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**Oceanography > Origins > Flashcards

Origins Flashcards

1
Q

Atom

A
  • The smallest particle that can exist alone or in combinations with other atoms
  • The unit building block of all chemical compounds
  • In a neutral atom, protons = electrons
  • atomic num = num of protons
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2
Q

Chemical compound

A
  • Most matter is composed of a combination of atoms
  • Ex: table salt = NaCl
  • These compounds result from chemical reactions during which atoms combine via shared or transferred electrons (no changes occur in the nuclei of the individual atom)
  • Atoms can share electrons (covalent bond)
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3
Q

Nebula

A

Cloud of gases and space dust from which all bodies in the solar system formed

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4
Q

Galaxy

A
  • Huge rotating aggregation of stars, dust, gas and debris held together by gravity
  • 100 billion galaxies in universe
  • 100 billion stars in each galaxy
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5
Q

Nebular hypothesis

A
  • Nebula → solar system
  • Gravity concentrates material at center of cloud (eventually become the sun)
  • Protoplanets from the accretion of smaller particles in eddies
  • Different materials condense at different temps
  • Planet composition dpend on proximity to hot protosun
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6
Q

Eddy

A
  • rotating/swirling feature
  • current flows towards the objet that created the eddy
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7
Q

Birth, life, and death of stars

A
  • Spinning solar nebula (protostar)
    • Mainly composed of hydrogen (H) and helium (He)
    • Heavier elements like oxygen (O) and carbon (C) formed by nuclear fusion
  • Mature star
  • Red giants & supernovas = dying stars
    • Seeding other solar systems with heavier elements
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8
Q

Nuclear Fusion

A
  • Energy-producing process that takes place continuously in sun and other stars
    • In core of sun:
      • temp is 10 million degrees C
      • Hydrogen → helium + energy
    • This energy sustains life on earth
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9
Q

Planet compositions

A
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10
Q

Formation of Earth

A
  • Aggregation of particles
  • Bombardment of meteors and asteroids
  • Gravitational compression and heat from radioactive decay and fusion cause partial melting
  • Formation of density layers / Density stratification into core, mantle, and crust
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11
Q

Density stratification

A
  • Formation of density layers
    • Stratification into core, mantle, and crust
    • density = mass / volume
    • layering of materials of different densities (higher density at the bottom)
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12
Q

Earth’s Internal Structure

A
  • Layers defined by:
  • Chemical composition and physical properties
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13
Q

How do we know the age of earth and rocks?

A
  • Radioactive decay and dating
  • Half life: how long until half has decayed
  • As elements decay they turn into something [insert image decay chain]
  • Carbon-14 used to measure things on a human timeline
  • Uranium-335 used for dating the Earth
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14
Q

Origin of Earth’s Atmosphere

A
  • Outgassing of volatile gases from within the earth during density stratification
  • Contained water vapor, c02, hydrogen, lots of noxious gases like methane, hydrogen sulfide
  • This early atmosphere was very different than today - very little oxygen
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15
Q

Origin of Earth’s Oceans

A
  • Most of the water comes from outgassing of Earth → condensation → rain
  • Some additional water comes from icy comets
  • Ocean in place at ~4 billion years (compared to earth’s formation at 4.6 billion years)
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16
Q

Why is the ocean salty?

A
  • Rain falls on rocks
  • In contact with rainwater, rocks chemically break down, releasing elements into surface water
  • Then these elements are carried by rivers into the ocean, contributing to its salinity levels
  • Ocean is not getting saltier over time
    • Salt settles into sea floor sediments
17
Q

How did life come to be in the oceans?

A
  • “Based on a funamentally different chemical structure than the soldi Earht”
  • “Chemical phenomenon”
  • “Capable of undergoing Darwinian evolution”
  • “Based on molecules that transfer material and energy in complex cycles”
  • Chemical composition on Earth’s crust: mainly oxygen and silicon
  • Chemical composition of life: carbon and oxygen
18
Q

Organic molecules

A
  • the building blocks of life and all contain carbon
    • amino acids
    • carbohydrates
    • Nucleic acids
    • lipids
19
Q

How did life evolve on Earth?

A
  • Early hypothesis: inorganic molecules could spontaneously form organic molecules and the building blocks of life
  • Result = production of organic molecules under conditions simulating early earth
  • Or, an extraterrestrial source? Panspermia Hypothesis: organic molecules carries on meteorites to Earth
20
Q

Morphological evidence for life

A
  • fossils
  • trace fossils
  • biogenic structures
  • Problem: not many suitable sedimentary rocks left, most of them destroyed through tectonic processes
21
Q

Geochemical evidence for life

A
  • Direct: molecular fossils (=biomarkers), genomic evidence
  • Indirect: metabolic byproducts (like oxygen) and tracers (isotopes, trace metals)
22
Q

Where did life start?

A
  • Likely in deep sea, near hydrothermal vents or cold seeps
  • Protected stable regions
  • Mimics conditions on early earth
  • Organic molecules → cells → advanced organisms
23
Q

Procaryotes

A

first livign organisms, lack a nucleus, single cellular, bacteria & archea

24
Q

Eucaryotes

A

have nucleus, single or multi cellular, animals, plants, fungi, etc

25
Q

Cyanobacteria

A
  • inventors of oxygenic photosynthesis
    • Ocean phenomena
    • Oldest fossils at 3.5 billion years ago
    • Other types of photosynthesis before, but these were first to split water into oxygen
26
Q

Phytoplankton

A
  • the ocean’s invisible forest
    • Main driver in the oxygenation of the planet
    • Generate 50% of oxygen on planet
    • Microscopic; both procaryotes and eucaryotes
    • Diatoms, coccolithophores, dinoflagellates
    • Cycling carbon and oxygen by life
      • Photosynthesis, cellular respiration
27
Q

Evolution of life

A
28
Q

The effect of photosynthetic life on the atmosphere

A
  • Photosynthesis from phytoplankton and plants
  • Natural cycle created by plants is altered by humans
  • The rise of atmospheric O2
29
Q

The Great Oxidation event

A
  • Photosynthesis invented a billion years before the spike
  • Abundance of BIFs (Banded iron formations): red minerals (iron oxides, rust) which precipitated when the oceans became oxic
30
Q

Why is there such a long lag between the beginning of
photosynthesis and the rise in atmospheric oxygen?

A

*in early ocean, lots of dissolved iron. oxygen produced by phytoplankton reacts with this iron
and becomes red sediment
*once dissolved iron in ocean is used up, oxygen could start accumulating in the atmosphere

31
Q

More recent history of Earth’s atmospheric oxygen

A

low levels = extinction events

32
Q

Oxygen in atmosphere leads to Ozone

A

Ozone is critical gas that shields the damaging UV rays from the sun

**Oceanography (15 decks)

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