Earth Science Notes Human Impacts On Land

Human Impacts BIG IDEA Protecting the human interests of health, safety and resource management depends on an understanding of natural hazards and human impacts on Earth systems.

Human Impacts Human Activities that Impact Land Population Growth Farming Mining Land Development Waste Disposal

Population Growth Population growth = death rate and the birthrate. However, when the death rate is high, the birthrate is normally also high. Population growth is directly related to: current population, birth rate, death rate. Growth rate = Birth Rate - Death Rate 1.3% = 2.2% - 0.9% (today) Of these the Birth Rate is the most important contributor, specifically the Fertility Rate (#children/woman) Why? Because death rates have stabilized...

Population Growth

Population Growth Populations of countries go through 4 stages Preindustrial Stage little population growth because harsh social conditions lead to both high death and high birth rates. Transitional Stage when industrialization begins and health care improves, resulting in lowered death rates, but birth rates remain high. Most of the developing world here. Industrial Stage when the birth rate drops due to modernization (and its accompanying social changes). Many developed countries and a few developing countries here. Postindustrial Stage I recognized by further reductions in birth rates, approaching or even below zero population growth. Approximately 13% of the world population (mostly European countries) is in this stage.

Population Growth

Population Growth

Population Growth Notice the difference in the age distribution is impacted by the countries’ stage in development

How many people can the Earth support? Population Growth Carrying Capacity (K) How many people can the Earth support? Physical carrying capacity = “packing density”, limited only by space and resources Cultural carrying capacity is always less Still there is a large difference of opinion regarding how many people the earth can support. Accepted range for K is 10-20 billion people

Population Growth Factors affecting carrying capacity Food availability Water Environmental conditions Space.

Population Growth UN projects the WP will reach 28 billion by 2150 (about 4X today's population) Some scientists project the Earth’s population will stabilized around 2030. Falling birthrates due to developing nations Possible increase in death rate Current death rates is 9d/1000 This puts average age of death at 111 in the future Based on average age of death worldwide at 75 years, this puts the death rate a 13.3d/1000

Farming Impacts Fertilizers Positive Impacts: Increases variety, abundances of Food Allows food to be grown cheaper Negative Impacts: Can increase soil acidity (apply lime) Can runoff into lakes and streams Kill aquatic life, overgrown lakes

Farming Impacts Grazing of Livestock Soil degradation Increases runoff due to soil compaction Soil/Water contamination (e. coli) Soil Erosion Reduces plant density Factor leading to desertification

Farming Impacts

Mining Impacts Creates Acidic Mine Drainage (AMD) Mining of Minerals When metal ores are mined metals in rock can oxidize and release H+ (acid ions) into streams. Nationwide, over 12,000 miles of rivers and streams and over 180,000 acres of lakes and reservoirs are adversely affected by contaminated water draining from abandoned mines. River and Groundwater are contaminated AMD has adverse affects on wildlife

Mining Impacts Acid Mine Drainage

Mining Impacts Mining of Minerals Causes Erosion and Deposition The mining process releases large quantities of sediment that are transported by water erosion. The sediment eventually drops out of the water and deposition occurs at some point downstream.

Erosion and Deposition Mining Impacts Erosion and Deposition

Mining Impacts Mining of Minerals Habitat Modification Mining adversely affects aquatic habitats (i.e. lakes, ponds, streams, rivers), terrestrial habitats (i.e. deserts, grasslands, forests) Change topography of the land Change waterways and draining

Mining Impacts Mining of Minerals

Impacts of Land Development Increased runoff and flooding Less flow during dry seasons Increased erosion

Impacts of Land Development Reduced Farmland It is estimated that 1.5 million acres of productive farmland are lost every year to urbanization. How can we feed an increasing population with a decrease in farmland?

Impacts of Land Development Deforestation The clearing of forest for agriculture, logging, or development Deforestation creates loss of habitat Tropical forests contain the greatest diversity of wildlife on the planet May lead to the extinction of species Deforestation can affect regional climates Fewer trees = less evaporation/transpiration = less rain = dryer climate.

Impacts of Land Development

Impacts of Land Development

Impacts of Land Development

Impacts of Waste Disposal Hazardous Waste Wastes that can catch fire, cause cancer, or are generally poisonous. HW needs to be disposed of differently than our everyday garbage

Impacts of Waste Disposal A waste is hazardous if it exhibits one or more of the following characteristics: IGNITABILITY — catch fire CORROSIVITY — acidic, eat through metals REACTIVITY — unstable, may explode. TOXICITY — harmful or fatal when ingested or absorbed

Impacts of Waste Disposal Dealing with Waste Sanitary Landfills Where everyday garbage is deposited Designed to prevent liquid waste from draining into the soil. Lined with clay or plastic liner, have fluid collection system, and air vents.

Impacts of Waste Disposal Dealing with Waste Phytoremediation Use of plants in the removal of contaminants from contaminated soil, water, sediments, and air. Cheaper / more aesthetically pleasing (pretty)

Phytoremediation Examples Pollutant Medium plant(s) Petroleum & Hydrocarbons Soil & Groundwater Alfalfa, poplar, juniper, fescue Heavy Metals Soil Hybrid poplar, grasses Radionuclides Groundwater Sunflowers Indian mustard, cabbage Expolsives waste Duckweed, parrotfeather Nitrates Hybrid poplar

Impacts of Waste Disposal Dealing with Waste Enzymes Substances that speed up chemical reactions. Ennzymes breaking down of pollutants in simpler, more harmless substances

Summary Be able to… Describe factors that affect human population growth Define carrying capacity (K) Explain how each human activity described impacts the environment Describe methods of limiting human impacts