Seasonal and shorter-term variations in particulate atmospheric nitrate in Baltimore (original) (raw)
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Observations of fine and coarse particle nitrate at several rural locations in the United States
Atmospheric Environment, 2008
Nitrate comprises an important part of aerosol mass at many non-urban locations during some times of the year. Little is known, however, about the chemical form and size distribution of particulate nitrate in these environments. While submicron ammonium nitrate is often assumed to be the dominant species, this assumption is rarely tested. Properties of aerosol nitrate were characterized at several IMPROVE monitoring sites during a series of field studies.
Hourly and 24-h observational data from the 2009 LADCO Winter Nitrate Study
The data file contains hourly observed data for the LADCO Winter Nitrate Study, compiled by Charlie Stanier and colleagues. The intensive monitoring campaign ran from January 1, 2009 - March 31, 2009. It involved hourly time resolution inorganic particles and gases (and other variables) at four sites: Milwaukee, WI; Mayville, WI; Yorkville, GA; and Atlanta, GA. Acknowledgement to the original team that collected the measurements or otherwise contributed to the LADCO WNS. Eric Edgerton, ARA Donna Kenski, LADCO Mike Caughey, Illinois State Water Survey Bill Adamski, WDNR Joseph Hoch, WDNR Joe Leair, WDNR Jerry Medinger, WDNR Dan Nickolie, WDNR Mary Mertes, WDNR Bruce Rodger, WDNR Bart Sponseller, WDNR John Hillery, WDNR Janel Hanrahan, WDNR Laura Carnahan, WDNR Please use these data for model evaluation and other research purposes. Please cite Stanier et al. (2012) as noted below and the LADCO reports listed below as appropriate. A list of measured variables for one of the cities is: ...
npj Climate and Atmospheric Science
Inorganic nitrate production is critical in atmospheric chemistry that reflects the oxidation capacity and the acidity of the atmosphere. Here we use the oxygen anomaly of nitrate (Δ17O($$\rm{NO}_{3}^{-}$$ NO 3 − )) in high-time-resolved (3 h) aerosols to explore the chemical mechanisms of nitrate evolution in fine particles during the winter in Nanjing, a megacity of China. The continuous Δ17O($$\rm{NO}_{3}^{-}$$ NO 3 − ) observation suggested the dominance of nocturnal chemistry (NO3 + HC/H2O and N2O5 + H2O/Cl−) in nitrate formation in the wintertime. Significant diurnal variations of nitrate formation pathways were found. The contribution of nocturnal chemistry increased at night and peaked (72%) at midnight. Particularly, nocturnal pathways became more important for the formation of nitrate in the process of air pollution aggravation. In contrast, the contribution of daytime chemistry (NO2 + OH/H2O) increased with the sunrise and showed a highest fraction (48%) around noon. The ...
Atmospheric Environment, 2004
Ambient particles in Baltimore, Maryland were characterized from April through November 2002 using the real-time single particle mass spectrometer, RSMS III. When particles containing nitrate were examined, two types of ultrafine particle events were revealed: a large burst of nominally ''pure'' nitrate particles in the 50-90 nm size range, and a smaller (and less frequent) burst of ''pure'' particles in the 50-90 nm size range that grew to 110-220 nm with time. Coincident with both of these events was an increase in the number of mixed composition particles containing nitrate, suggesting that they were formed by condensation of ammonium nitrate onto pre-existing particles. Meteorological variables, particle number concentrations and continuous nitrate mass measurements were compared to the single particle data. Number and mass concentrations estimated from RSMS III correlated well with similar measurements with other techniques. Ultrafine nitrate particle events were observed during periods of low temperature and high relative humidity as expected from ammonium nitrate equilibrium considerations. During these events, the partitioning of ammonium nitrate to the particle phase strongly influenced the particle number concentration as well as the chemical composition. r
Causes of the elevated nitrate aerosol levels during episodic days in Taichung urban area, Taiwan
Atmospheric Environment, 2010
The purpose of this study is to explore the possible reasons accounting for elevated nitrate aerosol levels during high particulate days (HPD) in Taichung urban area of central Taiwan. To achieve this goal, simultaneous measurements of particulate and gaseous pollutants were carried out from September 2004 to April 2005 using an annular denuder system (ADS). The formation rate of NO 2 to nitrate aerosol, calculated using the relevant chemical reactions, was employed to interpret enhanced nitrate aerosol concentrations during HPD. The observations showed that nitrate concentration during HPD was 14 times higher than that during low particulate days (LPD). The average formation rate during HPD was 4.0% h À1 , which was 3.1 times higher than that during LPD. The quantitative analysis showed that the formation rate was mainly influenced by temperature and relative humidity. Lower temperature and higher relative humidity led much nitrate aerosol formation in HPD. Moreover, the residence time analysis of air masses staying over the studied area showed that the slow-motion air retained high nitrate concentrations due to more nitrate aerosol converted from the precursors in NOx-rich areas.
Formation of atmospheric nitrate under high Particulate Matter concentration
World Review of Science, Technology and Sustainable Development, 2011
This study was primarily initiated to understand the consistently moderate levels of nitrogen oxides (NOx) in Indian cities in spite of increasing NOx emissions. The research objective was to understand NO 3 formation as a NOx function, and other atmospheric constituents. For this purpose, air quality monitoring was conducted at four locations in Delhi city, India (during October-November, 2000), representing various land-use patterns. The NO 3 levels were found to be 4.9-15.1 µgm-3 in PM 2.5 and 7.3-21.9 µgm-3 in PM 10. The high NO 3 levels could provide a plausible explanation for moderate NOx concentration levels in Delhi city.
Filterable water-soluble organic nitrogen in fine particles over the southeastern USA during summer
Atmospheric Environment, 2011
Time integrated high-volume PM 2.5 samples were collected separately during day and night from 1 August to 10 September 2008 at a paired urban (Atlanta)-rural (Yorkville) sites as part of the August Mini-Intensive Gas and Aerosol Study (AMIGAS). Selected filters (n ¼ 96, 48 for each site) were analyzed for a suite of water-soluble chemical species, including major inorganic ions, water-soluble organic carbon (WSOC), water-soluble total and inorganic nitrogen (WSTN and WSIN), and levoglucosan. Semicontinuous analyses of PM 2.5 mass, soluble ions, WSOC, and gaseous O 3 , SO 2 , NO, NO 2 , NO y , CO, and meteorological parameters were also carried out in parallel. This study focuses on the characteristics of filterable water-soluble organic nitrogen (WSON), estimated by the difference in the measured concentrations of WSTN and WSIN, determined from aqueous filter extracts. At both sites, WSON varied from below the limit of detection (25 ng-N m À3 ) to w600 ng-N m À3 and on average contributed w10% to WSTN mass, with the majority of soluble nitrogen being ammonium (w82%). WSON:WSOC (or N:C) mass ratios ranged between 0 and 27% at both the sites with a median value of w5%, similar to what has been reported in another study in the southeastern USA. At both the urban and rural sites median nighttime levels of WSON and N:C were observed to be consistently higher than daytime values. Based on correlation analyses, daytime WSON sources appeared different than nighttime sources, especially at the urban site. Overall, the data suggest the importance of coal-combustion (e.g., link to SO 2 ), vehicle emissions, soil dust and biomass burning as WSON sources, and that nitrogenous organic compounds are likely a fairly small fraction of the secondary organic aerosol for this location during summer.
Environmental Science Technology, 1992
A l-year atmospheric measurement program was conducted throughout the South Coast Air Basin in the greater Los Angeles area during 1986 to determine the long-term average concentration patterns of gaseous HNO, and aerosol nitrates. Upwind of the air basin at San Nicolas Island, HNO, levels are very low, averaging 0.3 pg m-3 (0.1 ppb) over the year 1986. Annual average HN03 concentrations ranged from 3.1 pg m-3 (1.2 ppb) near the Southern California coast to 6.9 pg m-3 (2.7 ppb) at an inland site in the San Gabriel Mountains. At most monitoring stations, a majority of the inorganic nitrate ("OB plus its reaction product, aerosol nitrate) was in the aerosol phase. Conversion of HN03 to aerosol nitrates was most pronounced at Rubidoux, near Riverside, CA, where on the average 94% of the inorganic nitrate was found in the aerosol phase, and where fine particle nitrate concentrations exceeded 109 pg rn-, during the peak 24-h period examined.
Analysis of levels of nitrates and derivatives of ammonia in an urban atmosphere
Science of The Total Environment, 1997
To estimate the various ammoniacal compounds in the atmosphere and determine the role of nitrogen oxides and ammonia in the formation of nitrates as a function of temperature and relative humidity, a statistical model based on multiple linear regression was devised. The model was developed using the results from atmospheric samples of both primary (ammonia, sulfur dioxide, nitrogen dioxide, nitric oxide) and secondary pollutants (ammonium, nitrates, sulfates and chlorides) taken over a l-year period from three monitoring stations in a large French city. To identify the ammoniacal compounds, NH,+, the dependent variable, was examined as a function of several explanatory variables: NO,, SOi-and Cl-. From the equations in the model, the presence of ammonium nitrate and ammonium hydrogen sulfate were predicted in the Spring-Summer. In the Winter, derivatives of nitrous acid were predicted. It was shown that there was a deficit in ammonium ions, related to the presence of unstable NH&l. To study the formation of atmospheric nitrates, NO;, the dependent variable was examined as a function of several explanatory variables: NO, NOz, NH,, temperature and humidity. Two mechanisms emerged for the formation of nitrates, one in the gas phase during the Spring-Summer period, the other in the liquid phase during the Autumn-Winter period, in which nitrogen dioxide appeared to play a major role. In both cases, temperature and the concentration of ammonia were statistically significant factors. Since secondary pollutants tend to be spread evenly throughout the urban area, in contrast to the more localized gaseous and unstable pollutants, the identification of the main atmospheric particles provides further evidence for epidemiological investigations. 0 1997 Elsevier Science B.V.