Environmental Science Concepts: Resources, Pollution, and Ecosystem Dynamics
1. Resource Definitions and Pollution Classification
1.1 Resource Definitions
Define:
- (a) Renewable resources: Resources that are naturally replenished.
- (b) Non-renewable resources: Resources that exist in fixed amounts and are not naturally replenished on a human timescale.
1.2 Classification of Pollutants
(A) Depending upon their nature of existence:
- Quantitative: Normally occurring in nature.
- Qualitative: Do not normally occur.
(B) Depending upon the form in which they persist after being released in the environment:
- Primary: Emitted and persist in the same form (e.g., smoke, ash, dust, sulfur dioxide, hydrocarbon).
- Secondary: Formed from primary pollutants present in the environment (e.g., SO3, NO2). Nitrogen and hydrocarbon can form PAN (Peroxyacyl Nitrate), increasing toxicity.
(C) According to their nature of disposal:
- Biodegradable
- Non-biodegradable (Associated with Biomagnification)
Sources of Pollution
Natural Sources of Pollution
- Volcanic eruptions
- Forest fires
- Dust storms
- Bacteria, spores, pollens
- Decay in organic matter
- Salt spray
Man-made or Anthropogenic Sources of Pollution
Industrialization, automobiles, overpopulation, deforestation, nuclear explosions, overexploitation of natural resources, construction of buildings, roads, and dams, use of explosives in wars, use of fertilizer and pesticides, quarrying, and mining.
3. Biodiversity Definition and Levels
Based on the provided document, here is a detailed definition of biodiversity and its major levels.
Biodiversity, or biological diversity, is defined as the variety and variability among all groups of living organisms and the ecological complexes in which they are found. It includes the differences in genes within a species and the richness of all plant and animal species across various spatial scales. Biodiversity also represents the degree of nature’s variety in the biosphere.
Levels of Biodiversity
Biodiversity exists at three main levels:
Genetic Diversity
This refers to the genetic variability found within a single species. Each individual of an animal or plant species differs widely in its genetic makeup from other individuals. Genes are the basic units of hereditary information passed from one generation to the next, giving each individual its unique characteristics. Genetic diversity is essential for a healthy breeding population of a species.
Species Diversity
This level is concerned with the number of different plant and animal species present in a particular region. It broadly represents the richness and abundance of species within a community.
Ecosystem Diversity
This is the organization of species within an area into distinct plant and animal communities. It represents the wide variety of different ecosystems that exist on Earth. For any specific geographical region, there are distinctive ecosystems.
4. Major Sources of Water and Air Pollution
Water Pollution Sources
Water pollution is caused by the introduction of foreign substances (organic, inorganic, radiological, and biological) into water, which degrades its quality and makes it unsuitable for beneficial use. The primary sources of water pollution mentioned in the document are:
- Sewage, industrial waste, and synthetic chemicals: A significant portion of the limited water supply is polluted by these materials.
- Organic pollutants: These include oxygen-demanding waste, disease-causing waste, synthetic organic compounds like pesticides, detergents, and pharmaceuticals, as well as oil and agricultural runoff.
- Inorganic pollutants: These consist of mineral acids, inorganic salts, metal compounds, trace elements, cyanides, sulfates, and nitrates. Heavy metals such as mercury (Hg), cadmium (Cd), and lead (Pb) are noted as being the most toxic.
- Suspended solids and sediments: These result from soil erosion, agricultural development, mining, and construction activities.
- Radioactive materials and thermal pollution are also listed as sources.
Air Pollution Sources
Air pollution is defined as an excessive concentration of foreign matter in the air that harms individuals or damages property. The sources of air pollution can be either natural or man-made.
Natural Sources
- Volcanic eruptions: These release poisonous gases like sulfur dioxide ($\text{SO}_2$), hydrogen sulfide ($\text{H}_2\text{S}$), and carbon monoxide (CO).
- Forest fires.
- Natural organic and inorganic decays.
- Pollen grains: These can cause allergic reactions in people.
- Wind-blown dust.
Anthropogenic (Man-made) Sources
- Rapid Industrialization: Industries such as pulp and paper, chemical, metallurgical plants, and refineries release pollutants like $\text{CO}_2$, $\text{SO}_2$, CO, $\text{NO}$, and $\text{H}_2\text{S}$.
- Transportation: Automobile exhausts release smoke from the incomplete combustion of carbon-based matter, producing pollutants like CO, $\text{CO}_2$, and hydrocarbons.
- Burning of Fossil Fuels and Fires: The byproducts of burning wood, coal, and fossil fuels are poisonous gases such as CO, methane ($\text{CH}_4$), $\text{SO}_2$, and nitrogen oxides ($\text{NO}_x$).
- Deforestation: This disrupts the natural balance of $\text{CO}_2$ and $\text{O}_2$ in the environment.
- Increase in Population: This leads to the emission of greenhouse gases and a loss of forest cover.
- Agricultural activities: The use of various pesticides and insecticides contributes to air pollution.
- Radioactive fallout: Nuclear reactions and nuclear weapon testing contribute to nuclear pollution.
7. Causes and Effects of Thermal and Nuclear Pollution
Thermal Pollution
Thermal pollution is defined as the presence of waste heat in water, which can lead to undesirable changes in the natural environment.
Causes
A major cause of thermal pollution is the use of water for cooling in industries, particularly power plants. These plants use only about one-third of the energy produced from fossil fuels, and the rest is wasted as heat. Cold water is taken from a body of water for cooling and then returned to the source at a temperature that is 10–15 degrees higher.
Effects
The increase in water temperature has several negative effects on aquatic ecosystems. It decreases the solubility and penetration of oxygen in the water. This reduction in dissolved oxygen can harm or kill fish and other aquatic life.
Nuclear Pollution
Nuclear pollution is caused by radioactive fallout from sources such as nuclear reactions and nuclear weapon testing.
Causes
Human activities, specifically nuclear reactions and the testing of nuclear weapons, are the primary contributors to nuclear pollution.
Effects
Nuclear pollutants are extremely harmful to living organisms. They pose a significant threat to the health of humans, animals, and vegetation.
12. Role of Individuals in Reducing Environmental Pollution
The provided documents suggest several ways individuals can contribute to reducing various forms of environmental pollution. The overall message is that personal actions, hygiene, and awareness are key to prevention.
Water Pollution Control
To control water pollution, individuals are encouraged to use pesticides and fertilizers judiciously. The reuse of treated water is also an encouraged practice. The documents also stress the importance of “self hygiene, sanitation, and public awareness”.
Air Pollution Mitigation
While the documents focus more on the large-scale sources of air pollution like industrialization and transportation, they mention that the increase in population leads to global warming and the emission of greenhouse gases. This implies that individual choices related to population and consumption have an impact. The document also lists “Deforestation” as a man-made source of air pollution and notes that “the deforestation by man for his own needs has disturbed the balance of $\text{CO}_2$ and $\text{O}_2$ Concentration”. This suggests that individuals can play a role in reducing deforestation.
Land and Noise Pollution Prevention
For noise pollution, the document states that a main source is “increasing population and urbanization,” which suggests a link to individual actions. The document also offers specific actions for individuals to control noise pollution at the source, such as “reducing the noise levels from domestic sectors,” “low voice speaking,” and avoiding the use of loudspeakers.
The documents also offer ways to prevent land pollution, including:
- Planting trees everywhere.
- Bringing more land under farming.
- Disposing of waste matter immediately.
- Avoiding excessive use of fertilizers and pesticides.
- Avoiding drilling for more underground water.
UNIT 1 TOPIC: Food Chain, Food Web, and Pyramids
Transfer of Energy in an Ecosystem
This one-way flow of energy is governed by the laws of thermodynamics, which state that:
- The energy cannot be created nor destroyed but may be transferred from one form to another.
- During the energy transfer, there is degradation of energy from a concentrated form to a dispersed form (Heat).
Food Chain
Organisms at one level feed upon organisms at the lower level. Trophic Levels: Each link in a food chain is known as a trophic level.
The food chains in the ecosystem help to maintain:
- The biodiversity of nature
- The feeding relationship of nature
- Flow of the energy of the ecosystem
- Passage of nutrients from one organism to another
Significance of food chain: Biomagnification.
Food Web
A food web is a group of several interconnected food chains. In a food web, an organism gets food from more than one group of organisms.
Ecological Pyramids
An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or productivity at each trophic level in a given ecosystem.
A. Pyramid of Energy
Shows the amount of energy in calories ($\text{Kcal} / \text{cal}$).
B. Pyramid of Biomass
Shows the biomass of all organisms and individuals.
C. Pyramid of Numbers
Shows the number of individuals feeding at each trophic level.
Pyramids of Numbers
- Shows graphically the population, or abundance, in terms of the number of individual organisms involved at each level in a food chain.
- This shows the number of organisms in each trophic level without any consideration for their individual sizes or biomass.
- The pyramid is not necessarily upright. For example, it will be inverted if beetles are feeding from the output of forest trees, or parasites are feeding on large host animals.
Pyramid of Biomass
- Shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time.
- It is a graphical representation of biomass (total amount of living or organic matter in an ecosystem) present per unit area in different trophic levels.
Pyramid of Energy
- Shows the production or turnover (the rate at which energy or mass is transferred from one trophic level to the next) of biomass at each trophic level.
- When an ecosystem is healthy, this graph produces a standard ecological pyramid.
- This is because in order for the ecosystem to sustain itself, there must be more energy at lower trophic levels than there is at higher trophic levels.
- This allows organisms on the lower levels to not only maintain a stable population but also to transfer energy up the pyramid.