CBSE Class 10 Science Notes: Our Environment

🌱 Ecosystems: The Web of Life

An ecosystem is a community of living organisms (plants, animals, microbes) interacting with each other and their physical environment (air, water, soil). It’s a dynamic system, constantly changing and evolving.

Definitions:

• Producers: These are the plants, algae, and some bacteria that create their own food through photosynthesis. They are the foundation of any food chain.
• Consumers: These organisms eat other organisms. They can be herbivores (eating plants), carnivores (eating animals), or omnivores (eating both).
• Decomposers: Bacteria and fungi that break down dead plants and animals, returning nutrients to the soil. They are essential for nutrient recycling.

Simple Food Chain Example:

Food Web: A complex network of interconnected food chains within an ecosystem.

💨 Environmental Problems: Pollution’s Impact

Environmental pollution harms our planet and our health. Let’s look at some types:

Types of Pollution:

• Air Pollution: Contamination of the atmosphere by harmful gases (carbon monoxide, sulfur dioxide) and particulate matter (dust, smoke).
• Water Pollution: Contamination of water bodies by sewage, industrial waste, pesticides, and other pollutants.
• Soil Pollution: Contamination of soil by industrial waste, pesticides, and improper waste disposal.

Causes:

• Industrial activities: Release of pollutants from factories and power plants.
• Vehicular emissions: Exhaust from cars, trucks, and other vehicles.
• Agricultural practices: Use of fertilizers and pesticides.
• Deforestation: Leads to soil erosion and loss of air purification.
• Improper waste disposal: Landfills and open dumping.

Short-Term Effects:

• Air Pollution: Respiratory problems (coughing, asthma), eye irritation.
• Water Pollution: Waterborne diseases, damage to aquatic life.
• Soil Pollution: Contamination of food crops, harm to soil organisms.

🌍 Ozone Depletion: Protecting Our Shield

The ozone layer, found in the stratosphere, absorbs most of the sun’s harmful ultraviolet (UV) radiation.

What it Means: Ozone depletion is the thinning of this protective layer, leading to increased UV radiation reaching the Earth’s surface.

Main Causes:

Chlorofluorocarbons (CFCs): These chemicals, previously used in refrigerants, aerosols, and some industrial processes, are a major cause of ozone depletion. When CFCs reach the stratosphere, they release chlorine atoms, which catalyze the breakdown of ozone molecules.

Overview of Chemical Reactions:

• CFCs are broken down by UV radiation, releasing chlorine atoms (Cl).
• A chlorine atom reacts with an ozone molecule ($O_3$) forming chlorine monoxide (ClO) and oxygen ($O_2$).
• The chlorine monoxide molecule then reacts with another ozone molecule to release a chlorine atom and forms two $O_2$ molecules.
• This released chlorine atom can then react with another ozone molecule, repeating the process.

Why it Matters: Increased UV radiation can cause:

• Skin cancer
• Cataracts
• Damage to plants and crops
• Disruption of aquatic ecosystems

🗑️ Waste Production: Managing Our Trash

Understanding the difference between different types of waste is crucial for proper management.

Definitions:

• Biodegradable Materials: These materials can be broken down by the action of microorganisms (bacteria, fungi) into simpler substances.
• Non-Biodegradable Materials: These materials cannot be broken down by microorganisms and persist in the environment for a long time.

Examples:

• Biodegradable: Food waste, paper, cotton, wood, leaves
• Non-Biodegradable: Plastics, metals, glass, synthetic fibers

♻️ Waste Management and Solutions: Reduce, Reuse, Recycle

Effective waste management is essential for a healthy environment. Let’s explore some key strategies:

Core Principles:

• Reduce: Minimize waste generation by reducing consumption. For example: using reusable bags, avoiding single-use plastics, and buying products with minimal packaging.
• Reuse: Use items multiple times for different purposes. For example: Reusing plastic containers, donating old clothes, repairing broken items.
• Recycle: Process used materials to create new products. For example: Recycling paper, plastic, glass, and metal.

Composting:

Composting is the natural process of decomposing organic matter (food scraps, yard waste) to produce a nutrient-rich soil amendment. It’s a great way to reduce waste sent to landfills and improve soil quality.

Safe Disposal Basics:

• Properly segregate waste into biodegradable and non-biodegradable categories.
• Dispose of waste in designated bins or collection centers.
• Avoid open dumping of waste.
• Follow local regulations for hazardous waste disposal (batteries, electronics, etc.).