Formation of atmospheric nitrate under high Particulate Matter concentration (original) (raw)
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Ammonia (NH3 ) not only plays important role in acidification and eutrophication of aquatic ecosystems1 but also neutralizing atmospheric acids (H2SO4, HNO3 and HCl) and forms inorganic aerosols2-4 [(NH4)2SO4, NH4NO3 and NH4Cl]. Agricultural practices, livestock, transport and industrial activities2,5 are different anthropogenic sources of atmospheric NH3, along with natural sources like forest fire and emission from soil. This study estimated concentration of NH3, NO and NO2 and related particulate matter (PM10) over northern Indo Gangetic Plain (IGP) and correlated NH3 concentration with related particulates in the formation of secondary aerosol over IGP.
Measurement of Ambient NH3, NO and NO2 at an Urban Area of Kolkata, India
MAPAN, 2015
Mixing ratios of ambient NH 3 , NO and NO 2 were measured in campaign mode at Kolkata a megacity of Indo-Gangetic plain of India to study the diurnal variation and mixing ratios of NH 3 , NO and NO 2 during 24-27 February 2012. The present study has been carried out on campaign based measurement of mixing ratios of NH 3 , NO and NO 2 for short period of time at Kolkata represent the indicative values over the region. The average mixing ratios of ambient NH 3 , NO and NO 2 were recorded as 43.4 ± 7.0 ppb, 46.0 ± 8.7 ppb and 31.9 ± 5.5 ppb at Kolkata. In the present case, significant diurnal variation of NH 3 , NO and NO 2 were recorded at Kolkata during study. Mixing ratio of ambient NH 3 reaches its maxima (78.9 ppb) at night and minimum during daytime. Result reveals that the ambient NH 3 mixing ratio is positively correlated with ambient NO (r 2 = 0.395) and NO 2 (r 2 = 0.404) mixing ratio and significant negatively correlated with ambient temperature (r 2 =-0.669). Surface wind direction and wind speed analysis indicates that the local acitivities (livestock, drainage, agriculture, vehicles etc.,) may be the possible sources of ambient NH 3 at the observational site of Kolkata.
"Mixing ratios of ambient NH3, NO and NO2 were measured over three different environments viz Delhi, Dibrugarh and Thiruvananthapuram during 2009-10 to study their diurnal variations, concentration and source strength. The average mixing ratio of NH3 over Delhi, Dibrugarh and Thiruvananthapuram were recorded as 13.24 ± 0.39, 13.46 ± 2.52 and 12.65 ± 1.51 ppb respectively. The average mixing ratio of NO2 was recorded as 12.69 ± 0.39 with maxima of 20.22 ppb and minima of 0.75 ppb over Delhi whereas, the mixing ratio of ambient NO2 ranges from 0.65 to 3.65 ppb and 0.83 to 3.02 over Dibrugarh and Thiruvananthapuram respectively. The mixing ratio of NO and NO2 varying significantly at all the three locations except NH3 might be due to source strength and meteorological conditions of the locations. Result reveals that the mixing ratio of ambient NH3 is positively correlated with ambient temperature (r2 = 0.872) and NO2 (r2 = 0.975) over Delhi whereas non-significant at other locations."
Atmospheric Deposition of Nitrogen compounds in Assam (India
— The study comprises estimate of wet deposited nitrogenous compounds in Assam (India). Deposition has been estimated from a survey works (2010-11) at urban and peri-urban areas of Assam. Air samples were collected by clinical syringe (10 cm 3) for Oxides of Nitrogen (NO, NO 2 : NOx) and reduced Nitrogen (NH 3 , NH 4 + : NHy). The samples were diffused into 10 cm 3 each of distilled water and 0.1N HCl respectively for estimation of mean concentration of weighted hydrogen (µeql-1), quantity of elemental nitrogen (N) or nitrate (NO 3-1) and ammonium (NH 4 +) ions expressed in mg l-1 or kg ha-1 y-1. The measured concentrations of the nitrogenous compounds were interpolated with a properly used Kriging Technique on a 1km x 1km grid covering districts characterised by varying congestions of population, vehicular transport and of industrial evidences. There were many fold variations of these air quality parameters among the major sites and locations of the pollutants e.g. nitrogen deposited through aerosol of its oxides ranged from 6.0-38 kg ha-1 yr-1 , whereas nitrogen accumulation from the reduced aerosol was 7-24 kg ha-1 yr-1. Tissue nitrogen in some indicator plant species (e.g.Pinus longifolia, Ficus benjamina), collected from the square grids of polluted areas was also elevated. Thus, the hypothesis that the Northeast India, especially Assam is also facing with enrichment of nitrogenous pollution due to anthropogenic activities, mass vehicular and industrial growth, was tested.
Atmospheric Environment, 2003
This paper presents the measurements of gaseous SO 2 , NO 2 , HNO 3 and NH 3 and particulate NH 4 + , NO 3 À and SO 4 2À at Rampur, a rural site of semi-arid region of India and annual mean concentrations are 3.772.2, 7.373.7, 0.770.6 and 6.774.2 and 1.070.4, 1.171.3 and 2.671.6 mg m À3 , respectively. Seasonal variation with higher concentration in winter is observed for gaseous SO 2 , NO 2 , and NH 3 and particulate NH 4 + . The concentration of HNO 3 and particulate NO 3
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.
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.
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 ...
Journal of Geophysical Research: Atmospheres, 2013
We used SCIAMACHY (10:00 LT) and OMI (13:30 LT) tropospheric NO 2 columns to study diurnal and seasonal patterns in NO 2 concentrations over India. Using characteristics of seasonal variability in tropospheric NO 2 columns, we present a simple methodology to identify the dominant NOx source category for specific regions in India. Regions where the dominant source category is classified as biomass burning are found generally to agree with the ATSR fire count distribution. Relating OMI NO 2 columns to surface NOx emission, we find that biomass burning emission account for an average flux of 1.55 Â 10 11 molecules cm À2 s À1 during the peak burning period. Furthermore, extrapolating this estimated flux to the total burned area for the year 2005, biomass burning is estimated to account for 72 Gg of N emissions. Additional analysis of fire events in Northeast India shows a marked increase in TES retrieved O 3 concentrations, suggesting significant photochemical ozone formation during the peak biomass burning period. Regions where the dominant source type was categorized as anthropogenic are in good agreement with the distribution of major industrial regions and urban centers in India. Tropospheric NO 2 columns over these anthropogenic source regions increased by 3.8% per year between 2003 and 2011, which is consistent with the growth in oil and coal consumption in India. The OMI-derived surface NO 2 mixing ratios are indirectly validated with the surface in situ measurements (correlation r = 0.85, n = 88) obtained from the air quality monitoring network in Delhi during August 2010 to January 2011. Most of the OMI-derived surface NO 2 values agree with surface-based measurements, supporting the direct utility of OMI observation for emission estimates. Finally, we use OMI NO 2 columns to estimate NOx emissions for selected large cites and major thermal power plants in India and compare these estimates with the INTEX-B and EDGAR emission inventory. We find that, for a few locations, OMI-derived emission show fair agreement; however, for many locations, NOx emissions differ from INTEX-B and EDGAR inventories.