117
evolution
resulting in oxygen depletion and mass mortality. An important effect of
eutrophication is therefore, next to increased productivity in the area, an
increased risk of a complete system deterioration. In most cases the
enhanced possibilities for phytoplankton growth lead to shifts in the species
composition of the algae, which becomes dominated by types that can
absorb the supplied nutrients most quickly. Phosphate and nitrogen
eutrophication leads to a shift in the system from diatoms (which need also
silicate) to flagellates. Food chains change accordingly, and the eutrophicated area becomes unsuitable for many species that lived there before.
evaporation transition of matter from the liquid into gaseous phase. Dissolved
substances remain in higher concentration in the solution. In seawater evaporation increases the salinity. Evaporation from the sea surface is promoted
by a low humidity of the air and by strong winds. The energy required for
evaporation (~Iatent heat) is extracted from the water that cools down. High
evaporation is found in the sub tropics, where in addition precipitation is
low. Here the highest salinities of the surface water are found.
evaporite sedimentary rock composed of minerals that have been precipitated
from solutions concentrated by the evaporation of the solvent. Examples
include: gypsum, anhydrite, rock salt and various nitrates and borates.
Evaporites usually form under arid or semi-arid conditions on coastal
plains just above normal high-tide level or in semi-isolated marine basins
with replenishment of seawater over a restrictive entrance. Evaporite
deposits can reach considerable thicknesses, with minerals layered in a
sequence depending upon their relative solubilities.
evenness ~diversity.
evolution the development of living organisms from the most primitive prokaryotes to vertebrates and man. The fossil record of marine and terrestrial sediments strongly suggests an oceanic genesis and that the invasion of the
land took place only a short (geological) time ago. Representatives of most
phyla can be traced in marine sediments while on land and in terrestrial
sediments only a limited number of phyla are represented. About 3.5 billion
year ago photoautotrophic (~metabolic diversity) bacteria appeared. After the
emergence of Cyanobacteria, equipped with a photosynthetic apparatus capable of decomposing water and simultaneously releasing oxygen, the ocean
and the atmosphere changed from an anoxic state to the oxic state. This permitted aerobic metabolism to evolve, leading ultimately (about 1.5 billion
years ago) to the emergence of eukaryotes. The proliferation of eukaryotic
species was associated with further changes in the composition of the
atmosphere and the hydrosphere. The concept of evolution was combined
with the idea of natural selection by C.R. Darwin (1809-1882) and A.R.
evolution
resulting in oxygen depletion and mass mortality. An important effect of
eutrophication is therefore, next to increased productivity in the area, an
increased risk of a complete system deterioration. In most cases the
enhanced possibilities for phytoplankton growth lead to shifts in the species
composition of the algae, which becomes dominated by types that can
absorb the supplied nutrients most quickly. Phosphate and nitrogen
eutrophication leads to a shift in the system from diatoms (which need also
silicate) to flagellates. Food chains change accordingly, and the eutrophicated area becomes unsuitable for many species that lived there before.
evaporation transition of matter from the liquid into gaseous phase. Dissolved
substances remain in higher concentration in the solution. In seawater evaporation increases the salinity. Evaporation from the sea surface is promoted
by a low humidity of the air and by strong winds. The energy required for
evaporation (~Iatent heat) is extracted from the water that cools down. High
evaporation is found in the sub tropics, where in addition precipitation is
low. Here the highest salinities of the surface water are found.
evaporite sedimentary rock composed of minerals that have been precipitated
from solutions concentrated by the evaporation of the solvent. Examples
include: gypsum, anhydrite, rock salt and various nitrates and borates.
Evaporites usually form under arid or semi-arid conditions on coastal
plains just above normal high-tide level or in semi-isolated marine basins
with replenishment of seawater over a restrictive entrance. Evaporite
deposits can reach considerable thicknesses, with minerals layered in a
sequence depending upon their relative solubilities.
evenness ~diversity.
evolution the development of living organisms from the most primitive prokaryotes to vertebrates and man. The fossil record of marine and terrestrial sediments strongly suggests an oceanic genesis and that the invasion of the
land took place only a short (geological) time ago. Representatives of most
phyla can be traced in marine sediments while on land and in terrestrial
sediments only a limited number of phyla are represented. About 3.5 billion
year ago photoautotrophic (~metabolic diversity) bacteria appeared. After the
emergence of Cyanobacteria, equipped with a photosynthetic apparatus capable of decomposing water and simultaneously releasing oxygen, the ocean
and the atmosphere changed from an anoxic state to the oxic state. This permitted aerobic metabolism to evolve, leading ultimately (about 1.5 billion
years ago) to the emergence of eukaryotes. The proliferation of eukaryotic
species was associated with further changes in the composition of the
atmosphere and the hydrosphere. The concept of evolution was combined
with the idea of natural selection by C.R. Darwin (1809-1882) and A.R.