ENVIRONMENTAL SCIENCE

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ENVIRONMENTAL SCIENCE
CHAPTER 3Ecosystems What Are They and How Do
They Work?
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Core Case Study Tropical Rainforests Are
Disappearing

• Found near the equator
• At one time covered 14 land surface, now covers
  only 2
• 50 worlds known terrestrial plant and animal
  species
• 50 destroyed or disturbed by humans
• Cutting trees
• Growing crops
• Grazing cattle
• Building settlements

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Core Case Study Tropical Rainforests Are
Disappearing

• Consequences of disappearing tropical rainforests
• Decreased biodiversity as species become extinct
• Accelerated global warming fewer trees to remove
  carbon dioxide from the atmosphere
• Changes regional weather patterns can lead to
  increase in tropical grasslands

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Sect. 3.1What Keeps Us and Other Organisms Alive?

• Concepts to learn in 3.1
• 1. The four major components of the earths
  life-support system are the atmosphere (air), the
  hydrosphere (water), the geosphere (rock, soil,
  sediment), and the biosphere (living things).
• 2. Life is sustained by the flow of energy from
  the sun through the biosphere, the cycling of
  nutrients within the biosphere, and gravity.

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Earth Has Four Major Life-Support Components

• 1. Atmosphere Thin layer of gases, surrounding
  earths surface. Consists of
• a. Troposphere contains the air we breathe
  (look up mixture) greenhouse gases
• b. Stratosphere contains ozone, which filters
  UV rays, allowing for life to exist
• Hydrosphere contains all of the water on or
  near the earths surface
• a. Which water source makes up the largest
  component?

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Earth Has Four Major Life-Support Components

• Geosphere 3 parts
• a. Core (extremely hot, mostly liquid rock)
• b. Mantle (mostly rock)
• c. Crust (thin outer layer)
• Biosphere includes all the parts of the
  atmosphere, hydrosphere geosphere where life is
  found.
• a. ecology focuses on this area
• b. It is a very thin layer of the earth
  atmosphere

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Three Factors Sustain Life on Earth

• 1. One-way flow of high-quality energy from the
  sun
• 2. Cycling of matter or nutrients through parts
  of the biosphere
• 3. Gravity

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Solar Energy Reaching the Earth (one way energy
flow)

• Suns energy reaches us as electromagnetic waves,
  seen as
• 1. Visible light
• 2. UV radiation
• 3. Heat
• Natural greenhouse effect What effect does it
  have on the earths energy?

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Solar Energy Reaching the Earth (one way energy
flow)

• The flow of energy in from the sun will equal
  the flow of energy out into the environment /
  atmosphere
• 1. Group discussion
• a. How does this happen?
• b. Is this energy recycled?

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Sect. 3.2 What Are the Major Components of an
Ecosystem?

• Some organisms produce the nutrients they need.
• Some get the nutrients they need by consuming
  other organism.
• Some recycle nutrients back to producers by
  decomposing the wastes and remains of organisms.

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Ecology

• Ecology How organisms interact with biotic
  (living) and abiotic (non-living) environments
• Ecology focuses on levels of matter ranging from
  the atomic level to the entire biosphere. 5
  levels
• 1. Organisms
• 2. Populations
• 3. Communities
• 4. Ecosystems
• 5. Biosphere

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Nonliving Components of Ecosystems

• Abiotic non-living components of ecosystems,
  which includes
• Water
• Air
• Nutrients
• Solar energy
• Rocks
• Heat

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Living Components of Ecosystems

• Biotic living components of ecosystems,
  including
• Plants
• Animals
• Microbes
• Dead organisms
• Waste products of dead organisms
• Waste products of living organisms

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Trophic Levels

• Trophic Levels feeding levels assigned to
  every organism in an ecosystem
• 1. Producers- called autotrophs
• a. Produce food thru photosynthesis
• 2. Consumers called heterotrophs
• a. Primary consumers herbivores (eat plants)
• b. Secondary consumers carnivores that eat
  herbivores
• Third-level consumers carnivores that eat
  carnivores
• Omnivores eat both plants and animals

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Additional Trophic Levels

• Decomposers
• Release nutrients from the dead bodies of plants
  and animals
• Detrivores
• Feed on the waste or dead bodies of organisms

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Production and Consumption of Energy

• Photosynthesis
• Carbon dioxide water solar energy ?glucose
  oxygen
• Aerobic respiration
• Glucose oxygen ? carbon dioxide water energy

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Energy Flow and Nutrient Recycling

• Ecosystems are sustained through
• 1. One-way energy flow from the sun
• 2. Nutrient recycling

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Science Focus Invisible Organisms

• Microorganisms/Microbes
• Bacteria
• Protozoa
• Fungi
• Phytoplankton

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Science Focus Invisible Organisms

• Microbes can cause disease
• Malaria
• Athletes foot
• Microbes are also beneficial
• Intestinal flora
• Purify water
• Phytoplankton remove carbon dioxide from the
  atmosphere

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Sect. 3.3 What Happens to Energy in an
Ecosystem?

• As energy flows through ecosystems in food chains
  and webs, the amount of chemical energy available
  to organisms at each succeeding feeding level
  decreases.

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Energy Flow in Ecosystems

• The chemical energy stored in all organisms flows
  thru ecosystems from one trophic level to another
• Food chain
• Sequence of organisms, each of which serves as a
  source of food for the next
• Includes food production, feeders, and
  decomposition
• Food web
• A more complex network of interconnected food
  chains.
• Consumers feed on more than one organism
• Organisms are eaten/decomposed by more than one
  organism

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Usable Energy by Trophic Level

• Energy flow thru food webs follows the second law
  of thermodynamics energy lost as heat
• Biomass The dry weight of all organic matter
  contained in its organisms
• 1. Each trophic level has one, but biomass
  decreases with increasing trophic level
• Ecological efficiency of energy transferred
  thru food chains is typically 10.
• See Pyramid of energy flow, fig. 3-10 pg 47
• 1. shows variable energy transfer efficiency
  between trophic levels

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Ecosystem efficiency in producing plant matter

• The amount of biomass an ecosystem is capable of
  producing is determined by its efficiency in
  capturing solar energy and converting it to
  chemical energy in food.
• Gross Primary Productivity (GPP) rate at which
  an ecosystems producers (mostly plants) convert
  solar energy into chemical energy (stored in
  biomass of their tissues)
• 1. plants do use some of their produced energy
  for their own respiration

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Two Kinds of Primary Productivity

• Net primary productivity (NPP) rate at which
  producers use photosynthesis to produce store
  chemical energy minus the rate at which they use
  some energy thru aerobic respiration.
• Planets NPP limits number of consumers
• Humans use, waste, or destroy between 10-55 of
  earths total potential NPP
• Human population is less than 1 of total biomass
  of earths consumers

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3-4 What Happens to Matter in an Ecosystem?

• Concept 3-4 Matter, in the form of nutrients,
  cycles within and among ecosystems and in the
  biosphere, and human activities are altering
  these chemical cycles.

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Biogeochemical Cycles

• Also called Nutrient cycles
• All cycles have a place where the nutrients
  accumulate, called reservoirs
• These nutrient cycles connect all organisms
  through time!
• Cycles are all driven by
• 1. solar energy
• 2. gravity

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Hydrologic Cycle

• Water cycle is powered by the sun. Involves 3
  processes
• Evaporation (from bodies of water)
• Precipitation (rain, snow, sleet)
• Transpiration water evaporation from plant
  surfaces
• Over bodies of water most water vapor comes
  from the oceans 84
• Over land 90 of water reaching the atmosphere
  comes from transpiration

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The Water Cycle

• As water moves thru its cycle, some will
  temporarily stored in
• 1. Living parts of the ecosystems
• a. EX Plants roots pull water into plants,
  which is stored in chemical compounds, then moved
  thru the ecosystem by transpiration and by plants
  being consumed
• 2. glaciers
• 3. Aquifers stores of groundwater under
  layers of rock, sand gravel

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The Water cycle

• An important feature of the water cycle is that
  as water passes thru, there is a natural renewal
  of water quality.
• 1. In a sense, it is like a water filter
  which filters out impurities.
• Lots of water is visible. How much of it is
  available to us as freshwater, usable for
  consumption?
• about 0.024 of the total volume of water

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Science Focus Waters Unique Properties

• Holds water molecules together (called hydrogen
  bonding)
• Water is liquid over a wide temperature range
• It changes temperature slowly
• Requires large amounts of energy to evaporate

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Additional Unique Properties of Water

• Dissolves a variety of compounds
• Filters out UV light from the sun
• Adheres to a solid surface allows capillary
  action in plants
• Expands as it freezes

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Carbon Cycle

• Based on carbon dioxide (CO2)
• It circulates thru the biosphere, hydrosphere
  atmosphere
• CO2 makes up 0.038 of atmospheres volume
• Major cycle processes that carbon cycles thru
• Aerobic respiration
• Photosynthesis
• Fossil fuel combustion and deforestation (both
  can lead to a build-up of CO2)
• Fossil fuels add CO2 to the atmosphere will cause
  an increase in temperature (and a decrease in CO2
  will decrease surface temperatures)

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Nitrogen Cycle

• Multicellular plants and animals cannot directly
  absorb and use atmospheric nitrogen (N2), which
  makes up most of the atmosphere (78)
• 1. Nitrogen is extremely important to the
  building of proteins, vitamins nucleic acids
• 2. Bacteria are our friends, because they
  convert N2 to a form which can be absorbed
• 3. There are 2 processes involved with this
  conversion Nitrogen Fixation and Nitrification
• 4. There are 2 additional processes in the
  nitrogen cycle Ammonification and
  Denitrification

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Nitrogen Cycle

• Nitrogen fixation specialized bacteria in soil
  and green algae in aquatic environments combine
  N2 with H2 to produce ammonia (NH3)
• 1. Some is converted to NH4 ions, and is
  absorbed by plants
• Nitrification NH3 and NH4 is converted by
  special bacteria into nitrate ions (NO3-)
• 1. plants will use it to make proteins (amino
  acids) nucleic acids vitamins

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Nitrogen Cycle

• Ammonification The process that decomposer
  bacterias accomplish when they eat decaying
  plants animals, converting their
  nitrogen-containing compounds into ammonia or
  ammonium ions.
• Denitrification A specialized process of
  bacteria in watery soil sediments of lakes
  oceans, that convert ammonia ammonia ions back
  into N2 gas, to be returned back into the
  nitrogen cycle again.

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Phosphorus Cycle

• Does not cycle through the atmosphere
• Its obtained mostly from terrestrial rock
  formations ocean floor sediments
• 1. water runs over rocks, slowly eroding off
  phosphorus salts (containing phosphate ions
  PO43-)
• It is the slowest moving of all the cycles
• The presence of phosphorus is a limiting factor
  on land and in freshwater ecosystems
• Biologically important for producers and
  consumers
• 1. part of energy transfer molecules ADP ATP
• 2. part of nucleic acids

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Sulfur Cycle

• Most sulfur stored in rocks and minerals, in
  ocean sediments
• Enters atmosphere through
• 1. Volcanic eruptions and processes
• 2. Anaerobic decomposition in swamps,
  bogs, and tidal flats
• 3. Sea spray
• 4. Dust storms
• 5. Forest fires

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Sulfur Cycle

• Biologically important to producers consumers
• 1. sulfur is an essential part of proteins
• 2. It is absorbed by plants thru their roots

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3-5 How Do Scientists Study Ecosystems?

• Scientists use field research, laboratory
  research, and mathematical and other models to
  learn about ecosystems.

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Field Research

• Collecting data in the field by scientists that
  are actively in the mud
• Remote sensing devices are also used to
  detect/scan the earths surface
• Geographic information systems (GIS) used to
  interpret display the information obtained thru
  remote sensing devices.

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Laboratory Research

• Simplified model ecosystems
• Culture tubes
• Bottles
• Aquariums
• Greenhouses
• Chambers with controllable abiotic factors
• How well do lab experiments correspond with the
  greater complexity of real ecosystems?
• Is best for doing controlled experiments!

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Scientific Studies of Ecosystems

• Models can be used
• 1. Mathematical
• 2. Computer simulations
• Models need to be fed real data collected in the
  field- baseline data before any meaningful
  interpretations can take place.
• Models must also determine relationships among
  the key variables

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Baseline Data to Measure Earths Health

• A baseline of data is needed in order to monitor
  any changes over time
• Many ecosystems lack this baseline data
• Call for massive program to develop baseline data