scholarly journals Changes in summertime ozone in Colorado during 2000–2015

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Tanja Bien ◽  
Detlev Helmig
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Oil And Gas ◽  
Ambient Air ◽  
Quality Standard ◽  
P Value ◽  
Nox Emissions ◽  
Mixing Ratios ◽  
June July ◽  
Surface O3

In 2016, the Denver Metro Area (DMA)/Northern Colorado Front Range (NCFR) was reclassified from a Marginal to a Moderate O3 Non-Attainment Area due to the prevalence of high summer ozone (O3) occurrences. Hourly surface O3 data collected during 2000–2015 from a total of 80 monitoring sites in the State of Colorado were investigated for geographical features in O3 behavior and O3 changes over time. We particularly focus on summer O3 (June, July, August), which is the time when most exceedances of the O3 National Ambient Air Quality Standard (NAAQS) have been recorded. Variables investigated include the statistical (5th, 50th (median), and 95th percentile) distribution of O3 mixing ratios, diurnal amplitudes, and their trends. Trend analyses were conducted for 20 site records that had at least ten years of data. The majority of Colorado ozone monitoring sites show an increase of the 5th (16 total; 11 of these are statistically significant (p-value ≤ 0.05) trends) and 50th (15 total; 4 statistically significant trends) percentile values. Changes for the 95th percentile values were smaller and less consistent. One site showed a statistically significant declining trend, and one site an increasing trend; the majority of other sites had slightly negative, albeit not statistically significant declining O3. Ozone changes at the two highest elevations sites (>2500 m asl) are all negative, contrasting increasing O3 at U.S. West Coast sites. NCFR urban sites do not show the rate of decreasing higher percentile O3 as seen for the majority of urban areas across the U.S. during the past 1–2 decades. The amplitudes of diurnal O3 cycles were studied as a proxy for nitrogen oxides (NOx) emissions and the diurnal O3 production chemistry. The majority of sites show a decrease in the median summer O3 diurnal amplitude (19 total/10 statistically significant). This is mostly driven by the increase in nighttime O3 minima, which is most likely a sign for a declining rate of nighttime O3 loss from titration with nitric oxide (NO), indicating a change in O3 behavior from declining NOx emissions. Since median and upper percentile surface O3 values in the DMA have not declined at the rates seen in other western U.S. regions, thus far the reduction in NOx has had a more pronounced effect on the lower percentile O3 distribution than on high O3 occurrences that primarily determine air quality. An assessment of the influence of oil and gas emissions on Colorado, and in particular DMA O3, is hampered by the sparsity of monitoring within oil and gas basins. Continuous, long-term, high quality, and co-located O3, NOx, and VOC monitoring are recommended for elucidating the geographical heterogeneity of O3 precursors, their changing emissions, and for evaluation of the effectiveness of O3 air quality regulations.

Smoke incursions into urban areas: simulation of a Georgia prescribed burn

2009 ◽  
Vol 18 (3) ◽  
pp. 336 ◽  
Author(s):  
Yongqiang Liu ◽  
Scott Goodrick ◽  
Gary Achtemeier ◽  
William A. Jackson ◽  
John J. Qu ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Ambient Air ◽  
Quality Standard ◽  
Prescribed Burn ◽  
Modeling Framework ◽  
North West ◽  
Transport Direction ◽  
Smoke Plumes ◽  
Ambient Air Quality Standard

This study investigates smoke incursion into urban areas by examining a prescribed burn in central Georgia, USA, on 28 February 2007. Simulations were conducted with a regional modeling framework to understand transport, dispersion, and structure of smoke plumes, the air quality effects, sensitivity to emissions, and the roles of burn management strategy in mitigating the effects. The results indicate that smoke plumes first went west, but turned north-west at noon owing to a shift in wind direction. The smoke then invaded metropolitan Atlanta during the evening rush hour. The plumes caused severe air quality problems in Atlanta. Some hourly ground PM2.5 (particulate matter not greater than 2.5 μm in diameter) concentrations at three metropolitan Atlanta locations were three to four times as high as the daily (24-h) US National Ambient Air Quality Standard. The simulated shift in the smoke transport direction and the resultant effects on air quality are supported by the satellite and ambient air measurements. Two sensitivity simulations indicate a nearly linear relation between the emission intensities and PM2.5 concentrations. Two other simulations indicate that the impacts on air quality for the residents of Atlanta during the evening commute could have been reduced if the starting time of the burn had been altered.

scholarly journals Evaluation of regional simulation of surface ozone over Southeast Asia using ground-based observation at two existing Global Atmospheric Watch stations

2021 ◽  
Vol 880 (1) ◽  
pp. 012006
Author(s):  
Didin Agustian Permadi ◽  
Nguyen Thi Kim Oanh
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Emission Inventory ◽  
Surface Ozone ◽  
Wrf Model ◽  
Ambient Air ◽  
Quality Standard ◽  
Ozone Pollution ◽  
Ozone Precursors ◽  
Remote Sites

Abstract High level of ground level ozone concentrations was found in most of Southeast Asian (SEA) large cities and often exceeded the national ambient air quality standard. Ozone and PM10 are among of the critical air quality parameters that cause the unhealthy air quality index. Effort to mitigate ozone pollution is greatly complicated due to the photochemistry processes therefore photochemical smog modelling has been widely used. Surface ozone simulation in SEA was done using CHIMERE and weather research forecast (WRF) model. Emission inventory of ozone precursors was done for three countries in the domain, i.e. Indonesia, Thailand and Cambodia. Modelling performance evaluation for meteorological parameters and ozone at the SEA big cities was done in another study. This paper focused on the model evaluation conducted at the two remote sites represented by 2 (two) global atmospheric watch (GAW) remote stations of Bukit Kototabang (BKT) and Danum Valley (DNV). Evaluation result showed an overestimation of observed ozone in BKT while a contradictive result was seen in DNV station which was due to the ozone chemistry and inaccurate estimation of emissions (both anthropogenic and biogenic emission). The evaluation conducted at the remote sites was not even better than that conducted previously at the urban areas. Statistically, only mean normalized gross error and unpaired peak accuracy values that satisfy the criteria for surface ozone modelling suggesting major improvement required for ozone precursors emission inventory data.

scholarly journals Detection of deep stratospheric intrusions by cosmogenic 35S

2016 ◽  
Vol 113 (40) ◽  
pp. 11131-11136 ◽  
Author(s):  
Mang Lin ◽  
Lin Su ◽  
Robina Shaheen ◽  
Jimmy C. H. Fung ◽  
Mark H. Thiemens
Keyword(s):  
Air Quality ◽  
Southern California ◽  
Ground Level ◽  
Ambient Air ◽  
Quality Standard ◽  
Quantitative Detection ◽  
Daily Maximum ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Stratospheric Intrusions

The extent to which stratospheric intrusions on synoptic scales influence the tropospheric ozone (O3) levels remains poorly understood, because quantitative detection of stratospheric air has been challenging. Cosmogenic 35S mainly produced in the stratosphere has the potential to identify stratospheric air masses at ground level, but this approach has not yet been unambiguously shown. Here, we report unusually high 35S concentrations (7,390 atoms m−3; ∼16 times greater than annual average) in fine sulfate aerosols (aerodynamic diameter less than 0.95 µm) collected at a coastal site in southern California on May 3, 2014, when ground-level O3 mixing ratios at air quality monitoring stations across southern California (43 of 85) exceeded the recently revised US National Ambient Air Quality Standard (daily maximum 8-h average: 70 parts per billion by volume). The stratospheric origin of the significantly enhanced 35S level is supported by in situ measurements of air pollutants and meteorological variables, satellite observations, meteorological analysis, and box model calculations. The deep stratospheric intrusion event was driven by the coupling between midlatitude cyclones and Santa Ana winds, and it was responsible for the regional O3 pollution episode. These results provide direct field-based evidence that 35S is an additional sensitive and unambiguous tracer in detecting stratospheric air in the boundary layer and offer the potential for resolving the stratospheric influences on the tropospheric O3 level.

scholarly journals Air quality measurements in the western Eagle Ford Shale

Elem Sci Anth ◽  
2020 ◽  
Vol 8 ◽  
Author(s):  
Geoffrey S. Roest ◽  
Gunnar W. Schade
Keyword(s):  
Air Quality ◽  
Oil And Gas ◽  
Ambient Air ◽  
Trace Gas ◽  
Ambient Air Quality ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Mixing Ratios ◽  
Trace Gas Emissions ◽  
The Us

The Eagle Ford Shale in southern Texas remains one of the most productive oil and gas regions in the US. Like the Permian Basin and Bakken Shale, ubiquitous natural gas flaring serves as an uncertain source of trace gas emissions within the Eagle Ford. A lack of ambient air quality data, especially in the western shale, impedes a thorough understanding of trace gas emissions within the shale and the subsequent local/regional air quality impacts. Meteorological and trace gas instrumentation was deployed to Shape Ranch in southwestern Dimmit County, near the US/Mexico border, from April to November of 2015. Mixing ratios of CO, NOx, O3, and VOCs did not exceed ambient air quality standards and were generally lower than mixing ratios measured in US cities, with the exception of alkanes. A non-negative matrix factorization demonstrated the dominance of oil and gas-sector emission sources in local trace gas variability, with combustion processes and transport of continental air also present. An analysis of NOx/CO and NOx/CO2 ratios during periods of O3 titration, identified by the ambient NOx/O3 ratio, suggested that combustion and biospheric sources contributed to emissions of NOx, CO, and CO2. In-plume NOx/CO2 ratios indicated relatively low-temperature combustion sources, with median NOx/CO2 ratios close to that expected for natural gas flaring (0.54 ppb/ppm), and much lower than emission ratios for internal combustion engines (>10 ppb/ppm). However, the NOx/CO2 ratio within these plumes exhibited a large variability, spanning more than an order of magnitude. Future research should focus on improving flaring emission factors and flaring volume estimates such that their air quality impacts can be better understood.

scholarly journals Assessment of the Effects of the Spanish National Air Pollution Control Programme on Air Quality

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 158 ◽  
Author(s):  
Marta G. Vivanco ◽  
Juan Luis Garrido ◽  
Fernando Martín ◽  
Mark R. Theobald ◽  
Victoria Gil ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Urban Areas ◽  
Transport Model ◽  
Ambient Air ◽  
Control Programme ◽  
Mitigation Measures ◽  
Nox Emissions ◽  
Air Pollution Control ◽  
The Impact

During the last few decades, European legislation has driven progress in reducing air pollution in Europe through emission mitigation measures. In this paper, we use a chemistry transport model to assess the impact on ambient air quality of the measures considered for 2030 in the for the scenarios with existing (WEM2030) and additional measures (WAM2030). The study estimates a general improvement of air quality for the WAM2030 scenario, with no non-compliant air quality zones for NO2, SO2, and PM indicators. Despite an improvement for O3, the model still estimates non-compliant areas. For this pollutant, the WAM2030 scenario leads to different impacts depending on the indicator considered. Although the model estimates a reduction in maximum hourly O3 concentrations, small increases in O3 concentrations in winter and nighttime in the summer lead to increases in the annual mean in some areas and increases in other indicators (SOMO35 for health impacts and AOT40 for impacts on vegetation) in some urban areas. The results suggest that the lower NOx emissions in the WEM and WAM scenarios lead to less removal of O3 by NO titration, especially background ozone in winter and both background and locally produced ozone in summer, in areas with high NOx emissions.

scholarly journals Surface ozone in the Colorado northern Front Range and the influence of oil and gas development during FRAPPE/DISCOVER-AQ in summer 2014

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
L. C. Cheadle ◽  
S. J. Oltmans ◽  
G. Pétron ◽  
R. C. Schnell ◽  
E. J. Mattson ◽  
...  
Keyword(s):  
Case Studies ◽  
Rural Areas ◽  
Oil And Gas ◽  
Surface Ozone ◽  
Primary Source ◽  
Ambient Air ◽  
Quality Standard ◽  
Front Range ◽  
Oil And Gas Development ◽  
Surface O3

High mixing ratios of ozone (O3) in the northern Front Range (NFR) of Colorado are not limited to the urban Denver area but were also observed in rural areas where oil and gas activity is the primary source of O3 precursors. On individual days, oil and gas O3 precursors can contribute in excess of 30 ppb to O3 growth and can lead to exceedances of the EPA O3 National Ambient Air Quality Standard. Data used in this study were gathered from continuous surface O3 monitors for June–August 2013–2015 as well as additional flask measurements and mobile laboratories that were part of the FRAPPE/DISCOVER-AQ field campaign of July–August 2014. Overall observed O3 levels during the summer of 2014 were lower than in 2013, likely due to cooler and damper weather than an average summer. This study determined the median hourly surface O3 mixing ratio in the NFR on summer days with limited photochemical production to be approximately 45–55 ppb. Mobile laboratory and flask data collected on three days provide representative case studies of different O3 formation environments in and around Greeley, Colorado. Observations of several gases (including methane, ethane, CO, nitrous oxide) along with O3 are used to identify sources of O3 precursor emissions. A July 23 survey demonstrated low O3 (45–60 ppb) while August 3 and August 13 surveys recorded O3 levels of 75–80 ppb or more. August 3 exemplifies influence of moderate urban and high oil and gas O3 precursor emissions. August 13 demonstrates high oil and gas emissions, low agricultural emissions, and CO measurements that were well correlated with ethane from oil and gas, suggesting an oil and gas related activity as a NOx and O3 precursor source. Low isoprene levels indicated that they were not a significant contributor to O3 precursors measured during the case studies.

scholarly journals Atmospheric Aerosols: Air Quality and Climate Change Perspectives

2015 ◽  
Vol 10 (3) ◽  
pp. 738-746 ◽  
Author(s):  
Shabana Manzoor ◽  
Umesh Kulshrestha
Keyword(s):  
Air Quality ◽  
Atmospheric Aerosols ◽  
Urban Areas ◽  
Ambient Air ◽  
Quality Standard ◽  
Vital Role ◽  
Cloud Formation ◽  
Pm10 And Pm2.5 ◽  
Suspended Particulate ◽  
Ambient Air Quality Standard

Recently, air quality has become a matter of concern of everyone. According to the reports, atmospheric aerosols play very crucial role in air quality. PM10 and PM2.5 aerosols are integral parts of total suspended particulate matter which affect our health. Often air quality has been reported very poor due to violation of National Ambient Air Quality Standard (NAAQS) limits. PM10 and PM2.5 limits are crossed for both residential as well as sensitive sites. This is one of the major reasons of increasing cases of respiratory diseases in urban areas. However, aerosol loadings alone are not the factor for deciding or predicting toxic and harmful effects of aerosols. Chemical composition and size ranges do matter. Aerosol loadings can be due to three major source categories viz. marine, crustal and anthropogenic. Since, marine and crustal content of aerosols are generally non-toxic and hence, degree of toxicity of air needs to be decided on the basis of anthropogenic fraction having metals, PAHs and other harmful content. Apart from air quality and health, atmospheric aerosols play vital role in other atmospheric processes such as cloud formation, radiative transfer and monsoon etc. Though there are several studies reported on different aspects of atmospheric aerosols, but most of the findings are sort of data reporting based on short term observations. Hence, there is need to investigate the atmospheric aerosols in order to demonstrate local and regional phenomenon on the basis of long term datasets.

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