-based image analysis applied to pansharpened QuickBird imagery (QBPS/OBIA) and multiple endmember spectral mixture analysis (MESMA) applied to SPOT imagery (SPOT/MESMA)—for estimating fractional cover of true shrub, subshrub, herb, and bare ground within CSS communities of southern California. We also explore the effectiveness of life-form cover maps for assessing CSS conditions. Overall and combined shrub cover (i.e., true shrub and subshrub) were estimated more accurately using QBPS/OBIA (mean absolute error or MAE, 8.9 %) than SPOT/MESMA (MAE, 11.4 %). Life-form cover from QBPS/OBIA at a 25?×?25 m grid cell size seems most desirable for assessing CSS because of its higher accuracy and spatial detail in cover estimates and amenability to extracting other vegetation information (e.g., size, shape, and density of shrub patches). Maps derived from SPOT/MESMA at a 50?×?50 m scale are effective for retrospective analysis of life-form cover change because their comparable accuracies to QBPS/OBIA and availability of SPOT archives data dating back to the mid-1980s. The framework in this study can be applied to other physiognomically comparable shrubland communities.     

Fire resistance of passive fire protection coatings after long-term weathering

Passive fire protection (PFP) systems are widely used by the oil, gas and chemical industries to protect offshore and onshore facilities against the effects of fire. However, there are concerns that the performance of PFP systems in a fire may have deteriorated because of weathering and/or that corrosion of the protected item may be taking place beneath the PFP systems. In May 1987, Shell UK began a long-term PFP weathering programme at a maritime test site using furnace tests to assess the fire performance of the materials. The programme was handed over to the Health and Safety Executive in October 1999 and was continued and extended to include the more severe jet fire testing of weathered specimens. This paper describes the effects of weathering on six epoxy intumescent PFP products and one cementitious PFP product in common use. The results are discussed in relation to alterations in physical form, corrosion of the substrate and changes in fire resistance.     

Abatement of Ammonia and Hydrogen Sulfide Emissions from a Swine Lagoon Using a Polymer Biocover

ABSTRACT

The purpose of this research was to determine the efficiency of a polymer biocover for the abatement of H₂S and NH₃ emissions from an east-central Missouri swine lagoon with a total surface area of 7800 m². The flux rate of NH₃, H₂S, and CH₄ was monitored continuously from two adjacent, circular (d = 66 m) control and treatment plots using a nonintrusive, micrometeorological method during three independent sampling periods that ranged between 52 and 149 hr. Abatement rates were observed to undergo a temporal acclimation event in which NH₃ abatement efficiency improved from 17 to 54% (p = <0.0001 to 0.0005) and H₂S abatement efficiency improved from 23 to 58% (p < 0.0001) over a 3-month period. The increase in abatement efficiency for NH₃ and H₂S over the sampling period was correlated with the development of a stable anaerobic floc layer on the bottom surface of the biocover that reduced mass transfer of NH₃ and H₂S across the surface. Analysis of methanogenesis activity showed that the biocover enhanced the rate of anaerobic digestion by 25% when compared with the control. The biocover-enhanced anaerobic digestion process was shown to represent an effective mechanism to counteract the accumulation of methanogenic substrates in the biocovered lagoon.     

Wintertime Vertical Variations in Particulate Matter (PM) and Precursor Concentrations in the San Joaquin Valley during the California Regional Coarse PM/Fine PM Air Quality Study

Abstract

Air quality monitoring was conducted at a rural site with a tower in the middle of California’s San Joaquin Valley (SJV) and at elevated sites in the foothills and mountains surrounding the SJV for the California Regional PM₁₀/M_2.5 Air Quality Study. Measurements at the surface and on a tower at 90 m were collected in Angiola, CA, from ecember 2000 through February 2001 and included hourly black carbon (BC), particle counts from optical particle counters, nitric oxide, ozone, temperature, relative humidity, wind speed, and direction. Boundary site measurements were made primarily using 24-hr integrated particulate matter (PM) samples. These measurements were used to understand the vertical variations of PM and PM precursors, the effect of stratification in the winter on concentrations and chemistry aloft and at the surface, and the impact of aloft-versus-surface transport on PM concentrations. Vertical variations of concentrations differed among individual species. The stratification may be important to atmospheric chemistry processes, particularly nighttime nitrate formation aloft, because NO₂ appeared to be oxidized by ozone in the stratified aloft layer. Additionally, increases in accumulation-mode particle concentrations in the aloft layer during a fine PM (PM_2.5) episode corresponded with increases in aloft nitrate, demonstrating the likelihood of an aloft nighttime nitrate formation mechanism. Evidence of local transport at the surface and regional transport aloft was found; transport processes also varied among the species. The distribution of BC appeared to be regional, and BC was often uniformly mixed vertically. Overall, the combination of time-resolved tower and surface measurements provided important insight into PM stratification, formation, and transport.     

COMPLEX I and II Model Performance Evaluation in Nevada and New Mexico

The COMPLEX I and COMPLEX II Gaussian dispersion models for complex terrain applications have been made available by EPA. Various terrain treatment options under IOPT(25) can be selected for a particular application, one of which [IOPT(25) = 1] is an algorithm similar to that of the VALLEY model. A model performance evaluation exercise involving three of the available options with both COMPLEX models was carried out using SF⁶ tracer measurements taken during worst-case stable impaction conditions in complex terrain at the Harry Allen Plant site in southern Nevada. The models did not reproduce observed concentrations on an event by event basis, as correlation coefficients for 1-h concentrations of 0-0.3 were exhibited. When observed and calculated cumulative frequency distributions for 1-h and 3-h concentrations were compared, a close correspondence between observations and concentrations calculated with COMPLEX I, IOPT(25) = 2 or 3 was noted; both options consistently overestimated observed concentrations. With IOPT(25) = 1, upper percentile (maximum) values in the calculated frequency distribution exceeded the corresponding IOPT(25) = 2 or 3 value by roughly a factor of 2, and observed values by 2.5-5. COMPLEX II typically produced maximum values 2-4 times as great as COMPLEX I for the same terrain treatment option. From these results it is concluded that: 1) the physically unrealistic sector-spread approach used in VALLEY and COMPLEX I under stable impaction conditions is a surrogate for wind direction variation, and 2) the doubling of the plume centerline concentration due to ground reflection under terrain impingement conditions that is included in IOPT(25) = 1 is inappropriate.

These findings were found to be consistent with an analysis of noncurrent observed and calculated SO₂ χ/Q frequency distributions for 1, 3, and 24 hours near the Four Corners Plant in New Mexico. The comparison involved a four-year calculated χ/Q data set and a two-year observed χ/Q data set at the worst-case high terrain impact location near the plant.     

Transport and dispersion during wintertime particulate matter episodes in the San Joaquin Valley, California

Data analysis and modeling were performed to characterize the spatial and temporal variability of wintertime transport and dispersion processes and the impact of these processes on particulate matter (PM) concentrations in the California San Joaquin Valley (SJV). Radar wind profiler (RWP) and radio acoustic sounding system (RASS) data collected from 18 sites throughout Central California were used to estimate hourly mixing heights for a 3-month period and to create case studies of high-resolution diagnostic wind fields, which were used for trajectory and dispersion analyses. Data analyses show that PM episodes were characterized by an upper-level ridge of high pressure that generally produced light winds through the entire depth of the atmospheric boundary layer and low mixing heights compared with nonepisode days. Peak daytime mixing heights during episodes were -400 m above ground level (agl) compared with -800 m agl during nonepisodes. These episode/nonepisode differences were observed throughout the SJV. Dispersion modeling indicates that the range of influence of primary PM emitted in major population centers within the SJV ranged from -15 to 50 km. Trajectory analyses revealed that little intrabasin pollutant transport occurred among major population centers in the SJV; however, interbasin transport from the northern SJV and Sacramento regions into the San Francisco Bay Area (SFBA) was often observed. In addition, this analysis demonstrates the usefulness of integrating RWP/RASS measurements into data analyses and modeling to improve the understanding of meteorological processes that impact pollution, such as aloft transport and boundary layer evolution.     

Development and Integration of Quantitative Real-Time PCR Methods for Detection of Mitochondrial DNA and Methanobrevibacter smithii nifH Gene as Novel Microbial Source Tracking Tools

A novel microbial source tracking (MST) method based on the detection of human and non-human markers was developed and applied to track the origin of fecal pollution in water systems. Mitochondrial DNA sequences were used to develop new quantitative real-time polymerase chain reaction (qPCR) assays for dog, poultry, and gull. The targets were included as part of a toolbox including human, cow, pig, and sheep assays. A primer and probe set for the detection of the human-specific nifH gene of Methanobrevibacter smithii was also designed as an indicator of human fecal contamination. The assays were tested for specificity and applied to fecal-spiked surface waters and environmental samples collected from two river catchments impacted by sources of human and non-human fecal contamination. The MST methods described were applicable to both spiked waters and environmental samples, and using the two approaches the origin of fecal pollution could be successfully determined in mixed source fecally polluted waters.