1. Science Behind Environmental Science
Chapter 2
Science Behind Environmental Science

2. Conservation of Matter
Matter can be changed
from one form to another
Cannot be created or destroyed
by ordinary physical or chemical processes

3. Conservation of Matter
In nature
Organisms use food supply
Little waste generated
Natural processes can recycle this waste

4. Conservation of Matter
Human population generates waste that
is not easily disposed of
may persist in nature indefinitely
may be harmful or toxic

5. Ecosystems Organisms and surrounding environment Abiotic Biotic
all the biotic and abiotic components
Abiotic
nonliving components of ecosystem
Biotic
living components of ecosystem

6. Biotic versus Abiotic Biotic Abiotic trees decaying logs deer wolves
squirrels
worms in soil
bacteria in soil
Abiotic
water
oxygen gas
atmosphere
amount of sunlight
acidity of water
type of soil
acidity of soil

7. Energy Laws First Law of Energy Energy cannot be created or destroyed
Can be converted
radiant to chemical energy
chemical energy to heat or kinetic energy
chemical energy to thermal energy
thermal energy to electrical energy

8. Energy Laws Second Law of Energy Every time energy is converted . . .
some energy is lost as heat

9. Flow of Energy An ecosystem is an energy system
All processes depend on energy
Nothing happens without flow of energy
Energy = ability to do work
moves from concentrated areas to become dispersed and unorganized

10. Flow of Energy
Energy source in most ecosystems = sun

11. Energy Flow Complete ecosystem has three types of organisms Producers
Transformers
Decomposers

12. Energy Flow Producers Transformers Decomposers
produce new food from photosynthesis
usually green plants
Transformers
change food into more complex organic molecules
Decomposers
break down organic materials for reuse

13. Energy Flow Four fundamental biotic processes synthesis photosynthesis
respiration
decomposition

14. Synthesis Change in composition, size, shape, structure
Organisms use nutrients, minerals, water
to produce growth and reproduction
Synthesis means “to make or form”

15. Photosynthesis Converts water and carbon dioxide into sugar
requires a catalyst
chlorophyll
green pigment
requires energy
from sun

16. Photosynthesis Photosynthesis original source of most food
also produces oxygen

17. Respiration Breaks down food to release energy
converts sugar into
water, carbon dioxide, and energy
Both plants and animals undergo respiration

18. Decomposition A special type of cellular respiration
Organic matter broken down to smaller organic compounds
Recycles chemicals in bodies of organisms
Follow-up Questions:
Oxygen is converted to what molecule during cellular respiration? Glucose is converted to what molecule during cellular respiration? What waste product is given off during decomposition?

19. Ultimate Concept John Muir Everything on Earth part of an ecosystem
“When we try to pick out anything by itself, we find it hitched to everything else in the universe.”
Everything on Earth part of an ecosystem
Everything is connected
Doing something to one part affects some or all parts of system

20. Natural Cycles Living organisms mostly composed of
carbon, hydrogen, nitrogen, and oxygen

21. Natural Cycles These elements used over and over again
Carbon atom found in sugar molecule of plant
Sugar consumed by an animal
Atom becomes part of animal muscle
When animal dies, it enters decomposers
Eventually, atom taken up by a plant again

22. Elemental Cycle The circular flow of elements
from living organisms to nonliving matter
All elements making up living tissue
all have elemental cycles
Two important elemental cycles
carbon
nitrogen

23. Carbon Cycle Carbons atoms cycle between living organisms
most abundant element in living organisms
the atmosphere
the oceans
the soil

24. Carbon Cycle Carbon enters living organisms through photosynthesis
takes carbon dioxide (CO2) from atmosphere
using light, turns CO2 into sugars
sugars used to form plant tissue
roots, stems, leaves

25. Carbon Cycle Carbon in plant material can enter animals
Animals consume plants
Respiration by plants and animals
returns CO2 to atmosphere
Plants and animals die
decay and release CO2 as gas
may form fossil fuels

26. Carbon Cycle Carbon dioxide returns to atmosphere through respiration
through decay of plants and animals
by burning fossil fuels
Living organisms die and are converted to fossil fuels

27. Carbon Cycle Oceans absorb and release CO2
high atmospheric carbon content:
Oceans absorb CO2
low atmospheric carbon content:
Oceans release CO2 to atmosphere
Oceans have maintained carbon content
Carbon in atmosphere remains fairly constant

28. Carbon Cycle and Global Warming
Carbon content of atmosphere has been rising
Burning of fossil fuels has increased
Carbon content of atmosphere has increased
Studies indicate that increasing carbon content is associated with increasing global temperatures

29. Cure for Global Warming?
Oceanic algae
addition of iron to seawater
stimulates algae growth
growth takes carbon dioxide from atmosphere
Scientists debate where CO2 goes next
bottom of the ocean or back to atmosphere?

30. Nitrogen Cycle Nitrogen cycles from nitrogen gas in atmosphere
to nitrates in soil
back to atmosphere as nitrogen gas

31. Nitrogen Cycle Nitrogen makes up 80 percent of air
most abundant element in atmosphere
must be combined with oxygen before it can be used by organisms

32. Nitrogen Cycle Nitrogen fixation
Nitrogen gas converted to nitrates
Nitrogen fixation can occur several ways
bacteria
industrial processes
lightning and decay

33. Nitrogen Cycle Nitrogen fixation bacteria
capable of converting nitrogen to nitrates

34. Nitrogen Cycle Nitrogen-fixing bacteria found in soil
roots of some plants
capable of making own nitrogen fertilizer

35. Nitrogen Cycle Nitrogen fixation industrial processes
converts nitrogen gas to nitrates
nitrogen first converted to ammonia
ammonia then converted to nitrates
nitrates used to make fertilizers

36. Nitrogen Cycle Nitrogen fixation lightning decay
electrical current passes through nitrogen
converts nitrogen gas to useable compounds
decay
nitrates released by decaying wastes
also released from decaying organisms

37. Nitrogen Cycle Denitrification Accomplished by
nitrates are broken down
returns nitrogen gas to atmosphere
Accomplished by
some bacteria
Nitrates in runoff enter surface water

38. Water One of most important resources
environmental effects and benefits
maintains more even temperature in environment
erosion
dilutes and flushes away contaminants

39. Water Biological effects and benefits required nutrient
controls temperature of organisms
solvent for nutrients
cools surface of skin and leaves
provides protection for some species

40. Water Cycle Water moves from What drives the water cycle?
ocean to atmosphere
to land in form of rain and snow
to rivers and stream
back to ocean
What drives the water cycle?
solar energy and gravity

41. Water Cycle Water enters atmosphere
evaporation from oceans
transpiration
controlled evaporation from pores in plant leaves
sweating
breathing
Moisture from these sources forms clouds

42. Water Cycle Moisture collects in atmosphere to form clouds
Clouds release stored water
rain and snow
Gravity draws water to Earth’s surface
Gravity draws water back to ocean

43. Energy Flow Ecologists represent energy flow with food chain
Sequence of organisms that eat and are eaten
Starts with producers

44. Energy Flow Producers eaten by herbivores
also called primary consumers

45. Energy Flow Ecologists represent energy flow with food chain
Herbivores eaten by carnivores
meat-eating organisms
also called secondary consumers

46. Energy Flow Decomposers final stop in the food chain
break down tissues of other organisms

47. sun A typical food chain Tertiary consumer top carnivore
Secondary consumer
carnivore
Primary consumer
heterotrophs
herbivore
Producer
autotrophs
Decomposers
Fungi
Bacteria

48. Energy Flow Food chain in ecosystems more complex Forms food webs
Usually many food chains are interwoven
Forms food webs
Many food chains linked together
Also forms a food pyramid
arranges organisms in a ranking order
rank related to dominance in food web

49. Ecosystem Change Human intervention may change food chains
Human activity may displace some organisms
Many times, top predators are removed

50. Ecosystem Change Some organisms cannot adapt to human presence
decline in number
replaced by organisms that tolerate humans

51. Biological Succession
Always occurring
Environments are rarely stable
always changing
Two types
primary
secondary

52. Biological Succession
Primary succession
occurs where no organisms existed before
cooled lava is an example
Over time, lichen and fungi appear
Pioneer species: first organisms growing in new environment
Soil begins to develop and plants appear

53. Biological Succession
Climax community
plants that occupy environment when succession complete

54. Biological Succession
Secondary succession
occurs when ecosystem is damaged
forest fire is an example
ecosystem changed by fire
supports organisms from earlier stage in succession

55. Biological Succession
Change that occurs in an environment
One kind of organism replaces another
Also called ecological succession
two forms
primary
secondary

56. Disturbances
Disturbances are often necessary for community development & survival

57. Ecological cycle
fire as part of a natural community cycle

58. Ecological succession
The sequence of community changes after a disturbance
transition in species composition over ecological time
years or decades
Mt. St. Helens

59. { Succession From bare soil, then… bacteria lichens & mosses grasses
Change in species mix over time
From bare soil, then…
bacteria
lichens & mosses
grasses
shrubs
trees {
make soil

60. Succession
from mosses & lichens
= pioneer species
to shrubs & trees

61. Climax forest
The species mix of climax forest is dependent on the abiotic factors of the region
solar energy levels
temperature
rainfall
fertility & depth of soil
birch, beech, maple, hemlock