As a Matter of Fact
BY NC ND
THE AROMA OF THE SEASIDE
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The characteristic smell of the seaside stems from
volatile organic compounds that contain sulfur. Some
of these compounds are emitted by algae in the sea, as
a result of enzymatic activity or bacterial action, whilst
others can be emitted by decomposing seaweed on
the beach itself.
Hydrogen sulfide gas is produced by
decomposing seaweed; the anaerobic
breakdown of sulfates in the seaweed
leads to the production of the gas. It is
toxic in high concentrations, but as it is
produced naturally in the body, humans
have mechanisms to break it down, so can
tolerate low concentrations.
COMPOUNDS FROM BACTERIA
is a compound found in algae cells,
which acts as an osmolyte (maintains
cell volume and water levels). This
compound can be broken down by
both enzymes and bacteria, and this
can produce dimethylsulfide (DMS).
DMS is considered a major component
of the smell of the sea.
DMS also has a role in cloud formation. Less than 10% of the DMS formed in the
ocean gets to the atmosphere. Chemical reactions in the air can break it down
into aerosols (tiny particles of a solid or liquid suspended in air). Water vapour can
condense around these particles, and result in cloud formation. Other, non-DMS-derived aerosols also contribute, including dust and soot.
AEROSOLS CLOUDS REFLECT LIGHT (cooling effect)