Chapter 27 : Human Impact on Earth’s Resources

Chapter 27:Human Impact on Earth’s Resources All living things need basic needs to survive Air, food, water, shelter

Resources and Population Growth As a population increases the demand for natural resources increases Exponential growth – pattern of growth in which a population grows faster as it increases in size (J-shaped curve), results in population explosion

Limits of Population Growth Limiting factors – cause a population to stop increasing (s-shaped curve) • Availability of food, water, or clean air • Capacity – number of organisms that any given environment can support • If population size exceeds the carrying capacity temporarily, the number of deaths will increase or the number of births will decrease, until the population size returns to the carrying capacity (equilibrium)

Impact on Land Resources - Extraction of Mineral Resources • Surface Mining – mineral and ore deposits found just beneath the Earth’s surface • Underground mining – mineral resources lie deep under the ground. Waste material must be removed & brought to the surface so when rainwater seeps through it takes toxins to the streams.

Surface Mining Control and Reclamation Act • Requires mining companies to restore the land to its original contours and to replant vegetation - reclamation

Agriculture • Biodiversity – wide variety of different species (forests, parks) • Monoculture – planting of just 1 species • Easier for farmers to sow, fertilize, and harvest crops • Disease can spread more rapidly which will result in the loss of crops

Urban development (Urbanization) • 70% of North Americas population lives in urban and suburban areas • Development takes land away from agricultural use, puts pressure on farmland to increase production • Fewer opportunities for rainwater to soak into the ground • Groundwater supplies are not recharged and flooding increases • Produces large volumes of solid wastes

Human impact on Air Resources • Smog – type of haze caused when solar radiation from the sun interacts with exhaust from automobiles • Created when nitrogen oxide, carbon monoxide, & hydrocarbons are converted to O3 when exposed to sunlight • Occurs in the form of particulate matter – solid particles in the air such as ash, pollen, dust, asbestos fibers, etc

Deforestation: clearing of forests without adequate replanting • Clear cutting - the complete removal of all the trees in the area. • (loss of topsoil and clogging streams with excess sediment. • New laws require buffer zones of trees which reduce the amount of runoff.

Global impacts Greenhouse effect – when the Earth’s atmosphere traps energy from the Sun in the troposphere & heats up the earth

Global Warming: increase in earth’s average temperature. (burning of fossil fuels)

Acid Precipitation Forms when sulfur dioxide and nitrogen oxides combine with water in the atmosphere to produce sulfuric acid and/or nitric acid. Coal burning power plants Sulfur dioxide can also be added by volcanoes

Acid Precipitation May flow into rivers and lakes causing damage to aquatic life (plants and animals) May change the pH of soil and, over time harm vegetation May weaken trees so that they are more easily harmed by insects and disease May damage stone buildings and statues and corrode metal at a faster rate

Ozone Depletion Layer of ozone in the stratosphere that protects humans from harmful UV radiation Chlorofluorocarbons (CFC’s) destroy ozone Montreal Protocol banned the use of CFC’s CFC’s come from refrigerants, cleaning agents, aerosol, etc.

Reducing Air Pollution • Wet Scrubber – device installed at coal-burning power plants to reduce sulfur dioxide and particulate matter emission • Replace older automobiles with newer ones with more efficient engines

Chapter 27 : Human Impact on Earth’s Resources