Geology Reference
In-Depth Information
ligand: a moiety acting as a Lewis base that shares a pair of electrons
with a metal atom thereby forming a complex; ligands can be neutral
(e.g.,H
2
O) or anionic (e.g.,Cl
, HCO
3
) species.
lithogenous material: substances coming from the continents as a result
of weathering processes; the most important components being quartz
and the clay minerals (kaolinite, illite, montmorillonite, and chlorite).
lysocline: the depth at the sediment-water interface at which appreciable
dissolution of CaCO
3(s)
starts to occur.
marine boundary layer: lowest portion of the atmosphere (from 0.25 to
3.5 km) in contact with the ocean surface.
metallothionein: A protective protein that binds heavy metals such as
cadmium and lead thereby detoxifying such contaminants.
molal concentration: the number of moles of solute per kg of solution.
molar concentration: the number of moles of solute in a litre (dm
3
)of
solution (i.e., molarity).
molecular viscosity: small-scale internal fluid friction that is due to the
random motion of the molecules within a smooth-flowing fluid.
mutagen: a chemical substance that induces a change in the of DNA of
cells.
nitrification: the stepwise oxidation of NH
4
1
to NO
2
and eventually to
NO
3
.
nitrogen fixation: the direct uptake and assimilation of molecular nitro-
gen (N
2
) by organisms.
ocean conveyor belt: see thermohaline circulation.
ochre: a natural hydrated form of ferric oxide, often precipitated from
acid mine drainage.
oestrogenic: related to, behaving like, or causing effects similar to the
natural female sex hormone in vertebrates.
oligotrophic: a term used of lakes that are poorly productive in terms of
organic matter formed because of a low nutrient supply,
i.e., the
opposite of eutrophic.
osmoregulatory: a term used of an organism that actively regulates the
osmotic concentration of its internal fluids.
oxygen compensation depth: the horizon in the water column at which
the rate of O
2
production by photosynthesis equals the rate of respira-
tory O
2
oxidation.
permeability: the capacity, e.g., of a rock, to transmit water.
petrogenic hydrocarbon: an organic compound originating from unburnt
fossil fuels.
photic zone: the upper surface of the ocean in which photosynthesis can
occur, typically taken to be the depth at which sunlight radiation has
declined to 1% of the magnitude at the surface.
