Bio-distribution of Elements
Biological functions of the living organisms require 27 elements of which 15 are metals. The elements required in major quantities are potassium, magnesium, sodium and calcium. Minor quantities of manganese, iron, cobalt, copper, zinc and molybdenum and trace amounts of vanadium, chromium, tin, nickel and aluminium are required at least by some organisms.
Bulk quantities of group 1 and group 2 metals are required to balance the electrical charges associated with negatively charged organic macro molecules in the cell, and also to maintain the osmotic pressure inside the cell, to keep it turgid and prevent its collapse.
The elements required for living organisms are found in earth’s crust, rivers and sea water. (Fig) gives the abundance of the elements in earth’s crust, river water and ocean water.
Different elements have different role to play in biological systems. The functions and toxicity some of the elements in biological systems are given Below
Biological Function: Essential to all organisms with the possible exception of blue-green algae; major cation in intracellular fluids in animals; essential for transmission of nerve impulse and cardiac function.
Toxicity: Extremely toxic to mammals when injected intravenously emesis prevents oral toxicity.
Comments: Pollution problem possible from leaching of fertilizers land.
Biological Function: Essential to all organisms. Present in all chlorophylls. Has other electrochemical and enzyme-activating functions.
Comments: May cause deficiencies of other elements (e.g. Fe) bythe effect of the alkalinity of dolomite.
Biological Function: Important for nerve functioning in animals. Major cation of extracellular fluid in animals.
Toxicity: Relatively harmless except in excessive amount (lethal dose ca 3g KG-1) Associated with some forms of hypertension.
Comments: Tolerance of and/or dependence upon sodium chloride can be an important consideration for the survival of plants and aquatic animals. This depends upon osmotic regulation rather than sodium specificity.
Biological Function: Essential for all organisms; used in cell walls, bones, and some shells as structural component important electrochemically and involved in blood clotting
Toxicity: Relatively harmless
Comments: May cause deficiencies of other elements (e.g. Fe) by effect of alkalinity of lime stone.
Biological Function: Essential for all organisms enzymes deficiencies in soil lead to infertility in mammals, bone malformation in growing chicks
Toxicity: Moderately toxic
Biological Function: Essential for all organisms.
Toxicity: Normally only slight toxicity, but excessive intake can cause siderosis and damage to organs through excessive iron storage (hermo-chromatosis)
Comments: A very abundant element (5 per cent of earth’s crust) may not be available at high pHs
Biological Function: Essential for many organisms including mammals activates a number of enzymes vitamin B12
Toxicity: Very toxic to plants and moderately so when injected intravenously in mammals.
Comments: Extensive areas are known where low soil cobalt affects the health of grazing animals.
Biological Function: Essential to all organisms constituent of redox enzymes and hemocyanin
Toxicity: Very toxic to most plants highly toxic to invertebrates, moderately so to mammals.
Comments: Pollution from industrial smoke and possibly from agricultural use. Wilson’s disease, genetic recessive, results in toxic increase in copper storage.
Biological Function: Essential to all organisms; used in >70 enzymes; stabilizes coiled ribosomes. Plays a role in sexual maturation and reproduction.
Toxicity: Moderately to slightly toxic; orally causes vomiting and diarrohea.
Comments: Pollution from industrial smoke may cause lung disease: use of zinc promotes cadmium pollution. Certain areas (e.g. Iran and Egypt) are zinc deficient.
Biological Function: Essential to all organisms with the possible exception of green algae; used in enzymes connected with nitrogen fixation and nitrate reduction.
Toxicity: Moderately toxic and antagonistic to copper molybdenum excesses in pasturage can cause copper deficiency.
Biological Function: Essential to ascidians (sea squirts), which concentrate in a million-fold from sea water. Essential to chicks and rats. Deficiencies cause reduced growth, impaired reproduction and survival of young, impaired tooth and bone metabolism and feather development. May be a factor in manic depressive illness.
Toxicity: Highly toxic to mammals if injected intravenously.
Comments: Possible pollutant from industrial smokes may cause lung disease.
Biological Function: Essential; involved in glucose metabolism and diabetes;potentiates effect of insulin. Presence in glucose tolerance factor from brewer’s yeast questioned.
Toxicity: Highly toxic as Cr(VI) carcingenic moderately toxic as Cr(III).
Comments: Potential pollutant since amount used industrially is large compared with normal biological levels; normally relatively unavailable because of low solubility. Cr(VI) used in comfort cooling towers environmental hazards
Biological Function: Weak evidence for ultratrace essentiality in rats.
Toxicity: Organotin compounds used as bacteriostats and fungistats; its use in anti-foulant boat paints now discouraged because of danger to estuarine and marine life.
Biological Function: Essential trace element.Chicks and rats raised on deficient diet show impaired liver function and morphology;stabilizes coiled ribosomes. Active metal in several hydrogenases and plant ureases.
Toxicity: Very toxic to most plants, moderately so to mammals carcinogenic.
Comments: Local industrial pollutant of air and water.
Biological Function: May activate succinic dehydrogenase and aminolevulinate dehydrase. The latter is involved in porphyrin synthesis.
Toxicity: Moderately toxic to most plants slightly toxic to mammals.Suggested as involved in the etiology of Alzheimer’s disease and other neurologic diseases.
Comments: Relatively inaccessible except in acidic media as a result of insolubility of Al(OH)3. Soils and waters high in A13+ and low in Mg2+ and Ca2+ implicated in neurologic diseases.