Non-methane hydrocarbon (C&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;–C&amp;lt;sub&amp;gt;8&amp;lt;/sub&amp;gt;) sources and sinks around the Arabian Peninsula

Bourtsoukidis, Efstratios; Ernle, Lisa; Crowley, John N.; Lelieveld, Jos; Paris, Jean-Daniel; Pozzer, Andrea; Walter, David; Williams, Jonathan

doi:10.5194/acp-19-7209-2019

Cited by 53 publications

(71 citation statements)

References 93 publications

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“…With VOC and NO x emissions from ship exhausts (Boersma et al, 2015;Endresen, 2003;Huang et al, 2018) and VOCs from oil and gas operations (Buzcu and Fraser, 2006;Gilman et al, 2009Gilman et al, , 2013Schade and Roest, 2016;Milazzo et al, 2017), the air around the Arabian Peninsula is expected to contain significant levels of pollution. In Saudi Arabian cities, OH reactivity has been reported to range from 14 to 42 s −1 (from the sum of individual measurements), dominated by alkenes (Barletta et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

et al. 2019

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Abstract. The Arabian Peninsula is characterized by high and increasing levels of photochemical air pollution. Strong solar irradiation, high temperatures and large anthropogenic emissions of reactive trace gases result in intense photochemical activity, especially during the summer months. However, air chemistry measurements in the region are scarce. In order to assess regional pollution sources and oxidation rates, the first ship-based direct measurements of total OH reactivity were performed in summer 2017 from a vessel traveling around the peninsula during the AQABA (Air Quality and Climate Change in the Arabian Basin) campaign. Total OH reactivity is the total loss frequency of OH radicals due to all reactive compounds present in air and defines the local lifetime of OH, the most important oxidant in the troposphere. During the AQABA campaign, the total OH reactivity ranged from below the detection limit (5.4 s−1) over the northwestern Indian Ocean (Arabian Sea) to a maximum of 32.8±9.6 s−1 over the Arabian Gulf (also known as Persian Gulf) when air originated from large petroleum extraction/processing facilities in Iraq and Kuwait. In the polluted marine regions, OH reactivity was broadly comparable to highly populated urban centers in intensity and composition. The permanent influence of heavy maritime traffic over the seaways of the Red Sea, Gulf of Aden and Gulf of Oman resulted in median OH sinks of 7.9–8.5 s−1. Due to the rapid oxidation of direct volatile organic compound (VOC) emissions, oxygenated volatile organic compounds (OVOCs) were observed to be the main contributor to OH reactivity around the Arabian Peninsula (9 %–35 % by region). Over the Arabian Gulf, alkanes and alkenes from the petroleum extraction and processing industry were an important OH sink with ∼9 % of total OH reactivity each, whereas NOx and aromatic hydrocarbons (∼10 % each) played a larger role in the Suez Canal, which is influenced more by ship traffic and urban emissions. We investigated the number and identity of chemical species necessary to explain the total OH sink. Taking into account ∼100 individually measured chemical species, the observed total OH reactivity can typically be accounted for within the measurement uncertainty (50 %), with 10 dominant trace gases accounting for 20 %–39 % of regional total OH reactivity. The chemical regimes causing the intense ozone pollution around the Arabian Peninsula were investigated using total OH reactivity measurements. Ozone vs. OH reactivity relationships were found to be a useful tool for differentiating between ozone titration in fresh emissions and photochemically aged air masses. Our results show that the ratio of NOx- and VOC-attributed OH reactivity was favorable for ozone formation almost all around the Arabian Peninsula, which is due to NOx and VOCs from ship exhausts and, often, oil/gas production. Therewith, total OH reactivity measurements help to elucidate the chemical processes underlying the extreme tropospheric ozone concentrations observed in summer over the Arabian Basin.

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Section: Introductionmentioning

confidence: 99%

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

et al. 2019

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“…The uptake coefficient to the particle phase is represented by γ and the ClNO 2 yield (per N 2 O 5 taken up) by f . on temperature, relative humidity (RH), and aerosol composition (Brown et al, 2006(Brown et al, , 2009(Brown et al, , 2016Riedel et al, 2012b;Wagner et al, 2013;Morgan et al, 2015;Phillips et al, 2016). A value of ≈ 0.03 has been derived from measurements in the polluted marine environment (Aldener et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Shipborne measurements of ClNO<sub>2</sub> in the Mediterranean Sea and around the Arabian Peninsula during summer

et al. 2019

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Abstract. Shipborne measurements of nitryl chloride (ClNO2), hydrogen chloride (HCl) and sulfur dioxide (SO2) were made during the AQABA (Air Quality and climate change in the Arabian BAsin) ship campaign in summer 2017. The dataset includes measurements over the Mediterranean Sea, the Suez Canal, the Red Sea, the Gulf of Aden, the Arabian Sea, the Gulf of Oman, and the Arabian Gulf (also known as Persian Gulf) with observed ClNO2 mixing ratios ranging from the limit of detection to ≈600 pptv. We examined the regional variability in the generation of ClNO2 via the uptake of dinitrogen pentoxide (N2O5) to Cl-containing aerosol and its importance for Cl atom generation in a marine boundary layer under the (variable) influence of emissions from shipping and the oil industry. The yield of ClNO2 formation per NO3 radical generated was generally low (median of ≈1 %–5 % depending on the region), mainly as a result of gas-phase loss of NO3 dominating over heterogeneous loss of N2O5, the latter being disfavoured by the high temperatures found throughout the campaign. The contributions of ClNO2 photolysis and OH-induced HCl oxidation to Cl-radical formation were derived and their relative contributions over the diel cycle compared. The results indicate that over the northern Red Sea, the Gulf of Suez, and the Gulf of Oman the formation of Cl atoms will enhance the oxidation rates of some volatile organic compounds (VOCs), especially in the early morning.

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“…The actinic flux was measured by a spectral radiometer. Non methane hydrocarbons (NMHC) mixing ratios were measured by a gas chromatograph with flame ionization detector (GC−FID), for a detailed instrumental description see Bourtsoukidis et al (2019). Formaldehyde mixing ratios were determined by a modified and optimized version of the commercially available AL4021 (Aero-Laser, Germany), which utilizes the Hantzsch technique (Stickler et al, 2006).…”

Section: Meteorological Data and Other Trace Gasesmentioning

confidence: 99%

“…Around the Arabian Peninsula, the mixing ratios of individual carbonyl compounds varied over a wide range, from tens of ppt to ppb levels. In this study, we divided the dataset geographically into eight regions (Figure 2 Gulf (AG), the same as those described by Bourtsoukidis et al (2019). Figure 2 shows the abundance of aliphatic, aromatic and unsaturated carbonyl compounds (carbonyls) for each region.…”

Section: Overview Of Carbonyl Compoundsmentioning

confidence: 99%

“…Within brackets under the region acronyms the main characteristics of the air masses are indicated, based on variability-lifetime results (b factor) from Bourtsoukidis et al (2019) and acetone mixing ratios in this study. The data used for map plotting was from public domain GIS data found on the Natural Earth web site (http://www.naturalearthdata.com) and was read into Igor using the IgorGIS XOP beta.…”

Section: Overview Of Carbonyl Compoundsmentioning

confidence: 99%

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Measurements of carbonyl compounds around the Arabian Peninsula indicate large missing sources of acetaldehyde

Wang

Edtbauer

Stönner

et al. 2020

Preprint

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Abstract. Volatile organic compounds (VOCs) were measured around the Arabian Peninsula using a research vessel during the AQABA campaign (Air Quality and Climate Change in the Arabian Basin) from June to August 2017. In this study we examine carbonyl compounds (CxHyO), measured by a proton transfer reaction mass spectrometer (PTR-ToF-MS), and present both a regional concentration distribution and a budget assessment for these key atmospheric species. Among the aliphatic carbonyls, acetone had the highest mixing ratios in most of the regions traversed, varying from 0.43 ppb over the Arabian Sea to 4.5 ppb over the Arabian Gulf, followed by formaldehyde (measured by Hantzsch monitor, 0.82 ppb over the Arabian Sea and 3.8 ppb over the Arabian Gulf) and acetaldehyde (0.16 ppb over the Arabian Sea and 1.7 ppb over the Arabian Gulf). Unsaturated carbonyls (C4–C9) varied from 10 to 700 ppt during the campaign, and followed similar regional mixing ratio dependence as aliphatic carbonyls, which were identified as oxidation products of cycloalkanes over polluted areas. An empirical method based on hydrocarbon ratios was applied to investigate the photochemical source strength of the aliphatic carbonyls. While the distribution and relative concentration enhancements of the C3–C8 aliphatic carbonyls could be explained by this method, that of acetaldehyde could not. A smaller but still significant discrepancy was found when comparing measurements to global chemistry-transport model (EMAC) results, with the model underestimating the measured acetaldehyde mixing ratio up to an order of magnitude. Implementing a photolytically driven marine source of acetaldehyde significantly improved the agreement between measurements and model, particularly over the remote regions (e.g. Arabian Sea). However, the newly introduced acetaldehyde source was still insufficient to describe the observations over the most polluted regions (Arabian Gulf and Suez), where model underestimation of primary emissions and biomass burning events are possible reasons.

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Non-methane hydrocarbon (C<sub>2</sub>–C<sub>8</sub>) sources and sinks around the Arabian Peninsula

Cited by 53 publications

References 93 publications

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

Shipborne measurements of ClNO<sub>2</sub> in the Mediterranean Sea and around the Arabian Peninsula during summer

Measurements of carbonyl compounds around the Arabian Peninsula indicate large missing sources of acetaldehyde

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Non-methane hydrocarbon (C&lt;sub&gt;2&lt;/sub&gt;–C&lt;sub&gt;8&lt;/sub&gt;) sources and sinks around the Arabian Peninsula

Cited by 53 publications

References 93 publications

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

Shipborne measurements of total OH reactivity around the Arabian Peninsula and its role in ozone chemistry

Shipborne measurements of ClNO&lt;sub&gt;2&lt;/sub&gt; in the Mediterranean Sea and around the Arabian Peninsula during summer

Measurements of carbonyl compounds around the Arabian Peninsula indicate large missing sources of acetaldehyde

Contact Info

Product

Resources

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Non-methane hydrocarbon (C<sub>2</sub>–C<sub>8</sub>) sources and sinks around the Arabian Peninsula

Shipborne measurements of ClNO<sub>2</sub> in the Mediterranean Sea and around the Arabian Peninsula during summer