Geology Reference
In-Depth Information
Figure 1 A schematic representation of the ocean reservoir. The source and sink fluxes are
designated as g and n, referring to gross and net fluxes, thereby indicating that
interactions within the boundary regions can modify the mass transfer. Within
seawater, the p " d term signifies that substances can undergo particulate-
dissolved interactions. However, it must be appreciated that several transporta-
tion and transformation processes might be operative
(Adapted from Chester, 1990. 1 )
Ocean for Pb, identified by its isotopic signature as originating from petrol
additives. Wind-borne transport is greatest in low latitudes and the Sahara
Desert is known to act as an important source of dust. Also, the airborne
flux of nutrients, notably nitrogenous compounds, has become increasingly
recognised as important both in some coastal waters, such as Chesapeake
Bay, and large seas, including the Mediterranean Sea. In contrast, glacial
activity makes little impact on the World Ocean. Glacier-derived material
tends to be comprised of physically weathered rock residue, which is
relatively insoluble. In addition, the input is largely confined to Polar
Regions, with Antarctica responsible for approximately 90% of
the
material.
Although volatilisation and subsequent evasion to the atmosphere can be
important for elements, such as Se and Hg that undergo biomethylation,
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