UGC NET Environmental Science Unit-VI: Environmental Pollution and Control Syllabus

Unit-VI: Environmental Pollution and Control syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Unit-VI: Environmental Pollution and Control in UGC NET Environmental Science, not a summary of it.

1. 1

   Air Pollution

   8 topics

   • Sources and Types of Pollutants
   • Sampling and Monitoring of Air Pollutants
   • Principles and Instruments for Measurements
   • Impact of Air Pollutants
   • Dispersion of Air Pollutants
   • Control Devices for Particulate Matter
   • Control of Gaseous Pollutants
   • Indoor Air Pollution, Vehicular Emissions, and Urban Air Quality
2. 2

   Noise Pollution

   5 topics

   • Sources of Noise Pollution
   • Measurement of Noise Indices
   • Noise Dose and Noise Pollution Standards
   • Noise Control and Abatement Measures
   • Impact of Noise and Vibrations
3. 3

   Water Pollution

   7 topics

   • Types and Sources of Water Pollution
   • Impact on Humans, Plants, and Animals
   • Measurement of Water Quality Parameters
   • Microbiological Analysis
   • Drinking Water Treatment
   • Wastewater Treatment
   • Common Effluent Treatment Plant
4. 4

   Soil Pollution

   5 topics

   • Physico-Chemical and Biological Properties of Soil
   • Analysis of Soil Quality
   • Soil Pollution Control
   • Industrial Effluents and Their Interactions with Soil Components
   • Soil Micro-organisms and Their Functions
5. 5

   Thermal, Marine Pollution and Radioactive

   3 topics

   • Sources of Thermal Pollution
   • Sources and Impact of Marine Pollution
   • Radioactive Pollution

Unit-VI: Environmental Pollution and Control flashcards for UGC NET Environmental Science

23 of 52 cards from the Unit-VI: Environmental Pollution and Control deck — real questions with worked answers.

1. What is the difference between primary and secondary air pollutants? Give one example of each.

   Primary pollutants are emitted directly from a source (e.g., SO2, CO, NOx, particulate matter). Secondary pollutants form in the atmosphere by chemical reactions of primary pollutants (e.g., ozone, PAN, sulfuric acid aerosol).

2. Classify air pollutants by their physical state.

   Gaseous pollutants (SO2, NOx, CO, hydrocarbons, O3) and particulate pollutants (dust, smoke, fumes, mist, fog, aerosols). Particulates are further classified as settleable (>10 micron) and suspended (<10 micron).

3. What instrument is used for collecting and measuring suspended particulate matter in ambient air, and on what principle does it work?

   The High Volume Sampler (HVS). Air is drawn at a high flow rate (1.1-1.7 m3/min) through a pre-weighed filter paper; SPM concentration is the mass gain divided by the volume of air sampled (expressed as micrograms/m3).

4. State the principle used to measure SO2 in ambient air by the standard reference method.

   The West-Gaeke (modified pararosaniline) method: SO2 is absorbed in sodium/potassium tetrachloromercurate to form a dichlorosulfitomercurate complex, which reacts with pararosaniline and formaldehyde to give a colored complex measured colorimetrically at 560 nm.

5. What is the standard analytical method for measuring NO2 in ambient air?

   The Jacobs-Hochheiser / modified Griess-Saltzman method: NO2 is absorbed in sodium hydroxide/arsenite, then reacted with sulphanilamide and NEDA to form an azo dye measured colorimetrically at 540 nm.

6. How does a non-dispersive infrared (NDIR) analyzer measure carbon monoxide?

   CO selectively absorbs infrared radiation at a characteristic wavelength (~4.6 micron). The NDIR analyzer measures the reduction in IR transmitted through the sample, which is proportional to CO concentration.

7. What is an isokinetic sampling, and why is it important for stack particulate sampling?

   Isokinetic sampling means the velocity of gas entering the sampling nozzle equals the velocity of the gas in the stack/duct. It is essential so that the particulate sample is representative; non-isokinetic sampling over- or under-estimates particle concentration due to inertial effects.

8. List four major health impacts of air pollutants on humans.

   Respiratory diseases (bronchitis, asthma), reduced lung function, cardiovascular disease, and carcinogenesis (e.g., lung cancer from PAHs/benzene). CO causes carboxyhemoglobin formation reducing oxygen transport; lead affects the nervous system.

9. What was the chemical cause and effect of the 1952 London Smog and the Los Angeles smog, and how do they differ?

   London smog is reducing/classical smog (SO2 + smoke + fog, cold humid conditions). Los Angeles smog is photochemical/oxidizing smog (NOx + hydrocarbons + sunlight forming ozone and PAN, warm dry conditions).

10. What is the lapse rate, and how do the dry adiabatic lapse rate (DALR) and environmental lapse rate (ELR) determine atmospheric stability?

    Lapse rate is the rate of decrease of temperature with altitude. DALR is ~9.8 deg C/km. If ELR > DALR atmosphere is unstable (good dispersion); if ELR < DALR it is stable (poor dispersion); if ELR = DALR it is neutral.

11. What is a temperature inversion and why is it dangerous for air quality?

    A temperature inversion occurs when temperature increases with altitude (warm air over cool air), creating a stable layer that traps pollutants near the ground and prevents vertical dispersion, leading to severe pollution episodes.

12. Write the Gaussian plume equation concept used to model dispersion of air pollutants from a point source.

    The Gaussian plume model assumes pollutant concentration follows a normal (Gaussian) distribution in the horizontal and vertical directions. Concentration C is proportional to Q/(2*pi*u*sigma_y*sigma_z) with exponential terms in y and z; Q=emission rate, u=wind speed, sigma_y and sigma_z=dispersion coefficients.

13. Name the six classic plume behaviors based on atmospheric stability.

    Looping (unstable), Coning (neutral), Fanning (stable/inversion), Lofting (inversion below, unstable above), Fumigation (inversion above, unstable below - most hazardous at ground), and Trapping (inversions both above and below).

14. How is the effective stack height calculated, and what is plume rise?

    Effective stack height (H) = physical stack height (h) + plume rise (delta-h). Plume rise is the additional height the plume gains due to its momentum (exit velocity) and buoyancy (temperature difference), commonly estimated by Holland's formula.

15. Compare the working principle of a cyclone separator and a settling chamber for particulate control.

    A gravity settling chamber removes large particles (>50 micron) by reducing gas velocity so particles settle by gravity. A cyclone separator uses centrifugal force from spiral gas flow to throw particles (>10 micron) to the walls; it is more efficient and compact.

16. On what principle does an electrostatic precipitator (ESP) work, and what is its typical efficiency?

    An ESP charges particles using a high-voltage corona discharge (discharge electrode), then collects the charged particles on oppositely charged collecting plates. Efficiency is very high (99-99.9%) and it can collect fine particles down to <1 micron.

17. What is a fabric (bag) filter and what is its main operating limitation?

    A baghouse/fabric filter passes dust-laden gas through woven or felted fabric bags that trap particles (very high efficiency, even sub-micron). Main limitations: cannot handle high-temperature gases (fabric damage), moist/sticky dust clogs bags, and high pressure drop.

18. Name three methods for controlling gaseous pollutants and the principle of each.

    Absorption (gas dissolved into liquid in a scrubber, e.g., SO2 in lime slurry), Adsorption (gas adheres to solid surface like activated carbon), and Combustion/Incineration (oxidizing pollutants e.g., catalytic/thermal afterburners). Condensation is also used.

19. What is flue gas desulfurization (FGD) and name the most common wet FGD reagent?

    FGD removes SO2 from combustion exhaust gases. The most common wet method is limestone/lime scrubbing, where SO2 reacts with calcium carbonate/hydroxide slurry to form calcium sulfite/sulfate (gypsum).

20. List four major indoor air pollutants and their sources.

    Radon (soil/rock under buildings), Carbon monoxide and NO2 (combustion of fuels for cooking/heating), Formaldehyde/VOCs (paints, furniture, adhesives), and particulate matter/tobacco smoke. Biomass cooking causes high indoor pollution in rural areas.

21. What is a catalytic converter and what reactions does a three-way catalytic converter perform?

    A catalytic converter (Pt, Pd, Rh catalysts) reduces vehicular emissions: it oxidizes CO to CO2, oxidizes unburned hydrocarbons to CO2 and H2O, and reduces NOx to N2 and O2 (three-way action).

22. What is the Air Quality Index (AQI), and how many categories does India's National AQI use?

    AQI is a number used to communicate how polluted air is and associated health effects. India's National AQI (2015) has 6 categories: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), and Severe (401-500).

23. List the major sources of noise pollution.

    Industrial (machines, generators), Transportation (road traffic, railways, aircraft), Construction activities, Domestic/community sources (loudspeakers, appliances), and commercial/social events. Transportation is the largest contributor in urban areas.

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