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https://hdl.handle.net/2115/86950

Marine sediment as a likely source of methyl and ethyl iodides in subpolar and polar seas

英語

2022

Springer Nature

Communications Earth & Environment

3(1)

180

Elevated methyl and ethyl iodide concentrations in bottom waters may be linked to diatom aggregates and phytodetritus from the spring bloom settling to the sea floor, according to shipborne observations and laboratory-based incubation experiments in the Bering and Chukchi Seas and Funka Bay, Japan. The surface ocean is an important source of longer-lived volatile organic iodine compounds, such as methyl and ethyl iodide. However, their production in deep waters is poorly constrained. Here, we combine shipborne seawater and sediment core analyses to investigate the temporal and vertical distribution of methyl and ethyl iodide concentrations in the Bering and Chukchi Seas in July 2017 and 2018, and Funka Bay, Japan, between March 2018 and December 2019. We find the highest methyl and ethyl iodide concentrations in sediment porewaters and at the sediment surface. In Funka Bay, concentrations in the sediment and bottom waters strongly increased following the spring bloom and subsequent settling of phytodetritus to the seafloor. Dark incubation experiments suggest that diatom aggregates are a source of methyl and ethyl iodide to the ambient water. Our findings suggest that phytodetritus at the seafloor is a potential source of volatile organic iodine compounds to the water column in polar and subpolar coastal oceans.

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