Publication details

Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution

Authors

KIM K. JU J. KIM B. CHUNG H.Y. VETRÁKOVÁ Ľubica HEGER Dominik SAIZ-LOPEZ A. CHOI W. KIM J.

Year of publication 2019
Type Article in Periodical
Magazine / Source ENVIRONMENTAL SCIENCE & TECHNOLOGY
MU Faculty or unit

Faculty of Science

Citation
Web http://dx.doi.org/10.1021/acs.est.8b06638
Doi http://dx.doi.org/10.1021/acs.est.8b06638
Keywords NITROUS-ACID; UNFROZEN SOLUTION; SEA-SURFACE; EMISSIONS; WATER; ICE; CHEMISTRY; OXIDATION; SEAWATER; SNOW
Description A new mechanism for the abiotic production of molecular iodine (I-2) from iodate (IO3-), which is the most abundant iodine species, in dark conditions was identified and investigated. The production of I-2 in aqueous solution containing IO3- and nitrite (NO2-) at 25 degrees C was negligible. However, the redox chemical reaction between IO3- and NO2- rapidly proceeded in frozen solution at -20 degrees C, which resulted in the production of I-2, I-, and NO3-. The rapid redox chemical reaction between IO3- and NO2- in frozen solution is ascribed to the accumulation of IO3-, NO2-, and protons in the liquid regions between ice crystals during freezing (freeze concentration effect). This freeze concentration effect was verified by confocal Raman microscopy for the solute concentration and UV-visible absorption spectroscopy with cresol red (acid-base indicator) for the proton concentration. The freezing-induced production of I-2 in the presence of IO3- and NO2- was observed under various conditions, which suggests this abiotic process for I-2 production is not restricted to a specific region and occurs in many cold regions. NO2--induced activation of IO3- to I-2 in frozen solution may help explain why the measured values of iodine are larger than the modeled values in some polar areas.