Isotopic Evidence Unveils Fossil Fuels Contribution to Atmospheric Iodine

Abstract

Iodine is a crucial nutrient for public health, and its presence in the terrestrial atmosphere is a key factor in determining the prevalence of iodine deficiency disorders. While oceanic iodine emissions decrease at lower sea surface temperatures, the primary contributors to atmospheric iodine can vary from oceanic sources in the summer to other sources in winter. However, the specific sources and their respective contributions have remained unexplored. Fortunately, the atomic ratio of 129 I to 127 I significantly differs between nuclear activity and fossil fuels like coal and petroleum, which formed millions to billions of years ago. This distinction makes 129 I a valuable tool for identifying iodine sources. In our study, we analyzed iodine isotopes and incorporated additional indicators such as element content in PM 2.5 samples. Our findings reveal, for the first time, that in winter inland areas, fuel oil, alongside coal combustion, is a significant source of atmospheric iodine. This research enhances our comprehension of the impact of human activities on iodine levels in the environment. This understanding is crucial not only for addressing iodine deficiency-related health concerns but also for comprehending stratospheric ozone depletion, a phenomenon closely associated with atmospheric iodine.

Climate Control of Iodine Isotopic Composition Evidenced by Argentine Entisols Records

“…The higher‐level 129 I produced at high latitudes has limited meridional diffusion, with much of it settling on the land surface at high latitudes. Similar evidence was found for modern iodine isotopes in aerosols from Chinese metropolises, where remarkable latitudinal differences were attributed to the limited meridional diffusion of high‐level 129 I (Fan, Chang, et al., 2023; Fan, Xu, et al., 2023). Considering this, latitudinal differences in 129 I production rates must be considered when investigating the spatial and temporal distributions of natural 129 I/ 127 I in the future.…”