Enhance your understanding of Environmental Chemistry with comprehensive exercises and notes. Cover key topics like pollution, green chemistry, and sustainable practices to excel in exams and deepen your knowledge.
Q. 4 Discuss in detail the components of the environment.
The environment is composed of several key components:
- Atmosphere: The layer of gases surrounding Earth, including oxygen, nitrogen, carbon dioxide, and others. It protects life on Earth by blocking harmful solar radiation.
- Lithosphere: The solid outer part of the Earth, comprising rocks, soil, and minerals. It supports terrestrial ecosystems and human infrastructure.
- Hydrosphere: All the water on Earth’s surface, including oceans, rivers, lakes, and groundwater. It is crucial for life, as it supports aquatic ecosystems and is essential for human consumption.
- Biosphere: The global sum of all ecosystems, where living organisms interact with the other components of the environment. This includes all plants, animals, and microorganisms.
Q. 5 Describe the natural and human sources of carbon monoxide, nitrogen oxides, and sulphur oxides.
- Carbon monoxide (CO):
- Natural sources: Wildfires, volcanic eruptions, and the oxidation of methane in the atmosphere.
- Human sources: Incomplete combustion of fossil fuels from vehicles, industrial processes, and residential heating.
- Nitrogen oxides (NOx):
- Natural sources: Lightning strikes, microbial activity in soils, and wildfires.
- Human sources: Burning of fossil fuels in vehicles, power plants, and industrial activities.
- Sulphur oxides (SOx):
- Natural sources: Volcanic eruptions and the decomposition of organic matter.
- Human sources: Burning of coal and oil, particularly in power plants and industrial processes like refining.
Q. 6 What is acid rain and how does it affect our environment?
Acid rain is rainfall that contains elevated levels of hydrogen ions (low pH) due to the presence of sulphuric and nitric acids, formed from sulfur dioxide (SO₂) and nitrogen oxides (NOx) emissions.
Effects on the environment:
- Aquatic life: Acid rain lowers the pH of water bodies, harming fish and other aquatic organisms.
- Soil: It leaches essential nutrients like calcium and magnesium from the soil, reducing soil fertility.
- Vegetation: It damages the leaves of plants, stunts growth, and weakens trees, making them more vulnerable to diseases.
- Built structures: Acid rain corrodes buildings, statues, and infrastructure, especially those made of limestone and marble.
Q. 7 What is smog? Explain the pollutants which are the main cause of photochemical smog.
Smog is a type of air pollution caused by the interaction of sunlight with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs).
- Photochemical smog: Formed when sunlight reacts with nitrogen oxides and hydrocarbons from vehicle emissions, creating harmful ozone (O₃) at ground level.
- Main pollutants:
- Nitrogen oxides (NOx): Emitted by vehicles and industrial processes.
- Volatile organic compounds (VOCs): Released from vehicle exhaust, industrial emissions, and solvents.
- Ozone (O₃): A secondary pollutant formed through the reaction of NOx and VOCs in sunlight, contributing to respiratory issues and environmental damage.
Q. 8 Why is the ozone layer depleting? What will happen when the concentration of ozone will be decreased?
The ozone layer is depleting due to the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS), which break down ozone molecules (O₃) in the stratosphere.
- Consequences of ozone depletion:
- Increased exposure to harmful ultraviolet (UV) radiation, leading to higher rates of skin cancer, cataracts, and immune system suppression in humans.
- Disruption of marine ecosystems, particularly affecting plankton, which form the base of the aquatic food chain.
- Harm to plant life, which could reduce agricultural productivity.
Q. 9 How is oil spillage affecting the marine life?
Oil spills cause significant harm to marine ecosystems:
- Coating of animals: Oil coats the fur and feathers of marine animals such as birds and otters, reducing their insulation and buoyancy, leading to hypothermia or drowning.
- Toxicity: The chemicals in oil are toxic to marine organisms, damaging their organs and reproductive systems.
- Contamination of food chains: Oil contaminants enter the food chain, affecting not only marine organisms but also humans who consume seafood.
Q. 10 How detergents are a threat to aquatic animal life?
Detergents contain surfactants, phosphates, and other chemicals that can harm aquatic life:
- Surfactants: Disrupt the membranes of aquatic organisms, leading to cell damage and death.
- Phosphates: Promote eutrophication, leading to algal blooms that deplete oxygen in water, creating dead zones where aquatic life cannot survive.
- Bioaccumulation: Some detergent chemicals accumulate in aquatic organisms, affecting their health and the health of those higher up the food chain.
Q. 12 Explain how pesticides are dangerous to human beings.
Pesticides are hazardous to humans through:
- Acute toxicity: Exposure to high doses can cause immediate health issues such as nausea, dizziness, and respiratory problems.
- Chronic exposure: Long-term exposure can lead to serious health effects, including cancer, neurological disorders, reproductive issues, and developmental problems in children.
- Bioaccumulation: Pesticides can accumulate in the food chain, leading to higher concentrations in humans through consumption of contaminated food and water.
Q. 13 Discuss industrial waste effluents.
Industrial waste effluents are liquid waste products discharged by industries. They may contain:
- Toxic chemicals: Such as heavy metals (lead, mercury), volatile organic compounds (VOCs), and acids, which can contaminate water sources and harm both human and environmental health.
- Nutrients: Excess nitrogen and phosphorus from agricultural and food industries can cause eutrophication in water bodies.
- Thermal pollution: Waste heat discharged into water bodies can disrupt ecosystems by altering temperature conditions and reducing oxygen levels.
Q. 14 How water is purified i.e., made potable. Discuss in detail.
Water purification involves several steps to remove contaminants and make it safe for drinking:
- Coagulation and flocculation: Chemicals (coagulants) are added to water to bind small particles into larger clumps (flocs).
- Sedimentation: The flocs settle at the bottom of a sedimentation tank.
- Filtration: The water passes through sand, gravel, or charcoal filters to remove smaller particles.
- Disinfection: Chlorine, ozone, or ultraviolet light is used to kill harmful bacteria, viruses, and parasites.
- Additional treatment: Fluoridation and pH adjustments may be done before distribution to consumers.
Q. 15 What are leachates?
Leachates are liquids that have percolated through solid waste (in landfills or contaminated soil) and extracted dissolved or suspended materials. Leachates often contain harmful chemicals and pollutants, which can contaminate soil and groundwater if not properly managed.
Q. 16 Explain the process of incineration of industrial waste.
Incineration is a waste treatment process that involves burning industrial waste at high temperatures (800°C to 1000°C). The waste is converted into ash, flue gases, and heat.
Steps involved in incineration:
- Waste preparation: Sorting and pre-treating waste materials to ensure safe combustion.
- Combustion: The waste is burned in a controlled environment, reducing the volume of solid waste by up to 90%.
- Energy recovery: The heat generated during incineration can be used to produce electricity or steam.
- Emission control: Pollutants in flue gases are treated using filters and scrubbers to minimize environmental harm.
