Geology Reference
In-Depth Information
oxygen concentrations (hypoxia or anoxia depending upon the organic
loading) in sub-surface waters and/or sediments.
flocculation: process of combining particulate material into larger par-
ticles facilitated by particle surfaces being coated with organic material.
halmyrolysis: low-temperature reactions in seawater reactions producing
secondary material from components of continental or volcanic origin;
essentially an extension of chemical weathering of lithogenous compo-
nents.
halocline: a region in the water column that exhibits a sharp change in
salinity.
hermaphroditic: having both male and female sexual organs.
humic substances: large, refractory molecules formed as a result of
decomposition of organic matter.
hydrogenous material: matter produced abiotically within the water
column.
hydrophobic: the low affinity for water or 'water-hating tendency' of a
chemical as measured by its octanol/water partition coefficient.
hydrothermal waters: formed when seawater circulates into a fissured
rock matrix and, under conditions of elevated temperature and pressure,
results in compositional changes in the aqueous phase occur due to
seawater-rock interactions.
hyperkeratosis: skin lesion condition, often in the form of nodules on the
palms of the hands and soles of the feet, which can be brought about by
exposure to inorganic arsenic in drinking water.
hyperpigmentation: in the case of chronic arsenic poisoning, a finely
freckled, 'raindrop' pattern of pigmentation that is particularly pro-
nounced on the trunk and extremities.
hypolimnion: the stratum of water below the thermocline.
hypoxia: waters that are deficient in oxygen.
imposex: the imposition of male sex organs on female marine gastro-
pods, notably resulting from exposure to tributyltin compounds.
ion pair: the transient coupling of a cation and anion, formed by the
collision of oppositely charged ions due to electrostatic attraction,
during which each ion retains its own co-ordinated water envelope.
isopycnal: line (imaginary or on a chart) or an imaginary surface
connecting points, which have the same density.
latent heat of evaporation: the heat required (or released) to convert a
unit mass of a substance from a liquid to a gas state (or from gas to
liquid) at the same temperature and pressure.
latent heat of fusion: the heat required (or released) to convert a unit
mass of a substance from a solid to the liquid state (or from liquid to
solid) at the same temperature and pressure.
