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  • 1
    Electronic Resource
    Electronic Resource
    Iodine Chemistry and its Role in Halogen Activation and Ozone Loss in the Marine Boundary Layer: A Model Study (1999)
    Springer
    Journal of atmospheric chemistry 32 (1999), S. 375-395 
    Details
    ISSN: 1573-0662
    Keywords: aerosol ; iodine chemistry ; halogen chemistry ; marine boundary layer ; modeling ; ozone loss ; sea salt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A detailed set of reactions treating the gas and aqueous phase chemistry of the most important iodine species in the marine boundary layer (MBL) has been added to a box model which describes Br and Cl chemistry in the MBL. While Br and Cl originate from seasalt, the I compounds are largely derived photochemically from several biogenic alkyl iodides, in particular CH2I2, CH2ClI, C2H5I, C3H7I, or CH3I which are released from the sea. Their photodissociation produces some inorganic iodine gases which can rapidly react in the gas and aqueous phase with other halogen compounds. Scavenging of the iodine species HI, HOI, INO2, and IONO2 by aerosol particles is not a permanent sink as assumed in previous modeling studies. Aqueous-phase chemical reactions can produce the compounds IBr, ICl, and I2, which will be released back into the gas phase due to their low solubility. Our study, although highly theoretical, suggests that almost all particulate iodine is in the chemical form of IO-3. Other aqueous-phase species are only temporary reservoirs and can be re-activated to yield gas phase iodine. Assuming release rates of the organic iodine compounds which yield atmospheric concentrations similar to some measurements, we calculate significant concentrations of reactive halogen gases. The addition of iodine chemistry to our reaction scheme has the effect of accelerating photochemical Br and Cl release from the seasalt. This causes an enhancement in ozone destruction rates in the MBL over that arising from the well established reactions O(1D) + H2O → 2OH, HO2 + O3 → OH + 2O2, and OH + O3 → HO2 + O2. The given reaction scheme accounts for the formation of particulate iodine which is preferably accumulated in the smaller sulfate aerosol particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006179901037
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Multiphase Halogen Chemistry in the Tropical Atlantic Ocean (2012)
    ACS (American Chemical Society)
    In:  Environmental Science & Technology, 46 (19). pp. 10429-10437.
    Details
    Publication Date: 2020-07-31
    Description: 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 Cl-2 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.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1021/es300209f
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Evolving research directions in Surface Ocean - Lower Atmosphere (SOLAS) science (2013)
    CSIRO
    In:  Environmental Chemistry, 10 (1). pp. 1-16.
    Details
    Publication Date: 2018-09-12
    Description: This review focuses on critical issues in ocean–atmosphere exchange that will be addressed by new research strategies developed by the international Surface Ocean–Lower Atmosphere Study (SOLAS) research community. Eastern boundary upwelling systems are important sites for CO2 and trace gas emission to the atmosphere, and the proposed research will examine how heterotrophic processes in the underlying oxygen-deficient waters interact with the climate system. The second regional research focus will examine the role of sea-ice biogeochemistry and its interaction with atmospheric chemistry. Marine aerosols are the focus of a research theme directed at understanding the processes that determine their abundance, chemistry and radiative properties. A further area of aerosol-related research examines atmospheric nutrient deposition in the surface ocean, and how differences in origin, atmospheric processing and composition influence surface ocean biogeochemistry. Ship emissions are an increasing source of aerosols, nutrients and toxins to the atmosphere and ocean surface, and an emerging area of research will examine their effect on ocean biogeochemistry and atmospheric chemistry. The primary role of SOLAS is to coordinate coupled multi-disciplinary research within research strategies that address these issues, to achieve robust representation of critical ocean–atmosphere exchange processes in Earth System models.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1071/EN12159
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Halocarbon sources and emissions over the Western Pacific (2011)
    In:  [Talk] In: EGU General Assembly 2011, 03.-08.04.2011, Vienna, Austria .
    Details
    Publication Date: 2019-09-23
    Description: Natural, short-lived halocarbons play a role in the tropospheric and stratospheric ozone budget. The tropical oceans are a known source of reactive iodine and bromine to the atmosphere in the form of iodinated and brominated very short lived substances (VSLS), as e.g. methyl iodide (CH3I), bromoform (CHBr3) and dibromomethane (CH2Br2), which contribute to tropospheric and stratospheric halogens. Elevated atmospheric concentrations above the oceans are related to oceanic supersaturations of the compounds, caused by photochemical and biological production. The tropical Western Pacific is of special interest since it is a largely uncharacterized region for the oceanic compounds and in certain regions a projected hot spot for their emissions and transport pathways through the free troposphere into the stratosphere. From 9 to 25 October 2009 the IFM-GEOMAR (Kiel, Germany) conducted a cruise with RV Sonne in the tropical Western Pacific to investigate trace gas emissions on a 4030 nm (7,500 km) and 60 degrees latitude covering transit between Tomakomai (Japan, 42°N/ 141°E) and Townsville (Australia, 19°S/ 146°E). We will present highlights of the oceanic and atmospheric halogen (inorganic and organic compounds) and ozone measurements, as well as transport simulations of the organic compounds with the Lagrangian particle dispersion model FLEXPART, including the photochemical decay and the wash out of the VSLS source and product gases.
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 5
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    Shipborne MAX-DOAS Measurements of Reactive Halogen Species over the Western Pacific and the Eastern North Atlantic (2011)
    Details
    Publication Date: 2023-01-31
    Description: Reactive halogen species (RHS) exert various influences on the photochemistry of the marine boundary layer. They are formed in the marine atmosphere for example from precursors released from sea salt aerosols, through the degradation of organo-halogens emitted by certain algae, or from inorganic aqueous reactions. The halogen radicals (BrO and IO) can destroy ozone catalytically, oxidize dimethyl sulfide (DMS) or cause the formation of new aerosol particles. However, there are still open questions concerning the abundance and significance of RHS in the marine boundary layer over the open ocean. Therefore, measurements of BrO and IO abundances were carried out during two ship cruises in two different parts of the ocean, i.e. the Western Pacific and the Eastern Tropical North Atlantic. The measurements were performed with Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). From the spectral analysis of spectra of scattered sunlight recorded at different elevation angles, information about the vertical distribution and the concentration of trace gases can be derived. During the "TransBrom-Sonne" cruise on the German research vessel “Sonne” in the Western Pacific from Tomakomai, Japan (42°N/ 141°E) to Townsville, Australia (19°S/ 146°E) during October 2009, BrO could be detected in very small amounts in the marine boundary layer (MBL) close to Micronesia and Papua New Guinea, with maximum BrO mixing ratios around 2 ppt and a detection limit of 0.8 ppt. During the whole cruise, tropospheric IO clearly exceeded the detection limit of 0.6 ppt. The bulk of the IO was located in the lower troposphere up to 1 km. In the tropics, the IO concentration reached maximum values between 1 and 2.5 ppt. IO was measured in the Western Pacific for the first time and was used as input for model calculations of tropospheric chemistry. Further measurements of BrO and IO were carried out during a campaign on the German research vessel “Poseidon” in June 2010 in the Eastern North Atlantic from Las Palmas, Gran Canaria via the Cape Verde Islands and back along the West African Coast to Vigo, Spain. Close to the Mauritanian Coast tropospheric BrO could be detected at a maximum mixing ratio of approximately 10 ppt at an assumed layer height of 1 km, whereas IO was present only in very small amounts close to the detection limit during the whole cruise. The measurements indicate that reactive halogens, in particular iodine, are likely to have a significant impact on the photochemistry of the marine boundary layer, at least in oceanic regions of upwelling waters or of large biological activity.
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 6
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    Shipborne MAX-DOAS Measurements of Reactive Halogen Species over the Western Pacific and the Eastern North Atlantic (2011)
    Details
    Publication Date: 2023-01-31
    Description: Reactive halogen species (RHS) exert various influences on the photochemistry of the marine boundary layer. They are formed in the marine atmosphere for example from precursors released from sea salt aerosols, through the degradation of organo-halogens emitted by certain algae, or from inorganic aqueous reactions. The halogen radicals (BrO and IO) can destroy ozone catalytically, oxidize dimethyl sulfide (DMS) or cause the formation of new aerosol particles. However, there are still open questions concerning the abundance and significance of RHS in the marine boundary layer over the open ocean. Therefore, measurements of BrO and IO abundances were carried out during two ship cruises in two different parts of the ocean, i.e. the Western Pacific and the Eastern Tropical North Atlantic. The measurements were performed with Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). From the spectral analysis of spectra of scattered sunlight recorded at different elevation angles, information about the vertical distribution and the concentration of trace gases can be derived. During the "TransBrom-Sonne" cruise on the German research vessel “Sonne” in the Western Pacific from Tomakomai, Japan (42°N/ 141°E) to Townsville, Australia (19°S/ 146°E) during October 2009, BrO could be detected in very small amounts in the marine boundary layer (MBL) close to Micronesia and Papua New Guinea, with maximum BrO mixing ratios around 2 ppt and a detection limit of 0.8 ppt. During the whole cruise, tropospheric IO clearly exceeded the detection limit of 0.6 ppt. The bulk of the IO was located in the lower troposphere up to 1 km. In the tropics, the IO concentration reached maximum values between 1 and 2.5 ppt. IO was measured in the Western Pacific for the first time and was used as input for model calculations of tropospheric chemistry. Further measurements of BrO and IO were carried out during a campaign on the German research vessel “Poseidon” in June 2010 in the Eastern North Atlantic from Las Palmas, Gran Canaria via the Cape Verde Islands and back along the West African Coast to Vigo, Spain. Close to the Mauritanian Coast tropospheric BrO could be detected at a maximum mixing ratio of approximately 10 ppt at an assumed layer height of 1 km, whereas IO was present only in very small amounts close to the detection limit during the whole cruise. The measurements indicate that reactive halogens, in particular iodine, are likely to have a significant impact on the photochemistry of the marine boundary layer, at least in oceanic regions of upwelling waters or of large biological activity.
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Poster
  • 7
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    Dimethylsulphide and halocarbon concentrations taken from 10m integrated samples during the 2012 KOSMOS Finland Mesocosm experiment (2016)
    PANGAEA
    In:  Supplement to: Webb, Alison L; Leedham-Elvidge, Emma; Hughes, Claire; Hopkins, Frances E; Malin, Gill; Bach, Lennart Thomas; Schulz, Kai Georg; Crawfurd, Katharine J; Brussaard, Corina P D; Stuhr, Annegret; Riebesell, Ulf; Liss, Peter S (2016): Effect of ocean acidification and elevated fCO2 on trace gas production by a Baltic Sea summer phytoplankton community. Biogeosciences, 13(15), 4595-4613, https://doi.org/10.5194/bg-13-4595-2016
    Details
    Publication Date: 2024-03-06
    Description: The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on trace gas biogeochemistry, a large-scale mesocosm experiment was performed off Tvärminne Research Station, Finland in summer 2012. During the second half of the experiment, dimethylsulphide (DMS) concentrations in the highest fCO2 mesocosms (1075-1333 µatm) were 34 % lower than at ambient CO2 (350 µatm). However the net production (as measured by concentration change) of seven halocarbons analysed was not significantly affected by even the highest CO2 levels after 5 weeks exposure. Methyl iodide (CH3I) and diiodomethane (CH2I2) showed 15 % and 57 % increases in mean mesocosm concentration (3.8 ± 0.6 pmol L-1 increasing to 4.3 ± 0.4 pmol L-1 and 87.4 ± 14.9 pmol L-1 increasing to 134.4 ± 24.1 pmol L-1 respectively) during Phase II of the experiment, which were unrelated to CO2 and corresponded to 30 % lower Chl-? concentrations compared to Phase I. No other iodocarbons increased or showed a peak, with mean chloroiodomethane (CH2ClI) concentrations measured at 5.3 (± 0.9) pmol L-1 and iodoethane (C2H5I) at 0.5 (± 0.1) pmol L-1. Of the concentrations of bromoform (CHBr3; mean 88.1 ± 13.2 pmol L-1), dibromomethane (CH2Br2; mean 5.3 ± 0.8 pmol L-1) and dibromochloromethane (CHBr2Cl, mean 3.0 ± 0.5 pmol L-1), only CH2Br2 showed a decrease of 17 % between Phases I and II, with CHBr3 and CHBr2Cl showing similar mean concentrations in both Phases. Outside the mesocosms, an upwelling event was responsible for bringing colder, high CO2, low pH water to the surface starting on day t16 of the experiment; this variable CO2 system with frequent upwelling events implies the community of the Baltic Sea is acclimated to regular significant declines in pH caused by up to 800 µatm fCO2. After this upwelling, DMS concentrations declined, but halocarbon concentrations remained similar or increased compared to measurements prior to the change in conditions. Based on our findings, with future acidification of Baltic Sea waters, biogenic halocarbon emissions are likely to remain at similar values to today, however emissions of biogenic sulphur could significantly decrease from this region.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification; Chloroiodomethane; DATE/TIME; Day of experiment; Dibromochloromethane; Dibromomethane; Diiodomethane; Dimethyl sulfide, dissolved; Iodoethane; Iodomethane; KOSMOS_2012_Tvaerminne; MESO; Mesocosm experiment; Mesocosm label; SOPRAN; Surface Ocean Processes in the Anthropocene; Treatment; Tribromomethane
    Type: Dataset
    Format: text/tab-separated-values, 1911 data points
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    DATA PANGAEA
  • 8
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    Dimethylsulphide (DMS), dimethylsulphonioproionate (DMSP) and halocarbon concentrations taken from 25m integrated samples during the 2011 SOPRAN Bergen Raunefjord Mesocosm experiment, Norway (2016)
    PANGAEA
    In:  Supplement to: Webb, Alison L; Malin, Gill; Hopkins, Frances E; Ho, Kai Lam; Riebesell, Ulf; Schulz, Kai Georg; Larsen, Aud; Liss, Peter S (2016): Ocean acidification has different effects on the production of dimethylsulfide and dimethylsulfoniopropionate measured in cultures of Emiliania huxleyi and a mesocosm study: a comparison of laboratory monocultures and community interactions. Environmental Chemistry, 13(2), 314, https://doi.org/10.1071/EN14268
    Details
    Publication Date: 2024-02-01
    Description: The human-induced rise in atmospheric carbon dioxide since the industrial revolution has led to increasing oceanic carbon uptake and changes in seawater carbonate chemistry, resulting in lowering of surface water pH. In this study we investigated the effect of increasing CO2 partial pressure (pCO2) on concentrations of volatile biogenic dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP), through monoculture studies and community pCO2 perturbation. DMS is a climatically important gas produced by many marine algae: it transfers sulfur into the atmosphere and is a major influence on biogeochemical climate regulation through breakdown to sulfate and formation of subsequent cloud condensation nuclei (CCN). Overall, production of DMS and DMSP by the coccolithophore Emiliania huxleyi strain RCC1229 was unaffected by growth at 900 µatm pCO2, but DMSP production normalised to cell volume was 12 % lower at the higher pCO2 treatment. These cultures were compared with community DMS and DMSP production during an elevated pCO2 mesocosm experiment with the aim of studying E. huxleyi in the natural environment. Results contrasted with the culture experiments and showed reductions in community DMS and DMSP concentrations of up to 60 and 32 % respectively at pCO2 up to 3000 µatm, with changes attributed to poorer growth of DMSP-producing nanophytoplankton species, including E. huxleyi, and potentially increased microbial consumption of DMS and dissolved DMSP at higher pCO2. DMS and DMSP production differences between culture and community likely arise from pH affecting the inter-species responses between microbial producers and consumers.
    Keywords: Chloroiodomethane; DATE/TIME; Day of experiment; Dibromochloromethane; Dibromomethane; Diiodomethane; Dimethyl sulfide, dissolved; Dimethylsulfoniopropionate; Dimethylsulfoniopropionate, particulate; Iodoethane; Iodomethane; KOSMOS_2011_Bergen; MESO; Mesocosm experiment; Mesocosm label; Raunefjord; SOPRAN; Surface Ocean Processes in the Anthropocene; Treatment; Tribromomethane
    Type: Dataset
    Format: text/tab-separated-values, 2590 data points
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    DATA PANGAEA
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