Environmental Pollution Study Guide

Introduction to Environmental Pollution

• Developmental activities, including construction, transportation, and manufacturing, deplete natural resources and generate vast amounts of waste.
• Waste generation leads to the pollution of air, water, soil, and oceans, as well as global environmental issues like global warming and acid rain.
• Untreated or improperly treated waste is a primary driver of river pollution and environmental degradation.
• The consequences of environmental degradation include poor human health and a loss of crop productivity.

Definitions of Pollution and Pollutants

• Pollution: Defined as the addition of undesirable material into the environment resulting from human activities.
• Pollutants: Defined as physical, chemical, or biological substances unintentionally released into the environment which are directly or indirectly harmful to humans and other living organisms.
• Human activities affecting the environment include:
  • Stone crushers adding suspended particulate matter ($SPM$) and noise.
  • Automobiles emitting nitrogen oxides ($NO_x$), sulphur dioxide ($SO_2$), carbon dioxide ($CO_2$), carbon monoxide ($CO$), unburnt hydrocarbons, and black soot.
  • Domestic sewage and agricultural runoff containing pesticides and fertilizers polluting water bodies.
  • Effluents from tanneries containing harmful chemicals and emitting foul odors.

Classification of Pollution Types

• Environmental pollution is categorized into the following types:
  • Air pollution.
  • Noise pollution.
  • Water pollution.
  • Soil pollution.
  • Thermal pollution.
  • Radiation pollution.

Air Pollution and Particulate Matter

• Definition of Air Pollution: The presence of any solid, liquid, or gaseous substance (including noise and radioactive radiation) in the atmosphere at concentrations injurious to humans, organisms, plants, property, or normal environmental processes.
• Primary Causes: Fossil fuel use in power plants, industries, transportation, mining, construction, and stone quarries.
• Types of Air Pollutants:
  • Suspended Particulate Matter ($SPM$).
  • Gaseous pollutants (e.g., $CO_2$, $NO_x$, etc.).
• Characteristics of Particulate Matter:
  • Size ranges from $0.001$ to $500\,\mu m$ in diameter.
  • Particles less than $10\,\mu m$ float and move freely with air currents.
  • Particles greater than $10\,\mu m$ tend to settle down.
  • Particles less than $0.02\,\mu m$ form persistent aerosols.
• Major Particulate Pollutants:
  • Suspended Particulate Matter/Dust: Sources include smoke from domestic, industrial, and vehicular soot. Effects include reduced sunlight and visibility, corrosion, pneumoconiosis, asthma, cancer, and lung diseases.
  • Fly Ash: Ejected by thermal power plants during coal burning. It settles on vegetation, adds to air $SPM$, and contains leachates with harmful materials. It is now used for brick making and landfill.
  • Lead and Metal Particles: Tetraethyl lead ($TEL$) was used as an anti-knock agent in petrol. Lead particles from exhaust damage the kidney and liver, interfere with red blood cell development, and lower intelligence in children. Mining and metallurgy release oxides of iron, aluminum, manganese, magnesium, and zinc, causing developmental disorders and reproductive failure in plants.
• Ambient Air SPM Levels (Year 2000 Data in $mg/m^3$):
  • Permissible limits: Residential ($140 - 200\,mg/m^3$), Industrial ($360 - 500\,mg/m^3$).
  • Agra: Residential ($349$), Industrial ($388$).
  • Bhopal: Residential ($185$), Industrial ($160$).
  • Delhi: Residential ($368$), Industrial ($372$).
  • Kanpur: Residential ($348$), Industrial ($444$).
  • Kolkata: Residential ($218$), Industrial ($405$).
  • Nagpur: Residential ($140$), Industrial ($157$).

Gaseous Air Pollutants

• Carbon Compounds ($CO$ and $CO_2$): Sources include automobile exhaust and burning wood/coal. Effects: Respiratory problems and the Greenhouse effect.
• Sulphur Compounds ($SO_2$ and $H_2S$): Sources include power plants, refineries, and volcanic eruptions. Effects: Respiratory problems in humans, chlorosis (loss of chlorophyll) in plants, and acid rain.
• Nitrogen Compounds ($NO$ and $N_2O$): Sources include motor vehicle exhaust and atmospheric reactions. Effects: Eye/lung irritation, low plant productivity, and acid rain (damages metals and stone).
• Hydrocarbons (Benzene, Ethylene): Sources include automobiles and petroleum industries. Effects: Respiratory problems and carcinogenic properties.
• Fibres (Cotton, Wool): Sources include textiles and carpet weaving. Effects: Lung disorders.

Prevention and Control of Air Pollution

• Indoor Air Pollution Control:
  • Faulty building design leads to poor ventilation.
  • Pollutants include Volatile Organic Compounds ($VOCs$) from paints/carpets, disinfectants, and pathogens in hospital waste (spores).
  • Burning wood and biomass in rural areas causing acute respiratory problems (wheezing, sore throat, asthma).
  • Control Strategies: Replace wood/dung with biogas, kerosene, or electricity; use smokeless chullahs (improved stoves); design well-ventilated kitchens; plant least-smoky trees like baval (Acacia nilotica); use charcoal; cover kitchen waste; and sterilize rooms.
• Industrial Pollution Control:
  • Use cleaner fuels like Liquefied Natural Gas ($LNG$).
  • Employ environment-friendly processes to minimize waste.
  • Control Devices:
    1. Filters: Remove particulates; Baghouse systems use cotton or synthetic fibres (low temp) or glass cloth (high temp up to $290^{\circ}C$).
    2. Electrostatic Precipitators ($ESP$): Charge dust with ions and collect them on oppositely charged surfaces.
    3. Inertial Collectors: Use inertia to collect heavier particles; the 'Cyclone' is a common example.
    4. Scrubbers: Wet collectors that trap particles in liquid medium. Alkaline solutions are used to remove $SO_2$.
  • Additional Measures: Increase chimney height; shift industries away from populated areas; maintain green belts.
• Vehicular Pollution Control:
  • Emission standards and catalytic converters.
  • Pollution Under Control ($PUC$) certificates to ensure legal limits are met.
  • Reducing sulphur content in diesel to $0.05\%$.
  • Banning tetraethyl lead in petrol.
  • Encouraging Compressed Natural Gas ($CNG$) for public transport.

Ozone Layer Depletion and the Ozone Hole

• The stratosphere contains an ozone ($O_3$) layer protecting Earth from ultraviolet ($UV$) radiation.
• Chlorofluorocarbons ($CFCs$), used in refrigeration and aerosols, release chlorine that splits $O_3$ into oxygen ($O_2$).
• Ozone Hole: Thinned areas of the ozone shield over Arctic and Antarctic regions.
• Consequences: Sunburn, cataracts, blindness, skin cancer, and reduced forest productivity.
• Montreal Protocol (1990 Amendment): Global agreement to phase out $CFCs$.

Global Warming and the Greenhouse Effect

• Greenhouse gases ($CO_2$, methane, nitrous oxide, water vapour, and $CFCs$) trap outgoing infrared radiation.
• This trapping increases the thermal energy in the atmosphere, leading to a rise in global temperature.
• Predicted Impact: A temperature rise of $5^{\circ}C$ by the end of the century could melt polar ice caps, increase sea levels, and cause coastal flooding.

Noise Pollution

• Definition: "Sound without value" or "unwanted sound."
• Measurement: Decibels ($dB$).
• Standards: WHO prescribes $45\,dB$ by day and $35\,dB$ by night. Levels above $80\,dB$ are hazardous.
• Noise Intensities:
  • Quiet Conversation: $20 - 30\,dB$.
  • Loud Conversation: $60\,dB$.
  • Traffic/Lawn Mower: $60 - 90\,dB$.
  • Heavy Truck: $90 - 100\,dB$.
  • Motor Cycle: $105\,dB$.
  • Beat Music/Aircraft: $120\,dB$.
  • Jet Engine/Space Vehicle Launch: $140 - 179\,dB$.
• Sources: Radios, TVs, generators, traffic, industries, loudspeakers, firecrackers, and farm machines.
• Effects: Sleep disturbance, hypertension, aggression, depression, and permanent hearing loss.
• Control: Improved vehicle design, noise mounds/walls, electric locomotives, soundproofing generators, restricting nighttime loudspeaker use, and planting green belts of trees.

Water Pollution

• Definition: Addition of undesirable substances in water.
• Point Source: Pollutants discharged from a specific location (e.g., a drain pipe).
• Non-point Source: Pollutants from diffused areas (e.g., agricultural runoff, construction sites, abandoned mines).
• Sources and Contaminants:
  • Pesticides: Contaminants like $DDT$ move up the food chain, concentrating at higher trophic levels.
  • Heavy Metals: Lead, zinc, arsenic, copper, mercury, and cadmium.
    • Arsenic: Causes skin lesions, dry skin, and skin cancer (reported in West Bengal, Orissa, Bihar, U.P.).
    • Mercury: Causes Minamata disease in humans and dropsy in fish.
    • Cadmium: Causes Itai-Itai disease.
    • Lead: Causes displexia.
  • Oil Pollution: Spills from tankers, rigs, and pipelines kill marine life.

Thermal Pollution

• Power plants (thermal and nuclear) use approximately $30\%$ of abstracted water for cooling.
• Discharged hot water can increase the receiving water body's temperature by $10$ to $15^{\circ}C$ above ambient levels.
• Impact on Aquatic Life:
  • Decreases dissolved oxygen ($DO$).
  • Increases metabolism and affects growth in fish.
  • Declines swimming efficiency and predator avoidance.
  • Reduces biological diversity.
• Control: Use of cooling ponds to allow water to cool before release.

Ground Water Pollution and Eutrophication

• Ground Water Pollution: Caused by improper sewage disposal, dumping manures, agricultural chemicals, and industrial effluents.
• Eutrophication (Derived from Eu meaning well/healthy and trophy meaning nutrition):
  • Nutrient enrichment (nitrogen and phosphorus) in water bodies leads to excessive growth of algae, duckweed, and water hyacinth.
  • Water Bloom/Algal Bloom: Sudden explosive growth of phytoplankton imparting green color.
  • Phytoplankton release tokens that kill fish.
  • As plants die, heterotrophic bacteria deplete Dissolved Oxygen ($DO$), increasing Biological Oxygen Demand ($BOD$), leading to total ecosystem collapse and offensive smells.

Water Treatment and Recycling

• Sewage Treatment Stages:
  1. Primary Treatment: Removes suspended particulates and floating matter via sedimentation, coagulation/flocculation, filtration, and disinfection. The residue is called sludge.
  2. Secondary Treatment: Removes organic solids through microbial decomposition.
  3. Tertiary Treatment: Removes nutrients (nitrogen, phosphorus), disinfects pathogenic bacteria, and uses aeration to remove $H_2S$ and reduce $CO_2$.
• Water Recycling: Involves reusing waste water by the original user prior to discharge, repetitive use with or without treatment to conserve limited sources.

Soil Pollution

• Definition: Addition of substances adversely affecting soil quality or fertility.
• Sources:
  • Solid Waste: Mixture of plastics, cloth, glass, metal, and organic matter.
  • Plastics: Low-density polyethylene ($LDPE$) is non-biodegradable, blocks drains, and kills animals if ingested. Burning plastics releases $CO$, $CO_2$, phosgene, and dioxins.
  • Industrial Waste: Fly ash, slag, chemical residues, and nuclear waste.
  • Agricultural Waste: Fertilizers (causing eutrophication) and pesticides (toxic/carcinogenic).
• Control: Stop plastic use (use cloth/paper bags); treat sewage before use as fertilizer; vermicomposting for organic waste; incinerate biomedical waste.

Radiation Pollution

• Definition: Increase over the natural background radiation.
• Major Incidents: Chernobyl (Russia, 1986); Three Mile Island (USA, 1979).
• Types of Radiation:
  1. Non-ionizing Radiation: Longer wavelengths (near infra-red to radio waves). Have enough energy to excite atoms to vibrate (e.g., microwave ovens) but not ionize them.
  2. Ionizing Radiation: Short wavelengths ($UV$, X-rays, Gamma rays) and particles (Alpha, Beta, Neutrons). Can knock electrons out of atoms, breaking chemical bonds in proteins and $DNA$.
• Radiation Damage:
  • Somatic Damage (Radiation Sickness): Affects cells not associated with reproduction. Includes skin reddening, hair loss, lung fibrosis, white blood cell reduction, and cataracts.
  • Genetic Damage: Affects reproductive cells, leading to mutations and abnormalities passed to offspring.
• Radiation Dose: Measured in rem (radiation equivalent in man). Background radiation is $< 1\,mrem$. Doses up to $100\,rem$ allow for some cellular repair or permanent change. Doses $> 100\,rem$ lead to tissue failure and radiation sickness.

Questions & Discussion

• Q: Define pollutant and pollution.
  • A: Pollutants are agents causing environmental pollution. Pollution is the addition of undesirable materials due to human activity.
• Q: Name three devices that control pollution.
  • A: Filters, electrostatic precipitators, and scrubbers.
• Q: What is a PUC certificate?
  • A: A Pollution Under Control certificate ensuring vehicle exhaust levels are within legal limits.
• Q: What metals cause Minamata and Itai-Itai?
  • A: Mercury causes Minamata; Cadmium causes Itai-Itai.
• Q: What term describes the residue after primary treatment?
  • A: Sludge.
• Q: What effect does thermal pollution have on fish?
  • A: Swimming efficiency declines and metabolism increases.