Geology Reference
In-Depth Information
salinity (S%):ameasureofthesaltcontentofseawater;atypicalvaluefor
oceanic waters being 35 g kg
1
.
scavenge: the process by which sinking particles remove dissolved sub-
stances (metals and organic material) by surface adsorption.
siderophore: a low molecular weight substance synthesized by a variety of
micro-organisms to sequester Fe that is often in limited supply in the
environment.
sigma-tee (r
t
): the density (actually the specific gravity and hence it is a
dimensionless number) of water at atmospheric pressure based on temper-
ature and salinity in situ.
sorption: either or both adsorption or absorption of a chemical substance to
a surface.
specific heat: the amount of heat required to raise the temperature of 1 g of
a substance by 1 1C.
super-saturation: the unstable state of a solution or vapour that contains
more solute or gas than its solubility or vapour pressure allows.
surface tension: the work required to expand the surface of a liquid by unit
area; the cohesive force exerted at the surface of a liquid that makes it
tend to assume a spherical shape because molecules at the surface are not
surrounded by molecules on all sides and accordingly they interact more
strongly with those directly adjacent to them on and below the surface.
surfactants: surface-active or wetting agents that decrease the surface
tension of a liquid.
thermocline: that zone between the warm surface water and colder deeper
water, e.g., of a lake, in which the temperature changes most rapidly.
thermohaline circulation: the global deepwater circulation driven by den-
sity differences, which in turn are caused by variations in salinity or
temperature.
tidal prism: the difference in the volume of water in a water body between
low and high tides.
troposphere: the lowest region of the atmosphere, extending to an altitude
of 8-18 km.
T-S diagram: a plot of temperature against salinity, with applications in
defining water masses of different origin.
turbidity currents: the muddy and turbulent flow of sediment-laden waters
along the seafloor caused by sediment slumping that transport copious
amounts of material, including coarse-grained sediments, to the deep sea.
upwelling: the transport of sub-surface water to the ocean surface.
zooplankton: animal component of the planktonic community.