Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine

Carpenter, Lucy J.; MacDonald, S. M.; Shaw, Marvin; Kumar, Ravi; Saunders, R. W.; Parthipan, Rajendran; Wilson, Julie; Plane, J. M. C.

doi:10.1038/ngeo1687

Cited by 316 publications

(498 citation statements)

References 27 publications

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“…Correlation studies of ground-and ship-based IO and reactive iodine (IO x = IO + I) measurements with oceanic variables have shown that there is a negative correlation with Chl a and CDOM (colored dissolved organic matter), suggesting that the additional iodine production over the oceans is not biological and could be inhibited by the presence of increased biological activity or organic matter Gómez Martín et al, 2013;Großmann et al, 2013). This provides evidence for the widespread abiotic iodine source proposed by Garland and Curtis (1981): the sea surface oxidation of I − by O 3 to yield HOI and I 2 , which are then either released directly to the atmosphere or react with dissolved organic matter (Garland and Curtis, 1981;Martino et al, 2009;Carpenter et al, 2013). In addition, the correlation analysis showed significant correlations of IO x with sea surface temperature (SST) and salinity (SSS), which suggests that this abiotic mechanism will be influenced by oceanic variables.…”

Section: Introductionmentioning

confidence: 69%

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

et al. 2014

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Abstract.Reactive iodine compounds play a significant role in the atmospheric chemistry of the oceanic boundary layer by influencing the oxidising capacity through catalytically removing O 3 and altering the HO x and NO x balance. The sea-to-air flux of iodine over the open ocean is therefore an important quantity in assessing these impacts on a global scale. This paper examines the effect of a number of relevant environmental parameters, including water temperature, salinity and organic compounds, on the magnitude of the HOI and I 2 fluxes produced from the uptake of O 3 and its reaction with iodide ions in aqueous solution. The results of these laboratory experiments and those reported previously , along with sea surface iodide concentrations measured or inferred from measurements of dissolved total iodine and iodate reported in the literature, were then used to produce parameterised expressions for the HOI and I 2 fluxes as a function of wind speed, sea-surface temperature and O 3 . These expressions were used in the Tropospheric HAlogen chemistry MOdel (THAMO) to compare with MAX-DOAS measurements of iodine monoxide (IO) performed during the HaloCAST-P cruise in the eastern Pacific ocean . The modelled IO agrees reasonably with the field observations, although significant discrepancies are found during a period of low wind speeds (< 3 m s −1 ), when the model overpredicts IO by up to a factor of 3. The inorganic iodine flux contributions to IO are found to be comparable to, or even greater than, the contribution of organo-iodine compounds and therefore its inclusion in atmospheric models is important to improve predictions of the influence of halogen chemistry in the marine boundary layer.

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Section: Introductionmentioning

confidence: 69%

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

et al. 2014

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“…Several mechanisms have been introduced to explain the observations and are still under active discussion (e.g. Lawler et al, 2014;Carpenter et al, 2013;MacDonald et al, 2014). Some of these discrepancies may be explained by assuming seasonal or yearly cycles of the iodine sources, but there are also several uncertainties in the iodine chemical mechanism Saiz-Lopez et al, 2012b).…”

Section: P S Monks Et Al: Tropospheric Ozone and Its Precursorsmentioning

confidence: 99%

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

et al. 2015

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Abstract. Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone-climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales.

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“…As a consequence, CH 3 I is the main iodocarbon in the model that, through efficient transport within deep convection cells, is expected to reach the TTL. Additionally, abiotic oceanic sources of HOI and I 2 have been included in the lowest layer of the model, based on recent laboratory studies of the oxidation of aqueous iodide by atmospheric ozone deposited on the ocean surface [Carpenter et al, 2013]. Figure 1 summarizes in a simplified schematic the main gas-and condensed-phase iodine photochemistry processes in the troposphere and stratosphere.…”

Section: Model and Experimentsmentioning

confidence: 99%

“…The most recent estimates indicate that between 2 and 8 parts per trillion by volume (pptv) of VSL Br are injected to the stratosphere [World Meteorological Organization (WMO), 2014]. In the case of iodine, the oceans provide the main source of iodine compounds to the atmosphere [Carpenter et al, 2013;Saiz-Lopez et al, 2012a] where they reduce the global warming effect of ozone in the marine troposphere [Saiz-Lopez et al, 2012b]. Recent studies have reported values of 0.2-0.4 pptv of iodine monoxide (IO) in the free troposphere over the subtropical station of Izaña in the Atlantic Ocean (Canary Islands) [Puentedura et al, 2012] and 0.1-0.2 pptv range throughout the tropical free troposphere of the Pacific Ocean , demonstrating the ubiquitous presence of the radical in the marine free troposphere.…”

Section: Introductionmentioning

confidence: 99%

Injection of iodine to the stratosphere

Saiz‐Lopez

Baidar

Cuevas

et al. 2015

Geophysical Research Letters

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We report a new estimation of the injection of iodine into the stratosphere based on novel daytime (solar zenith angle < 45°) aircraft observations in the tropical tropopause layer and a global atmospheric model with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25–0.7 parts per trillion by volume), between 2 and 5 times larger than the accepted upper limits, can be injected into the stratosphere via tropical convective outflow. At these iodine levels, modeled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower stratosphere and can exert a stratospheric ozone depletion potential equivalent to, or even larger than, that of very short‐lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the stratospheric ozone layer.

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Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine

Cited by 316 publications

References 27 publications

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

Injection of iodine to the stratosphere

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