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Environmental Science
Chp. 3
Earth’s Environmental Systems
The Dynamic Earth
Chp. 3 vocabulary terms (40)
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Matter
Atom
Element
Nucleus
Molecule
Compound
Hydrocarbon
Solution
Macromolecule
Protein
Nucleic acid
Carbohydrate
Photosynthesis
Cellular
Respiration
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Lipid
pH
Feedback loop
Erosion
Geosphere
Lithosphere
Biosphere
Atmosphere
Hydrosphere
Crust
Mantle
Core
Primary
producer
•Tectonic plate
•Landform
•Deposition
•Evaporation
•Transpiration
•Precipitation
•Condensation
•Aquifer
•Groundwater
•Nutrient
•Biogeochemical
cycle
•Eutrophication
•Nitrogen fixation
The Gulf of Mexico’s Dead Zone
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Page 63 in textbook
Apply the DecisionMaking Template to
analyze your small
group’s proposed
solution.
Building Blocks of Chemistry
• Matter: all material in the universe
that has mass and volume
• Atoms: basic unit of matter
– Nucleus: central core of an atom,
protons, neutrons
– Atomic #: number of protons in atom’s
nucleus
– Electrons: negatively charged particles
• Element: smallest unit of a chemical
substance with a given set of
properties
Bonding
• Bonding is an attraction that
involves sharing or transfer of
electrons
• Covalent bond: sharing of
electrons and forming a molecule
• When the electrons are shared
unequally, it is a polar covalent
bond
• Ionic bond: electrons transfer
completely from one atom to
another, forming oppositely
charged ions
Molecules & Compounds
• Molecule: 2 or more atoms of same
element joined by covalent bonds (ex.
O2, N2)
• Compound: substance composed of
atoms of 2 or more different elements
(H2O, CO2)
• Organic compounds: associated with
living organisms, chains of carbon
• Inorganic compounds: lack carbon-tocarbon bonds
• Hydrocarbons: organic compounds
containing only hydrogen & carbon;
some hazardous when burned
Solutions
• Solution: mixture in which
ingredients are evenly
distributed
• Solutions can be liquids,
gases or solids
• Mixture: without chemical
bonding, will separate out
in time
Macromolecules
• Proteins, nucleic acids, carbohydrates,
and lipids are the building blocks of life
• Organic compounds combine to form
long chains of repeated molecules
called polymers
• Lipids are not polymers but are
essential to life
• They are called macromolecules
because of their large size
Proteins
• Organic compounds (C
chains)
• Made up of C,H,O,N
• Make tissue, support, store
energy, transport substances,
immune system
• Hormones (chem.
messengers)
• Enzymes (catalysts)
Nucleic Acids
• Direct protein synthesis
• DNA – hereditary
information
• RNA- copies of DNA used in
making the proteins
• Sugar-phosphate backbone
with nitrogenous bases
Carbohydrates
• Polymers with CH2O formula
• Glucose – monomer/simple
sugar that provides a building
block for complex
carbohydrates
• Provides energy
• Cellulose in plants
Lipids
• Fats/oils: store energy, which is
released when they burn (ex:
petroleum fuels release
hydrocarbons)
• Phospholipids: primary component
of cell membranes
• Waxes: make up biological
structures
• Steroids/hormones: cell membrane
component, chemical messengers
Water Molecule
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H 2O
Over 70% of our planet
97% is salt water
3% freshwater: more than
2/3 is frozen, unavailable
• Life on Earth depends on
water
• Scientists believe life
began in water
• Every organism relies on
water for its survival
Properties of Water
• Water’s single Oxygen atom
attracts electrons stronger
than its 2 Hydrogen atoms
• Polar molecule with a more
negative oxygen end and
more positive hydrogen ends
• Water molecules are
attracted to each other and
therefore form hydrogen
bonds
Cohesion/Adhesion
• Water sticks to itself
• Allows transport of materials
• Graduated cylinder…you
measure the amount by the
bottom of the meniscus
• Think of water on a penny that
bubbles up until finally gravity is
stronger than the hydrogen bonds
and it flows over
Resistance to Temperature Change
• Heating weakens hydrogen bonds,
but it doesn’t initially increase
molecular motion
• So, water can absorb more energy
with only a small temperature
change
• This stabilizes aquatic climates
• Coastal areas are cooler in hot
weather and warmer in cold
weather
• Ex. – Seattle, London
Ice Density
• Water molecules when frozen
are further apart than in liquid
water
• Therefore, ice is less dense than
liquid water, which is the reverse
of most other compounds
• So, ice floats!!!
• Ice insulates bodies of water,
preventing them from freezing
solid in winter
Universal Solvent
• Water molecules bond well with
other polar molecules
• Positive end of one molecule is
attracted to the negative end of the
other molecule
• Therefore, water can hold or
dissolve many other molecules
• Because of this property, water is
often called the “universal
solvent”
Acids, Bases, pH
• In any water solution, some
molecules separate into ions
(hydrogen ion H+ and hydroxide
ion OH-)
• Acids release H+ ions
• Bases release OH- ions
• pH scale measures acidity
• Neutral: 7
• Acids: less than 7 pH
• Bases: greater than 7 pH
• Each point is a tenfold difference
Small Group Activity
• Is table salt (NaCl) a compound? How
can you tell?
• List the 4 types of macromolecules.
Explain one role of each in the human
body.
• What are 4 properties of water? How
would each of these help fish living in a
freshwater pond?
Interacting Systems
• Systems receive inputs, process these inputs,
and produce outputs
• Earth’s environment consists of complex,
interlinked systems
• Systems seldom have defined boundaries
• Systems may exchange energy, matter and
information with other systems
• Ex. Gulf of Mexico: inputs of water,
sediments, nutrients, pollutants; outputs of
shrimp and fish which then become inputs to
other systems
Feedback Loops
• Involves cause (input) and effect
(output), and can be cyclical
• Negative feedback loop: output
acts as input that causes the
system to move in the other
direction; stabilizes the system
• Positive feedback loop: rather
than stabilizing, it drives a
system to an extreme and can
alter it dramatically; rare, but are
common in systems changed by
humans (Ex. Erosion)
Earth’s Spheres
• Geosphere: all the rock at and
below Earth’s surface (crust,
mantle, outer core, inner core)
– Lithosphere: outermost layer of the
geosphere
• Biosphere: 7km above & below
Earth’s surface that supports life,
includes nonliving
• Atmosphere: layers of gases
surrounding our planet
• Hydrosphere: all the water on
Earth’s surface, underground, & in
the atmosphere
The Geosphere
• Crust: thin layer of relatively cool
rock that forms the Earth’s outer skin
• Mantle: very hot but mostly solid rock
• Core: lies below the mantle, HOT
– Outer core is molten metals (iron, nickel)
– Inner core is a dense ball of solid metal
• Convection current: heat from the
outer core pushes soft rock upward as
it warms; rock sinks downward as it
cools; creates a giant conveyer belt
that drives plate tectonics
Plate Tectonics
• Tectonic plates: large plates of
lithosphere dragged along by the
asthenosphere
• 15 major tectonic plates
• Move 2-15 cm/year
• Collisions & separations of plates
result in landforms (ex. Mountains),
islands & continents
• Landforms influence climate
• Climate, soil formation, erosion, &
deposition affect life inhabiting
different regions
Types of Plate Boundaries
• Divergent plate boundary: magma
surges upward, pushing plates
apart and creating new crust as it
cools
– mid-Atlantic ridge
• Transform plate boundary: when 2
plates meet, they slip & grind
alongside one another, creating
friction (earthquakes)
• Convergent plate boundary: plates
collide, causing one plate to
subduct (trench & volcanoes)
and/or mountain-building
Biosphere & Atmosphere
• Biosphere is where living & nonliving
things interact (the “living Earth”)
• Atmosphere is the gases that support &
protect the entire biosphere
• Ozone: layer of O3 gas that protects the
biosphere from the sun’s UV radiation
• Greenhouse gases help keep the Earth
warm enough to support life (CO2,
methane); human activity has increased
the greenhouse gases, leading to global
warming.
Hydrosphere
• Water cycles through the lithosphere,
biosphere & atmosphere endlessly
• As a means of transport & as a
solvent, water plays key roles in
nearly every ecosystem
• 97.5% of Earth’s water is salt water
• 2.5% is freshwater
• 75% of freshwater is tied up as ice
• 0.5% is unfrozen fresh water available
for drinking and watering crops
• Shortages & conflicts occur
The Water Cycle
• Roles that water plays in our
environment
• Water moves into the atmosphere
by evaporation & transpiration
– Natural distillation process, creating
pure water by filtering out minerals &
pollutants
• Warm temperatures & strong winds
speed up evaporation (liquid to gas)
• Water returns to Earth’s surface
through precipitation as water
vapor condenses from gas to
liquid)
Ground Water
• Some precipitation & surface
water soaks down through soil
and rock to recharge
underground reservoirs
(aquifers)
• Aquifers are layers of rock & soil
that hold groundwater
• Water table is the upper limit of
the groundwater
• Groundwater takes 100s-1000s of
years to recharge fully, if ever
Nutrient Cycling
• Nutrients: matter organisms require
for life
• Matter may be transformed but it
cannot be created or destroyed (law
of conservation of matter)
• Macronutrients: required in large
amounts (ex. N, C, P)
• Micronutrients: needed in small
amounts
• Nutrients cycle through the
environment endlessly in
biogeochemical cycles.
The Carbon Cycle
• Producers play vital
roles in cycling of
carbon in
ecosystems
• Carbon atoms are
everywhere, from
fossil fuels to DNA
to plastics to
medicines
Photosynthesis/Producers
• Primary producers are organisms
that produce their own food (plants,
algae and bacteria)
• Producers use the sun’s energy and
chemical energy along with CO2 to
produce carbohydrates (C6H12O6)
• Photosynthesis uses the sun’s
energy with CO2 out of the
environment & H2O, breaking the
bonds to give off O2 and
produce carbohydrates
Consumers/Decomposers
• Carbon in a producer is
passed on to a consumer or a
decomposer
• Consumers are organisms that
must eat other organisms to
obtain their nutrients
• Decomposers are organisms
that break down wastes &
dead organisms (ex. Bacteria,
Fungi)
Cellular Respiration
• Is NOT breathing
• Process in which organisms use O2
to release the chemical energy of
sugars and give off CO2 and H2O
• It is the chemical reverse of
photosynthesis
• Organisms do not release all of the
carbon they take in, making them a
major carbon sink
• Energy=ATP
Where’s the Carbon???
• Sediments: when organisms die in
water, their remains settle in sediments
– Sedimentary rock, limestone, fossil fuels
• Oceans: absorb carbon from the
atmosphere, runoff, undersea volcanoes,
and wastes/remains of organisms
• Human impacts: shift carbon from
lithosphere (burning fossil fuels) to the
atmosphere (CO2); deforestation reduces
plants available to use it
• Missing carbon sink: 1-2 billion metric
tons unaccounted for by scientists
The Phosphorus Cycle
• Involves mainly the lithosphere
and the oceans
• Key component of cell
membranes, DNA, RNA
• Released naturally when rocks are
worn down by water/wind
• Minimal availability to organisms,
so plant/algae growth jumps when
available, causing eutrophication
• Extreme cases cause hypoxia/ᛎO2
• Found in fertilizers, detergents
The Nitrogen Cycle
• Relies on bacteria to make nitrogen useful
to organisms and to return it to the
atmosphere
• Nitrogen: 78% of atmosphere
• Essential ingredient in proteins, DNA, RNA
• Nitrogen gas cannot cycle out of the
atmosphere and into organisms without
lightning, bacteria or human technology
• Nitrogen fixation: nitrogen gas to ammonia
by nitrogen fixing bacteria
• Nitrification: ammonia to nitrates
• Denitrification: nitrates to nitrogen gas
• Legumes’ roots host nitrogen-fixing bacteria
Conflicting Interests
• Humans learned to fix nitrogen to
synthesize ammonia, increasing its
flow out of the atmosphere and into
other reservoirs
• Burning fossil fuels releases NO,
which forms NO2, leading to acid rain
• N’s natural scarcity & reintroduction
by man leads to eutrophication (ex.
Dead Zone in Gulf of Mexico)
• US Congress passed the Harmful
Algal Bloom & Hypoxia Research
and Control Act in 1998/2004
Proposals for Reducing Gulf of
Mexico Dead Zone
• Reduce nitrogen fertilizer use on Midwest farms
• Change the timing of fertilizer use to minimize runoff
during the rainy season
• Plant alternative crops
• Manage nitrogen-rich livestock manure better
• Restore nitrogen-absorbing wetlands in the Mississippi
River basin
• Construct artificial wetlands to filter farm runoff
• Improve sewage treatment
• Restore frequently flooded lands to reduce runoff
• Restore wetlands near the Mississippi River’s mouth to
improve nitrogen-absorbing ability