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Chapter 6 – Humans in the Biosphere

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1 Chapter 6 – Humans in the Biosphere

2 6-1 A Changing Landscape Earth as an island – we need to need to see how models can be used to make predictions about complex systems… Hawaii pg 139 Among human activities that affect the biosphere are - hunting and gathering – decreases natural species in certain areas; has caused major mass extinctions

3 - agriculture – created dependable food source… villages settled… habitat destruction, introduced species, pest control, irrigation - industry – machines and factories use fossil fuels (coal, oil, natural gas) - urban development – discarded wastes… pollution, movement to suburbs… habitat destruction

4 American artist Chris Jordan recreated Seurat’s masterpiece with digital images of 106,000 aluminum cans - the number used in the US every thirty seconds!


6 6-2 Renewable and nonrenewable resources
Tragedy of the commons – idea that any resource that is free and accessible may eventually be destroyed. Renewable resource – can regenerate or be replenished by a chemical cycle; trees, water

7 Nonrenewable resources – cannot be replenished by natural processes; fossil fuels burn and energy is given off *** a population of trees may be nonrenewable if ecosystem changes

8 Sustainable development – use ecological studies to see how we are impacting the environment in order to save resources Land resources – soil can be permanently damaged - soil erosion and desertification occur when humans change environment… contour plowing and leaving in roots can help

9 Forest resources – used for materials, oxygen, habitats, and food
- deforestation can lead to erosion and loss of habitats Fishery resources – oceans and lakes provide a lot of food – aquaculture - overfishing is an example of the tragedy of the commons

10 Air resources – cities produce smog, a pollutant from the burning of fossil fuels that can cause health problems -acid rain – nitric and sulfuric acids with a high pH which can kill plants and animals

11 Chemical Transformation Emissions to Atmosphere
Formation of Acid Rain Chemical Transformation Nitric acid Sulfuric acid Condensation Emissions to Atmosphere Nitrogen oxides Sulfur dioxide Dry Fallout Precipitation Acid rain, fog, snow, and mist particulates, gases Industry Transportation Ore smelting Power generation

12 Freshwater resources – pollution threatens water supplies; improperly discarded chemicals, domestic sewage

13 6-3 Biodiversity Biodiversity = the sum total of the genetically based variety of all organisms in the biosphere - one of Earth’s greatest natural resources.

14 Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs.

15 Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.

16 Species Diversity

17 Pollution – DDT, a pesticide, became more concentrated as it moved up the food web… biological magnification

18 Biological Magnification of DDT
Fish-Eating Birds Magnification of DDT Concentration 10,000,000 100,000 10,000 1,000,000 1 1000 Large Fish Small Fish Zooplankton Producers Water

19 Introduced species – humans transport plants and animals around the world that take over a new habitat

20 Conserving Biodiversity
- managing endangered species, protecting habitats, fishing regulations

21 Sustainable Agriculture
Cover Crops Legumes, grasses, and other cover crops recycle soil nutrients, reduce fertilizer need, and prevent weed growth. Controlled Grazing By managing graze periods and herd densities, farmers can improve nutrient cycling, increase the effectiveness of precipitation, and increase the carrying capacity of pastures. Biological Pest Control The use of predators and parasites to control destructive insects minimizes pesticide use as well as crop damage Contour Plowing Contour plowing reduces soil erosion from land runoff. On hilly areas, plowing is done across the hill rather than straight up and down. Crop Rotation Different crops use and replenish different nutrients. By rotating crops, the loss of important plant nutrients is decreased. A B C Yr. 1 Yr. 2 Yr. 3 corn alfalfa oats alfalfa (plowed in)

22 6-4 Charting a Course for the Future
Ozone depletion – ozone layer absorbs harmful ultraviolet radiation; evidence exists that chlorofluorocarbons, CFCs, could damage the ozone layer; use of most CFCs are banned in US Global Climate Change – increase in the average temperature of the Biosphere; some scientists attribute this to human activities and the burning of fossil fuels… CO2

23 Ecosystem Services Solar energy Production of oxygen
Storage and recycling of nutrients Regulation of climate Purification of water and air Storage and distribution of fresh water Food production Nursery habits for wildlife Detoxification of human and industrial waste Natural pest and disease control Management of soil erosion and runoff

24 How does everything fit?

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