Reactive nitrogen and ozone over the western Pacific: Distribution, partitioning, and sources

Abstract. Measurements of ozone and NO 2 were carried out in the marine environment of the Bay of Bengal (BoB) during the winter months, December 2008-January 2009, as part of the second Integrated Campaign for Aerosols, gases and Radiation Budget conducted under the Geosphere Biosphere Programme of the Indian Space Research Organization. The ozone mixing ratio was found to be high in the head and the southeast BoB with a mean value of 61 ± 7 ppb and 53 ± 6 ppb, respectively. The mixing ratios of NO 2 and CO were also relatively high in these regions. The spatial patterns were examined in the light of airflow patterns, air mass back trajectories and other meteorological conditions and satellite retrieved maps of tropospheric ozone, NO 2 , CO, and fire count in and around the region. The distribution of these gases was strongly associated with the transport from the adjoining land mass. The anthropogenic activities and forest fires/biomass burning over the Indo Gangetic Plains and other East Asian regions contribute to ozone and its precursors over the BoB. Similarity in the spatial pattern suggests that their source regions could be more or less the same. Most of the diurnal patterns showed decrease of the ozone mixing ratio during noon/afternoon followed by a nighttime increase and a morning high. Over this oceanic region, photochemical production of ozone involving NO 2 was not very active. Water vapour played a major role in controlling the variation of ozone. An attempt is made to simulate ozone level over the north and south BoB using the photochemical box model (NCAR-MM). The present observed features were compared with those measured during the earlier cruises conducted in different seasons.

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“…(Tonnesen and Dennis, 2000). Similar ratios were reported from the marine environment of Pacific (Singh et al, 1996a, b).…”

Section: Spatial Variation Of Ozone and Nosupporting

confidence: 73%

“…On the other hand, NO 2 is found to be comparable over the head BoB and southeast BoB. The NO 2 measured over the BoB were higher than the values over the north Atlantic and western and tropical Pacific Singh et al, 1996a and b). Most often O 3 /NO 2 ratio is used as an indicator of ozone sensitivity to NO 2 .…”

Section: Spatial Variation Of Ozone and Nomentioning

confidence: 97%

Distribution of ozone and its precursors over Bay of Bengal during winter 2009: role of meteorology

2011

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“…It has been postulated that the overestimation of the HNO3 to NO,• ratio is largely due to an over prediction of HNO3 concentrations in the models and that this discrepancy is due to an important yet unknown chemical pathway involving the heterogeneous removal of HNO3 from the atmosphere [Singh et al, 1996;Thakur et al, 1999]. Because of the uncertainty of their importance, heterogeneous processes are currently neglected in most tropospheric chemistry models.…”

Section: Introductionmentioning

confidence: 99%

A laboratory study of the heterogeneous reaction of nitric acid on calcium carbonate particles

Goodman¹,

Underwood²,

Grassian³

2000

J. Geophys. Res.

169

179

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Abstract. It has been postulated that the reaction of nitric acid with calcium carbonate, namely, CaCO3(s) + 2HNO3(g) -0 Ca(NO3)2(s) + CO2(g) + H20(g), plays an important role in the atmosphere. In this study, transmission FTIR spectroscopy, diffuse reflectance UV-visible spectroscopy, transmission electron microscopy and a Knudsen cell reactor coupled to a quadrupole mass spectrometer have been used to investigate the heterogeneous reactivity of HNO3 on CaCO3 at 295 K as a function of relative humidity. Transmission FTIR spectroscopy was used to probe both gas-phase and adsorbed products and showed that the reaction of HNO3 and CaCO3 is limited to the surface of the CaCO3 particle in the absence of adsorbed water. However, in the presence of water vapor, the reaction is greatly enhanced and is not limited to the surface of the particle producing both solid calcium nitrate and gaseous carbon dioxide. The enhanced reactivity of the particles is attributed to the presence of a layer of adsorbed water on the particle surface. The amount of adsorbed water on the particle surface is strongly dependent on the extent of the reaction. This can be understood in terms of the increased hydrophilicity of calcium nitrate as compared to calcium carbonate. Data from experiments using a mass-calibrated Knudsen cell reactor showed the stoichiometry for the reaction determined from gas-phase species deviated from that expected from the balanced equation. Water adsorption on the particle surface and gases dissolved into the water layer appear to be the cause of this discrepancy. The measured uptake coefficient accounting for the BET area of the sample is determined to be 2.5 + 0.1 x 10 -4 for HNO3 on CaCO3 under dry conditions and is found to increase in the presence of water vapor. Atmospheric implications of the results presented here are discussed. This current laboratory study is motivated by the above modeling studies. Here we attempt to discern whether mineral aerosols containing CaCO3 would be a sufficient sink for HNO3 that could reduce the HNO3 to NO• ratio in the atmosphere. The following issues concerning the heterogeneous reactivity of HNO3 on CaCO3 particles are addressed in this study:(1) does nitric acid react with CaCO3 according to reaction (1)?; (2) is the reaction of nitric acid limited to the surface of the CaCO3 particles?; (3) does water adsorbed on the particle surface play a key role in the reaction?; (4) do the physicochemical properties of the particle change after reaction with HNO37; (5) is the reaction 29,053

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“…Atmospheric PAN is exclusively from tropospheric photochemical reactions, and hence, PAN has been considered as a better indicator of photochemical smog pollution than O 3 (McFadyen and Cape, 2005). PANs are thermal unstable compounds, they are quite stable in the midand upper troposphere under low temperature, and can be transported over long distances from polluted continental regions into the remote areas where they release NOx under high temperature (Honrath et al, 1996;Kondo et al, 1997;Singh et al, 1996), and hence PANs act as important temporary NOx reservoirs and control the photochemical production of O 3 in the remote troposphere (Singh and Hanst, 1981). Due to the particular importance of PANs on atmospheric chemistry, a great number of PANs measurements have been conducted intensively in developed countries, including the urban regions (Grosjean et al, 2001;Marley et al, 2007;Roberts et al, 1995) and remote area (Hartsell et al, 1994;Roberts et al, 2004;Singh et al, 1990Singh et al, , 1992Williams and Grosjean, 1991).…”

Section: Introductionmentioning

confidence: 99%

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

Zhang

Liu

et al. 2014

Journal of Environmental Sciences

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Reactive nitrogen and ozone over the western Pacific: Distribution, partitioning, and sources

Cited by 179 publications

References 44 publications

Distribution of ozone and its precursors over Bay of Bengal during winter 2009: role of meteorology

Distribution of ozone and its precursors over Bay of Bengal during winter 2009: role of meteorology

A laboratory study of the heterogeneous reaction of nitric acid on calcium carbonate particles

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

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