1. Earth Science Notes
Human Impacts On Land

2. 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.

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

4. 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...

6. Population Growth

7. 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.

8. Population Growth

9. Population Growth

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

12. 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 billion people

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

14. 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

15. 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

17. 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

18. Farming Impacts

20. 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

21. Mining Impacts
Acid Mine Drainage

22. 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.

23. Erosion and Deposition
Mining Impacts
Erosion and Deposition

24. 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

25. Mining Impacts
Mining of Minerals

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

28. 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?

29. 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.

30. Impacts of Land Development

31. Impacts of Land Development

32. Impacts of Land Development

33. 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

34. 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

35. 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.

37. 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)

38. 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

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

40. 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