Objective

1
Objective

• Students will be able to analyze the laws of
  thermodynamics in order to illustrate the
  continuous flow of energy in the biosphere.

2
Chapter 3 Matter, Energy, Life

• To the best of our knowledge, our Sun is the
  only star proven to grow vegetables. Philip
  Scherrer, Stanford University

3
Matter

• All matter is composed of atoms of a certain
  number of elements.
• Isotopes atoms of the same element with
  differing neutron numbers.
• In Env. Sci. we focus on isotopes because they
  are often unstable, thus spontaneously emitting
  particles. Examples uranium plutonium can
  give us radioactive waste and nuclear energy.

4
Acids Bases

• Acids (acidic) have an excess of H ions. pHlt7
• Bases (alkaline) have an excess of OH- ions. pHgt7
• Neutral (distilled H2O) equal balance of H and
  OH- ions. pH7
• Acids cause environmental damage because the H
  ions react with living tissue and also nonliving
  substances like rocks or other land features that
  can erode under acid rain.

5
pH Scale

• The pH Scale is LOGARITHMIC.
• This means that each step on the scale is ten
  times more than the previous step.
• For example, a pH of 2 is ten times more acidic
  than a pH of 3, and 100 times more acidic than a
  pH of 4.
• Likewise a pH of 13 is ten times more alkaline
  than a pH of 12, and 100 times more alkaline than
  a pH of 11.

6
Buffers

• A solutions pH can be neutralized by adding
  buffers.
• For example, acid rain can be buffered by
  alkaline earth (rocks soil, predominantly
  limestone).

7
Energy

• Energy the ability to do work examples heat,
  light, electricity, chemical energy, etc.
• Kinetic energy energy of motion
• Potential energy stored energy that is
  available for use. Examples food, gas.
• Energy is measured in calories (heat) or joules
  (work).

8
Energy Quality

• Low-quality energy that is diffused, dispersed,
  and low in temperature. Example the heat
  energy stored in the oceans.
• High-quality energy that is intense,
  concentrated, and high in temperature used to
  carry out work. Examples fire, electricity, oil
• Many alternative energy sources are low-quality
  compared to the high-quality energy sources we
  have become accustomed to (oil, gas, electricity,
  coal).

9
Thermodynamics Energy Transfers

• Thermodynamics deals with how energy is
  transferred in natural processes deals with the
  rates of flow and the transformation of energy
  from one form or quality to another.
• Energy conversions underlie all ecological
  processes.

10
Laws of Thermodynamics

• First Law - Matter can be neither created nor
  destroyed, only reused over time. (Also known as
  the Law of Conservation of Matter)
• Second Law With each successive energy transfer
  or transformation in a system, less energy is
  available to do work i.e., every time energy is
  used is to do work, some of that energy is
  dissipated or lost as heat.
• The Second Law results in increased entropy,
  meaning that everything in the universe tends to
  fall apart, slow down, and get more disorganized
  with time (including humans!!).

11
Energy for Life

• Nearly all life on Earth depends on the sun for
  energy to create cells and carry out life
  processes.
• Exceptions to this rule are chemosynthetic
  bacteria which oxidize hydrogen sulfide for
  energy. This process can support entire living
  systems deep in the ocean, beyond the reach of
  sunlight.

12
Solar Energy Sun

• Essential to life for two reasons
• 1. provides warmth (Earths water atmosphere
  help to moderate, maintain, and distribute the
  suns heat.)
• 2. provides light (solar radiation)
  photosynthesis converts solar radiation into
  useful, high quality chemical energy in the form
  of glucose.

13
Solar Calculations

• How much of the available solar energy is
  actually used by organisms?
• The amount of incoming solar radiation is about
  1,372 W/m2 at the top of the atmosphere (1
  watt1J/s). However, more than ½ may be
  reflected or absorbed by clouds, dust, and gases
  (ozone) in the atmosphere.
• Of the solar radiation that reaches Earth, about
  10 is UV, 45 is visible light, and 45 is
  infrared (heat). The majority of this is either
  absorbed by land and water or reflected by snow
  and ice.
• Of all the visible light that reaches Earth,
  plants can only use red and blue light for
  photosynthesis, which amounts to only 1 to 2 of
  all sunlight falling on plants. This small
  percentage represents the energy base for
  virtually all life in the biosphere!

14
Photosynthesis vs. Cellular Respiration

• 6H2O 6CO2 light (energy)
  C6H12O6 6O2 process of making glucose
  energy is captured
• C6H12O6 6O2 6H2O 6CO2
  energy process of using glucose energy is
  released

15
What is an Ecosystem?

• Consists of a collection of organisms and all the
  physical aspects of their habitat, such as the
  soil, water, and weather.
• Population- all the members of a species living
  in a given area at the same time.
• Community all the populations living and
  interacting in a particular area.
• Ecosystem composed of a biological community
  and its physical environment (includes biotic
  abiotic factors).
• Most ecosystems are open, i.e., they exchange
  materials organisms with other ecosystems.
  Example stream, river
• Closed ecosystem very little enters or leaves.
  Example - aquarium

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How does Photosynthesis Provide the Energy that
Drives all Ecosystems?

• Plants capture some of the suns light and store
  it as chemical energy in organic molecules.
• This is what we call food, i.e. fruits veggies.
  A scientific term is Primary Productivity.
• Critical Thinking How does primary productivity
  determine the amount of energy available in an
  ecosystem?

17
Productivity, or Biomass

• Biomass the amount of biological material
  produced in a given area during a given period of
  time.
• Primary Productivity producers or autotrophs
• Secondary Productivity consumers or
  heterotrophs
• Gross Primary Productivity the total amount of
  energy that producers fix a percentage of this
  is used for the maintenance needs of the
  producers themselves
• Net primary productivity - the energy available
  to other trophic levels

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What is a Food Chain?

• A Food Chain Illustrates how Energy is
  Transferred among Organisms in an Ecosystem.

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What is a Food Web?

• In most ecosystems, energy doesnt follow simple,
  straight paths because individual organisms feed
  on multiple sources.
• These connections can be represented in a Food
  Web.
• Next slide, then Borneo story.

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How are Food Webs both Simple Complex?
21
Who eats what?!?

• Herbivores plant eaters ex. - cows
• Carnivores meat eaters ex. - wolves
• Omnivores eat both plants and meat ex.
  humans, bears
• Scavengers clean up dead carcasses of larger
  animals ex. crows, vultures, hyenas
• Detritivores consume litter, debris, and dung
  ex. ants, beetles, copepods
• Decomposers breakdown and recycle organic
  matter ex. fungi and bacteria

22
What is an Energy Pyramid How does it Represent
different Trophic Levels?

• Illustrates the amount of energy transferred in
  an ecosystem.
• Each block of the Energy Pyramid represents a
  unique Trophic Level.

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Energy is Limited

• Available energy decreases at each level, because
  at every trophic level energy is lost as heat.
• 10 rule Each block of the pyramid can only
  obtain 10 of the energy below it.
• Why? Some of the food that organisms eat is
  undigested and doesnt provide usable energy.
  Also, some is used in the daily process of
  surviving or lost as heat and so cant be eaten
  as biomass by a higher trophic level.

24
Objective Drill

• Students will demonstrate that matter cycles
  through and between living systems and the
  physical environment in order to show how energy
  is constantly being recombined in different ways.
• Your body contains vast numbers of carbon atoms.
  How is it possible that some of these carbon
  atoms may have been part of the body of a
  prehistoric creature?

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How are Matter and Energy Recycled in an
Ecosystem?

• Nutrients are substances needed by the body for
  energy, growth, maintenance.
• Five very important Nutrients are Water, Carbon,
  Nitrogen, Phosphorus, Sulfur.
• These Nutrients are Recycled through
  Biogeochemical Pathways
• Hydrologic Cycle
• Carbon Cycle
• Nitrogen Cycle
• Phosphorus cycle
• Sulfur Cycle

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The Hydrologic Cycle (H2O)
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The Water Cycle Contd

• Solar energy evaporates H2O from seas and land
• Winds distribute water vapor around the globe
• Condenses into clouds
• Water precipitates over land and oceans
• Precipitation and Runoff from land enters Lakes
  Rivers
• Returns to ocean
• Precipitation enters Groundwater through
  Percolation
• Water enters animals through drinking and eating,
  and returns to the atmosphere through exhalation
  and sweating

28
The Carbon Cycle
29
Carbon Cycle Contd

• Carbon is the key ingredient in all living
  organisms.
• CO2 is released into the atmosphere by
• volcanic activity
• respiration
• the burning of fossil fuels
• the decomposition of organic matter.
• Plants then take up this CO2 in photosynthesis.
  Animals obtain carbon by eating plants.
• Plants and animals release CO2 through
  respiration.

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Carbon Cycle Continued

• The carbon atoms in coal and oil arent released
  until it is burned for fuel.
• Enormous amounts of carbon are locked up as CaCO3
  (calcium carbonate) in the shells of aquatic
  organisms. Eventually, this will probably become
  limestone.
• Therefore, the ocean is considered a carbon sink
  because it removes carbon from the atmosphere,
  thus reducing green-house gases.
• Huge forests are also carbon sinks.

31
Human Interactions with the Carbon Cycle

• The burning of fossil fuels and the act of
  deforestation have released an abundance of
  carbon back into the atmosphere.
• This excess of atmospheric carbon is a greenhouse
  gas and results in global warming, which in turn
  has adversely affected global weather patterns,
  i.e., more intense storms, heat waves, drought,
  flooding, and even the eventual melt of the polar
  ice caps.
• By working toward the goal of sustainable
  development, we can limit the amount of carbon
  re-released into the atmosphere and slow the
  process of global warming.

32
The Nitrogen Cycle

• http//www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp
  29/animations/ch29/1_nitrogen_cycle.swf

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Nitrogen

• Nitrogen is the most abundant element in the
  atmosphere, existing as a gas (N2). The
  atmosphere is the primary sink for nitrogen.
• However, most plants can only use Nitrogen in the
  form of Nitrate (NO3-).
• Nitrogen Fixation (the process of combining
  nitrogen with Hydrogen to form Ammonia, NH3) is
  accomplished by Lightning and by Bacteria that
  live in soil and in the roots of certain plants
  (legumes).
• This ammonia is then converted, or oxidized, to
  nitrite and then to nitrate by bacteria in a
  process called Nitrification.
• Now, it is in a form that plants can use.

34
Nitrogen Contd

• Plants then absorb Nitrogen through the soil with
  the help of the Nitrogen Fixing Bacteria and use
  it for making chlorophyll.
• Animals, including humans, obtain Nitrogen by
  Eating Plants and other Animals that contain
  Nitrogen.
• We use nitrogen for making proteins and DNA.

35
Nitrogen Contd

• Decomposers (fungi bacteria) break down
  decaying animals and thereby release Nitrogen as
  Ammonia (NH3). Again, this process is called
  Nitrogen Fixation.
• Then, denitrifying bacteria in the soil take up
  the ammonia and oxidize it into nitrites (NO2-)
  and nitrates (NO3-). Again, this is called
  Nitrification. In this way, it is ready for reuse
  by plants.
• In the reverse process, Denitrification,
  Nitrogen is converted from NO3- and NO2- to N2,
  and returned to the atmosphere as a gas.

36
Problems with Nitrogen

• By using nitrate-rich synthetic fertilizers,
  cultivating nitrogen-fixing crops, and burning
  fossil fuels, we have more than doubled the
  amount of nitrogen cycling through our
  environment.
• This causes a loss of soil nutrients (calcium and
  potassium).
• Acidification of rivers and lake
• Rising concentrations of the greenhouse gas
  nitrous oxide.
• It also encourages the spread of weeds into areas
  occupied by native plant species adapted to
  nitrogen-poor environments.
• Nitrogen-rich runoff causes toxic algal and
  dinoflagellate blooms.

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The Phosphorus Cycle
38
Phosphorus Continued

• Begins when phosphorus is leeched from rocks and
  minerals over long periods of time.
• Usually transported in aqueous form because,
  unlike nitrogen, it has no atmospheric form.
• It is then taken in by produces and consequently
  eaten by consumers, and finally rereleased
  through decomposition.

39
Phosphorus Cycle

• Energy-rich, phosphorus-containing compounds are
  primary participants in energy transfer reactions
• The amount of available phosphorus in an
  environment can have a dramatic effect on
  productivity, therefore it is termed a limiting
  factor.
• The phosphorus cycle takes an inordinate amount
  of time to complete. Ex. deep sediments of the
  oceans and lithosphere are significant phosphorus
  sinks of extreme longevity. Phosphate ores that
  are now being mined for fertilizers represent
  exposed ocean sediments that are millennia old.
• Phosphates can be found in everyday household
  cleaners like laundry and dish soaps. When this
  water reaches lakes, streams, and/or oceans, the
  abundance of phosphorus stimulates plant,
  photosynthetic bacteria, and algal growth, making
  it a major contributor to water pollution.

40
The Sulfur Cycle
41
Sulfur Cycle

• Most of the earths sulfur is tied up underground
  in rocks and minerals such as pyrite (iron
  disulfide) or gypsum (calcium sulfate).
• It is released into the atmosphere by the process
  of weathering and erosion, emissions from deep
  sea vents, volcanic eruptions.
• Bacteria also sequester sulfur in biogenic
  deposits or release it into the environment,
  depending on oxygen concentrations, pH and light
  levels.
• Humans release vast amounts of sulfur through the
  burning of fossil fuels. These are termed
  anthropogenic emissions, meaning created by
  humans.
• Complicated by the large number of oxidation
  states that the sulfur element can assume, i.e.,
  H2S, SO2, SO4-2, elemental sulfur, to name a
  few.

42
Sulfur Continued

• Can produce
• acid rain
• human health problems
• damage to buildings
• damage to vegetation
• reduced visibility
• cloud cover that cools cities and may be slightly
  offsetting greenhouse effects of rising CO2
  concentrations.

43
Biogeochemical Contaminants

• Any or all of the elements and compounds of the
  biogeochemical cycles can cause EUTRIFICATION of
  aquatic areas.
• Eutrification rivers, lakes, streams, etc. that
  have become rich in organic matter to the point
  of oxygen depletion.

44
Exit Ticket

• Choose one of the Material Cycles (carbon,
  nitrogen, phosphorus, or sulfur) and identify the
  components of the cycle in which you participate.
  For which of these components would it be
  easiest to reduce your impacts?