Oceanography is the study of the earth's oceans and their interconnected ecosystems, geological, chemical and physical processes. It includes the study of geological, chemical, physical, meteorological and biological aspects of the oceans. The development of the oceans and atmosphere has evolved over geologic time through processes like volcanic outgassing, asteroid impacts and plate tectonics. Modern oceanography developed through historic voyages of exploration and the rise of dedicated oceanographic research institutions.

1. Chemical Oceanography
M. Lutfi Firdaus
ml.firdaus@gmail.com
0822-1721-6770
(Oseanografi Kimia)

2. Silabus:
• Pendahuluan, Sejarah Pembentukan Laut, dll.
• Komposisi Unsur Kimia Utama/Makro
• Komposisi Unsur Kimia Mikro
• Karakter Unsur Hara
• Gas Terlarut
• Sistem Karbonat
• UTS
• Radioisotop
• Senyawa Organik di laut
• Deposisi – Sedimentasi
• Sedimen, kimia sedimen, diagenesis
• Proses Kimia di laut
• Pencemaran laut
• UAS

3. 3
Jenis dan Bobot Penilaian:
• Nilai Tugas + Kuis 20%
• Nilai Praktikum 30%
• Nilai UTS 25%
• Nilai UAS 25%
Indikator Kelulusan:
• A = 80 -100
• B = 70 -79
• C = 56 – 69
• D = 45 – 55
• E = 0 – 44
Sumber Belajar:
1. Chester R., Marine Geochemistry, Blackwell Publishing.
2. Elderfield H., The Oceans and Marine Geochemistry, Elsevier.
3. Millero FJ., Chemical Oceanography, CRC Press
4. Dll.

4. Oceanography: is the study of the earth's oceans and
their interlinked ecosystems , geological, chemical and
physical processes
•Geological : the study of geologic processes in the
oceans (plate tectonics, coastal morphology)
•Chemical : the study of the chemistry of the oceans
•Meteorological : the study of the interaction between
atmosphere and the oceans
•Physical : the study of the physical attributes of the
oceans (temperature-salinity, waves, currents)
•Biological : the study of the flora and fauna of the
oceans

5. History
Geologic Time

6. Bombardment From Space
For the first half billion years of its existence, the
surface of the Earth was repeatedly pulverized by
asteroids and comets of all sizes
One of these collisions formed the Moon

7. Formation of the Moon
The Giant Impact
Hypothesis predicts that
around 50 million years
after the initial creation of
Earth, a planet about the
size of Mars collided with
Earth
This idea was first
proposed about 30 years
ago, but it took
calculations by modern
high-speed computers to
prove the feasibility

8. Formation of the Moon
This collision had to be very spectacular!
A considerable amount of material was blown off into
space, but most fell back onto the Earth

9. Formation of the Moon
Part of the material from the collision remained in orbit
around the Earth
By the process collision and accretion, this orbiting material
coalesced into the Moon

10. The Core
About 100 million years after initial accretion,
temperatures at depths of 400 to 800 km below the
Earth’s surface reach the melting point of iron
In a process called global
chemical differential, the
heavier elements, including the
melted iron, began to sink
down into the core of the Earth,
while the lighter elements such
as oxygen and silica floated up
towards the surface

11. Global Chemical Differentiation
This global chemical differential was completed by about
4.3 billion years ago, and the Earth had developed an
inner and outer core, a mantle and crust

12. Chemical Composition of Earth
Whole Earth:
Fe+O+Si+Mg = 93%
Crust:
Si+O+Al = 82%
Each of the major layers has a distinctive
chemical composition, with the crust being
quite different from the Earth as a whole

13. Lithosphere: strong, rocky outer shell of the solid
Earth including all the crust and the upper part of
the mantle to a depth of ~100 km (forms the
plates)
Asthenosphere: weak,ductile layer of the mantle
beneath the lithosphere; deforms to
accommodate the motions of the overlying plates
Deep Mantle: mantle beneath the asthenosphere
(~400 to 2900 km in depth)
Outer core: liquid shell composed of mostly iron
Inner core: innermost sphere composed primarily
of solid iron
Chemical Composition of Earth

14. Continents: Formed from solidified magma that
floated up from the Mantle
Chemical Composition of Earth
Oceans and Atmosphere:
Fluid and gaseous outer
layers believed to have been
created by out-gassing of
gases and fluids from volcanic
eruptions (in a process called
volatile transfer)

15. The Evolving Atmosphere
Right after its creation, the Earth is thought to have had a thin
atmosphere composed primarily of helium (He) and hydrogen (H) gases
The Earths gravity
could not hold these
light gases and they
easily escaped into
outer space
Today, H and He are
very rare in our
atmosphere

16. The Evolving Atmosphere
For the next several hundred million years, volcanic
out-gassing began to create a thicker atmosphere
composed of a wide variety of gases
The gases that were released were probably similar to
those created by modern volcanic eruptions

17. These would include:
Water vapor (H2O)
Sulfur dioxide (SO2)
Hydrogen sulfide (H2S)
Carbon dioxide (CO2)
Carbon Monoxide (CO)
Ammonia (NH3)
Methane (CH4)
The Evolving Atmosphere
Note that oxygen (O2) gas is not created by volcanic
eruptions

18. It is hypothesized that water vapor escaping from the
interior of the Earth via countless volcanic eruptions created
the oceans (this took hundreds of millions of years)
Creating the Oceans

19. Astronomers also
hypothesize that comets
impacting the Earth were
a major source of water
that contributed to
creation of the oceans
Remember, that comets
are best described as
“dirty ice balls”
Creating the Oceans

20. Creating the Oceans
The earliest evidence of surface water on Earth
dates back about 3.8 billion years

21. A billion Year Old Earth
By 3.5 billion years ago, when the Earth was a billion
years old, it had a thick atmosphere composed of CO2,
methane, water vapor and other volcanic gases
By human standards this
early atmosphere was very
poisonous
It contained almost no oxygen
Remember, today our
atmosphere is 21% oxygen

22. A billion Year Old Earth
By 3.5 billion years ago, the Earth also had
extensive oceans and seas of salt water, which
contained many dissolved elements, such as iron

23. Present Ocean

24. Magellan Expedition
The journey of the Magellan expedition, the first voyage around the world.
Only 18 out of 260 sailors managed to return after three years of dangerous
travel.

25. Cook’s Voyages

26. • James Cook, a commander in the British Royal Navy, is
credited with leading voyages that greatly contributed to
scientific oceanography.
• Some of the accomplishments of James Cook and his
scientists include:
– Verification of calculations of planetary orbits
– Charting of New Zealand and the Great Barrier Reef,
Tonga and Easter Island
– Initiation of friendly relations with many native populations
– Sampling marine life, land plants and animals
– Recording data concerning the ocean floor and
geological formations
Voyaging Combined with Science
to Advance Ocean Studies

27. The First Scientific Expeditions
Were Undertaken by Governments
• The HMS Beagle (1831), on which Charles Darwin served as a naturalist,
voyaged to South America and some Pacific Islands.
• (BELOW) HMS Challenger expedition of 1872-1876 was the first oceanic
expedition dedicated to scientific research.

28. Voyages for Science in the 20th
Century
• What advances in oceanic exploration
occurred in the 20th century?
– Polar Exploration – explorers reached both the North
and South poles in the twentieth century
– The Meteor Expedition – first expedition to use modern
optical and electronic equipment for oceanographic
investigation
– The Atlantis – investigations on this research vessel
confirmed the presence of the Mid-Atlantic Ridge.
– The Trieste – a blimp-like bathyscaphe which descended
into the Challenger Deep area of the Mariana Trench
– Glomar Challenger – samples obtained by scientists on
this drilling ship provided confirming evidence for
seafloor spreading and plate tectonics.

29. The Rise of Oceanographic
Institutions
• Three of the most prominent oceanographic
institutions in the United States:
– Woods Hole Oceanographic Institution
– Scripps Institution of Oceanography
– Lamont-Doherty Earth Observatory of
Columbia University

30. CTD Sampling

31. Chloride (Cl-
) 55.07%
Sodium (Na+
) 30.62%
Sulfate (SO4
2-
) 7.72%
Magnesium (Mg 2+
) 3.68%
Calcium (Ca 2+
) 1.17%
Potassium (K+
) 1.10%
Bicarbonate (HCO3
-
) 0.40%
Bromide (Br -
) 0.19%
Strontium (Sr 2+
) 0.02%
Boron (B 3+
) 0.01%
Fluoride (F-
) 0.01%
Major Constituents of Seawater
(% by weight)

34. Seawater
• Salinity=total amount of solid material
dissolved in water (g/1000g)
• Typical salinity is 35 o/oo or ppt
• Brackish (hyposaline) < 33 ppt
• Hypersaline > 38 ppt

35. – Salinity is the total amount of dissolved salts in water;
grams of salts per kilogram of water (g/kg) or as parts
per thousand (ppt).
– Seawater has 11 major constituents that make up
more than 99.99% of all dissolved materials.
– Although salinity may vary, the major constituents are
well mixed and present in the same relative
proportions.
Salinity

36. Measuring salinity
• Evaporation / Penguapan
• Chemical analysis
–Principle of Constant Proportions
–Chlorinity
• Electrical conductivity (salinometer)

37. How salinity changes
• Salinity changes by adding or
removing water
• Salinity decreases by
–Precipitation (rain/snow)
–River runoff
–Melting snow

38. • Salinity increases by
–Evaporation
–Formation of sea ice
• Hydrologic cycle describes recycling
of water

39. Dissolved substances
• Added to oceans
– River input (primarily)
– Circulation through mid-ocean ridges
• Removed from oceans
– Salt spray
– Recycling through mid-ocean ridges
– Biogenic sediments (hard parts and fecal
pellets)
– Evaporites

40. Hydrologic cycle

41. Horizontal variations of salinity
• Polar regions: salinity is lower, lots of
rain/snow and runoff
• Mid-latitudes: salinity is high, high rate of
evaporation
• Equator: salinity is lower, lots of rain
• Thus, salinity at surface varies primarily
with latitude

42. Fig. 6-20

43. Vertical variations of salinity
• Surface ocean salinity is variable
• Deeper ocean salinity is nearly the
same (polar source regions for
deeper ocean water)
• Halocline, rapid change of salinity
with depth

45. Atomic structure
• Nucleus
• Protons and neutrons
• Electrons
• Ions are charged atoms

46. Water molecule
• H2O
• Two hydrogen, one oxygen
• Bonded by sharing electrons
• Bend in geometry creates polarity
• Dipolar molecule

48. Dipolar molecule
• Weak negative charge at O end
• Weak positive charge at H end
• Hydrogen bonds
• Weak bonds between water
molecules and ions
• Explains unusual properties of water

49. Fig. 6-3

50. Two unusual properties
• High surface tension
–Hydrogen bonding creates “skin”
–Important for living organisms
• Capillarity
• Universal solvent
–Electrostatic bond between dipolar
water and ions
–Ocean is salty

51. Fig. 6.4

52. Fig. 6-5b

53. Thermal properties of water
• Solid, liquid, gas on Earth’s surface
• Water has high freezing point
• Water has high boiling point
• Water has high heat capacity
• Water has high latent heats

54. Fig. 6-7

55. Heat capacity
• Heat absorbed or released with
changes in state
• Latent heats of
–Melting; freezing
–Vaporization, evaporation
–Condensation

56. Global thermostatic effects
• Moderate global temperature
• Evaporation removes heat from
oceans
• Condensation adds heat to
atmosphere
• Heat re-distributed globally

57. Differences in day and night temperatures

58. Water density
• Maximum density at 4oC
• Ice less dense than liquid water
–Atomic structure of ice
–Ice floats
• Increased salinity decreases
temperature of maximum density

59. Fig. 6-10

60. Fig. 6-8

61. Residence time
• Average length of time a substance
remains dissolved in seawater
• Long residence time = unreactive
– Higher concentration in seawater
• Short residence time = reactive
– Smaller concentration in seawater
• Steady state
– Ocean salinity nearly constant through time

62. Dissolved gases
• Solubility depends on temperature,
pressure, and ability of gas to escape
• Gases diffuse from atmosphere to ocean
– Wave agitation increases amount of gas
– Cooler seawater holds more gas
– Deeper seawater holds more gas

63. Conservative vs.
nonconservative constituents
• Conservative constituents change
slowly through time
–Major ions in seawater
• Nonconservative constituents change
quickly due to biological and chemical
processes
–Gases in seawater

64. Oxygen and carbon dioxide in
seawater
• Nonconservative
• O2 high in surface ocean due to
photosynthesis
• O2 low below photic zone because of
decomposition
• O2 high in deep ocean because
source is polar (very cold) ocean

65. • CO2 low in surface ocean due to
photosynthesis
• CO2 higher below photic zone
because of decomposition
• Deeper seawater high CO2 due to
source region and decomposition

66. Acidity and alkalinity
• Acid releases H+ when dissolved in
water
• Alkaline (or base) releases OH-
• pH scale measures acidity/alkalinity
–Low pH value, acid
–High pH value, alkaline (basic)
–pH 7 = neutral

67. Carbonate buffering
• Keeps ocean pH about same (8.1)
• pH too high, carbonic acid releases H+
• pH too low, bicarbonate combines with
H+
• Precipitation/dissolution of calcium
carbonate CaCO3 buffers ocean pH
• Oceans can absorb CO2 from
atmosphere without much change in pH

68. Fig. 6-17

69. Density of seawater
• 1.022 to 1.030 g/cm3
• Ocean layered according to density
• Density of seawater controlled by
temperature, salinity, and pressure
– Most important influence is temperature
– Density increases with decreasing
temperature

70. • Salinity greatest influence on density
in polar oceans
• Pycnocline, rapid change of density
with depth
• Thermocline, rapid change of
temperature with depth
• Polar ocean is isothermal

72. Layers of ocean
• Mixed surface
layer
• Pycnocline
• Deep ocean

73. Water and Seawater

74. The Main Tectonic Plates:

75. Plate Boundaries
There are four types of plate boundaries:
1. • Divergent boundaries -- where new crust is generated as the plates pull away
from each other.
2. • Convergent boundaries -- where crust is destroyed as one plate dives under
another.
3. • Transform boundaries -- where crust is neither produced nor destroyed
as the plates slide horizontally past each other.
4. • Plate boundary zones -- broad belts in which boundaries are not well defined
and the effects of plate interaction are unclear.

76. Convergent boundaries - Summary

78. Soils: meters thick
Supports terrestrial life on earth.
The interface, the first point of contact,
between the earth’s surface and the external
environment.