Browsing by Author "Yunus, Siti S. M."

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    Comprehensive organic emission profiles, secondary organic aerosol production potential, and OH reactivity of domestic fuel combustion in Delhi, India
    (Frontiers, 2021-01-21) Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Hopkins, James R.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mandal, Tuhin K.; Gadi, Ranu; Sahu, Lokesh K.; Rickard, Andrew R.; Lee, James D.; Hamilton, Jacqueline F.
    Domestic solid fuel combustion is a major source of organic compounds to the atmosphere in gas and aerosol phases; however, large uncertainties exist in the current understanding of the gas-to-particle partitioning and the drivers of the reactivity of these emissions. This study developed comprehensive, model-ready organic emission profiles for domestic solid fuel combustion sources collected from Delhi, India. It also examined the organic species responsible for secondary organic aerosol (SOA) production potential and hydroxyl radical (OH) reactivity of these emissions. The profiles spanned the entire volatility range, including non-methane volatile organic compounds (NMVOCs, effective saturation concentration, C* = 3 × 106 to 1011 μg m−3), intermediate-volatility organic compounds (IVOCs, C* = 300 to 3 × 106 μg m−3), semi-volatile organic compounds (SVOCs, C* = 0.3–300 μg m−3) as well as low- and extremely low-volatility organic compounds (L/ELVOCs, where LVOC C* ≤ 0.3 μg m−3). The profiles predicted that IVOCs would contribute significantly to SOA production and that the combustion of fuel wood and charcoal released some of the smallest proportions of SVOCs. A model was developed to examine SOA production from burning emissions which estimated that phenolics would contribute 10–70% of the SOA. Furanics were the most important reactive species, contributing 9–48% of the OH reactivity and 9–58% of the SOA. Different combustion sources were also compared, with emissions from fuel wood, crop residue, cow dung cake and municipal solid waste (MSW) burning shown to be 30, 90, 120 and 230 times more reactive with the OH radical than emissions from liquefied petroleum gas (LPG) fuel. This study also estimated 3–4 times more SOA from cow dung cake combustion and 6–7 more from MSW combustion than fuel wood under comparable combustion conditions. The results of this study suggest that emissions from the combustion of domestic solid fuel sources in Delhi have the potential to significantly degrade local and regional air quality. As a result, more effective mitigation strategies are required to limit the impacts of solid fuel combustion on human health in countries like India.
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    Emission estimates and inventories of non-methane volatile organic compounds from anthropogenic burning sources in India
    (Elsevier, 2021-06-08) Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Hopkins, James R.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Wild, Oliver; Nemitz, Eiko; Gadi, Ranu; Sahu, Lokesh K.; Mandal, Tuhin K.; Gurjar, Bhola R.; Rickard, Andrew R.; Lee, James D.; Hamilton, Jacqueline F.
    Comprehensive, spatially disaggregated emission inventories are required for many developing regions to evaluate the relative impacts of different sources and to develop mitigation strategies which can lead to effective emission controls. This study developed a 1 km2 non-methane volatile organic compound (NMVOC) emission model for the combustion of fuel wood, cow dung cake, municipal solid waste (MSW), charcoal, coal and liquefied petroleum gas (LPG) in India from 1993 to 2016. Inputs were selected from a range of detailed fuel consumption surveys and recent emission factors measured during comprehensive studies of local burning sources. For the census year of 2011, we estimated around 13 (5–47) Tg of NMVOCs were emitted from biomass and MSW combustion in India. Around 54% of these emissions were from residential solid biofuel combustion, 23% from open burning of MSW, 23% from crop residue burning on fields and <1% from LPG for cooking. NMVOC emissions from residential combustion were shown to be highly sensitive to the amount of cow dung cake combusted and this acted as a key pollution source across the Indo-Gangetic Plain. The results of this study indicate that multiple mitigation strategies are required across several different categories of burning source to achieve effective NMVOC emission reduction.
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    Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India
    (European Geosciences Union /Copernicus Publications, 2021-02-18) Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Farren, Naomi J.; Hopkins, James R.; Ward, Martyn W.; Swift, Stefan J.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu; Ahlawat, Sakshi; Yadav, Lokesh; Sharma, Sudhir K.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mullinger, Neil; Gadi, Ranu; Sahu, Lokesh K.; Tripathi, Nidhi; Rickard, Andrew R.; Lee, James D.; Mandal, Tuhin K.; Hamilton, Jacqueline F.
    Biomass burning emits significant quantities of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) in a complex mixture, probably containing many thousands of chemical species. These components are significantly more toxic and have poorly understood chemistry compared to volatile organic compounds routinely quantified in ambient air; however, analysis of I/SVOCs presents a difficult analytical challenge. The gases and particles emitted during the test combustion of a range of domestic solid fuels collected from across Delhi were sampled and analysed. Organic aerosol was collected onto Teflon (PTFE) filters, and residual low-volatility gases were adsorbed to the surface of solid-phase extraction (SPE) discs. A new method relying on accelerated solvent extraction (ASE) coupled to comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–ToF-MS) was developed. This highly sensitive and powerful analytical technique enabled over 3000 peaks from I/SVOC species with unique mass spectra to be detected. A total of 15 %–100 % of gas-phase emissions and 7 %–100 % of particle-phase emissions were characterised. The method was analysed for suitability to make quantitative measurements of I/SVOCs using SPE discs. Analysis of SPE discs indicated phenolic and furanic compounds were important for gas-phase I/SVOC emissions and levoglucosan to the aerosol phase. Gas- and particle-phase emission factors for 21 polycyclic aromatic hydrocarbons (PAHs) were derived, including 16 compounds listed by the US EPA as priority pollutants. Gas-phase emissions were dominated by smaller PAHs. The new emission factors were measured (mg kg−1) for PAHs from combustion of cow dung cake (615), municipal solid waste (1022), crop residue (747), sawdust (1236), fuelwood (247), charcoal (151) and liquefied petroleum gas (56). The results of this study indicate that cow dung cake and municipal solid waste burning are likely to be significant PAH sources, and further study is required to quantify their impact alongside emissions from fuelwood burning.
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    Emissions of non-methane volatile organic compounds from combustion of domestic fuels in Delhi, India
    (European Geosciences Union/Copernicus Publications, 2021-02-18) Stewart, Gareth J.; Acton, W. Joe F.; Nelson, Beth S.; Vaughan, Adam R.; Hopkins, James R.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu; Ahlawat, Sakshi; Yadav, Lokesh; Sharma, Sudhir K.; Dunmore, Rachel E.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mullinger, Neil; Gadi, Ranu; Sahu, Lokesh K.; Tripathi, Nidhi; Rickard, Andrew R.; Lee, James D.; Mandal, Tuhin K.; Hamilton, Jacqueline F.
    Twenty-nine different fuel types used in residential dwellings in northern India were collected from across Delhi (76 samples in total). Emission factors of a wide range of non-methane volatile organic compounds (NMVOCs) (192 compounds in total) were measured during controlled burning experiments using dual-channel gas chromatography with flame ionisation detection (DC-GC-FID), two-dimensional gas chromatography (GC × GC-FID), proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and solid-phase extraction two-dimensional gas chromatography with time-of-flight mass spectrometry (SPE-GC × GC–ToF-MS). On average, 94 % speciation of total measured NMVOC emissions was achieved across all fuel types. The largest contributors to emissions from most fuel types were small non-aromatic oxygenated species, phenolics and furanics. The emission factors (in g kg−1) for total gas-phase NMVOCs were fuelwood (18.7, 4.3–96.7), cow dung cake (62.0, 35.3–83.0), crop residue (37.9, 8.9–73.8), charcoal (5.4, 2.4–7.9), sawdust (72.4, 28.6–115.5), municipal solid waste (87.3, 56.6–119.1) and liquefied petroleum gas (5.7, 1.9–9.8). The emission factors measured in this study allow for better characterisation, evaluation and understanding of the air quality impacts of residential solid-fuel combustion in India.