our environment

• Our environment is often discussed in media and global summits, and we will study how various factors in the environment interact with each other and how we impact the environment
• In Class IX, we saw how different materials are cycled in the environment in separate biogeochemical cycles, and we will now see how human activities affect these cycles
• What happens when we add our waste to the environment

  1. Collect waste material from homes

  2. Bury the material in a pit or container

  3. Keep the material moist and observe at 15-day intervals

  4. Identify materials that remain unchanged over long periods

  5. Identify materials that change form and structure over time

  6. Identify materials that change the fastest
• Biodegradable


  Substances that are broken down by biological processes
• Non-biodegradable


  Substances that are not broken down by biological processes, may persist in the environment or harm the ecosystem
• Ecosystem


  All the interacting organisms in an area together with the non-living constituents of the environment
• Components of an ecosystem

  • Biotic (living organisms)
  • Abiotic (physical factors like temperature, rainfall, wind, soil, minerals)
• Types of ecosystems


  • Natural (forests, ponds, lakes)
  • Human-made (gardens, crop-fields)
• Organisms in an ecosystem

  • Producers (green plants, certain blue-green algae)
  • Consumers (herbivores, carnivores, omnivores, parasites)
  • Decomposers (bacteria, fungi)
• Creating an aquarium


  1. Provide fish with free space, water, oxygen, food

  2. Add aquatic plants and animals to make it self-sustaining

  3. Clean the aquarium periodically
• Ponds and lakes do not need to be cleaned in the same way as aquariums
• Food chain


  Series of organisms feeding on one another
• Trophic levels in a food chain

  • Producers (autotrophs)
  • Primary consumers (herbivores)
  • Secondary consumers (small carnivores)
  • Tertiary consumers (larger carnivores)
• Green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert it into food energy
• When green plants are eaten by primary consumers, a great deal of energy is lost as heat to the environment, some goes into digestion and work, and the rest goes towards growth and reproduction
• An average of 10% of the food eaten by a consumer is turned into its own body and made available for the next level of consumers
• Food web


  Relationship between organisms in an ecosystem shown as a series of branching lines
• The flow of energy in an ecosystem is unidirectional, it does not revert back to the previous trophic level
• Trophic levels


  1. Energy loss at each step

  2. Very little usable energy remains after four trophic levels
• There are generally a greater number of individuals at the lower trophic levels of an ecosystem, the greatest number is of the producers
• Food chains


  • Length and complexity vary greatly
  • Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms
  • Instead of a straight line, the relationship can be shown as a series of branching lines called a food web
• The flow of energy in an ecosystem is unidirectional
• The energy that is captured by the autotrophs does not revert back to the solar input and the energy which passes to the herbivores does not come back to autotrophs
• As energy moves progressively through the various trophic levels it is no longer available to the previous level
• Biological magnification


  The phenomenon where harmful chemicals get accumulated progressively at each trophic level, with the maximum concentration in human bodies at the top of the food chain
• Food grains, vegetables, fruits, and meat contain varying amounts of pesticide residues that cannot always be removed by washing or other means
• Ozone (O3) is a molecule formed by three atoms of oxygen that shields the Earth's surface from ultraviolet radiation
• Formation of ozone


  1. UV radiation splits apart some molecular oxygen (O2) into free oxygen (O) atoms

  2. These atoms then combine with the molecular oxygen to form ozone
• The amount of ozone in the atmosphere began to drop sharply in the 1980s due to synthetic chemicals like chlorofluorocarbons (CFCs)
• Improvements in lifestyle have resulted in greater amounts of waste material generation, with more disposable and non-biodegradable items
• Disposal of electronic waste can release hazardous materials that affect the environment
• Plastics are recycled, but the recycling process can have an impact on the environment
• Human Impact on Environment

  Ways humans affect the environment, including pollution, deforestation, climate change, overexploitation, and disruption of ecosystems.