ENVIRONMENTAL CHEMISTRY; ENVIRONMENTAL POLLUTION.pdf

Environmental pollution is the
excessive addition of harmful
substances into the environment,
affecting the living conditions of
humans, animals, and plants

1. ENVIRONMENTAL
POLLUTION

2. ENVIRONMENTAL POLLUTION
•Environmentalpollutionisthe
excessiveadditionofharmful
substancesintotheenvironment,
affectingthelivingconditionsof
humans,animals,andplants.

3. CAUSES OF
POLLUTION

4. CAUSES OF POLLUTION
•Rapid Population Growth:
Leads to increased waste and
resource consumption.
•Industrialization:
Contributes to air, water, and land
pollution.

5. CAUSES OF POLLUTION
•Urbanization:
Overcrowding and waste
mismanagement.
•Misuse of Natural Resources:
Over-exploitation leads to environmental
degradation.

6. CAUSES OF POLLUTION
•Natural Phenomena:
Events like volcanic eruptions
contribute to pollution.
•Fossil Fuel Transportation:
Emissions from vehicles and other
transport modes.

7. TYPES OF
POLLUTION
•AIR POLLUTION
•WATER POLLUTION
•LAND/SOIL POLLUTION
•NUCLEAR POLLUTION
•THERMAL POLLUTION
•NOISE POLLUTION

8. TYPES OF POLLUTION
•Air Pollution:
Caused by the release of harmful substances
into the air, affecting living beings and
property.
•Water Pollution:
Contamination of water bodies due to
industrial discharge, sewage, and
chemicals.

9. TYPES OF POLLUTION
•Land/Soil Pollution:
Accumulation of waste, chemicals,
and other harmful substances in
thesoil
•Nuclear Pollution:
Release of radioactive substances

10. TYPES OF POLLUTION
•Thermal Pollution:
Heat discharge into water bodies
affecting aquatic life.
•Noise Pollution:
Harmful noise levels from industrial,
transport, and urban activities.

11. AIR POLLUTION
•Air pollution is the release of
harmful substances into the
atmosphere, primarily caused by
industrial processes, vehicle
emissions, and other human
activities.

12. SOURCES OF AIR
POLLUTION

13. SOURCES OF AIR POLLUTION
•Motor Vehicle Exhaust:
Emission of harmful gases.
•Industrial Processes:
Factories releasing pollutants.

14. SOURCES OF AIR POLLUTION
•Heat and Power Generation:
Use of fossil fuels.
•Fertilizer Plants and Auto Manufacturing:
Emissions of chemicals and
particulates.

15. SOURCES OF AIR POLLUTION
•Building Demolition and Solid Waste Disposal:
Release of dust and toxic substances.
•Natural Events:
Volcanic eruptions, forest fires

16. COMMON AIR
POLLUTANTS
AND THEIR
EFFECTS

17. Common Air Pollutants and Their Effects
•Ozone:
Forms smog, causes lung issues, and
damages plants.
•VOCs (Volatile Organic Compounds):
Released during fuel combustion, causing
cancer and harming plants.

18. Common Air Pollutants and Their Effects
•NOx (Nitrogen Dioxide):
Forms smog, acid rain, and damages
respiratory systems.
•CO (Carbon Monoxide):
Causes respiratory and cardiovascular
issues.

19. Common Air Pollutants and Their Effects
•PM-10 (Particulate Matter):
Causes lung damage, respiratory issues,
and environmental dirtiness.
•Sulphur Dioxide:
Causes lung damage and acid rain.

20. Common Air Pollutants and Their Effects
•Lead:
Found in paints and batteries; causes nerve
and brain damage.

21. 13.3.3 Nature of Pollution Sources
•Air pollution can originate from both human
activities and natural events. The main
sources include stationary and area sources,
mobile sources, agricultural sources, and
natural sources.

22. (i) Stationary and Area Sources
•Stationary Sources:
These are fixed sources of pollution, such as power
plants, chemical industries, and manufacturing facilities,
which emit consistent amounts of pollutants.
•Area Sources:
Smaller stationary sources located close together, such as
residential areas with wood-burning stoves or small
factories, which collectively produce significant pollution.

23. (ii) Mobile Sources
•Mobile Sources:
These include all moving sources of pollution,
primarily on-road vehicles like cars and trucks.
Non-road sources also fall under this category,
such as gas-powered lawn equipment, farm
machinery, construction equipment, boats,
planes, and trains.

24. (iii) Agricultural Sources
•Agricultural Sources:
Pollution from farming activities, including runoff
containing fertilizers, insecticides, herbicides, and
pesticides. Manure from confined animal operations
emits gases such as ammonia, which can be released
into the air from storage areas or fields. Silage liquor
and animal waste are particularly harmful due to their
low pH and high biological oxygen demand (BOD),
which can cause water pollution when spilled

25. (iv) Natural Sources
•Natural Sources:
These are non-human-related pollution sources, such as
volcanic eruptions that release particulate matter, forest
fires that emit large amounts of pollutants, hydrocarbons
from plants, and dust storms. Wild animals also
contribute to natural pollution. Although natural
pollution is unavoidable, human induced pollution
exacerbates the problem and requires control measures.

26. 13.3.4 IMPACTS OF AIR POLLUTION
•Pollutions are due to atmospheric
deposition of nitrogen (NOx) and other
chemical contaminants.

27. The effects of nitrogen can be seen in the following:
•Acid rain
Nitrogen oxide (NO
x) is one of the key air pollutants which
causes acid deposition, and results in adverse effects on
aquatic and terrestrial ecosystems. Acid deposition
increases the acidity of water and soils. Increases in water
acidity can impair the ability of certain fishes and aquatic
life to grow, reproduce and survive. Increases in soil
acidity can impair the ability of some types of trees to
grow and resist disease.

28. The effects of nitrogen can be seen in the following:
•Smog
It is a collection of pollutants. It is formed by NO
x,
particulate matter and humidity, all mixed together.
Smog reduces how far and how clearly we can see
through the air, an effect called visibility reduction
or regional haze. General atmospheric conditions
are that haze and ozone occur at the same time and
the mix of the two is called smog.

29. The effects of nitrogen can be seen in the following:
•Eutrophication
Reduced levels of dissolved oxygen in water due to increased
mineral and organic nutrient deposits produce algae and other
water plants that choke other forms of life in the oxygen
competition. Soil erosion, phosphorous and direct runoff from
feedlot operations and intensive agriculture are the main cause.
When excess nitrogen causes accelerated growth of algae, the
algae blocks sunlight, needed for submerged aquatic vegetation
to grow, when the algae dies it sinks to the bottom and
decomposes in a process which depletes the water of oxygen.

30. The effects of nitrogen can be seen in the following:
•Accumulation
Nitrogen compounds percolate through soil and
reach drinking water sources, and these nitrate
contaminants pollute the water.

31. The effects of chemical contaminants can be seen in
the following:
•Bioaccumulation
Chemical contaminants increase with concentration as it moves through
the food chain.
Example: An invertebrate eats contaminated algae, a small fish eats many
contaminate invertebrates, a large fish eats many small fish, and humans
eat the big fish which is now loaded with the chemical.
Chemical contaminant can accumulate and bind to the sediments they
deposit on. When this happens, the chemical contaminants are moved
wherever the sediments are moved. Chemical contaminants can change a
plant species composition, and make species more susceptible to disease,
weather and insect damage. Changes such as these challenge a species
ability to reproduce and develop.

32. The effects of chemical contaminants can be seen in
the following:
•Persistent
Chemical contaminants do not break down or
diminish over time.

33. 13.3.5 CLASSIFICATION OF AIR POLLUTANTS
•Air pollutants are classified into two types
according to their origin:
Primary pollutants
which are directly injected into
air, e.g. SO
2, CO, oxides of
nitrogen, dust particles, etc.
Secondary pollutants
which are not directly introduced into
air but are found in the atmosphere by
chemical or photochemical reactions
among the constituent of air, e.g.
ozone, PAN, etc.

34. Another method of classification of air pollutants is
based on their physical state:
•Gases, e.g. CO, NO, hydrocarbon vapours,
SO2, etc.
•Aerosol particulates which involve solids
such as smoke and dust and liquids like fog,
sprays, etc.

35. A third type of classification is based on the chemical
composition of the pollutant
•Inorganic pollutants:
Oxides of N2, CO, SO2, H2S, etc.
•Organic pollutants:
Hydrocarbons, aldehydes, ketones, etc.

36. 13.3.6 SOURCES, ILL EFFECTS AND REMEDIES OF
AIR POLLUTANTS
There are six primary pollutants of air
•SO
2(Sulphur Dioxide)
•CO (Carbon
Monoxide)
•oxides of nitrogen
•Volatile organic
vapours
•Particulate matter
•Ozone

37. 13.3.6.1 Sulphur Dioxide
Natural source
•Volcanic eruptions produce gases containing SO2.
When plants decay they produce H2S, which gets
oxidized in air by ozone to form SO2.
H
2S + O
3 H
2O + SO
4
-2

38. 13.3.6.1 Sulphur Dioxide
•Anthropogenic sources
•Combustion of sulphurcontaining fossil fuels is the
main manmade source. Roasting of sulphideores of
metals also produce SO2.
•The concentration of SO2 in air always remained below
the permissible level. The concentration of SO2 is high
only in low altitude regions due to anthropogenic forces.
2FeS + 3O
2 2FeO +2S0
2

39. Ill effects of SO2
•On human beings
•Concentration of SO2 to about 20 ppm may cause eye irritation and
affect digestive systems. Concentration above 400 ppm may be fatal.
•On plants
•Plants are damaged even at 1 ppm and for some plants yellowing of
leaves takes place due to the presence of sulphurdioxide content in air.
•On materials
•Yellowing of paper, loss of strength due to corrosion of metals and loss of strength of
buildings may be caused by SO2. Acid rain is also caused by SO2.

40. Control of SO2 Pollution
•The main source of SO2 is the burning of coal. Control of SO2
pollution may be done by passing the emitted gases through
a slurry of limestone when SO2 is absorbed. Air is blown
through the slurry to convert calcium sulphiteto calcium
sulphate.
•In fluidized bed combustion finely powdered coal and limestone is
fed into the chamber and fluidized by blowing air about 1000
degrees Celsius. All the above changes takes place in the chamber.

41. 13.3.6.2 CARBON MONOXIDE
•Natural source by the oxidation of methane
from marshy places by O2.

42. 13.3.6.2 CARBON MONOXIDE
•Anthropogenic sources
•Incomplete combustion of carbon and carbon-
containing fuels. CO is one of the major pollutants
present in automobile exhaust gases.
•Reaction of CO2 with carbon at high temperature.
CO
2+ C 2CO

43. CARBON MONOXIDE
•Ill effects on human beings
10 ppm is the admissible level of CO in air.
Concentration above 110 ppm affects the
respiratory system. At higher concentration it leads
to headache, fatigue, unconsciousness and finally to
death. This is caused because CO forms a stable
complex carboxyhemoglobinwith hemoglobin of
the blood. Hemoglobin loses its capacity to carry
oxygen to the cells.

44. Control of CO Pollution
•The main source of CO pollution is automobile
exhaust. These emissions are controlled by using a
catalytic converter where CO is oxidized to CO2.

45. 13.3.6.3 ORGANIC VAPOURS
•Natural source
From marsh gas and from gases from petroleum
wells.
•Anthropogenic source
The major source is from the unburnt gases of
automobile exhaust from various industrial
processes, perfumes we use in day-to-day life.

46. ORGANIC VAPOURS
•Ill effects
On their own hydrocarbons do not produce any pollution. They are
however converted to photochemical oxidants called PAN (peroxyacyl
nitrate) by a series of reactions. PAN is the cause of photochemical smog.
•Control of hydrocarbon pollution
The main source of anthropogenic hydrocarbon pollution is exhaust gases
of automobiles. Control can be done by having a catalytic converter which
helps in the oxidation of hydrocarbons to CO2 and water.

47. 13.3.6.4 OXIDES OF NITROGEN
•The three oxides of nitrogen found in the
atmosphere are:
•(N
2O) nitrous oxide
•(NO) nitric oxide and
•(NO
2) nitrogen dioxide.

48. OXIDES OF NITROGEN
•Natural source
By biological oxidation of nitrogenous compounds in the soil N
2O
and NO are formed. This easily gets oxidized to NO
2, in air.
During lightning N
2and O
2of air combine to form NO which then
gets oxidized to NO
2.
•Anthropogenic source
Internal combustion engines operate at high temperatures. N
2
and O
2of the air in the engine form NO and then NO
2. Thus, the
exhaust gases from IC engine contain NO and NO
2.

49. OXIDES OF NITROGEN
•Ill effects of oxides of nitrogen
•On human beings
•Causes eye irritation and respiratory problems, produces acid-
induced irritation and lung cancer.
•On plants
•Nil
•On materials
•Causes acid rain which damages old monuments and buildings.
•Causes formation of photochemical smog which leads to poor
visibility of roads and landing difficulties to aircrafts.

50. OXIDES OF NITROGEN
•Control of the oxides of nitrogen
In the IC engines catalytic converter is used for the
decomposition of the oxides of nitrogen to N2 and
O2.

52. •includes particles around 10
µm in size, forming solid
(dust, soot) and liquid (fog,
mist) aerosols.

53. •Natural Sources:
Dust storms and forest fires release particulate matter into
the air.
•Anthropogenic Sources:
•Soot
is produced by burning coal, wood, fuel oil, waste, and
tobacco.
•Dust
originates from material handling, ore processing, powder
mixing, construction, mining, house cleaning, body sprays,
crop spraying, engine exhaust, and fly ash from power plants
and cement industries.

54. •can cause respiratory issues;
(smoke-related TB),
asbestosis from silica dust,
lead poisoning, and kidney
problems from mercury dust.

55. •Various methods for the control
of particulate matter in air are
available depending on the size
of particles, their physical
nature and the economy
involved.

56. 1.Fabric Filter
-consists of fibrous materials with
fine pores suspended in a chamber
-removes dust from dry gases by t
rapping particles in fibrous material,
with dust collected via mechanical
shaking or air blasts.

57. 2.Gravity Separation
-Air flows slowly
through dust-settling
tanks, allowing
heavier particles to
settle in the conical
sections, with purified
air exiting.
Gravity Separator

58. 3.Cyclone Separator:
-Uses centrifugal force to separate
dust from gas by swirling air in a
cylindrical chamber, collecting dust
in the conical base while purified
air exits through the top of the
inner tube.

59. 4.Wet Scrubber:
-Impure air rises through a tower
while water is sprayed from the top,
washing dust particles and soluble
gases out of the air, with sludge c
ollectingat the bottom.

60. 5.Electrostatic Precipitators
-Cottrell Electrostatic Precipitators use high-
voltage metal electrodes to ionize gas
molecules, charging dust particles
negatively, which are then attracted to
collection electrodes and removed. This
method is efficient and low-maintenance
but has a high initial cost and only removes
particulate matter, not gaseous impurities.

61. -results from air pollution when burning fuels
produces gases like nitrogen oxides and sulfur
dioxide, which react with water droplets in clouds
to form sulfuric and nitric acids, leading to rain
with a lower pH that harms the environment.
•Rainwater is slightly acidic since it dissolves
varying amounts of CO2 from air. The lowest pH
of rainwater is 5.6.H2O + CO2 →H2CO3
(CARBONIC ACID)

62. •Acid rain is caused by pollutants such as
nitrogen oxides and sulfur dioxide from
burning fuels, which react with water in
clouds to create sulfuric and nitric acids,
resulting in rain that is more acidic. Burning
sulfur-containing fossil fuels produces SO2,
which reacts with rainwater and air to form
H2SO4. S + O2 → SO2
H2O + SO2 +1/2 O2 → H2SO4

63. •Automobile exhaust contains nitric
oxide. In contact with air it forms
nitrogen dioxide which dissolves in
water to form nitrous and nitric
acids.
NO+1/2 O2 → NO2
2NO + H20 → HNO2 + HNO3

64. 1.Acid rain kills fish, reduces their reproductive
rates, impairs green algae growth, destroys
beneficial bacteria, and increases metal ion
concentrations in water, harming aquatic life.
2.Lower pH washes away essential soil
nutrients like potassium and magnesium,
reduces plant growth, and destroys
nitrifying bacteria, decreasing soil fertility.

65. 3. Acid rain damages buildings by leaching
away reinforcement materials.
4. Acid rain erodes building materials like
marble, limestone, and metals, causing
"stone leprosy"
The reaction is:
CaCO3 + 2H → Ca² + H₂O + CO

67. -Government Action: Increase subsidies for
public transport to reduce reliance on personal
cars.
-Energy Conservation:Turnoff lights and use
energy-efficient appliances to lower power plant
emissions.
-Personal Efforts: Walk, cycle, and carpool to
decrease vehicle pollution.

68. Ozoneexistsintwodistinctlayersofthe
atmosphere:ground-levelor'bad'ozoneinthe
troposphere,whichisharmfultohealthandthe
environment,and'good'ozoneinthe
stratosphere,whichprotectslifeonEarthfrom
thesun’sharmfulultravioletrays.Whileground-
levelozonecontributestourbansmogand
damagesvegetation,stratosphericozoneplaysa
crucialroleinshieldingtheplanetfromexcessive
UVradiation.

75. Ozone
-agasthatoccursbothinthe
earth’supperatmosphereandat
groundlevel.Ozonecanbe‘good’or
‘bad’foryourhealthandthe
environment,dependingonits
locationintheatmosphere.
-occursintwolayersofthe
atmosphere.Thelayerclosesttothe
earth’ssurfaceisthetroposphere.
Here,ground-levelor‘bad’ozoneisan
airpollutantthatisharmfultobreathe
anditdamagescrops,treesandother
vegetation.

76. Inthestratosphere,ozoneisformedfromoxygenby
photochemicalmeans.OxygenmoleculeabsorbsUVlight
anddissociatestoformoxygenatomswhichcombine
withO2moleculestoformozone.
O
22(O)
O
2+(O)O
3
OzoneinturnabsorbsshortwaveUVanddecomposestoO
2
andO.
O3O2+(O)

77. Thus,adynamicequilibriumexistsbetweenO2andO3andaconstant
concentrationofozoneismaintainedinthestratosphere.Thisozonecover
preventsharmfulradiationstoreachtheearth’ssurface.Thethinlayerofozone
gasinthestratosphere(ozonelayer)isshieldinglifeonearthfromtheharmfulUV
lightcomingfromthesun(‘goodozone’)(Fig.13.21).
Ozoneisharmfulattheearthlevel,beingveryreactiveandirritanttothehuman
eyes(theso-calledbadozone).

78. Ozone
•is produced naturally in the stratosphere.
But this ‘good’ ozone is gradually being
destroyed by man-made chemicals
referred to as ozone-depleting
substances (ODS):
•chlorofluorocarbons (CFCs)
•hydro-chlorofluorocarbons (HCFCs)
•carbon tetrachloride
•methyl chloroform

79. Thissubstancescanbefound:
•Coolants
•foaming agents
•fire extinguishers
•Solvents
•Pesticides
•Halon’s: used for
firefighting
•aerosol propellants,
•Refrigerators
•blowing agents for
foams
•aerosol propellants
•Methyl Bromide
(used for
agriculture)

81. Ozonedepletion
•
•

82. OverexposuretoUV
•
•
•

83. According to scientists, certain manmade
chemicals are major contributors to the
problem. These chemicals are called ozone-
depleting substances (ODS).
•
•
•
•
•

85. ProtectingtheStratospheric
OzoneLayer:
•
•
•

86. Ozonecanbegoodorbad
dependingonwhereitislocated.
•
•

87. CLEANAIRACT:
•

88. •

90. Global Warming
•istheincreaseofaverageworld
temperaturesasaresultofwhatis
knownasthegreenhouseeffect.It
happenswhengreenhousegases
(carbondioxide,watervapour,nitrous
oxideandmethane)trapheatandlight
fromthesunintheearth’satmosphere,
whichincreasesthetemperature.Asthe
greenhousegasesbuildupinthe
atmospheretheearthgetshotter.This
hurtspeople,animalsandplants.Many
cannottakethechange,sotheydie.

91. Global Warming
•Majorcontributingfactorfor
greenhouseeffectisCO2.AlotofCO2
getsreleasedintotheatmosphereby
combustionoffuelsinvariousfieldslike
thermalpowerplants,automobiles,etc.
TheincreaseinconcentrationofCO2is
expectedtoincreasethetemperatureof
theearthby0.4percenteveryyear.To
aggregatethesituationthegreeneries
oftheearthwhichactasCO2linksare
beingdestroyedbyman..

93. Greenhouse Effect
•Duetoincreaseintemperatureofthe
earth’sevaporationofsurfacewaterwill
increasewatervapourcontentinthe
atmosphereandinturnincreasethe
atmospherictemperature.Thisleadsto
themeltingoficeinArcticandAntarctic
regions,increaseinseawaterlevelsand
manycitiesontheseashoremayget
submerged.
•Globalwarmingmayresultinwarmer
tropicaloceanscausingtheformationof
cyclonesandhurricanes.

94. Greenhouse Gases
•Carbondioxide
easilysolubleinwater:the
oceanscontainenormousamounts
ofit,butthetemperatureincrease
(duetothegreenhouseeffect)
reducesitswatersolubility,releasing
newgasintotheatmosphere,and
acceleratingthegreenhouseeffect.

95. Greenhouse Gases
•Methane
isreleasedduringcoal-mining
activities,oilexplorationandwhen
vegetationisburntduringland
clearance.Themainsourceof
methanethoughisagricultural
activity.Itisreleasedfromwetlands
suchasricepaddiesandfrom
animals,particularlycud-chewing
specieslikecows.

96. Greenhouse Gases
•Nitrousoxide
Nitrousoxidecomesfromboth
naturalandmanmadeprocesses.Man-
influencedsources,whichrepresent
about45percentofoutputtothe
atmosphere,aremainlyfossilfuel
combustion,asinpowerstations;useof
nitrogenousfertilizers;burningrain
forestsandhumanandanimalwaste.
N2Ocontributesabout6percenttothe
greenhouseeffectatthemoment.

97. Greenhouse Gases
•CFCs
CFCsfoundinfridges,air
conditioners,aerosols,etc.areextremely
effectivegreenhousegases.ACFC
moleculeis10,000timesmoreeffective
intrappingheatthanaCO2molecule,
methaneisabout30timesmore
effective.Methanemoleculessurvivefor
10yearsintheatmosphereandCFCsfor
110years.Itisthisthatcausespeopleto
wanttobanthemcompletely.

99. Global Climatic Trend
•Withthegreatlyimprovedmethods
comparedtothepast,thereisabig
increaseinatmosphericCO2
concentrationduetohumanactivity,
withsignificantclimaticconsequences.
•Thegloballyaveragedsurface
temperatureisprojectedtoincreaseby
1.4–5.8°Covertheperiodof1990-2100:
therateofwarming,too,should
increasecomparedtolastcentury.

100. Global Climatic Trend
1.Heatwaves,droughts,drier
soils.
2.Increasedevaporationand
precipitationduetohigher
energyintheatmosphere:more
frequentandextremeweather
events(storms,tornados,
hurricanes).Evidenceisbuilding
upatanalarmingrate.

101. Global Climatic Trend
3.Sealevelswillgoonraising:
erosionofsandybeachesorflooding
ofcoastalsealevelsarealready
risingatarateof1–2mmeachyear
duetoexpansionofthetoplayerof
theoceansastheywarmandthe
meltingofthepolaricecaps.The
predictedriseby2050isbetween20
and50cm.Thiswillcauseincreased
floodingincoastalareasandriver
estuaries.

102. Global Climatic Trend
4.Easiertransmissionofsome
infectiousdiseases,includingmalaria
andyellowfever.
Theemissionsofthemostpersistent
greenhousegases(carbondioxide,
nitrogendioxide,perfluorocarbons)
havealastingeffectontheclimate,
e.g.aboutaquarterofcarbon
dioxidepersistsintheatmosphere
severalcenturiesaftertheemission.

104. Control Measures:
•energy conservation, including better use of public
transport;
•cleaner, more efficient cars;
•energy efficiency by greater use of gas which produces less
CO2 than coal and oil, and through pollution-free
renewable energy such as solar power, wave and wind
energy;
•we need to stop destroying rain forests (deforestation) and
start replanting trees (afforestation) to soak up carbon
dioxide.