biology 14.1-14.3

14.1 Pollutants

• Pollution: Addition of harmful materials or pollutants to the environment, materials that aren't usually harmful unless excessive.

• Sulfur Dioxide: Released into the air when fossil fuels are burned, contributing to respiratory issues and environmental damage.

• Nitrogen Oxides: Emitted from burning fossil fuels in factories, power stations, and vehicles, leading to the formation of acid rain and impacting air quality. These convert to nitric and nitrous acids in the atmosphere.

• Acid Rain: Rain whose pH level has been lowered by the presence of dissolved acids (sulfuric acid, nitric acid, nitrous acid); can harm plants, damage buildings, and affect water in lakes and rivers.

• Fine Particulate Matter: Micro-scale liquid or solid particles (dust) that can cause respiratory diseases in humans.

• Carbon Monoxide: A pollutant released when carbon-containing compounds burn in low oxygen conditions, posing serious health risks.

• Photochemical Smog: A thick brownish mist formed by unburned hydrocarbons emitted by incomplete combustion in engines and nitrogen oxides reacting in sunlight, common in urban areas. Causes eye and throat irritation, breathing difficulties, and can lead to serious health issues such as birth defects and premature death.

14.2 Greenhouse Effect

• Greenhouse Effect: The trapping of heat near the Earth's surface. Similar to greenhouses that trap heat for plant growth, certain gases in the atmosphere (CO2, Methane, CFCs) trap radiation.

• Greenhouse Gases: These gases prevent long-wave radiation (infrared radiation) from escaping the atmosphere, which maintains Earth's warmth.

• Enhanced Greenhouse Effect: Excessive heat is trapped due to an increase in greenhouse gases, leading to global warming. Factors contributing to this include:

  • Increased CO2 from fossil fuel combustion in motor vehicles and industries, and deforestation.

  • Methane increases due to cattle farming, population growth, accidental natural gas leaks, and the decay of organic wastes.

  • CFCs used in refrigeration and as propellants damage the ozone layer, which protects Earth from harmful ultraviolet radiation.

• Effects of Global Warming:

  • Alters precipitation levels;

  • Leads to the melting of polar ice caps;

  • Results in increased rainfall or dry deserts;

  • Affects the stability of ecosystems;

  • Contributes to food shortages as food chains become disrupted.

14.3 Nuclear Pollution

• Ionizing Radiation: High-energy radiation (gamma rays, X-rays, beta particles) that can cause harmful side effects such as DNA mutations leading to cancer and birth defects.

• Radiation Sickness: High doses of radiation exposure can cause nausea, vomiting, hair loss, and burns.

• Nuclear Power Plants: Use ionizing radiation from radioactive materials to produce heat and electricity. If not designed and maintained properly, they can release harmful radioactive materials into the environment, contaminating air, water, and ecosystems.

• Food Chain Impacts: Animals in affected ecosystems may ingest contaminated food or water, passing the radioactive materials up the food chain.

14.4 Human Impacts

• Food Scarcity Causes: Insufficient food production can result from natural crises (droughts, floods, crop diseases), political disturbances, overpopulation, economic crises, and outdated agricultural methods.

• Famine: A widespread and extreme scarcity of food often followed by increased death rates. Causes include an increase in food demand putting pressure on land and ecosystems.

• Modern Agriculture Techniques: Heavy machinery and chemicals are used to enhance crop growth, which can lead to soil contamination and reduced soil health.

• Monoculture: The practice of growing a single species in an area, often non-native, decreases biodiversity, increases pest populations, and makes crops susceptible to diseases.

• Pesticides: Chemicals to kill pests can harm beneficial species and lead to resistance among pest populations, and may not break down easily in nature.

• Fertilizers: While they replenish nutrients, they can also cause soil and water pollution.

14.5 Selective Breeding

• Selective Breeding: A method to enhance crop production through the selection of parent organisms for desirable traits, such as disease resistance, nutritional quality, and adaptability. However, it reduces biodiversity, threatening ecosystem stability.

14.6 Mechanized Agriculture

• Mechanized Agriculture: Involves the use of large machinery, which can lead to soil destruction and pollution from leaks.

• Livestock Production: Intensive livestock farming requires antibiotics to prevent disease but may lead to antibiotic resistance.

• Overgrazing: Occurs when livestock graze land excessively, resulting in soil degradation and risk of desertification.

14.7 Human Use of Forests

• Forests: Provide timber, raw materials, habitats, and participate in water cycles and climate regulation.

• Deforestation: Large-scale tree removal disrupts the balance of oxygen and carbon dioxide, contributing to global warming and water cycle disturbances.

• Habitat Destruction: Leads to biodiversity loss and species extinction.

• Human Activities: Mining and overharvesting can also cause habitat destruction, further threatening ecosystems and species.