These observations provide evidence of autocatalytic iodine release from atmospheric aerosol

Atmospheric iodine, dominated by ocean emissions, is important in atmospheric chemistry for two main reasons, a) its remarkable capacity to form new particles that can grow to cloud condensation nuclei (CCN) sizes, thereby establishing a direct link between iodine emissions and CCN in remote regions; b) iodine is a very efficient ozone depleting substance in the troposphere. The changing evolution of these two processes is particularly relevant since global iodine emissions have tripled in the last 70 years.

Key to the abovementioned atmospheric implications is the recycling of reactive iodine from heterogeneous reactions on seasalt aerosols. This process was hypothesized over two decades ago to proceed via aerosol uptake of gaseous hypoiodous acid (HOI) and its…

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(Photograph by Andrea Baccarini)

Measurements in the Arctic show that iodine forms particles that grow to cloud condensation nuclei.

New atmospheric particle formation is one is the largest uncertainties in climate simulations. The source of new particles in the central Arctic has remained elusive since the first aerosol measurements in the Arctic in 1991.

In this study, we report observation that show iodine to be the main source of new particles in the central Arctic. The observations were made during an expedition to the central Arctic in 2018 (Microbiology-Ocean-Cloud-Coupling in the High Arctic, MOCCHA) onboard the Swedish icebreaker Oden. The results not only highlight the remarkable capacity that iodine oxides have to form new particles but also show that these new particles grow to cloud condensation nuclei (CCN) sizes, thereby establishing a direct…

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Laboratory experiments show the transition between iodine precursor gas phase molecules and molecular clusters of growing size.

New atmospheric particle formation is one is the largest uncertainties in climate simulations. Although it is known for the last two decades that iodine oxides form new particles in the lower atmosphere, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism.

In this study, we combine laboratory experiments, theory and modelling to reveal the mechanism that connects oceanic iodine emissions and atmospheric particle formation. The results show that the gas to particle conversion proceed primarily via clustering of iodine oxides and that the composition of nanometric particles (iodic acid) is due to the processing of these clusters in the…

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Simulations at the air-water interface shows that IONO2 does not react directly with iodine acids, but forms a halogen bond, for the first time proposed to occur on an atmospheric aqueous surface.

The atmospheric chemistry of iodine is important because of its role in catalytic ozone loss and new particle formation, which have an influence in the energy balance of the atmosphere. Iodine nitrate (IONO2) is one of the main reservoir species in the atmospheric iodine cycle. It is formed via the reaction of iodine oxide and nitrogen dioxide. The primary fate of IONO2 is believed to be, besides photolysis, uptake by aerosol surfaces, leading to particulate iodine activation.

In this study, we have conducted simulations on the interaction of IONO2 with the iodine acids (HIO3 and HIO2) that compose atmospheric ultrafine iodine particles. The results indicate that…

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(Photograph by Alfons Puertas / Observatorio Fabra)

Natural halogens are estimated to destroy 10–20 % of tropospheric O3. This study uses an Earth system model to project varying natural halogen emissions and investigate their impact on tropospheric O3 over the 21st century.

New research, led by CSIC, CONICET, NCAR and Lancaster University, shows that emissions of natural halogens (chlorine, bromine and iodine) buffer the increase in global tropospheric ozone (O3), an air pollutant and greenhouse gas, as climate changes during the 21st century.  At present, natural halogens (dominated by ocean emissions) are estimated to destroy 10–20 % of global tropospheric O3 burden.

The findings in a new Nature Climate Change paper reveal a strong buffering capacity of natural halogens controlling tropospheric O3, as the climate warms. In this century, the…

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This study presents the first observation of an important intermediate in the oxidation of DMS, a compound naturally emitted from the oceans that produces sulfate aerosols, which in turn affect cloud formation and climate.

Dimethyl sulfide (DMS, (CH3)2S), emitted by the oceans, is the most abundant biological source of sulfur in the marine atmosphere. Atmospheric DMS is oxidized to condensable products that form secondary aerosols that affect the Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei.

An international study with the participation of the IQFR, presents the first detection in the atmosphere of hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), an intermediate product in the oxidation scheme of DMS. This product, identified through global-scale airborne observations during the ATom campaign from the…

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