Properties of Sea Water Flashcards

1
Q

What makes water special?

A
  • Physical propety: water has great heat capacity
  • Chemical property: very good solvent
  • Implications for Earth and ocean, directly affect chemitsry of seawater and how the ocean moderates Earth’s temperature
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2
Q

Other important aspect of water: density, light, pH, gases

A
  • Density changes as a result of chanegs in temp and changes in salinity –> ocean circulation
  • Light does not travel far in the ocean, but sound does –> life in the ocean
  • the pH of seawater is relatively constant, 8.2 –> life in the ocean
  • gases (oxygen, carbon dioxide) dissolve easily in sea water –> climate
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3
Q

Thermostatic properties

A

Properties that act to moderate changes in temp
* high heat capacity - amount of heat needed to produce a unity change in temp
* high latent heat - amount of heat that can be absorbed when it changes state
* strong thermal inertia - ability to hold onto stored energy

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4
Q

How to change states of matter?

A

Change in heat/energy

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5
Q

Temperature

A

The property of the water that changes as heat is added or removed

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6
Q

Heat

A

A measure of the amount of energy contained in a volume of water

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7
Q

Heat capcity

A

The amount of energy (or heat) required to raise the temperature of 1 g of a substance by 1 degree C (measured in calories per gram per degree)

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8
Q

Latent heat

A
  • Energy is being added, but the temperature does not chaneg (the energy is “hidden away” in the water)
  • Certian amount of heat need to be added to chaneg temp of water. releases or absorbed heat during phase change
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9
Q

How to exchange energu between low and high latitudes?

A

Evaporation and condensation

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10
Q

Water density

A

Mass / volume
kg / m^3 or g / cm^3 or g / mL
Controlled by temperature and salinity (and pressure)

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11
Q

Desnity of pure freshwater and seatwater

A

1000 kg / m^3 = 1 g / m^3
1022 to 1030 kg / m^3

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12
Q

Why does water become less dense as it freezes?

A
  • Water is packed less desnly is ice
  • Change in density comes from change in volume
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13
Q

Effect of salinity on density

A
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14
Q

Salinity

A

The total amount of dissolved inorganic solids in the water
* Average salinity is 3.5% = 35 ppt
* Open ocean 33-38%

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15
Q

How does salinity impact ocean

A
  • Increases the density
  • Lowers the freezing point of water from 0 C to -1.9 C
  • Increases pH of water from 7 to 8.1
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16
Q

Salinity ranges in ocean

A
17
Q

Processes affecting salinity

A
18
Q

Why is ocean salty?

A
  • Ocean cotnains erosian products, transported into ocean
  • by rivers, deopsition from volcanoes or hydrothermal vents
  • Sodium from land, chloride from hydrothermal
  • Balanced by slow removal of sediemtns
19
Q

Why does salinity not change over millions of years?

A
  • The ocean is in steady steady state: what goes in must come out
  • Salt is added at same rate it is removed
20
Q

Principle of constant proportions

A
  • Ratio of major salts ions in sea water are cosntant (regardless of salinity)
  • If you measure the concentration of one iron you can estimate the others
  • Elements that follow this principle are called conservative elements (do not change with water depth)
21
Q

Non-conservative elements

A
  • Elements involved in biological processes vary greatly in space and time
  • Nutrients are often depleted in the surface due to comsuption by phytoplankton, and high at depth due to recycyling
  • Phosphate and nitrate
22
Q

Residence time

A

amount of element in the ocean / rate the element is added or removed
* Average length of time a substance remainds dissolved in water
* Major salt ions (Na, Cl) –> high concentration, long residence time
* Nutrients (Fe, P, N) –> low concentration, short residence time

23
Q

Oceans pH buffering system

A
  • pH of seawater is well buffered, meaning it does not vary much (7.6 to 8.3 = slightly alkaline)
  • Too much CO2 dissolution will exceed the buffering capacity –> ocean acidification
  • Biological systems need a stable environment to do their biology
24
Q

ph with ocean depth
Calcium Carbonate Compensation Depth (CCD)

A
  • Deep water is more acidic
  • Calcium carbonate is in the surface, but dissolves below the CCD
  • Calcium carbonate sediments only accumulate in relatively shallow water “marine snow”
  • Below the CCD water is relatively corrosive (low pH) and calcium carbonate dissolves
25
Q

Gases in the ocean

A
  • Gases like oxygen, nitrogen, and carbon dioxide are continuously exchanged between the atmosphere and the ocean, but their relative proportions differ
  • Biological activity in the ocean uses up oxygen and carbon dioxide
26
Q

Distribution of gases by depth in ocean (O2 and CO2)

A
  • Oxygen concentrations higher in surface layer than in atmosphere (photosynthesis)
  • Carbon dioxide concentrations in the deep water increases because of respiration
27
Q

Why is the ocean blue?

A
  • Red is absorbed fastest
28
Q

Photic zone

A

Sunlit surface of the ocean