Various forms and function of essential nutrients-

Nitrogen- required by plants in greatest amount, it is absorbed by plants as NO2–, NO3– and NH4+ . It is one of the major constituent of proteins, nucleic acids and vitamins.

Phosphorus- Absorbed by plants from soil in the form of phosphate ions. It is the constituent of cell membrane. All nucleic acids and nucleotides require phosphorus.

Potassium – absorbed as potassium ions (K+). Help to maintain cation-anion balance in cells. It is involved in protein synthesis, opening and closing of stomata.

Calcium – absorbed by plants from soil in form of Calcium ions (Ca2+). Used in synthesis of cell wall. It activates certain enzymes.

Magnesium- absorbed by plants in form of Mg2+ ions. It activates the enzymes for respiration, photosynthesis, and involved in synthesis of DNA and RNA. It is constituent of chlorophyll.

Sulphur- plants obtain sulphur in form of sulphate (SO42-). Present in amino acids (cysteine, methionine) and is main constituent of coenzymes and vitamins.

Iron- obtained in the form of ferric iron (Fe3+). It is important constituent of protein involved in transport system.

Manganese-absorbed in form of Mn2+ ions. Main function is splitting of water to liberate Hydrogen and Oxygen during photosynthesis.

Zinc-obtained as Zn2+ ions. Activate enzymes like carboxylases. Needed in formation of Auxin.

Copper –absorbed as cupric ions(Cu2+). Involved in various metabolic activities and redox reactions.

Boron-absorbed as BO33- or B4O72- ions. Required for uptake of calcium, cell elongation and pollen germination.

Chlorine – it is absorbed in form of Cl– ions. Determine the solute concentration and splitting of water during photosynthesis

Notes on Environmental Chemistry:

Components of Environment:

👉Atmosphere: This comprises a blanket of gaseous layer around earth.

👉Hydrosphere: This comprises about 96% of earth’s surface & includes all sources of water like oceans rivers lakes, glaciers, ground water etc.

👉Lithosphere: It refers to earth’s solid crust containing the outer mineral cover. It comprises soil, minerals, organic matter etc.

👉Biosphere: It refers to the domain of living organism in covalent with atmosphere hydrosphere as well as lithosphere. 

Environmental Pollution :
Process of contamination of the environment with harmful wastes arising mainly from human activities.

👉Pollutant:  Any substance or species produced either by a natural source or by human activity, which produces adverse effect on the environment.

👉Contaminant: A substance which does not occurs in nature but is introduced by human activity into the atmosphere affecting its composition.

👉Source: The site from which the pollution or contaminants originate.

👉Sink: The material or medium which consumes or interacts with a long lived pollutant is called sink.

👉Receptor : Anything that is affected by the pollutants.

👉Threshold limit value (TLV) : This indicates the permissible limit of a pollutant in atmosphere to which a healthy worker is exposed during hours a day or 40 hours a week for life time without any adverse effects. TLV are determined by experimentation on animals, by use of medical knowledge, epidemiology surveys & environmental studies. 

Tropospheric pollution or Air pollution:
It is the atmosphere condition in which the presence of certain concentration produce harmful effects on man and his environment. These substances include:

(i) Gases such as oxides of sulphur, CO, oxide of N2 and hydrocarbons

(ii)  Particulate matter such as dust, smoke, fumes etc.

(iii) Radioactive material & many others.

👉Primary pollutants : These are the pollutants which are emitted directly from the sources. Some examples are:

👉Particulate Matter  : Such as ash, smoke, dust, fumes etc.

👉Inorganic gases : Such as sulphur dioxide, carbon monoxide etc.


Particulate matter:

👉Soot: produced by incomplete combustion of carbonaceous fossils fuels such as coal, fuel oil, natural gas, wood etc in insufficient supply of oxygen.

👉Metal particles: These are released by various metal finishing operation. The micro particles of toxic metal & SO2 gas present in the polluted atmosphere get absorbed on the particles rendering them highly toxic.

👉Metal oxides : They are generated by combustion of fuels containing metallic compounds.

👉Lead salts: Their source is lead tetraethyl (Pb(C2H5)4) which is added to gasoline to improve its antiknock property. In order to avoid deposition of PbO suitable amounts of C2H4Cl2 & C2H4Br2 are added to gasoline along with Pb(C2H5)4.

👉Fly ash: It originates from the combustion of high ash fossil. It contains partially burnt particles of the fuels.

👉Asbestos dust: It originates from industrial units manufacturing asbestos sheets, gaskets ropes etc. Asbestos flowing & asbestos insulations also contribute towards asbestos dust in the atmosphere.

👉Solid Hydrocarbons: These are emitted from petroleum refineries & comprise of paraffins, olefins & aromatics.

👉Dust Particulates: Originate from natural, domestic, industrial or agricultural sources. These are thrown into atmosphere by volcanic eruptions, blowing of dust by wind, mining operations etc.

👉Acid mist : Sulphuric acid mist is produced when SO3 present in the atmosphere comes in contact with moisture. Nitric acid mist is produced when oxides of nitrogen, viz, NO & NO2, undergo the series of reactions in the atmosphere.

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