Stricter Ozone Ambient Air Quality Standard Has Beneficial Effect on Ponderosa Pine in California

Ambient air quality standards and control strategies are implemented to protect humans and vegetation from adverse effects. We used a process-based tree-growth model (TREGRO) to show that over the past 37 years, changes in O₃ exposure, with accompanying variation in climate, are reflected in changes in the growth of Pinus ponderosa Dougl. ex Laws. in the San Bernardino Mountains near Los Angeles, California, USA. Despite variation in temperature and precipitation over the study period (1963–1999), O₃ exposure consistently reduced simulated tree growth. Simulated growth reductions increased concurrent with increasing O₃ exposure. The maximum growth reduction occurred in 1979. As O₃ exposures decreased during the 1980s and 1990s, effects on growth also decreased. This implies that emission control strategies taken to reduce exposures to attain O₃ standards benefited P. ponderosa growth in the San Bernardino Mountains. This modeling approach provides a powerful tool for solving the difficult problem of evaluating regulatory effectiveness by simulating plant response using long-term climate and air pollution exposure records for a given region.Phone 541 754-4621 Fax 541 754-4799     

Determination of volatile organic compound emissions and ozone formation from spraying solvent-based pesticides

Large-scale agricultural activities have come under scrutiny for possible contributions to the emission of ozone precursors. The San Joaquin Valley (SJV) of California is an area with intense agricultural activity that exceeds the federal ozone standards for more than 30 to 40 d yr(-1) and the more stringent state standards for more than 100 d yr(-1). Pesticides are used widely in both agricultural and residential subregions of the SJV, but the largest use, by weight of "active ingredient," is in agriculture. The objective of the study was to determine the role of pesticide application on airborne volatile organic compounds (VOC) concentrations and ozone formation in the SJV. The ozone formation from the pesticide formulation sprayed on commercial orchards was studied using two transportable smog chambers at four application sites during the summers of 2007 and 2008. In addition to the direct measurements of ozone formation, airborne VOC concentrations were measured before and after pesticide spraying using canister and sorbent tube sampling techniques. Soil VOC concentrations were also measured to understand the distribution of VOCs between different environmental compartments. Numerous VOCs were detected in the air and soil samples throughout the experiment but higher molecular weight aromatic hydrocarbons were the primary compounds observed in elevated concentrations immediately after pesticide spraying. Measurements indicate that the ozone concentration formed by VOC downwind of the orchard may increase up to 15 ppb after pesticide application, with a return back to prespray levels after 1 to 2 d.     

Estimation of biogenic emissions with satellite-derived land use and land cover data for air quality modeling of Houston-Galveston ozone nonattainment area

The Houston-Galveston Area (HGA) is one of the most severe ozone non-attainment regions in the US. To study the effectiveness of controlling anthropogenic emissions to mitigate regional ozone nonattainment problems, it is necessary to utilize adequate datasets describing the environmental conditions that influence the photochemical reactivity of the ambient atmosphere. Compared to the anthropogenic emissions from point and mobile sources, there are large uncertainties in the locations and amounts of biogenic emissions. For regional air quality modeling applications, biogenic emissions are not directly measured but are usually estimated with meteorological data such as photo-synthetically active solar radiation, surface temperature, land type, and vegetation database. In this paper, we characterize these meteorological input parameters and two different land use land cover datasets available for HGA: the conventional biogenic vegetation/land use data and satellite-derived high-resolution land cover data. We describe the procedures used for the estimation of biogenic emissions with the satellite derived land cover data and leaf mass density information. Air quality model simulations were performed using both the original and the new biogenic emissions estimates. The results showed that there were considerable uncertainties in biogenic emissions inputs. Subsequently, ozone predictions were affected up to 10 ppb, but the magnitudes and locations of peak ozone varied each day depending on the upwind or downwind positions of the biogenic emission sources relative to the anthropogenic NOx and VOC sources. Although the assessment had limitations such as heterogeneity in the spatial resolutions, the study highlighted the significance of biogenic emissions uncertainty on air quality predictions. However, the study did not allow extrapolation of the directional changes in air quality corresponding to the changes in LULC because the two datasets were based on vastly different LULC category definitions and uncertainties in the vegetation distributions.     

应对气候变化问题的法律调整机制

气候变化的不确定性决定对于其带来的不良环境影响也不能做出确切的预测。《联合国气候变化框架公约》、《京都议定书》及《关于消耗臭氧层物质的蒙特利尔议定书》的缔结和生效为各国一致行动提供了国际法上的依据。应当加强气候变化的科学研究，制定实施有效的政策法律措施，同时施加我国的大国影响，推动气候变化问题的国际解决进程。     

Urban sprawl and air quality in large US cities

This study presents the results of a paper of urban spatial structure and exceedances of the 8-h national ambient air quality standard for ozone in 45 large US metropolitan regions. Through the integration of a published index of sprawl with metropolitan level data on annual ozone exceedances, precursor emissions, and regional climate over a 13-year period, the association between the extent of urban decentralization and the average number of ozone exceedances per year, while controlling for precursor emissions and temperature, is measured. The results of this analysis support the hypothesis that large metropolitan regions ranking highly on a quantitative index of sprawl experience a greater number of ozone exceedances than more spatially compact metropolitan regions. Importantly, this relationship was found to hold when controlling for population size, average ozone season temperatures, and regional emissions of nitrogen oxides and volatile organic compounds, suggesting that urban spatial structure may have effects on ozone formation that are independent of its effects on precursor emissions from transportation, industry, and power generation facilities.     

Assessment and management of air quality for an opencast coal mining area

A study for the assessment and management of the air quality was carried out at Lakhanpur area of Ib Valley Coalfield in Orissa state in India. The 24-h average concentrations of total suspended particulate (TSP) matter, respirable particulate matter (PM10), sulphur dioxide (SO2) and oxides of nitrogen (NOx) were monitored during 1 year period. Samplings were done at a regular interval through out the year at 13 monitoring stations in the residential areas and four monitoring stations in the mining/industrial areas. The 24-hr average TSP and PM10 concentrations ranged from 338.8 to 799.8 microg m(-3) and 102.5-425.6 microg m(-3) for industrial area, and 72.3-497.1 microg m(-3) and 40.8-171.9 microg m(-3) for residential area, respectively. During the study period 24-hr and annual average TSP and PM10 concentrations exceeded the respective standards set in the national ambient air quality standard (NAAQS) protocol at most residential and industrial areas. However, 24-hr and annual average concentrations of SO2 and NOx were well within the prescribed limit of NAAQS both in the residential and industrial areas. The annual and 24-hr average concentrations varied from 23.3 to 36.8 microg m(-3) and 16.0-55.2 microg m(-3) for SO2 and 23.9-41.9 microg m(-3) and 19.0-58.1 microg m(-3) for NOx, respectively. The temporal variations of TSP and PM10 fitted polynomial trend with an average correlation coefficient (R2) of 0.77 (+/-0.17) for TSP and 0.85 (+/-0.10) for PM10. On average the PM10 in the ambient air of the mining area constituted 31.94 (+/-1.76)% of the TSP. The linear regression correlation coefficient (R2) between TSP with PM10 and NOx with SO2 was 0.86 (+/-0.12) and 0.57 (+/-0.20), respectively. Maximal concentrations of TSP and PM10 occurred within the mining site based on the kriging technique. A management strategy is formulated for effective control of air pollution at source and other mitigative measures recommended including implementation of green belts around the sensitive areas where the concentration of air pollutants exceeded the standard limit.     

Use of SOFEA to predict 1,3-D concentrations in air in high-use regions of California

Methyl bromide, a commonly used soil fumigant, is being phased out per the Montreal Protocol and multiple fumigants are being positioned as replacements. Most effective soil fumigants, including methyl bromide, have the potential for inhalation exposure if the material volatilizes from soil. Chronic exposures for the fumigant 1,3-dichloropropene (1,3-D) are managed in part by the California Department of Pesticide Regulation by limiting the annual amount that can be used within a given township. A stochastic/deterministic numerical system (SOil Fumigant Exposure Assessment system [SOFEA]) was developed using the USEPA air dispersion model ISCST3, field study observations for flux loss, and links to Geographic Information Systems (GIS). SOFEA was used retrospectively to simulate concentrations of 1,3-D in air for direct comparison with monitoring program observations conducted by California Air Resources Board in Fresno County. These results indicated slight overprediction but correct magnitudes for regional air concentrations, especially at the higher percentiles, and provide a performance test. SOFEA was also used, prospectively, to predict air concentrations in potential future-use scenarios. These simulations of chronic air concentrations in two high-use 1,3-D counties of California (Ventura, Merced) consisted of 25 contiguous townships treated either at 1.5 times the current township allocation (40,937 kg) or at the maximum levels of 1,3-D used between 1999 and 2006. Exposure predictions for large regions are necessary to evaluate chronic population-based lifetime exposure and risk to 1,3-D should use patterns change. SOFEA provides a tool to estimate regional air concentrations within high-use areas required for such risk assessments.     

The cost of crop damage caused by ozone air pollution from motor vehicles

The effects of ozone air pollution on the agricultural sector are an important environmental challenge facing policy makers. Most studies of the economic impact of air pollution on agriculture have found that a 25% reduction in ambient ozone would provide benefits of at least $1–2 billion annually in the United States. This paper extends existing research by estimating the benefits of a reduction in emissions from a major source of ozone formation: motor-vehicle emissions. An agricultural production model is combined with an analysis of motor-vehicle emissions and air quality to estimate the impacts of emissions from six different motor-vehicle classes, at both the regional and national level. The benefits to the agricultural sector from completely eliminating ozone precursor emissions from motor vehicles ranges between $3·5 and $6·1 billion annually.     

Using a choice experiment to measure the environmental costs of air pollution impacts in Seoul

Air pollution, a by-product of economic growth, has been incurring extensive environmental costs in Seoul, Korea. Unfortunately, air pollution impacts are not treated as a commercial item, and thus it is difficult to measure the environmental costs arising from air pollution. There is an imminent need to find a way to measure air pollution impacts so that appropriate actions can be taken to control air pollution. Therefore, this study attempts to apply a choice experiment to quantifying the environmental costs of four air pollution impacts (mortality, morbidity, soiling damage, and poor visibility), using a specific case study of Seoul. We consider the trade-offs between price and attributes of air pollution impacts for selecting a preferred alternative and derive the marginal willingness to pay (WTP) estimate for each attribute. According to the results, the households' monthly WTP for a 10% reduction in the concentrations of major pollutants in Seoul was found to be approximately 5494 Korean won (USD 4.6) and the total annual WTP for the entire population of Seoul was about 203.4 billion Korean won (USD 169.5 million). This study is expected to provide policy-makers with useful information for evaluating and planning environmental policies relating specifically to air pollution.     

Control Strategy Optimization for Attainment and Exposure Mitigation: Case Study for Ozone in Macon, Georgia

Implementation of more stringent 8-hour ozone standards has led the U.S. Environmental Protection Agency to designate nonattainment status to 474 counties nationwide, many of which had never previously violated air quality standards. As states select emission control measures to achieve attainment in these regions, their choices pose significant implications to local economies and the health of their citizens. Considering a case study of one such nonattainment region, Macon, Georgia, we develop a menu of potential controls that could be implemented locally or in neighboring parts of the state. The control menu offers the potential to control about 20–35% of ozone precursor emissions in most Georgia regions, but marginal costs increase rapidly beyond 15–20%. We link high-order ozone sensitivities with the control menu to identify cost-optimized strategies for achieving attainment and for alternative goals such as reducing spatially averaged or population-weighted ozone concentrations. Strategies targeted toward attainment of Macon ozone would prioritize local reductions of nitrogen oxides, whereas controls in the more densely populated Atlanta region are shown to be more effective for reducing statewide potential population exposure to ozone. A U.S. EPA-sanctioned approach for demonstrating ozone attainment with photochemical models is shown to be highly dependent on the choice of a baseline period and may not foster optimal strategies for assuring attainment and protecting human health.     

ENVIRONMENTAL AUDITING: An Approach for Characterizing Tropospheric Ozone Risk to Forests

/ The risk tropospheric ozone poses to forests in the United States is dependent on the variation in ozone exposure across the distribution of the forests in question and the various environmental and climate factors predominant in the region. All these factors have a spatial nature, and consequently an approach to characterization of ozone risk is presented that places ozone exposure-response functions for species as seedlings and model-simulated tree and stand responses in a spatial context using a geographical information systems (GIS). The GIS is used to aggregate factors considered important in a risk characterization, including: (1) estimated ozone exposures over forested regions, (2) measures of ozone effects on species' and stand growth, and (3) spatially distributed environmental, genetic, and exposure influences on species' response to ozone. The GIS-based risk characterization provides an estimation of the extent and magnitude of the potential ozone impact on forests. A preliminary risk characterization demonstrating this approach considered only the eastern United States and only the limited empirical data quantifying the effect of ozone exposures on forest tree species as seedlings. The area-weighted response of the annual seedling biomass loss formed the basis for a sensitivity ranking: sensitive-aspen and black cherry (14%-33% biomass loss over 50% of their distribution); moderately sensitive-tulip popular, loblolly pine, eastern white pine, and sugar maple (5%-13% biomass loss); insensitive-Virginia pine and red maple (0%-1% loss). In the future, the GIS-based risk characterization will include process-based model simulations of the three- to 5-year growth response of individual species as large trees with relevant environmental interactions and model simulated response of mixed stands. The interactive nature of GIS provides a tool to explore consequences of the range of climate conditions across a species' distribution, forest management practices, changing ozone precursors, regulatory control strategies, and other factors influencing the spatial distribution of ozone over time as more information becomes available.KEY WORDS: Ecological risk assessment; GIS; Ozone; Risk characterization; Forests; Trees     

Air quality impact of carbon monoxide emission from diesel engine electric power generators

An emissions inventory and the AERMOD View dispersion model were used to estimate the concentrations and the potential effects of carbon monoxide (CO) from diesel engine electric power generators operated by and providing electricity to a textile factory in Nigeria on its host air shed. The CO emissions from simultaneous operations of all of the electric power generators in the factory resulted in: 1‐hr average CO emissions of 4.2 to 54.5 micrograms per cubic meters (μg/m³) and 24‐hr average CO emissions of 0.3 to 20.9 μg/m³. The estimated 1‐hr averaging period maximum ground‐level concentrations of CO were deposited within the factory, while the 24‐hr maximum ground‐level concentrations are estimated at a distance 90 meters (m) from the factory in a southeast direction. The ground‐level concentrations of CO emanating from the textile factory are within the stipulated ambient air quality standards.     

Assessing local climate action plans for public health co-benefits in environmental justice communities

Climate change presents a complex environmental health and justice challenge for the field of urban planning. To date, the majority of research focuses on measuring local climate efforts and evaluating the general efficacy of adopted climate action plans (CAPs). Cumulatively, these studies argue that socio-economic and demographic variables (such as the fiscal health of cities, city size, and median household income) are important factors in implementing climate policies. Less studied are issues of environmental justice and the impacts of climate change on population health. Through interviews with urban planners and a document analysis of CAPs, this study assesses how California cities with high levels of pollution and social vulnerability address climate change and public health. The findings of this study show that CAPs in these cities rarely analyse whether greenhouse gas reduction strategies will also yield health co-benefits, such as a reduction in the co-pollutants of climate change (i.e. ozone, particulate matter, and nitrogen oxides). In many instances, the net co-benefits of health are not monetised, quantified, or even identified by local governments. In California's most impacted cities, climate planning activities and work on public health are happening in a parallel manner rather than through an integrated approach. The results suggest a need for increased opportunities for interagency coordination and staff training to conduct health analyses, free and easily accessible tools, methods for prioritising funding streams, and the development of partnerships with community-based organisations for linking climate planning with public health.     

Surface ozone and carbon monoxide levels observed at Oki, Japan: regional air pollution trends in East Asia

Simultaneous ground-based measurements of ozone and carbon monoxide were performed at Oki, Japan, from January 2001 to September 2002 in order to investigate the O(3) and CO characteristics and their distributions. The observations revealed that O(3) and CO concentrations were maximum in springtime and minimum in the summer. The monthly averaged concentrations of O(3) and CO were 60 and 234 ppb in spring and 23 and 106 ppb in summer, respectively. Based on direction, 5-day isentropic backward trajectory analysis was carried out to determine the transport path of air masses, preceding their arrival at Oki. Comparison between classified results from present work and results from the year 1994-1996 was carried out. The O(3) and CO concentration results of classified air masses in our analysis show similar concentration trends to previous findings; highest in the WNW/W, lowest in N/NE and medium levels in NW. Moreover, O(3) levels are higher and CO levels are lower in the present study in all categories.     

Sensitivity analysis of ground-level ozone concentration to emission changes in two urban regions of southeast Texas

Air pollutant emission is one of the predominant factors affecting urban air quality such as ground-level ozone formation. This paper assesses the impact of changing emission inventory scenarios, based on combinations of point, mobile, area/non-road and biogenic sources, on the tropospheric ozone concentration in two southeast Texas urban areas, i.e. Houston-Galveston and Beaumont-Port Arthur, during the rapid ozone formation event (ROFE) on August 25, 2000. The EPA's Community Multiscale Air Quality (CMAQ) modeling system with 1999 national emission inventory (NEI99) estimates and updated SAPRC99 chemical mechanism are used in the sensitivity analysis for twelve different emission scenarios. Based on model results, it is found that the point source emission of NOx and VOC contributes the greatest ozone peak in the ROFE. Removing Texas point sources of VOC and NOx emission from the inventory results in a reduction in peak O3 concentration by 128 and 70 ppbv in Houston urban area, respectively. Similar but less drastic impact from point source is also observed in the Beaumont-Port Arthur area. The effect on peak ozone concentration due to mobile, area and non-road sources emissions are less significant compared to that of point source emission. Reducing VOC emission appears to be more effective than reducing NOx emission in lowering peak O3 concentration in the studied region. Although biogenic emission can contribute up to 37 ppbv of peak ozone level over a large area, the affected area is away from the urban region of concern, and should not be the main cause for O3 non-attainment in the two urban areas. Removing CO emission from mobile sources does not lead to significant reduction (< 1 ppbv) in ozone concentrations. The modeled data also show that the transport of O3 precursors from adjacent states can cause a significant ozone plume near Beaumont due to its proximity to the state border based on the conditions during the August 25, 2000 O3 episode.     

Soils and vegetation of Santa Barbara Island,Channel Islands National Park,California, USA

The multifaceted development of an erosion surface on Santa Barbara Island, Channel Islands National Park, California, has led to this study of the relationship between soils and vegetation. A dry Mediterranean climate and past attempts at farming and introductions of alien species have led to vegetative degradation accompanied by both gully and surface erosion. Soil and vegetation analyses show this erosion to be in a location of transition. The soils are Typic Chromoxererts (Vertisol Order) with high clay, salinity, and sodium contents. The vegetation is ecotonal in nature, grading from a principally alien annual grassland withAvena fatua andAtriplex semibaccata to a shrub community dominated by the nativeSuaeda californica. Management toward revegetation and stabilization of this island ecosystem will be difficult with high clay, saline-sodic soils and disturbed vegetation.     

Development of drinking water standards for perchlorate in the United States

Perchlorate, an anion that originates as a contaminant in ground and surface waters, is both naturally occurring and manmade. Because of its toxicity, there has been increased interest in setting drinking water safety standards and in health effects when perchlorate is present at low (parts per billion (ppb)) levels. In January 2009, the EPA issued a heath advisory to assist state and local officials in addressing local contamination of perchlorate in drinking water. The interim health advisory level of 15 micrograms per liter (μg/L), or ppb, is based on the reference dose recommended by the National Research Council (NRC) of the National Academy of Sciences (NAS). This paper describes scope and extent of contaminant issues and a legal process of setting standards for perchlorate concentration in drinking water in the United States of America.     

Growth and yield responses of potato to mixtures of carbon dioxide and ozone

Elevated carbon dioxide (CO2) concentrations in the atmosphere can stimulate plant growth and yield, whereas ground-level ozone (O3) concentrations cause the opposite effect in many areas of the world. Recent experiments show that elevated CO2 can protect some plants from O3 stress, but this has not been tested for most crop species. Our objective was to determine if elevated CO2 protects Irish potato (Solanum tuberosum L.) from foliar injury and suppression of growth and yield caused by O3. An O3-resistant cultivar (Superior) and an O3-sensitive cultivar (Dark Red Norland) were exposed from within 10 d after emergence to maturity to mixtures of three CO2 and three O3 treatments in open-top field chambers. The three CO2 treatments were ambient (370 microL L(-1)) and two treatments with CO2 added to ambient CO2 for 24 h d(-1) (540 and 715 microL L(-1)). The O3 treatments were charcoal-filtered air (15 nL L(-1)), nonfiltered air (45 nL L(-1)), and nonfiltered air with O3 added for 12 h d(-1) (80 nL L(-1)). Elevated O3 and CO2 caused extensive foliar injury of Dark Red Norland, but caused only slight injury of Superior. Elevated CO2 increased growth and tuber yield of both cultivars, whereas elevated O3 generally suppressed growth and yield, mainly of Dark Red Norland. Elevated CO2 appeared to protect Dark Red Norland from O3-induced suppression of shoot, root, and tuber weight as measured at midseason but did not protect either cultivar from O3 stress at the final harvest. The results further illustrate the difficulty in predicting effects of O3 + CO2 mixtures based on the effects of the individual gases.     

Analysing the influence of different street vegetation on traffic-induced particle dispersion using microscale simulations

Urban vegetation can be viewed as compensation to the environmental drawbacks of urbanisation. However, its ecosystem function is not well-known and, for urban planning, vegetation is mainly considered as an element of urban design. This article argues that planning practice needs to re-examine the impact of vegetation cover in the urban fabric given our evaluation of vegetation's effects on air quality, including the dispersion of traffic-induced particles at street level. Using the three-dimensional microclimate model ENVI-met?, we evaluate these effects regarding the height-to-width ratio of streets flanked by buildings and the vertical and horizontal density of street vegetation. Our results reveal vegetation's effect on particle dispersion through its influence on street ventilation. In general, vegetation was found to reduce wind speed, causing inhibition of canyon ventilation and, consequently, an increase in particle concentrations. Vegetation was also found to reduce wind speed at crown-height and to disrupt the flow field in close vicinity to the canopy. With increasing height-to-width ratio of street canyons, wind speed reduction increases and the disturbance of the flow impacts across a canyon's entire width. We also found that the effect is more pronounced in configurations with poor ventilation, such as the low wind speed, perpendicular inflow direction, and in deep canyons cases.     

An Integrated Framework for Multipollutant Air Quality Management and Its Application in Georgia

Air protection agencies in the United States increasingly confront non-attainment of air quality standards for multiple pollutants sharing interrelated emission origins. Traditional approaches to attainment planning face important limitations that are magnified in the multipollutant context. Recognizing those limitations, the Georgia Environmental Protection Division has adopted an integrated framework to address ozone, fine particulate matter, and regional haze in the state. Rather than applying atmospheric modeling merely as a final check of an overall strategy, photochemical sensitivity analysis is conducted upfront to compare the effectiveness of controlling various precursor emission species and source regions. Emerging software enables the modeling of health benefits and associated economic valuations resulting from air pollution control. Photochemical sensitivity and health benefits analyses, applied together with traditional cost and feasibility assessments, provide a more comprehensive characterization of the implications of various control options. The fuller characterization both informs the selection of control options and facilitates the communication of impacts to affected stakeholders and the public. Although the integrated framework represents a clear improvement over previous attainment-planning efforts, key remaining shortcomings are also discussed.