Environmental Science

Chp. 3 Earth’s Environmental Systems The Dynamic Earth

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Chp. 3 vocabulary terms (40)

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

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Tectonic plate

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Landform

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Deposition

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Evaporation

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Transpiration

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Precipitation

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Condensation

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Aquifer

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Groundwater

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Nutrient

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Biogeochemical cycle

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Eutrophication

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Nitrogen fixation

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The Gulf of Mexico’s Dead Zone

Page 63 in textbook Apply the Decision Making 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. O 2 , N 2 ) • Compound: substance composed of atoms of 2 or more different elements (H 2 O, CO 2 ) • Organic compounds: associated with living organisms, chains of carbon • Inorganic compounds: lack carbon-to carbon bonds • Hydrocarbons: organic compounds containing only hydrogen & carbon; some hazardous when burned

Solutions

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Solution: mixture in which ingredients are evenly distributed

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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 CH 2 O 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

• H 2 O • 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 O 3 gas that protects the biosphere from the sun’s UV radiation • Greenhouse gases help keep the Earth warm enough to support life (CO 2 , 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

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5% is freshwater • 75% of freshwater is tied up as ice • 0

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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

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Some precipitation & surface water soaks down through soil and rock to recharge underground reservoirs (aquifers)

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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.

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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 CO 2 produce carbohydrates (C 6 H 12 O 6 ) to • Photosynthesis uses the sun’s energy with CO 2 out of the environment & H 2 O, breaking the bonds to give off O 2 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 O 2 to release the chemical energy of sugars and give off CO 2 and H 2 O • 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 (CO 2 ); 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/ ᛎ O 2 • 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 NO 2 , 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