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Influence of the Sea Surface Microlayer on Oceanic Iodine Emissions.

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posted on 2020-11-16, 14:55 authored by Liselotte Tinel, Thomas J Adams, Lloyd DJ Hollis, Alice JM Bridger, Rosie J Chance, Martyn W Ward, Stephen M Ball, Lucy J Carpenter
The influence of organic compounds on iodine (I2) emissions from the O3 + I- reaction at the sea surface was investigated in laboratory and modeling studies using artificial solutions, natural subsurface seawater (SSW), and, for the first time, samples of the surface microlayer (SML). Gas-phase I2 was measured directly above the surface of liquid samples using broadband cavity enhanced absorption spectroscopy. I2 emissions were consistently lower for artificial seawater (AS) than buffered potassium iodide (KI) solutions. Natural seawater samples showed the strongest reduction of I2 emissions compared to artificial solutions with equivalent [I-], and the reduction was more pronounced over SML than SSW. Emissions of volatile organic iodine (VOI) were highest from SML samples but remained a negligible fraction (<1%) of the total iodine flux. Therefore, reduced iodine emissions from natural seawater cannot be explained by chemical losses of I2 or hypoiodous acid (HOI), leading to VOI. An interfacial model explains this reduction by increased solubility of the I2 product in the organic-rich interfacial layer of seawater. Our results highlight the importance of using environmentally representative concentrations in studies of the O3 + I- reaction and demonstrate the influence the SML exerts on emissions of iodine and potentially other volatile species.

History

Citation

Environmental science & technology, 2020, 54, 20, 13228–13237

Author affiliation

School of Chemistry

Version

  • VoR (Version of Record)

Published in

Environmental science & technology

Volume

54

Issue

20

Pagination

13228–13237

Publisher

American Chemical Society (ACS)

issn

1520-5851

eissn

1520-5851

Acceptance date

2020-09-25

Copyright date

2020

Available date

2020-09-25

Spatial coverage

United States

Language

eng

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