ENVIRONMENTAL BIOLOGY AND TOXICOLOGY

2.  Pollution may be defined as ‘an undesirable change in
the physical, chemical or biological characteristics of
air, water and soil that harmfully affects human life or
create a potential health hazard of any living
organism’.
 Pollution is thus, direct or indirect change in
component of the biosphere i.e. harmful to living
components and in particular undesirable for man
adversely affecting the overall quality for life.
 The rapid industrialization and urbanisation have also
created several problems in the environment and
caused environmental pollution.

4.  Air pollution is the presence of substances in the
atmosphere that are harmful to the health of humans
and other living beings, or cause damage to the climate
or to materials.
 Air pollution is a mixture of solid particles and gases
in the air.
 Air pollution is caused by solid and liquid particles
and certain gases that are suspended in the air.
 These particles and gases can come from car and truck
exhaust, factories, dust, pollen, volcanoes and
wildfires.

5.  Water pollution is the contamination of water bodies,
usually as a result of human activities.
 Water bodies include for example lakes, rivers, oceans,
and groundwater. Water pollution results when
contaminants are introduced into the natural
environment.
 Water pollution occurs when harmful substances
often chemicals or microorganisms contaminate a
stream, river, lake, ocean, or other body of water,
degrading water quality and rendering it toxic to
humans or the environment.

6.  Soil contamination or soil pollution as part of land
degradation is caused by the presence of xenobiotics
(human-made) chemicals or other alteration in the
natural soil environment.
 Illegal dumping of the solid wastes, polluted water
absorbed by the soil, use of chemical fertilizers and
pesticides, dumping of minerals, oils, and radioactive
wastes are the major causes of soil pollution.

7.  Any substance which causes pollution is called a
pollutant. Thus pollutant can be defined as solid,
liquid or gaseous substance present in such a
concentration, which may be harmful or injurious to
the environment.
 Following are the important air, water and soil
pollutants:-
 1)Particulate matter:- Soot, fly ash, smoke, dust,etc.
 2)Gases:- SO2,NO,CO,CO2,.
 3)Acid droplets:- H2SO4, HNO3,etc.

8.  4) Fluorides.
 5)Halogens:- Chlorine, Bromine, Iodine.
 6)Heavy metals:- Hg, Cd, Pb, Zn, Ni, Cr.
 7)Agrochemicals:- Biocides like pesticides,
insecticides,etc.
 8)Organic substances:- Benzene, benzopyrenes.
 9)Photochemical oxidants:- These are secondary
pollutants like photochemical smog, ozone, etc.
 10)Solid wastes:- Rubber, plastic, glass, paper,etc.
 11)Radioactive waste.
 12)Noise.

10.  Air pollution is basically the presence of foreign
substances in air.
 The primary cause of pollution is action of people and
as population increases the problem also increases
proportionately.
 The variety of pollutants or air contaminations are
continuously emitted into the atmosphere.
 So these pollutants are usually divided into two
categories such as-
 PRIMARY POLLUTANTS
 SECONDARY POLLUTANTS

11.  The pollutants which are emitted directly from the
sources are called primary pollutants.
 Example: ash, smoke, dust, etc.
 Secondary Pollutants:
 The secondary pollutants are those that are formed in
the atmosphere by chemical interactions among
primary pollutants and normal atmospheric
constituents.
 Example: Sulphur trioxide, nitrate salts, etc.

12.  A natural pollutant is a pollutant created by
substances of natural origin such as volcanic dust,
sea salt particles, photochemically formed ozone,
and products of forest fibres, among others.
 These pollutants are released naturally in the
atmosphere. Among them are biological agents
such as pollen grains, bacteria and spores of fungi.

13.  Fine, dry powder consisting of tiny particles of earth or waste
matter lying on the ground or on surfaces or carried in the air is
defined as dust.
 Dust is made up of solid particles of the size ranging from 1 to
100u.These particles are larger than those found in colloids and
capable of temporary suspension in air or other gases.
 SMOKE:
 A visible suspension of carbon or other particles in air, typically
one emitted from a burning substance is called as smoke.
 Smoke particles consist predominantly of carbon particles and
other combustible materials.

14.  An amount of gas or vapour that smells strongly or is dangerous to inhale is
defined as fumes.
 Fumes are normally released from chemical or metallurgical processes.
 MIST:
 A cloud of tiny water droplets suspended in the atmosphere at or near the
earth's surface that limits visibility is called as mist.
 It is made up of liquid droplets generally smaller than 10u which are
formed by condensation in the condensation.
 FOG:
 Fog is nothing but visible aerosols in which the dispersed phase in
liquid.
 It is usually formed by condensation.

15.  The particulate matter can scatter and absorb the
sunlight, thus reducing visibility.
 Dust on snow and ice reduces reflection, increases
absorption and can promote melting.
 The particulate matter can cause toxic effects on
animals and humans and they are of three types:-
 1)Intrinsic toxicity due to chemical or physical
properties.
 2)Interference with clearance mechanisms in the
respiratory tract.
 3)Toxicity due to adsorbed toxic sbstance.

16.  1)Chronic bronchitis- Chronic bronchitis is inflammation
(swelling) and irritation of the bronchial tubes. These
tubes are the airways that carry air to and from the air sacs
in your lungs. The irritation of the tubes causes mucus to
build up.
 2)Bronchial asthma- Bronchial asthma is a medical
condition which causes the airway path of the lungs to
swell and narrow. Due to this swelling, the air path
produces excess mucus making it hard to breathe.
 3)Emphysema- Emphysema is a lung condition that
causes shortness of breath. In people with this disorder ,
the air sacs in the lungs (alveoli) are damaged.
 4)Lung cancer- Cancer is a disease in which cells in the
body grow out of control. When cancer starts in the lungs,
it is called lung cancer. Lung cancer begins in
the lungs and may spread to lymph nodes or other organs
in the body, such as the brain.

19.  Irritation of eyes.
 Irritation of nose, throat and respiratory tract.
 The constant exposure to polluted air causes increased
mortality and morbidity.
 Pollen grains dust particles may initiate asthmatic
attacks.
 Fluorosis is a disease of bone and caused due to
hydrogen fluoride. It also causes mottling of teeth.
 The heavy metals like lead, cadmium, nickel, etc.
affects the circulatory system and causes behavioural
disorders and even death.

20.  NECROSIS:- dead areas on a leaf structure are called
necrosis.
 CHLOROSIS:- it is the loss of chlorophyll and leads to
the yellowing of the leaf.
 EPINASTY:- leaf epinasty is a downward curvature of
the leaf due to higher rate of growth on the upper
surface.
 ABSCISSION:- the dropping of leaves is called
abscission.

21.  COMBUSTION
 ABSORPTION
 ADSORPTION
 MECHANICAL DEVICES
 FABRIC FILTERS
 WET SCRUBBERS
 ELECTROSTATIC PRECIPITATORS