UGC NET Paper One Unit 9: People, Development and Environment

Definition & Scope:

Environmental issues refer to problems that disrupt the normal functioning of ecosystems, affecting biodiversity, climate stability, and resource availability. These issues may arise due to natural phenomena or, more commonly, due to human activities. When ecosystems lose their ability to recover, the impact becomes severe.

Levels of Impact:

Environmental issues exist at local, regional, and global levels:

• Local: Waste disposal, water scarcity, desertification. In large parts of Eastern India, the groundwater is contaminated primarily by arsenic.Asked in Exam
• Regional & Global: Climate change, ocean acidification, ozone depletion. These large-scale crises demand collective global action.

Pollution Sources:

• Air pollution: Industries, power plants, vehicles.Asked in Exam
• Land pollution: Excessive chemical fertilizers.Asked in Exam
• Water pollution: Industrial discharges and various sources.Asked in Exam
• Noise pollution: Roads, aircraft, industry, high-intensity sonar.Asked in Exam

Composition & Distribution

Water (H₂O) is clear, tasteless, and odorless. We get water from surface water (lakes, rivers) and groundwater (aquifers).

Global Water Distribution (Decreasing Order):

Freshwater Quantity (Increasing Order):

Percentage Breakdown:

Water pollution occurs when harmful substances contaminate water bodies.

Types of Pollution Sources:

Specific Pollution Scenarios:

Organic Compounds:

• Petroleum Hydrocarbons: From oil spills and runoff.
• Volatile Organic Compounds (VOCs): From industrial solvents.
• Per- and Polyfluoroalkyl Substances (PFAS): Persistent "forever chemicals" from non-stick cookware and foams.
• Polychlorinated Biphenyls (PCBs):
  • The full form of PCB is Poly Chlorinated Biphenyls.Asked in Exam
  • Synthetic chemicals used in electrical transformers.
  • Bioaccumulate in fat tissues and cause cancer.
  • Restricted under the Stockholm Convention.

Inorganic Contaminants:

• Ammonia: From food processing waste.
• Heavy Metals: Lead, zinc, mercury, cadmium from emissions and industrial waste. In large parts of Eastern India, the groundwater is contaminated by Arsenic.Asked in Exam
• Nitrates and Phosphates: From fertilizers and sewage; cause eutrophication.
• Silt (Sediment): Increases turbidity. Muddy water has the highest turbidity.Asked in Exam
• Salt: From road de-icing and irrigation.

Pharmaceutical Pollutants (PPCPs):

• Includes medications and personal care products.
• Sewage plants often cannot remove them (requires fourth-stage treatment).
• Antibiotics from agriculture also contribute.

Solid Waste and Plastics:

• Enters via runoff and littering.
• Microplastics cause long-term contamination.

Overview:

Marine pollution is caused by industrial, agricultural, and residential waste. It includes harmful substances like plastics and chemicals. Excess carbon dioxide leads to ocean acidification, affecting marine life and ecosystem balance. This pollution damages the global economy through fisheries and tourism.

Specific Impacts:

• Coral Reefs: Coral reefs are threatened because of release of sewage in ocean waters near them.Asked in Exam
• Water Clarity: Release of sewage in oceans tends to reduce the clarity of ocean water.Asked in Exam

Sources of Marine Pollution:

• Land-Based Activities: 80% of marine pollution originates from land. Household, industrial, and farm waste reach oceans. Fertilizers and pesticides wash into rivers and seas, while soil erosion adds sediments, harming marine habitats.
• Marine Transportation: Ships release oil, waste, and noise pollution. Oil spills harm marine life, and ballast water introduces invasive species.
• Atmospheric Pollution: Pollutants from the air (dust, sulfur, nitrogen) settle into the ocean. Carbonic acid contributes to ocean acidification.
• Continental Shelves: Nearshore areas face the highest pollution levels due to industrial zones and urban wastewater.

Pathways of Pollution:

• Direct Discharge: Waste dumped directly into the ocean.
• Land Runoff: Pollutants carried by rainwater into rivers and then the ocean.
• Ship Pollution: Waste and oil discharged from ships.
• Bilge Pollution: Contaminants from the bilge water of ships.
• Atmospheric Pollution: Pollutants from the air settling into the ocean.
• Deep Sea Mining: Potential future source of pollution.

Definition:

Nutrient pollution is caused by excess nitrogen and phosphorus in water, leading to eutrophication and harmful algal blooms. It reduces oxygen, harming aquatic ecosystems.

Sources:

• Farm Runoff: Fertilizers and animal waste wash into water. This is a major contributor to eutrophication.
• Septic Tanks and Feedlots: Leaks release nutrients, raising nitrogen and phosphorus levels.
• Combustion Emissions: Fossil fuel burning releases nitrogen compounds which settle into lakes and oceans.
• Raw Sewage: Untreated sewage contains high nutrient levels, encouraging algal blooms.

Environmental Impact:

• Eutrophication: Algae overgrowth depletes oxygen levels, causing fish kills. Algae blocks sunlight, harming aquatic plants.
• Harmful Algal Blooms (HABs): Certain algae produce toxins harmful to life, impacting fisheries and tourism.
• Hypoxia (Dead Zones): Low oxygen levels make water uninhabitable. A major dead zone exists in the Gulf of Mexico.
• Acid Rain: Excess nitrogen lowers pH levels in lakes and rivers.
• Climate Change: Nitrous oxide accelerates global warming.

Definition:

Thermal pollution, also called "thermal enrichment," happens when human activities change the natural temperature of water. Unlike chemical pollution, it changes the physical properties of the water.

Causes:

• Industrial Cooling: Power plants and factories use water as a coolant and release it back at a higher temperature.
• Urban Runoff: Rainwater running off hot surfaces like rooftops and roads warms up natural water bodies.
• Reservoirs: Releasing very cold water from the bottom of reservoirs into warmer rivers.

Effects:

• Oxygen Depletion: Warm water holds less oxygen.
• Thermal Shock: A sudden change in temperature can kill fish and other wildlife accustomed to a specific range.

Definition:

Endocrine-disrupting chemicals (EDCs) are chemicals that can interfere with the body's hormones. Most of the emerging contaminants of water are Endocrine Disrupting Chemicals (EDCs).Asked in Exam

Common Sources:

• Plastic bottles and containers.
• Liners of metal food cans.
• Detergents and cosmetics.
• Flame retardant additives, found in the environment throughout the globe, are considered to be EDCs.Asked in Exam

Emerging Concerns:

Many of the emerging contaminants have been observed to bioaccumulate in wildlife and humans.Asked in Exam

Concepts:

Distinction:

1. Physical Parameters

Physical parameters describe the physical characteristics of water.

Key Parameters:

2. Chemical Parameters

Chemical parameters reflect the chemical composition and the presence of dissolved substances. pH, Hardness, DO, and BOD are chemical parameters of water quality.Asked in Exam

3. Biological Parameters

Biological water quality parameters check for the presence of waterborne pathogens and other microorganisms like bacteria and viruses.

Definition and Causes

Water hardness is the amount of dissolved calcium and magnesium in the water. These minerals cause the hardness of water and are present as chlorides, sulfates, and bicarbonates.

Characteristics and Impact

• Hardness in water can occur in both surface and underground waters.Asked in Exam
• Water hardness, due to calcium and magnesium ions, is classified as temporary or permanent. It leads to scale buildup in hot water pipes.Asked in Exam
• Hard water causes scaling in water distribution systems.Asked in Exam
• Hard water is considered safe for human consumption.Asked in Exam

Hard Water vs. Soft Water

Types of Hardness: Temporary vs. Permanent