Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer

Iodine chemistry has noteworthy impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone ( O 3 ) and changes to HO x ( OH∕HO 2 ) and NO x ( NO∕NO 2 ) ratios. Hitherto, studies have shown that the reaction of atmospheric O 3 with surface seawater iodide (I −...

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Published in:Atmospheric Chemistry and Physics
Main Authors: S. Inamdar, L. Tinel, R. Chance, L. J. Carpenter, P. Sabu, R. Chacko, S. C. Tripathy, A. U. Kerkar, A. K. Sinha, P. V. Bhaskar, A. Sarkar, R. Roy, T. Sherwen, C. Cuevas, A. Saiz-Lopez, K. Ram, A. S. Mahajan
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2020
Subjects:
Online Access:https://doi.org/10.5194/acp-20-12093-2020
https://doaj.org/article/b235d0b10f20451c821e46082f5af7ca
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spelling ftdoajarticles:oai:doaj.org/article:b235d0b10f20451c821e46082f5af7ca 2023-05-15T18:25:17+02:00 Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer S. Inamdar L. Tinel R. Chance L. J. Carpenter P. Sabu R. Chacko S. C. Tripathy A. U. Kerkar A. K. Sinha P. V. Bhaskar A. Sarkar R. Roy T. Sherwen C. Cuevas A. Saiz-Lopez K. Ram A. S. Mahajan 2020-10-01T00:00:00Z https://doi.org/10.5194/acp-20-12093-2020 https://doaj.org/article/b235d0b10f20451c821e46082f5af7ca EN eng Copernicus Publications https://acp.copernicus.org/articles/20/12093/2020/acp-20-12093-2020.pdf https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7324 doi:10.5194/acp-20-12093-2020 1680-7316 1680-7324 https://doaj.org/article/b235d0b10f20451c821e46082f5af7ca Atmospheric Chemistry and Physics, Vol 20, Pp 12093-12114 (2020) Physics QC1-999 Chemistry QD1-999 article 2020 ftdoajarticles https://doi.org/10.5194/acp-20-12093-2020 2022-12-31T13:46:49Z Iodine chemistry has noteworthy impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone ( O 3 ) and changes to HO x ( OH∕HO 2 ) and NO x ( NO∕NO 2 ) ratios. Hitherto, studies have shown that the reaction of atmospheric O 3 with surface seawater iodide (I − ) contributes to the flux of iodine species into the MBL mainly as hypoiodous acid (HOI) and molecular iodine ( I 2 ). Here, we present the first concomitant observations of iodine oxide (IO), O 3 in the gas phase, and sea surface iodide concentrations. The results from three field campaigns in the Indian Ocean and the Southern Ocean during 2015–2017 are used to compute reactive iodine fluxes in the MBL. Observations of atmospheric IO by multi-axis differential optical absorption spectroscopy (MAX-DOAS) show active iodine chemistry in this environment, with IO values up to 1 pptv (parts per trillion by volume) below latitudes of 40 ∘ S. In order to compute the sea-to-air iodine flux supporting this chemistry, we compare previously established global sea surface iodide parameterisations with new region-specific parameterisations based on the new iodide observations. This study shows that regional changes in salinity and sea surface temperature play a role in surface seawater iodide estimation. Sea–air fluxes of HOI and I 2 , calculated from the atmospheric ozone and seawater iodide concentrations (observed and predicted), failed to adequately explain the detected IO in this region. This discrepancy highlights the need to measure direct fluxes of inorganic and organic iodine species in the marine environment. Amongst other potential drivers of reactive iodine chemistry investigated, chlorophyll a showed a significant correlation with atmospheric IO ( R =0.7 above the 99 % significance level) to the north of the polar front. This correlation might be indicative of a biogenic control on iodine sources in this region. Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Indian Southern Ocean Atmospheric Chemistry and Physics 20 20 12093 12114
institution Open Polar
collection Directory of Open Access Journals: DOAJ Articles
op_collection_id ftdoajarticles
language English
topic Physics
QC1-999
Chemistry
QD1-999
spellingShingle Physics
QC1-999
Chemistry
QD1-999
S. Inamdar
L. Tinel
R. Chance
L. J. Carpenter
P. Sabu
R. Chacko
S. C. Tripathy
A. U. Kerkar
A. K. Sinha
P. V. Bhaskar
A. Sarkar
R. Roy
T. Sherwen
C. Cuevas
A. Saiz-Lopez
K. Ram
A. S. Mahajan
Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
topic_facet Physics
QC1-999
Chemistry
QD1-999
description Iodine chemistry has noteworthy impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone ( O 3 ) and changes to HO x ( OH∕HO 2 ) and NO x ( NO∕NO 2 ) ratios. Hitherto, studies have shown that the reaction of atmospheric O 3 with surface seawater iodide (I − ) contributes to the flux of iodine species into the MBL mainly as hypoiodous acid (HOI) and molecular iodine ( I 2 ). Here, we present the first concomitant observations of iodine oxide (IO), O 3 in the gas phase, and sea surface iodide concentrations. The results from three field campaigns in the Indian Ocean and the Southern Ocean during 2015–2017 are used to compute reactive iodine fluxes in the MBL. Observations of atmospheric IO by multi-axis differential optical absorption spectroscopy (MAX-DOAS) show active iodine chemistry in this environment, with IO values up to 1 pptv (parts per trillion by volume) below latitudes of 40 ∘ S. In order to compute the sea-to-air iodine flux supporting this chemistry, we compare previously established global sea surface iodide parameterisations with new region-specific parameterisations based on the new iodide observations. This study shows that regional changes in salinity and sea surface temperature play a role in surface seawater iodide estimation. Sea–air fluxes of HOI and I 2 , calculated from the atmospheric ozone and seawater iodide concentrations (observed and predicted), failed to adequately explain the detected IO in this region. This discrepancy highlights the need to measure direct fluxes of inorganic and organic iodine species in the marine environment. Amongst other potential drivers of reactive iodine chemistry investigated, chlorophyll a showed a significant correlation with atmospheric IO ( R =0.7 above the 99 % significance level) to the north of the polar front. This correlation might be indicative of a biogenic control on iodine sources in this region.
format Article in Journal/Newspaper
author S. Inamdar
L. Tinel
R. Chance
L. J. Carpenter
P. Sabu
R. Chacko
S. C. Tripathy
A. U. Kerkar
A. K. Sinha
P. V. Bhaskar
A. Sarkar
R. Roy
T. Sherwen
C. Cuevas
A. Saiz-Lopez
K. Ram
A. S. Mahajan
author_facet S. Inamdar
L. Tinel
R. Chance
L. J. Carpenter
P. Sabu
R. Chacko
S. C. Tripathy
A. U. Kerkar
A. K. Sinha
P. V. Bhaskar
A. Sarkar
R. Roy
T. Sherwen
C. Cuevas
A. Saiz-Lopez
K. Ram
A. S. Mahajan
author_sort S. Inamdar
title Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
title_short Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
title_full Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
title_fullStr Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
title_full_unstemmed Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer
title_sort estimation of reactive inorganic iodine fluxes in the indian and southern ocean marine boundary layer
publisher Copernicus Publications
publishDate 2020
url https://doi.org/10.5194/acp-20-12093-2020
https://doaj.org/article/b235d0b10f20451c821e46082f5af7ca
geographic Indian
Southern Ocean
geographic_facet Indian
Southern Ocean
genre Southern Ocean
genre_facet Southern Ocean
op_source Atmospheric Chemistry and Physics, Vol 20, Pp 12093-12114 (2020)
op_relation https://acp.copernicus.org/articles/20/12093/2020/acp-20-12093-2020.pdf
https://doaj.org/toc/1680-7316
https://doaj.org/toc/1680-7324
doi:10.5194/acp-20-12093-2020
1680-7316
1680-7324
https://doaj.org/article/b235d0b10f20451c821e46082f5af7ca
op_doi https://doi.org/10.5194/acp-20-12093-2020
container_title Atmospheric Chemistry and Physics
container_volume 20
container_issue 20
container_start_page 12093
op_container_end_page 12114
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