chelation
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chelation a term generally used for all kinds of reversible reactions between dissolved metal and organic matter, the organic matter being either in dissolved or solid form. In fact, chelation relates to stereometric claw-like binding of a metal by an organic molecule. This type of reaction is known in ionexchange resins, but also in dissolved organics such as EDTA (Ethylene
Diamine Tetra Acetic acid-dis odium salt). Seawater contains a number of
dissolved organic substances which are able to complex (chelate) metals,
such as copper. This complexing has to compete with all major and minor
cations present. It is essential to understand the complete system of chelation, using, if available, the stability constants for each organic-metal combination. ~complexation .
chelipeds ~Crustacea.
chemical oxygen demand (COD) is an index of the total organic carbon in a water
sample. The COD is determined by measuring the amount of oxidizing
reagent consumed during oxidation of organic matter with dichromate or
permanganate. ~biological oxygen demand (BOD).
chemical weathering the breakdown and dissolution of continental rocks, both
igneous and sedimentary, under the influence of rain and soil water. The dissolved chemical elements become constituents of water in streams and
rivers. The chemical composition of river water varies considerably between
various rivers, reflecting the different rock composition of continental
drainage basins. Eventually the river water enters the ocean, contributing the
major constituents (dissolved salts) in seawater.
chemolithoautotrophs ~metabolic diversity.
chemolithoheterotrophs ~metabolic diversity.
chemoorganotrophs ~metabolic diversity.
chemostat a continuous culture device for microorganisms controlled by the
limiting concentration of a nutrient or other substance.
chemostratigraphy stratigraphy based on the chemical composition of rocks,
such as the content of rare earth elements and organic carbon (~carbon, organic),
alkalinity, etc. ~stratigraphy.
chemotaxis the movement of an organism towards or away from a chemical substance. Positive chemotaxis is towards an attractant; chemicals that induce
negative chemotaxis are repellents.
52
chelation a term generally used for all kinds of reversible reactions between dissolved metal and organic matter, the organic matter being either in dissolved or solid form. In fact, chelation relates to stereometric claw-like binding of a metal by an organic molecule. This type of reaction is known in ionexchange resins, but also in dissolved organics such as EDTA (Ethylene
Diamine Tetra Acetic acid-dis odium salt). Seawater contains a number of
dissolved organic substances which are able to complex (chelate) metals,
such as copper. This complexing has to compete with all major and minor
cations present. It is essential to understand the complete system of chelation, using, if available, the stability constants for each organic-metal combination. ~complexation .
chelipeds ~Crustacea.
chemical oxygen demand (COD) is an index of the total organic carbon in a water
sample. The COD is determined by measuring the amount of oxidizing
reagent consumed during oxidation of organic matter with dichromate or
permanganate. ~biological oxygen demand (BOD).
chemical weathering the breakdown and dissolution of continental rocks, both
igneous and sedimentary, under the influence of rain and soil water. The dissolved chemical elements become constituents of water in streams and
rivers. The chemical composition of river water varies considerably between
various rivers, reflecting the different rock composition of continental
drainage basins. Eventually the river water enters the ocean, contributing the
major constituents (dissolved salts) in seawater.
chemolithoautotrophs ~metabolic diversity.
chemolithoheterotrophs ~metabolic diversity.
chemoorganotrophs ~metabolic diversity.
chemostat a continuous culture device for microorganisms controlled by the
limiting concentration of a nutrient or other substance.
chemostratigraphy stratigraphy based on the chemical composition of rocks,
such as the content of rare earth elements and organic carbon (~carbon, organic),
alkalinity, etc. ~stratigraphy.
chemotaxis the movement of an organism towards or away from a chemical substance. Positive chemotaxis is towards an attractant; chemicals that induce
negative chemotaxis are repellents.