Enhanced aerosol particle growth sustained by high continental chlorine emission in India

Gunthe, Sachin S.; Liu, Pengfei; Panda, Upasana; Raj, Subha S.; Sharma, Amit; Darbyshire, Eoghan; Reyes-Villegas, Ernesto; Allan, J. D.; Chen, Ying; Wang, Xuan; Song, Shaojie; Pöhlker, Mira L.; Shi, Liuhua; Wang, Yu; Kommula, Snehitha M.; Liu, Tianjia; Ravikrishna, R.; McFiggans, G.; Mickley, Loretta J.; Martin, Scot T.; Pöschl, Ulrich; Andreae, Meinrat O.; Coe, Hugh

doi:10.1038/s41561-020-00677-x

Cited by 135 publications

(158 citation statements)

References 72 publications

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“…Production of particle-phase chloride, presumed to be from uptake of gas-phase HCl, has been observed previously during fog/haze events in highly polluted urban India (Gunthe et al, 2021) and near an incinerator (Johnson et al, 1987). However, for this study in Kalamazoo, MI, road salting seems more plausible as the dominant source of increased PM2.5 Clduring wintertime fog.…”

Section: Competing Effects Of Environmental Conditionssupporting

confidence: 55%

Urban inland wintertime N2O5 and ClNO2 influenced by snow-covered ground, air turbulence, and precipitation

Kulju

McNamara

Chen

et al. 2021

Preprint

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Abstract. The atmospheric multiphase reaction of dinitrogen pentoxide (N2O5) with chloride-containing aerosol particles produces nitryl chloride (ClNO2), which has been observed across the globe. The photolysis of ClNO2 produces chlorine radicals and nitrogen dioxide (NO2), which alter pollutant fates and air quality. However, the effects of local meteorology on near-surface ClNO2 production are not yet well understood, as most observational and modeling studies focus on periods of clear conditions. During a field campaign in Kalamazoo, Michigan from January–February 2018, N2O5 and ClNO2 were measured using chemical ionization mass spectrometry, with simultaneous measurements of atmospheric particulate matter and meteorological parameters. We examine the impacts of atmospheric turbulence, precipitation (snow, rain) and fog, and ground cover (snow-covered and bare ground) on the abundances of ClNO2 and N2O5. N2O5 mole ratios were lowest during periods of lower turbulence and were not statistically significantly different between snow-covered and bare ground. In contrast, ClNO2 mole ratios were highest, on average, over snow-covered ground, due to saline snowpack ClNO2 production. Both N2O5 and ClNO2 mole ratios were lowest, on average, during rainfall and fog because of scavenging, with N2O5 scavenging by fog droplets likely contributing to observed increased particulate nitrate concentrations. These observations, specifically those during active precipitation and with snow-covered ground, highlight important processes, including N2O5 and ClNO2 wet scavenging, fog nitrate production, and snowpack ClNO2 production, that govern the variability in observed atmospheric chlorine and nitrogen chemistry and are missed when considering only clear conditions.

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Section: Competing Effects Of Environmental Conditionssupporting

confidence: 55%

Urban inland wintertime N2O5 and ClNO2 influenced by snow-covered ground, air turbulence, and precipitation

Kulju

McNamara

Chen

et al. 2021

Preprint

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“…To further understand the complex urban atmospheric chemistry in Delhi, more model constraints are required, such as the measurement of radical species and k(OH). The potential effects of chlorine chemistry were also not investigated in this study, and may have an important role in the local chemistry due to the prevalence of waste burning in the city (Gunthe et al, 2021). Satellite observations and aircraft measurements may also help develop our understanding of the regional impacts of regional agricultural biomass burning on Delhi from neighbouring states.…”

Section: Discussionmentioning

confidence: 99%

“…However, an ASA reduction will result in a decrease in AOD, which will in turn increase photolysis rates. A recent study by Chen et al, 2021 modelled the impact of AOD on photolysis in Delhi during November 2018, and found that halving the AOD results in a 14 % increase in j(NO2). In Delhi, total VOCs would need to be reduced by ~ 50 % to maintain current P(O3) rates if NOx were halved and photolysis rates increased by 14 %.…”

Section: The Impact Of Aerosol Surface Area On P(o3)mentioning

confidence: 99%

In situ Ozone Production is highly sensitive to Volatile Organic Compounds in the Indian Megacity of Delhi

Nelson

Stewart

Drysdale

et al. 2021

Preprint

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Abstract. The Indian megacity of Delhi suffers from some of the poorest air quality in the world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention in the city, high ground level ozone (O3) concentrations are an often overlooked component of pollution. O3 can lead to significant ecosystem damage, agricultural crop losses, and adversely affect human health. During October 2018, concentrations of speciated non-methane hydrocarbons volatile organic compounds (C2 – C13), oxygenated volatile organic compounds (o-VOCs), NO, NO2, HONO, CO, SO2, O3, and photolysis rates, were continuously measured at an urban site in Old Delhi. These observations were used to constrain a detailed chemical box model utilising the Master Chemical Mechanism v3.3.1. VOCs and NOx (NO + NO2) were varied in the model to test their impact on local O3 production rates, P(O3), which revealed a VOC-limited chemical regime. When only NOx concentrations were reduced, a significant increase in P(O3) was observed, thus VOC co-reduction approaches must also be considered in pollution abatement strategies. Of the VOCs examined in this work, mean morning P(O3) rates were most sensitive to monoaromatic compounds, followed by monoterpenes and alkenes, where halving their concentrations in the model led to a 15.6 %, 13.1 % and 12.9 % reduction in P(O3), respectively. P(O3) was not sensitive to direct changes in aerosol surface area but was very sensitive to changes in photolysis rates, which may be influenced by future changes in PM concentrations. VOC and NOx concentrations were divided into emission source sectors, as described by the EDGAR v5.0 Global Air Pollutant Emissions and EDGAR v4.3.2_VOC_spec inventories, allowing for the impact of individual emission sources on P(O3) to be investigated. Reducing road transport emissions only, a common strategy in air pollution abatement strategies worldwide, was found to increase P(O3), even when the source was removed in its entirety. Effective reduction in P(O3) was achieved by reducing road transport along with emissions from combustion for manufacturing and process emissions. Modelled P(O3) reduced by ~20 ppb h−1 when these combined sources were halved. This study highlights the importance of reducing VOCs in parallel with NOx and PM in future pollution abatement strategies in Delhi.

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“…Cl − is found in normally coarser particles and its formation might be from the mechanisms i.e., sea salt transformation and photochemical reaction (Chattopadhayay, 2012), biomass burning (Saud et al 2013), and use of fertilizers (Bakeer et al 2016 (Shepherd, 1993). Gunthe et al (2021) Like Cl − spatial variation of Na + is from 1.0 to 56.4 µg m − 3 . The highest concentration of Na + was observed at Rana Pratap Bagh (56.4 µg m − 3 ) (Fig.…”

Section: Water Soluble Ionic Species (Wsis) In Tspmentioning

confidence: 97%

Gridded distribution of total suspended particulate matter (TSP) and their chemical characterization over Delhi during winter

Jangirh

Ahlawat

Arya

et al. 2021

Preprint

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In the present study, total suspended particulate matter (TSP) samples were collected at 47 different sites (47 grids of 5 × 5 km2 area) of Delhi during winter (January-February 2019) in campaign mode. To understand the spatial variation of sources, TSP samples were analyzed for chemical compositions including carbonaceous species [organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC)], water-soluble total nitrogen (WSTN), water-soluble inorganic nitrogen (WSIN), polycyclic aromatic hydrocarbons (16 PAHs), water-soluble inorganic species (WSIS) (F−, Cl−, SO42−, NO2−, NO3−, PO43−, NH4+, Ca2+, Mg2+, Na+, and K+), and major & minor trace elements (B, Na, Mg, Al, P, S, Cl, K, Ca, Ti, Fe, Zn, Cr, Mn, Cu, As, Pd, F, and Ag). During the campaign, the maximum concentration of several components of TSP (996 µg/m3) was recorded at the Rana Pratap Bagh area representing a pollution hotspot of Delhi. The maximum concentrations of PAHs were recorded at Udhyog Nagar, a region close to heavily loaded diesel vehicles, small rubber factories, and waste burning areas. Higher content of Cl− and Cl−/Na+ ratio (> 1.7) suggests the presence of nonmarine anthropogenic sources of Cl− over Delhi. Minimum concentrations of OC, EC, WSOC, PAHs, and WSIS in TSP were observed at Kalkaji representing the least polluted area in Delhi. Enrichment factor < 5.0 at several locations and a significant correlation of Al with Mg, Fe, Ti, and Ca and C/N ratio indicated the abundance of mineral/crustal dust in TSP over Delhi. Principal component analysis (PCA) was also performed for the source apportionment of TSP and extracted soil dust was found to be the major contributor to TSP followed by biomass burning, open waste burning, secondary aerosol, and vehicular emissions.

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Enhanced aerosol particle growth sustained by high continental chlorine emission in India

Abstract: 2Cheng, Z. et al. Status and characteristics of ambient PM2.5 pollution in global megacities.

Cited by 135 publications

References 72 publications

Urban inland wintertime N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub> influenced by snow-covered ground, air turbulence, and precipitation

Urban inland wintertime N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub> influenced by snow-covered ground, air turbulence, and precipitation

In situ Ozone Production is highly sensitive to Volatile Organic Compounds in the Indian Megacity of Delhi

Gridded distribution of total suspended particulate matter (TSP) and their chemical characterization over Delhi during winter

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Enhanced aerosol particle growth sustained by high continental chlorine emission in India

Abstract: 2Cheng, Z. et al. Status and characteristics of ambient PM2.5 pollution in global megacities.

Cited by 135 publications

References 72 publications

Urban inland wintertime N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; and ClNO&lt;sub&gt;2&lt;/sub&gt; influenced by snow-covered ground, air turbulence, and precipitation

Urban inland wintertime N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; and ClNO&lt;sub&gt;2&lt;/sub&gt; influenced by snow-covered ground, air turbulence, and precipitation

In situ Ozone Production is highly sensitive to Volatile Organic Compounds in the Indian Megacity of Delhi

Gridded distribution of total suspended particulate matter (TSP) and their chemical characterization over Delhi during winter

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Product

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Urban inland wintertime N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub> influenced by snow-covered ground, air turbulence, and precipitation

Urban inland wintertime N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub> influenced by snow-covered ground, air turbulence, and precipitation