Geoscience Reference
In-Depth Information
The balance of energy in sea ice regions is, therefore, very
different depending on the frozen surface.
3.2.4.
Other exchanges of matter
The other exchanges of matter between the two environments,
ocean and atmosphere, are numerous and extremely important for the
climate and the dynamic and biogeochemical behavior of the oceans
and atmosphere. The gaseous exchanges of carbon, in the form of
carbonic gas (CO
2
), constitute an important sink for this gas with a
strong greenhouse effect (approximately 48% of anthropogenic
production has been absorbed by the ocean since the beginning of the
industrial era, even if this proportion has tended to diminish), and
therefore the exchanges of carbon have had a regulatory effect on the
evolution of the climate.
The exchanges of matter that will be discussed, therefore, concern
compounds dissolved in precipitations, exchanges of more or less
soluble gas (in both directions) and solid particles (in both directions).
Particles, gases or dissolved compounds coming from the
atmosphere can interact chemically (or photo-chemically) in seawater
and eventually can cause biological production, particularly in
euphotic layers by photosynthesis or, if they are organic in nature,
they cause bacterial production that will break them down. They can
also have a pollutant role (for example, certain organic compounds or
certain “toxic”
mineral compounds).
Some gases, resulting from chemical reactions linked to biological
activity then emitted into the atmosphere, play an important role in the
atmosphere's radiative balance (for example, the oxide of di-nitrogen
N
2
O, or the sulfur of dimethyl or DMS (CH
3
)
2
S, without, of course,
counting carbon dioxide.
The particles deposited on the sea ice modify its albedo (for
example, black carbon) or undergo heterogeneous chemical reactions
(in aqueous environments) at these interfaces. Those particles coming
from the surface can act as nuclei for condensation in clouds (salts
