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Chapter 3 Environmental Systems: Chemistry, Energy, and Ecosystems PowerPoint


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Title: Chapter 3 Environmental Systems: Chemistry, Energy, and Ecosystems PowerPoint

Chapter 3Environmental Systems Chemistry,
Energy, and EcosystemsPowerPoint Slides
prepared by Jay Withgott and Heidi Marcum
This lecture will help you understand
  • The nature of environmental systems
  • The fundamentals of environmental chemistry
  • The molecular building blocks of organisms
  • Energy and energy flow
  • Photosynthesis and respiration
  • Ecosystems and interactions
  • Fundamentals of landscape ecology
  • Carbon, phosphorus, nitrogen, and water cycles

What is a Dead Zone?What causes it?Where are
they located?
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Its Not Just Us
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Central Case The Gulf of Mexicos Dead Zone
  • Gulf of Mexico used to bring in 600 million
    kg/year shrimp, fish, and shellfish
  • Gulf dead zone a region of water so depleted
    of oxygen that marine organisms are killed or
    driven away
  • In 2000, this zone encompassed 22,000 km2 (8,500
    mi2) an area larger than New Jersey.
  • Hypoxia low concentrations of dissolved oxygen
  • Caused by fertilizer, runoff, sewage
  • The U.S. government proposed that farmers reduce
    fertilizer use.

The Earths systems
  • System a network of relationships among
    components that interact with and influence one
  • Exchange of energy, matter, or information
  • Receives inputs of energy, matter, or
    information, processes these inputs, and produces
  • Feedback loop a systems output serves as input
    to that same system
  • A circular process

Negative feedback loop
  • Negative feedback loop output resulting from a
    system moving in one direction acts as an input
    that moves the system in the other direction
  • Input and output neutralize one another
  • Stabilizes the system
  • Example body temperature
  • Most systems in nature

Positive feedback loop
  • Positive feedback loop instead of stabilizing a
    system, it drives it further toward an extreme
  • Examples erosion
  • Rare in nature
  • But are common in natural systems altered by

  • Negative Feedback LoopA change in which the
    variable being regulated brings about a response
    that moves the variable in the "opposite
    direction". for example you are inside and at
    normal body temperature(variable) then you go
    outside into the cold and your body temp begins
    to decrease(unintended event), your body responds
    by causing events that raise your
    temperature(intentional change) "back up to its
    original value"(raising your temp that was
    falling). this is mostly seen in homeostasis and
    you dont have to go outside for your body to do
    this because it is constantly happening all the
    time.Positive Feedback loopthis type of
    feedback loop accelerates a process and usually
    has no obvious means of being slowed or stopped.
    Think of an avalanche that started as a small
    snowball rolling down a steep hill. One example
    is child birth in mammals. A positive feedback
    loop occurs when a baby's head is pushed against
    the birth canal. the nerve signals from smooth
    muscle cells of the birth canal send info to the
    brain which then triggers a hormone release from
    the petuitary glands. the hormones then cause
    those "same smooth muscle cells" in the birth
    canal to contract with more force, which causes
    more signals to be sent to the brain and so on
    until the fetus is delivered

  • Define the following
  • Ecosystem
  • Positive feedback loop
  • Negative feedback loop
  • Hypoxia
  • Be sure to have your writing assignment complete
    by tomorrow (section 1, ch 3)
  • I will be checking it

Systems Approach
  • Looking at ENTIRE situation
  • Holistic approach
  • Dead fish
  • Look at entire ecosystem for cause
  • Amount of dissolved O2
  • Health of other fauna
  • Human impacts
  • Cancer
  • Look at possible factors to form plan of action
  • Diet
  • Exercise
  • Alcohol intake

Environmental systems interact
  • Natural systems are divided into categories
  • Lithosphere rock and sediment
  • Atmosphere the air surrounding the planet
  • Hydrosphere all water on earth
  • Biosphere the planets living organisms
  • Categorizing systems allows humans to understand
    earths complexity.
  • Most systems overlap

The Gulf of Mexico a systems perspective
  • Very high levels of nutrients such as nitrogen
    and phosphorus from a variety of sources cause
    the abnormally low levels of oxygen in the Gulf
    of Mexico.

Where it Begins
Eutrophication in the Gulf
  • Nutrients (nitrogen and phosphorus) from various
    Midwestern sources enter the Mississippi River,
    which causes.
  • Phytoplankton (microscopic algae and bacteria) to
    grow, then
  • Bacteria eat dead phytoplankton and wastes and
    deplete oxygen, causing
  • Fish and other aquatic organisms to suffocate
  • Eutrophication the process of nutrient
    overenrichment, blooms of algae, increased
    production of organic matter, and ecosystem

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  • Read article Independently and Quietly in class
  • AFTER everyone in class has completed the reading
    assignment, you can work in pairs to complete the
    writing assignment. We will discuss your points
    tomorrow in class
  • Look at the different projects I have created for
    you. You will be responsible for completing one
    on the due date.

Chemistry Crucial for Understanding
  • Any environmental issue
  • How gases contribute to global climate change
  • How pollutants cause acid rain
  • The effects of chemicals on the health of
    wildlife and people
  • Water pollution
  • Wastewater treatment
  • Hazardous waste
  • Atmospheric ozone depletion
  • Energy issues

Chemical building blocks
  • Matter all material in the universe that has
    mass and occupies space
  • Can be transformed from one type of substance
    into others
  • But it cannot be destroyed or created, which is
  • The law of conservation of matter
  • Helps us understand that the amount of matter
    stays constant
  • Recycled in nutrient cycles and ecosystems

Chemical building blocks
  • Element a fundamental type of matter, with a
    given set of properties
  • Chemists recognize 92 elements in nature and 20
    artificially created ones.
  • Elements abundant in nature carbon, nitrogen,
    hydrogen and oxygen
  • Periodic table of the elements summarizes
    information on the elements

Elements are composed of atoms
  • Atoms the smallest components that maintain an
    elements chemical properties
  • The atoms nucleus has protons (positively
    charged particles) and neutrons (particles
    lacking electric charge).
  • Atomic number the atoms number of protons
  • Electrons negatively charged particles
    surrounding the nucleus that balance the
    positively charged protons
  • Atoms may also gain or lose electrons to become
    ions electrically charged atoms.

The structure of an atom
Chemical building blocks
  • Isotopes atoms with differing numbers of
  • Mass number the number of protons and neutrons
  • Isotopes of an element behave differently.
  • Some isotopes are radioactive.
  • They decay until they become non-radioactive
    stable isotopes.
  • Emit high-energy radiation

Radioactive decay
  • Half-life the amount of time it takes for
    one-half of the atoms to give off radiation and
  • Different radioscopes have different half-lives
    ranging from fractions of a second to billions of
  • Uranium-235, used in commercial nuclear power,
    has a half-life of 700 million years.

Molecules and compounds
  • Molecules combinations of two or more atoms
    Covalently Bonded
  • Oxygen gas O2
  • Compounds a molecule composed of atoms of two or
    more different elements
  • Water two hydrogen atoms bonded to one oxygen
    atom (H20)
  • Carbon dioxide one carbon atom with two oxygen
    atoms (CO2)
  • Solutions no chemical bonding, but is a mixture
    of substances (i.e., blood, ocean water)

Hydrogen ions determine acidity
  • The pH scale ranges from 0 to 14 and quantifies
    the acidity or basicity of solutions.
  • Acidic solutions have a pH less than 7.
  • Basic solutions have a pH greater than 7.
  • Neutral solutions have a pH of 7 (i.e., pure
  • A substance with pH of 6 contains 10 times as
    many hydrogen ions as a substance with pH of 7.

  • Outline pages 49-56

Organic Compounds
  • Organic compounds carbon atoms joined by bonds
    that may include other elements
  • Such as nitrogen, oxygen, sulfur, and phosphorus
  • Hydrocarbons contain only carbon and hydrogen
  • Make up fossil fuels
  • The simplest hydrocarbon is methane (natural gas)
  • Can be a gas, liquid, or solid

Macromolecules lifes building blocks
  • Polymers long chains of repeated molecules
  • The building blocks of life
  • Macromolecules large-size molecules
  • Three types of polymers are essential to life
  • Proteins
  • Nucleic acids
  • Carbohydrates
  • Lipids are not polymers, but are also essential.

  • Produce tissues, provide structural support,
    store energy, and transport substances
  • Made up of chains of amino acids
  • Animal proteins generate skin, hair, muscles, and
  • Some function as components of the immune system
  • Can serve as enzymes molecules that promote
    chemical reactions

A special process involving proteins
  • Nucleic acid directs the production of proteins
  • Deoxyribonucleic acid (DNA) and ribonucleic acid
    (RNA) carry the hereditary information of
  • Long chains of nucleotides that contain sugar,
    phosphate, and a nitrogen base
  • Genes regions of DNA that code for
  • proteins that perform certain functions

Carbohydrates and lipids
  • Carbohydrates atoms of carbon, hydrogen, and
  • Sugars simple carbohydrates, 3-7 carbons long
  • Glucose provides energy for cells
  • Complex carbohydrates build structures and store
  • Starch used by plants to store energy
  • Animals eat plants to acquire starch.
  • Cellulose of plants and shells of insects
  • Lipids a chemically diverse group of compounds
    grouped together because they dont dissolve in
  • Energy, cell membranes, structural support, and

Cells compartmentalize macromolecules
  • Cell the basic unit of lifes organization
  • Eukaryotes contain a membrane-enclosed nucleus
    and various organelles that perform specific
  • Plants, animals, fungi, protists
  • Prokaryotes single-celled organisms lacking
    organelles and a nucleus
  • Bacteria and archaea

  • Go over reading assignment 1
  • Testing your comprehension questions 1-4
  • Seeking Solutions questions 1 and 5
  • Dead Zone Questions/Scenario
  • HW sec 2 reading assignment for tomorrows

  • After presenting Scenario 1 or 2, Work on the
  • Kinetic vs. Potential Energy
  • Explain how Photosynthesis works
  • Relate photosynthesis to Primary Productivity
  • Compare Photosynthesis to Cellular Respiration

Energy fundamentals
  • Energy an intangible phenomenon that can change
    the position, physical composition, or
    temperature of matter
  • Potential energy energy of position
  • Kinetic energy energy of motion
  • Chemical energy potential energy held in the
    bonds between atoms
  • Potential energy is changed into kinetic energy
    to produce motion, action, and heat.

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Energy is conserved...but changes in quality
  • First law of thermodynamics energy can change
    forms, but cannot be created or destroyed
  • Second law of thermodynamics the nature of
    energy changes from a more-ordered to a
    less-ordered state if no force counteracts this
  • Entropy an increasing state of disorder
  • For example, burning a log of firewood transforms
    the log from a highly organized product into
    light and heat energy, gases, smoke, and carbon

The suns energy powers life
  • The energy that powers Earths ecological systems
    originates mainly from the sun.
  • The sun releases radiation from the
    electromagnetic spectrum.
  • Some is visible light

  • Autotrophs (producers) produce their own food
    from the suns energy
  • Green plants, algae, and cyanobacteria
  • Photosynthesis the process of turning light
    energy from the sun into chemical energy
  • Carbon dioxide water suns energy is
    converted into sugars and high-quality energy.
  • Low-quality energy is turned into high-quality

Photosynthesis produces food
  • Chloroplasts organelles where photosynthesis
  • Contain chlorophyll a light-absorbing pigment
  • Light reaction solar energy is used to split
    water to form oxygen and a small, high-energy
    molecule that fuels the.
  • Calvin cycle links carbon atoms from carbon
    dioxide into sugar (glucose)
  • 6CO2 6H20 the suns energy
    C6H12O6 6O2

Cellular respiration releases chemical energy
  • Organisms can use chemical energy created by
    photosynthesis through cellular respiration.
  • Oxygen is used to convert glucose into water
    carbon dioxide energy.
  • Only 2/3 of the original energy input per glucose
    molecule is gained in respiration.
  • Occurs in autotrophs and organisms that feed on
  • Heterotrophs (consumers) organisms that gain
    energy by feeding on others
  • Animals, fungi, microbes

C6H12O6 6O2 6CO2 6H20
Energy and matter in ecosystems
  • Ecosystem all organisms and non-living entities
    occurring and interacting in a particular area
  • Animals, plants, water, soil, nutrients, etc.
  • Energy from the sun flows in one direction
    through ecosystems.
  • Energy is processed and transformed.
  • Matter is recycled within ecosystems.
  • Outputs heat, water flow, and waste

Energy is converted to biomass
  • Primary production conversion of solar energy to
    chemical energy by autotrophs
  • Gross primary production assimilation of energy
    by autotrophs
  • Net primary production (NPP) energy remaining
    after respiration, used to generate biomass
  • Available for heterotrophs
  • Productivity rate at which autotrophs convert
    energy to biomass

Net primary productivity of ecosystems
High net primary productivity ecosystems whose
plants rapidly convert solar energy to biomass
A global map of NPP
NPP increases with temperature and precipitation
on land, and with light and nutrients in aquatic
Nutrients can limit productivity
  • Nutrients elements and compounds that organisms
    consume and require for survival
  • Stimulate plant production
  • Lack of nutrients can limit production.
  • Nitrogen and phosphorus are important for plant
    and algal growth.
  • Oceanic primary productivity is highest in water
    near shore.
  • Over 200 dead zones now exist due to nutrient

Nutrient runoff devastates aquatic systems
  • Aquatic dead zones result from nutrient pollution
    from farms, cities, and industry.
  • Most dead zones are located near Europe and the
    eastern U.S.
  • Scientists are investigating innovative and
    economical ways to reduce nutrient runoff.

Phytoplankton blooms off the Louisiana coast.
Ecosystems Different Sizes
  • Ecosystems vary greatly in size.
  • The term ecosystem is most often applied to
    self-contained systems of moderate geographic
  • Adjacent ecosystems may interact extensively.
  • Ecotones transitional zones between two
    ecosystems in which elements of each ecosystem mix

Landscape ecology
  • Landscape ecology the study of how landscape
    structure affects the abundance, distribution,
    and interaction of organisms
  • Helpful for sustainable regional development
  • Useful for studying migrating birds, fish,
  • Patches ecosystems, communities, or habitat form
    the landscape and are distributed in complex
    patterns (a mosaic)

This landscape consists of a mosaic of patches of
5 ecosystems.
Conservation biology
  • If a habitat is distributed in patches, organisms
    face danger in traveling from one patch to
  • Patches spaced too far apart prevent travel
  • Conservation biologists study the loss,
    protection, and restoration of biodiversity
  • Humans are dividing habitat into small, isolated
  • Corridors of habitat can link patches.
  • Geographic information systems (GIS) computer
    software that layers multiple types of satellite
    data to create a complete picture of a landscape
  • Geology, vegetation, animal species, and human

  • Testing Your Comprehension Questions 5-7
  • Calculating Ecological Footprints
  • HW Complete the Testing Your Comprehension
    Questions, 8-10 after reading pages 63-69
    Biogeochemical Cycles

Nutrients circulate through ecosystems
  • Physical matter is circulated continually in an
  • Nutrient (biogeochemical) cycle the movement of
    nutrients through ecosystems
  • Pools (reservoirs) where nutrients remain for
    varying amounts of time
  • Flux movement of nutrients among pools
  • Can change over time

Activity 9/6/12
  • Carbon Cycle- 2
  • Phosphorus- 2
  • Nitrogen- 3
  • Nitrification
  • Denitrificaiton
  • Hydrologic- 2
  • Sulfur- 2
  • Create brochure, pamphlet, video, etc. explaining
    each in detail (no less than 5 min, no more than
  • 1 day in class (tomorrow)
  • Due Monday

The carbon cycle
  • Carbon cycle describes the routes that carbon
    atoms take through the environment
  • Through photosynthesis, producers move carbon
    from the air and water to organisms.
  • Respiration returns carbon to the air and oceans.
  • Decomposition returns carbon to the sediment, the
    largest reservoir of carbon.
  • Ultimately, it may be converted into fossil
  • The worlds oceans are the second largest
  • Obtain carbon from the air and organisms

The carbon cycle
Humans affect the carbon cycle
  • Burning fossil fuels moves carbon from the ground
    to the air.
  • Cutting forests and burning fields moves carbon
    from organisms to the air.
  • Todays atmospheric carbon dioxide reservoir is
    the largest in the past 800,000 years.
  • The driving force behind climate change

The phosphorus cycle
  • Phosphorus cycle describes the routes that
    phosphorus atoms take through the environment
  • No significant atmospheric component
  • Most phosphorus is within rocks and is released
    by weathering.
  • With naturally low environmental concentrations,
    phosphorus is a limiting factor for plant growth.
  • Phosphorus is a key component of cell membranes,
    DNA, RNA, and other biochemical compounds.

The phosphorus cycle
Humans affect the phosphorus cycle
  • Mining rocks for fertilizer moves phosphorus from
    the soil to water systems.
  • Wastewater discharge also releases phosphorus,
    which boosts algal growth and causes
  • May be present in detergents
  • Consumers should purchase phosphate-free

The nitrogen cycle
  • Nitrogen comprises 78 of our atmosphere and is
    contained in proteins, DNA, and RNA.
  • Nitrogen cycle describes the routes that
    nitrogen atoms take through the environment
  • Nitrogen gas is inert and cannot be used by
  • Needs lightning, bacteria, or human intervention
  • Nitrogen fixation Nitrogen gas is combined
    (fixed) with hydrogen by nitrogen-fixing bacteria
    or lightning to become ammonium
  • Can be used by plants
  • Nitrogen-fixing bacteria live in legumes (i.e.,

Nitrification and denitrification
  • Nitrification bacteria that convert ammonium
    ions first into nitrite ions then into nitrate
  • Plants can take up these ions
  • Animals obtain nitrogen by eating plants or other
  • Denitrifying bacteria convert nitrates in soil
    or water to gaseous nitrogen, releasing it back
    into the atmosphere

The nitrogen cycle
Humans affect nitrogen cycle
  • Excess nitrogen leads to hypoxia in coastal
  • Synthetic fertilizers doubled the rate of Earths
    nitrogen fixation.
  • Burning forests and fossil fuels leads to acid
  • Wetland destruction and increased planting of
    legumes has increased nitrogen-rich compounds on
    land and in water.
  • Increased emissions of nitrogen-containing
    greenhouse gases
  • Calcium and potassium in soil are washed out by
  • Reduced biodiversity of plants adapted to
    low-nitrogen soils.
  • Changed estuaries and coastal ecosystems and

Human inputs of nitrogen into the environment
Fully half of nitrogen entering the environment
is of human origin.
A law addressing hypoxia in the Gulf
  • The Harmful Algal Bloom and Hypoxia Research and
    Control Act (1998) called for an assessment of
    hypoxia in the Gulf and to
  • Reduce nitrogen fertilizer use in Midwestern
  • Change timing of fertilizer applications to
    minimize runoff
  • Use alternative crops
  • Manage livestock manure
  • Restore wetlands and create artificial ones
  • Improve sewage-treatment technologies
  • Evaluate these approaches
  • This Act has worked, and was reauthorized in 2003.

The hydrologic cycle
  • Water is essential for biochemical reactions and
    is involved in nearly every environmental system.
  • Hydrologic cycle summarizes how liquid, gaseous,
    and solid water flows through the environment
  • Oceans are the main reservoir.
  • Less than 1 is available as fresh water.
  • Evaporation water moves from aquatic and land
    systems to air
  • Transpiration release of water vapor by plants
  • Precipitation condensation of water vapor as
    rain or snow returns water from the air to
    Earths surface

  • Aquifers underground reservoirs of spongelike
    regions of rock and soil that hold
  • Groundwater water found underground beneath
    layers of soil
  • Water table the upper limit of groundwater held
    in an aquifer
  • Water may be ancient (thousands of years old).

The hydrologic cycle
Human impacts on hydrologic cycle
  • Damming rivers increases evaporation and
    infiltration into aquifers.
  • Altering the surface and vegetation increases
    runoff and erosion.
  • Spreading water on agricultural fields depletes
    rivers, lakes, and streams and increases
  • Overdrawing groundwater for drinking, irrigation,
    and industrial uses depletes groundwater
  • Removing forests and vegetation reduces
    transpiration and lowers water tables.
  • Emitting pollutants changes the nature of

  • Occurs in Atmosphere
  • Hydrogen Sulfide (H2S) (Sulfur Dioxide) SO2
    naturally (volcanoes), manmade (industry)
  • H2S O2 ---? SO2
  • SO2 O2 --? SO3 (sulfur tri-oxide) or
  • SO2 H2O -? H2SO4 (sulfuric acid) -? acid
    deposits, water and soils, plants and animals

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  • Life interacts with its abiotic environment in
    ecosystems through which energy flows and
    materials are recycled.
  • Understanding biogeochemical cycles is crucial.
  • Humans are causing significant changes in the
    ways those cycles function.
  • Understanding energy, energy flow, and chemistry
    increases our understanding of organisms, their
    environment, and how environmental systems
  • Thinking in terms of systems can teach us how to
    avoid disrupting Earths processes and how to
    mitigate any disruptions we cause.

  • Which of the following part of an atom has a
    positive charge?
  • a) Proton
  • b) Neutron
  • c) Electron
  • d) Hydrogen
  • e) Neutreno

  • Which of the following consists of a chemically
    diverse group of compounds that dont dissolve in
  • a) Nucleic acids
  • b) Proteins
  • c) Carbohydrates
  • d) Lipids
  • e) Polymers

  • Sugars, starches, and glucose are all
  • a) Lipids
  • b) Proteins
  • c) Carbohydrates
  • d) Nucleic acids
  • e) Synthetic molecules

  • According to the first law of thermodynamics
  • Energy cannot be created or destroyed
  • Things tend to move toward a more disorderly
  • Matter can be created, but not energy
  • Kinetic energy is the most efficient source of
  • Energy is constantly recycled

  • Which of the following organisms is an autotroph?
  • Deep-sea tubeworm
  • Horse
  • Pine tree
  • Human
  • None of these

  • A transitional zone between two ecosystems is
  • a) Conservation zone
  • b) Corridor
  • c) Reservoir
  • d) Ecotone
  • e) Patch

  • Humans have affected the nitrogen cycle in all of
    the following ways EXCEPT
  • a) Doubling the rate of nitrogen fixation
  • b) Increasing emissions of greenhouse gases
  • c) Lowering water tables
  • d) Changing estuaries and coastal ecosystems
  • e) Reducing diversity of plants adapted to
    nitrogen-poor soils

QUESTION Weighing the Issues
  • Who should be responsible for reducing nitrogen
    pollution and eutrophication off coastal waters?
  • a) Fishermen, since they reap the benefits of
  • b) Farmers, since they are causing much of the
  • c) Taxpayers, since they are getting both fish
    and food
  • d) The federal government, since its job is to
    protect American citizens and the environment

QUESTION Interpreting Graphs and Data
  • A molecule of the hydrocarbon ethane contains
  • a) 10 carbon atoms and 8 hydrogen atoms
  • b) 8 carbon molecules and 10 hydrogen enzymes
  • c) 2 carbon atoms and 6 hydrogen atoms
  • d) 2 different ions

QUESTION Interpreting Graphs and Data
  • Which is the most basic material?
  • a) Lemon juice
  • b) Acid rain
  • c) Rainwater
  • d) Seawater
  • e) Soft soap

QUESTION Interpreting Graphs and Data
  • According to this graph, which ecosystem has the
    lowest amount of biomass?

a) Temperate grassland b) Boreal forest
c) Savanna d) Tropical rainforest
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