The chemical signature of the sea is a sulfurous byproduct

Science · Published 18 October 2026 Swipe more like this →

In short: Dimethyl sulfide is the primary biological sulfur compound released into our atmosphere. While it is responsible for the distinct, pungent aroma of the ocean, its presence is a complex result of marine biology, bacterial metabolism, and even celestial chemistry.

Dimethyl sulfide (DMS) is a volatile, colorless to straw-colored liquid characterized by a very unpleasant odor, often described as resembling wild radish or cabbage. It has a boiling point of approximately 37.3 °C (99 °F) and a flash point below 0 °F, making it a highly flammable substance. Its molecular weight is 62.134, and it possesses a topological polar surface area of 25.3 Ų. The substance is less dense than water and produces vapors that are heavier than air. It is also known by several synonyms, including methyl sulfide and thiobismethane.

The compound is slightly soluble in water, with specific solubility noted at concentrations below 300 mMO. In the marine environment, DMS is primarily produced by phytoplankton through the breakdown of dimethylsulfoniopropionate (DMSP). This biological process may serve as an adaptive trait for marine algae. By releasing these gases, the organisms can potentially use the resulting clouds to disperse themselves globally. The compound is also a component of the odor produced when cooking certain vegetables like maize and beetroot.

Bacteria also play a critical role in the sulfur cycle by transforming dimethyl sulfoxide (DMSO) into DMS or metabolizing methanethiol. Beyond biology, DMS has been detected in comets, such as 67P/Churyumov-Gerasimenko, proving the compound can originate from non-living sources. In the brewing industry, the presence of this chemical can serve as an indicator of bacterial contamination. It can also be formed from S-Methylmethionine during the brewing process. Furthermore, it is a breakdown product of dimethylsulfoniopropionate, which is a major secondary metabolite in some marine algae.

Dimethyl sulfide is generated within industrial settings by reacting methanol and hydrogen sulfide using an aluminium oxide catalyst, or it arises from kraft pulping mills as a byproduct. The chemical is also a component of the volatiles given off by the dead-horse arum plant. These specific compounds contribute to an odor like rotting meat to attract pollinators. Additionally, it is a side product from the delignification process in kraft pulping mills.

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