Urban forest strategies of gradually replacing high emitters of biogenic volatile organic compounds (BVOC) with low-emitting species are being considered as voluntary or emerging control measures for maintenance of the 8-h ozone standard in the Sacramento Federal Non-Attainment Area (SFNA). We describe a regulatory modeling study demonstrating the air-quality impacts of such measures as well as of strategies that increase net canopy cover.The results indicate that changing the mix of urban trees can improve air quality. The daily reductions in ozone resulting from species replacement alone reach up to 0.50 ppb. With a more geographically targeted replacement, the daily reductions increase to 3 ppb. Population-weighted exposure to ozone is reduced by up to 34% relative to the NAAQS (120 ppb) and 12% relative to the CAAQS (90 ppb). The 8-h average peak ozone is reduced by 2%. If, in addition to species replacement, the net canopy cover is increased, the reductions in ozone become much larger but increases in ozone also occur. In some scenarios, the air-quality impacts are 10 times as large as those of only replacing 650,000 trees (control measure). Furthermore, because of the canopy growth (including the replacement trees) relative to 2000-2005, the SFNA is cooled by up to 1.2 degrees C by 2018 and 1.6 degrees C by 2023. (C) 2015 Elsevier Ltd. All rights reserved.

A direct sensitivity analysis technique (DDM-3D) has been integrated into the URM-1 ATM three-dimensional air quality model to efficiently provide an indication of which emission source types from various source areas have the greatest potential to impact pollutant levels. In this study, nine episodes were modeled to represent annual aerosol and wet deposition levels. Direct sensitivity analysis was then used to quantify the source/receptor relationship between emissions from thirteen geographic regions and pollutant levels in the Southern Appalachian Mountains (SAM). In particular, the impact of SO2 emission reductions on aerosol and wet deposition levels at ten Class I areas are discussed. SO2 emission reductions from different geographic regions displayed very different levels of impact on various sites within the SAM region. In general, the receptor sites showed the greatest response to emission reductions in the nearest states and regional sub-domains. Sites in Alabama and Georgia show the greatest response to reductions in emissions from Alabama and Georgia, respectively. The sites in North Carolina and Tennessee show the greatest response to emission reductions in Tennessee. And, the sites in Virginia and West Virginia show the greatest response to emission reductions in Virginia, West Virginia, and the Midwest sub-domain.

While the U.S. air quality management system is largely designed and managed on a state level, many critical air quality problems are now recognized as regional. In particular, concentrations of two secondary pollutants, ozone and particulate matter, are often above regulated levels and can be dependent on emissions from upwind states. Here, impacts of statewide emissions on concentrations of local and downwind states' ozone and fine particulate matter are simulated for three seasonal periods in the eastern United States using a regional Eulerian photochemical model. Impacts of ground level NOx (e.g., mobile and area sources), elevated NOx (e.g., power plants and large industrial sources), and SO2 emissions are examined. An average of 77% of each state's ozone and PM2.5 concentrations that are sensitive to the emissions evaluated here are found to be caused by emissions from other states. Delaware, Maryland, New Jersey, Virginia, Kentucky, and West Virginia are shown to have high concentrations of ozone and PM2.5 caused by interstate emissions. When weighted by population, New york receives increased interstate contributions to these pollutants and contributions to ozone from local emissions are generally higher. When accounting for emission rates, combined states from the western side of the modeling domain and individual states such as Illinois, Tennessee, Indiana, Kentucky, and Georgia are major contributors to interstate ozone. Ohio, Indiana, Tennessee, Kentucky, and Illinois are the major contributors to interstate PM2.5. When accounting for an equivalent mass of emissions, Tennessee, Kentucky, West Virginia, Virginia, and Alabama contribute large fractions of these pollutants to other states.

A “One-Atmosphere” modeling approach has been taken to help assess the impact of control strategies on air quality in the Southern Appalachians. The modeling system, consisting of RAMS, EMS-95 and URM, simulates gaseous and condensed phase pollutants, and uses a sectional approach to provide size distributions of the aerosol. It is also used to simulate dry and wet deposition. In this paper, the model’s results were compared against a suite of observations for ozone and PM concentrations, as well as wet deposition, for four episodes.Two of those episodes were relatively wet, and two drier. While the results tended to be good for both sets of episodes,there was a tendency to overestimate ozone and underestimate aerosols during the wet episodes.

BEIS3 was developed by the U.S. EPA to estimate emissions of biogenic substances such as isoprene, monoterpenes, oxygenated volatile organic compounds (OVOCs), and biogenic nitric oxide (BNO). These emissions are used as inputs to chemical transport models (CTMs) to calculate concentrations of ozone and other air pollutants. The current study addresses the uncertainties in biogenic emissions and the subsequent uncertainties in CTM predictions due to uncertainties in BEIS3 inputs and parameters. The primary focus of the study was on use of Monte Carlo probabilistic methods. However, because of the relative simplicity of the emissions equations, it was decided to also apply a standard analytical approach, as described in the current paper. In the analytical method, the partial derivative of the emissions equation is taken. Then both sides of the equation are squared and normalized, yielding an analytical expression for the relative uncertainty or variance in a given emission component, expressed as a function of the relative variance of the inputs and parameters. The relative uncertainties or variances in inputs and parameters had been estimated earlier by a combination of analysis of data and expert elicitation. To simplify the equations, it is assumed that there is no correlation between any of the inputs and/or parameters. The results of the analytical equations for relative uncertainties agreed approximately with the results of the full Monte Carlo method. For example, the total relative variance in isoprene emissions varied from 0.10 to 0.40, depend ing on TA. Total OVOC and monoterpene relative variances were similar, with values ranging from 0.10 to 0.26. Total BNO relative variances ranged from 0.22 to 0.71. By taking the square root of these relative variances, we obtain estimates of relative uncertainty in BEIS3 emissions in the range from about 0.3 to 0.8 (i.e., ± 30 to 80 %). It is suggested by the analytical equations that the relative uncertainties in emissions depend on the air temperature, TA, in the sense that one model input would contribute most of the variance at TA of 10 C and another input would contribute most at 30 C.

Observations indicate that ozone (O3) concentrations in surface air over the United States in summer contain a 20–45 ppbv background contribution, presumably reflecting transport from outside the North American boundary layer. We use a three‐dimensional global model of tropospheric chemistry driven by assimilated meteorological observations to investigate the origin of this background and to quantify its contribution to total surface O3on both average and highly polluted summer days. The model simulation is evaluated with a suite of surface and aircraft observations over the United States from the summer of 1995. The model reproduces the principal features in the observed distributions of O3and its precursors, including frequency distributions of O3concentrations and the development of regional high‐O3episodes in the eastern United States. Comparison of simulations with 1995 versus 1980 global fossil fuel emissions indicates that the model captures the previously observed decrease in the high end of the O3probability distribution in surface air over the United States (reflecting reduction of domestic hydrocarbon emissions) and the increase in the low end (reflecting, at least in the model, rising Asian emissions). In the model, background O3produced outside of the North American boundary layer contributes an average 25–35 ppbv to afternoon O3concentrations in surface air in the western United States. and 15–30 ppbv in the eastern United States during the summer of 1995. This background generally decays to below 15 ppbv during the stagnation conditions conducive to exceedances of the 8‐hour 0.08 ppmv (80 ppbv) National Ambient Air Quality Standard (NAAQS) for O3. A high background contribution of 25–40 ppbv is found during 9% of these exceedances, reflecting convective mixing of free tropospheric O3from aloft, followed by rapid production within the U.S. boundary layer. Anthropogenic emissions in Asia and Europe are found to increase afternoon O3concentrations in surface air over the United States by typically 4–7 ppbv, under both average and highly polluted conditions. This enhancement is particularly large (up to 14 ppbv) for O3concentrations in the 50–70 ppbv range, and would represent a major concern if the NAAQS were to be tightened.

A comprehensive three-dimensional Eulerian photochemical model (URM-1ATM) was developed that simulates urban and regional gas and size-resolved aerosol concentrations of pollutants in the atmosphere and both wet and dry deposition. In this study, RAMS and EMS-95 are used to generate meteorological and emission input files, respectively. The modeling system is then applied to simulate the evolution, transport, and removal of atmospheric pollutants over the Eastern US for the 11–19 July 1995 episode. Performance statistics are calculated for ozone, speciated fine particles, and acid deposition mass fluxes.

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AbstractDie ES R‐Spektren einer Reihe von Alkaliund Erdalkalimetallsalzen der Titelanionen nach Bestrahlung mit "Coxy‐Strahlen bei 77 K werden diskutiert.

Chemischer InformationsdienstVolume 6, Issue 24 Physical Inorganic Chemistry ChemInform Abstract: UNSTABLE INTERMEDIATES PART 152, RADICALS IN THALLOUS NITRATE MARTYN C. R. SYMONS, MARTYN C. R. SYMONSSearch for more papers by this authorDOUGLAS X. WEST, DOUGLAS X. WESTSearch for more papers by this authorJAMES G. WILKINSON, JAMES G. WILKINSONSearch for more papers by this author MARTYN C. R. SYMONS, MARTYN C. R. SYMONSSearch for more papers by this authorDOUGLAS X. WEST, DOUGLAS X. WESTSearch for more papers by this authorJAMES G. WILKINSON, JAMES G. WILKINSONSearch for more papers by this author First published: June 17, 1975 https://doi.org/10.1002/chin.197524050Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume6, Issue24June 17, 1975 RelatedInformation

AbstractAlle drei im Titel genannten Radikale haben ESR‐Spektren mit Satellitenlinien, . die 207Pb‐Hyperfeinkomponenten zuzuordnen sind.

Exposure of the alkali metal hexanitrocobaltate (III) salts to 60 Co γ-rays gave nitrogen dioxide as the major electron loss center together with two centers both considered to be formed by electron capture. One, identified as Co(NO2)3−5, showed strong hyperfine coupling to one 14N nucleus and normal e.s.r. parameters for 59 Co with an unpaired electron in the 3dz2 orbital. At 77K the other center had an e.s.r. spectrum comprised of a set of nearly isotropic features centered at g = 2.090 and separated by 11G; these are thought to arise from hyperfine coupling to six equivalent 14N nuclei. On cooling to 4.2K a broad, unresolved asymmetric bands was recorded with g = 2.133 and g∥ =2.000. We conclude that this center is Co(NO)4−6 undergoing a dynamic Jahn-Teller distortion at 77K which is largely quenched at 4.2K. This requires the coincidence that Aav(59Co) ≈ 0. The latter center was also formed by partial reduction of Na[Co(NO2)6] with sodium borohydride.