Multiphase Halogen Chemistry in the Tropical Atlantic Ocean

We used a one-dimensional model to simulate the chemical evolution of air masses in the tropical Atlantic Ocean, with a focus on halogen chemistry. The model results were compared to the observations of inorganic halogen species made in this region. The model could largely reproduce the measurements of most chlorine species, especially under unpolluted conditions, but overestimated sea salt chloride, BrCl, and bromine species. Agreement with the measurements could be improved by taking into account the reactivity with aldehydes and the effects of dimethyl sulfide (DMS) and Saharan dust on aerosol pH; a hypothetical HOX → X^– aqueous-phase reaction could also improve the agreement with measured Cl₂ and HOCl, especially under semipolluted conditions. The results also showed that halogens speciation and concentrations are very sensitive to cloud processing. The model was used to calculate the impact of the observed levels of halogens: Cl atoms accounted for 5.4–11.6% of total methane sinks and halogens (mostly bromine and iodine) accounted for 35–40% of total ozone destruction

Opinion: Papers that shaped tropospheric chemistry

Which published papers have transformed our understanding of the chemical processes in the troposphere and shaped the field of atmospheric chemistry? By way of expert solicitation and interactive peer review, this paper explores the influence of the ideas in peer-reviewed articles based on input from our community of atmospheric scientists. We explore how these papers have shaped the development of the field of atmospheric chemistry and identify the major landmarks in the field of atmospheric chemistry through the lens of those papers' impact on science, legislation and environmental events. We also explore the ways in which one can identify the papers that have most impacted the field and discuss the advantages and disadvantages of the various approaches. Our work highlights the difficulty of creating a simple list, and we explore the reasons for this difficulty. The paper also provides a history of the development of our understanding of tropospheric chemistry and points some ways for the future.</p

Observations of the release of non-methane hydrocarbons from fractured shale.

The organic content of shale has become of commercial interest as a source of hydrocarbons, owing to the development of hydraulic fracturing ("fracking"). While the main focus is on the extraction of methane, shale also contains significant amounts of non-methane hydrocarbons (NMHCs). We describe the first real-time observations of the release of NMHCs from a fractured shale. Samples from the Bowland-Hodder formation (England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the dynamic process of gas release upon fracturing of the shale. A wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic hydrocarbons) are released at parts per million or parts per billion level with temperature- and humidity-dependent release rates, which can be rationalized in terms of the physicochemical characteristics of different hydrocarbon classes. Our results indicate that higher energy inputs (i.e., temperatures) significantly increase the amount of NMHCs released from shale, while humidity tends to suppress it; additionally, a large fraction of the gas is released within the first hour after the shale has been fractured. These findings suggest that other hydrocarbons of commercial interest may be extracted from shale and open the possibility to optimize the "fracking" process, improving gas yields and reducing environmental impacts

Enhanced wintertime oxidation of VOCs via sustained radical sources in the urban atmosphere

Daytime atmospheric oxidation chemistry is conventionally considered to be driven primarily by the OH radical, formed via photolytic sources. In this paper we examine how, during winter when photolytic processes are slow, chlorine chemistry can have a significant impact on oxidative processes in the urban boundary layer. Photolysis of nitryl chloride (ClNO2) provides a significant source of chlorine atoms, which enhances the oxidation of volatile organic compounds (VOCs) and the production of atmospheric pollutants.We present a set of observations of ClNO2 and HONO made at urban locations in central England in December 2014 and February 2016. While direct emissions and in-situ chemical formation of HONO continue throughout the day, ClNO2 is only formed at night and is usually completely photolyzed by midday. Our data show that, during winter, ClNO2 often persists through the daylight hours at mixing ratios above 10–20 ppt (on average). In addition, relatively high mixing ratios of daytime HONO (65 ppt) provide a strong source of OH radicals throughout the day.The combined effects of ClNO2 and HONO result in sustained sources of Cl and OH radicals from sunrise to sunset, which form additional ozone, PAN, oxygenated VOCs, and secondary organic aerosol. We show that radical sources such as ClNO2 and HONO can lead to a surprisingly photoactive urban atmosphere during winter and should therefore be included in atmospheric chemical models.</div

Observations of the Release of Non-methane Hydrocarbons from Fractured Shale

The organic content of shale has become of commercial interest as a source of hydrocarbons, owing to the development of hydraulic fracturing (“fracking”). While the main focus is on the extraction of methane, shale also contains significant amounts of non-methane hydrocarbons (NMHCs). We describe the first real-time observations of the release of NMHCs from a fractured shale. Samples from the Bowland-Hodder formation (England) were analyzed under different conditions using mass spectrometry, with the objective of understanding the dynamic process of gas release upon fracturing of the shale. A wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic hydrocarbons) are released at parts per million or parts per billion level with temperature- and humidity-dependent release rates, which can be rationalized in terms of the physicochemical characteristics of different hydrocarbon classes. Our results indicate that higher energy inputs (i.e., temperatures) significantly increase the amount of NMHCs released from shale, while humidity tends to suppress it; additionally, a large fraction of the gas is released within the first hour after the shale has been fractured. These findings suggest that other hydrocarbons of commercial interest may be extracted from shale and open the possibility to optimize the “fracking” process, improving gas yields and reducing environmental impacts

Radical chemistry and ozone production at a UK coastal receptor site

Abstract. OH, HO2, total and partially speciated RO2, and OH reactivity (kOH′) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in north Norfolk, UK. Maximum measured daily OH, HO2 and total RO2 radical concentrations were in the range 2.6–17 × 106, 0.75–4.2 × 108 and 2.3–8.0 × 108 molec. cm−3, respectively. kOH′ ranged from 1.7 to 17.6 s−1, with a median value of 4.7 s−1. ICOZA data were split by wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW–SE sectors) and that over major urban conurbations such as London (SW sector). A box model using the Master Chemical Mechanism (MCMv3.3.1) was in reasonable agreement with the OH measurements, but it overpredicted HO2 observations in NW–SE air in the afternoon by a factor of ∼ 2–3, although slightly better agreement was found for HO2 in SW air (factor of ∼ 1.4–2.0 underprediction). The box model severely underpredicted total RO2 observations in both NW–SE and SW air by factors of ∼ 8–9 on average. Measured radical and kOH′ levels and measurement–model ratios displayed strong dependences on NO mixing ratios, with the results suggesting that peroxy radical chemistry is not well understood under high-NOx conditions. The simultaneous measurement of OH, HO2, total RO2 and kOH′ was used to derive experimental (i.e. observationally determined) budgets for all radical species as well as total ROx (i.e. OH + HO2 + RO2). In NW–SE air, the ROx budget could be closed during the daytime within experimental uncertainty, but the rate of OH destruction exceeded the rate of OH production, and the rate of HO2 production greatly exceeded the rate of HO2 destruction, while the opposite was true for RO2. In SW air, the ROx budget analysis indicated missing daytime ROx sources, but the OH budget was balanced, and the same imbalances were found with the HO2 and RO2 budgets as in NW–SE air. For HO2 and RO2, the budget imbalances were most severe at high-NO mixing ratios, and the best agreement between HO2 and RO2 rates of production and destruction rates was found when the RO2 + NO rate coefficient was reduced by a factor of 5. A photostationary-steady-state (PSS) calculation underpredicted daytime OH in NW–SE air by ∼ 35 %, whereas agreement (∼ 15 %) was found within instrumental uncertainty (∼ 26 % at 2σ) in SW air. The rate of in situ ozone production (P(Ox)) was calculated from observations of ROx, NO and NO2 and compared to that calculated from MCM-modelled radical concentrations. The MCM-calculated P(Ox) significantly underpredicted the measurement-calculated P(Ox) in the morning, and the degree of underprediction was found to scale with NO.</p

Images of Research 2019

Images Of Research 2019 Winners: Yang Chen – ‘Spiral Up and Down’ - Judges’ Prize Winner Dina El-Hamamsy – ‘Where is my patient Patient?’ - Joint Judges’ Prize Runners-up Tom Matheson – ‘Ginormous Genome’ (1) - Joint Judges’ Prize Runners-up Styliano Spathariotis – ‘Girl with a Metallic Earring’ - Katherine May People’s Choice Winner Soheb Mandhai – ‘The Cosmic Dance of Two Neutron Stars’ - People’s Choice Runner-up Brandon Fathy – ‘Speed, Space, and Time’ - Leicester Institute of Advanced Studies Interdisciplinary Prize Images Of Research 2018 submissions: Abbey Ellis – ‘Carving Out an Understanding’ (1) Abbey Ellis – ‘The Art of the Reproduction’ (2) Ahmed Elimam - Untitled Artur Soczawa-Stronczyk – ‘Do the locomotion with me’ Aseel Alfuhied – ‘Cosmic storm in the heart of darkness’ (1) Aseel Alfuhied – ‘Heart to Heart’ (2) Aseel Alfuhied – ‘Pop Heart’ (3) Beatriz Sanchez-Cano – ‘The Sun, our neural connection’ Cesare Cuzzola – ‘Buddha Day 2019’ Charlotte Barratt – ‘Sound’ (1) Charlotte Barratt – ‘Girl Praying’ (2) Chris Allen – ‘Perceptions and Realities: Building Community Resilience Against Extremism’ (1) Chris Allen – ‘Perceptions and Realities: Building Community Resilience Against Extremism’ (2) David Unwin – ‘Death flight’ Diane Urquhart – ‘Laying ghosts to rest’ Eloisa Rodrigues – ‘Tropical self-portrait’ Fernando Schlindwein – ‘Chaos in the heart’ (1) Fernando Schlindwein – ‘Porcupine’ (2) Graham Frobisher – ‘The 7th Decade Manager’ Hanna McQuail – ‘That colossal wreck, boundless and bare’ Hatice Kayman – ‘Immigrants have opportunities to do their festivals in London’ Hedwig Krawczyk – ‘Underwater Time Machines’ Hipolito Treffinger – ‘Layers’ Jacqueline Taylor – ‘Miriam Haughton at the British Academy’ Jan Vandeburie – ‘Dress to Impress’ Jennifer Beamer – ‘Human-Animal Relationships in Weaving’ John Goodwin – ‘Slow Sociology in South Wigston’ Kinga Kolodziej – ‘In a blink of an eye…’ (1) Kinga Kolodziej – ‘In a blink of an eye…’ (2) Kristina Wright – ‘Janus-Faced Seoul’ Kseniia Bondarenko – ‘Your brain drives me crazy’ (1) Kseniia Bondarenko – ‘Your brain drives me crazy’ (2) Liam Crawford – ‘The heartfelt love story between one nanoparticle and another’ Lisa Huddlestone – ‘Seeing the wood and the trees’ (1) Lisa Huddlestone – ‘Seeing the wood and the trees’ (2) Margarita Avgerinopoulou – ‘A dash of magic’ (1) Margarita Avgerinopoulou – ‘Fantasy at the making’ (2) Martha Papadopoulou – ‘The power of a drop’ (1) Martha Papadopoulou – ‘Every drop counts’! (2) Mayamin Altae - Untitled (or the Tennyson quote) Michael Curtis – ‘The arrival of the shoreline detective’ (1) Michael Curtis – ‘The arrival of the shoreline detective’ (2) Neelam Dave – ‘The damage bacteria can do’ Neil Harris – ‘Colour amongst the chaos’ Nitu Gupta – ‘Far Beyond Insecurities’ Nora Ngii Musyoka – ‘She’s Just the Other Half of Me’ Nukul Charlin – ‘Why are Ladyboy Tolerated in Thai Society?’ Pariyakorn Petkaew – ‘Be silent…Be thinking’ Rachel Belben – ‘Ardeadactylus longicollum’ (1) Rachel Belben – ‘Psittacosaurus’ (2) Roberto Sommariva - Untitled Saima Ahmad – ‘The Command Centre’ (1) Saima Ahmad – ‘Vial do you see it?’ (2) Saima Ahmad – ‘Beyond the Canopy’ (3) Samuel J Perry – ‘Metallic snowflakes’ (1) Samuel J Perry – ‘Metallic snowflakes’ (2) Stephanie Bowry – ‘Storm Clouds over Vaux-le-Vicomte’ Tom Matheson – ‘Ginormous Genome’ (2) Yewande Okuleye – ‘Commemoration, Remembrance and Bodies of Evidence’ Yewande Okuleye, Robert Garner – ‘From pain to pleasure: We no longer just eat our greens, it’s imperative to photograph share and like on Instagram.’ (1) Yewande Okuleye, Robert Garner – ‘A green plaque for animal ethics?’ (2) Yewande Okuleye, Robert Garner – ‘A green plaque for animal ethics?’ (3)</p