Chemical oceanography
Contents
History .................................................................................................................................................................................. 3
Scope of Chemical oceanography .............................................................................................................................. 5
The Earth’s oceans ........................................................................................................................................................... 7
Colligative properties of dilute solution: ............................................................................................................... 9
Characterization of a species from the determination of molar mass ........................................................................ 11
Water Anomalies: .......................................................................................................................................................... 13
Characteristics of water molecule: ................................................................................................................................. 16
Hydrogen bonding in water molecule ............................................................................................................................ 17
Constituents ..................................................................................................................................................................... 20
Residence time .................................................................................................................................................................. 21
Isotopic Nature of Water molecule: ....................................................................................................................... 22
Chemical Equilibrium ..................................................................................................................................................... 24
Trace elements ................................................................................................................................................................ 25
Mercury: ........................................................................................................................................................................... 26
Iron: ................................................................................................................................................................................... 28
Salinity Measurements ................................................................................................................................................ 29
Physical method: Evaporating water ............................................................................................................................. 29
Titration method .............................................................................................................................................................. 30
Chlorinity and Salinity: ................................................................................................................................................... 30
Salinity and Conductivity ................................................................................................................................................ 31
CONSTANCY OF COMPOSITION .............................................................................................................................. 33
Solubility: .......................................................................................................................................................................... 35
Solubility of Salts ............................................................................................................................................................. 35
Effects on Solubility: ........................................................................................................................................................ 37
Sources of gasses: ............................................................................................................................................................. 39
Atmospheric exchange by diffusion: .............................................................................................................................. 40
Alkalinity and control of pH ...................................................................................................................................... 42
Rates of Oxygen consumption: ................................................................................................................................. 44
Air-sea interaction: ....................................................................................................................................................... 45
Nutrients ............................................................................................................................................................................ 46
Phosphorus ....................................................................................................................................................................... 46
Nitrogen: ........................................................................................................................................................................... 49
Silicon ................................................................................................................................................................................ 52
Other nutrients ................................................................................................................................................................. 53
,DISSOLVED AND PARTICULATE ORGANIC COMPOUNDS IN SEAWATER ....................................... 54
Distribution of organic matter ........................................................................................................................................ 55
Marine Snow .................................................................................................................................................................... 56
Radioactivity .................................................................................................................................................................... 58
Reaction Kinetics of radioactivity .................................................................................................................................. 61
Carbon-14 and carbon dating ......................................................................................................................................... 62
CHEMICAL EXTRACTION OF USEFUL SUBSTANCES FROM THE SEA ................................................ 63
Salt from seawater ........................................................................................................................................................... 63
Extraction of metals from seawater ............................................................................................................................... 63
Fresh water from sea ....................................................................................................................................................... 64
Indian Ocean (Bay of Bengal and Arabian sea) ................................................................................................. 66
,History
1. What is Challenger expedition? What were the goals of it?
2. Antoine Laurent Lavoisier was reported to be the first chemist to analyze the major constituents of seawater -
describe his experiment and also the results.
key figures and their contributions:
1. Aristotle (384–322 BCE): Aristotle was an ancient philosopher and scientist who explored the origin and
nature of seawater. He considered various explanations, such as the metaphorical idea that the sea is "the sweat
of the earth" and believed water became salty due to the mixing of an earthy substance. Aristotle also noted the
bitter taste of seawater and conducted experiments highlighting the relative density difference between seawater
and fresh water. He made early observations on the organic chemistry of seawater, noting the presence of a fatty,
oily substance on its surface.
2. Robert Boyle (1627–1691): Known as the "father of modern chemistry," Boyle published a tract in 1673
titled "Observations and Experiments about the Saltness of the Sea." He conducted experiments on the
chemistry of seawater, including evaporation and residue weighing. Boyle recognized that even freshwater
sources contained small amounts of salt, indicating that ocean salt might accumulate from land runoff.
3. Edmond Halley (1656–1742): A versatile English natural scientist, Halley measured the rate of water
evaporation in the ocean and estimated the water exchange in the Mediterranean. He understood that variations
in seawater salinity were influenced by factors like river runoff, evaporation, precipitation, and ocean currents.
4. Luigi Ferdinando Marsili (1658–1730): Marsili is considered one of the early pioneers of oceanography. He
published the first book entirely dedicated to oceanography, covering various aspects, including seawater
properties and marine life. Marsili conducted measurements of seawater salinity, temperature, and seasonal
thermoclines. He was among the first to apply color tests to determine seawater acidity and recognized the
challenges in determining seawater salinity by residue weighing.
5. Antoine Laurent Lavoisier (1743–1794): Lavoisier, a renowned chemist, rejected the phlogiston theory and
introduced the concepts of oxidation and reduction. He conducted experiments on the major components of sea
salt and identified various salts in seawater, contributing to the understanding of its composition
Lavoisier (1772) attempted to analyze the major components of sea salt. He evaporated seawater, and extracted
the dried residue with alcohol and with alcohol–water mixtures and recrystallized the salts from the resulting
solutions. By this approach he was able to identify several products
CaCO3 - calcium carbonate
CaSO4·2H2O - gypsum, calcium sulfate
NaCl - sodium chloride
Na2SO4·xH2O - Glauber’s salt, sodium sulfate
MgSO4 - Epsom salt, magnesium sulfate
MgCl2 - magnesium chloride
This early attempt to analyze such a mixture of salts showed the complexity of seawater as a chemical system
and defined the approximate amounts of the major components.
6. Joseph Louis Gay-Lussac (1778–1850): Gay-Lussac is known for Gay-Lussac's law and significant
contributions to stoichiometry. He conducted experiments related to seawater composition and analyzed the
, concentration of total salt. His work contributed to understanding the relative constancy of seawater
composition and the concept of the "water column."
7. Alexander Marcet (1819): Marcet's analyses of seawater from various locations led to the observation that
seawater from around the world had nearly identical constituents and proportions. This insight laid the
foundation for the Principle of Constant Composition.
Challenger Expedition:
The Challenger Expedition was a significant scientific voyage undertaken from 1872 to 1876. It was the first
major oceanographic expedition organized specifically to gather data on the ocean and marine life. The
expedition was named after its ship, HMS Challenger, a British Royal Navy vessel. This was not the first
oceanographic expedition, but it was the biggest and most comprehensive up until that time. It was the most
scientifically well-conceived and it is often held to have marked the beginning of oceanography as a scientific
discipline. In 1871, a committee of the Royal Society formulated the goals of what was to become the
Challenger expedition, as follows (Yonge 1972):
(1) To investigate the Physical Conditions of the Deep Sea, in the Great Ocean-basins... in regard to Depth,
Temperature, Circulation, Specific Gravity and Penetration of Light ... at various ranges of depth from the
surface to the bottom.
(2) To determine the Chemical Composition of Sea Water ... at surface and bottom ... [and] various intermediate
depths... to include the Saline Constituents, the Gases, and the Organic Matter in solution, and the nature of any
particles found in suspension.
(3) To ascertain the Physical and Chemical characters of the Deposits everywhere in progress on the Sea-
bottom, and to trace, so far as may be possible, the sources of these deposits.
(4) To examine the Distribution of Organic Life throughout the areas traversed, especially in the deep Ocean-
bottoms and at different depths; with especial reference to the Physical and Chemical conditions already
referred to, and to the connection of the present with the past condition of the Globe.
Contents
History .................................................................................................................................................................................. 3
Scope of Chemical oceanography .............................................................................................................................. 5
The Earth’s oceans ........................................................................................................................................................... 7
Colligative properties of dilute solution: ............................................................................................................... 9
Characterization of a species from the determination of molar mass ........................................................................ 11
Water Anomalies: .......................................................................................................................................................... 13
Characteristics of water molecule: ................................................................................................................................. 16
Hydrogen bonding in water molecule ............................................................................................................................ 17
Constituents ..................................................................................................................................................................... 20
Residence time .................................................................................................................................................................. 21
Isotopic Nature of Water molecule: ....................................................................................................................... 22
Chemical Equilibrium ..................................................................................................................................................... 24
Trace elements ................................................................................................................................................................ 25
Mercury: ........................................................................................................................................................................... 26
Iron: ................................................................................................................................................................................... 28
Salinity Measurements ................................................................................................................................................ 29
Physical method: Evaporating water ............................................................................................................................. 29
Titration method .............................................................................................................................................................. 30
Chlorinity and Salinity: ................................................................................................................................................... 30
Salinity and Conductivity ................................................................................................................................................ 31
CONSTANCY OF COMPOSITION .............................................................................................................................. 33
Solubility: .......................................................................................................................................................................... 35
Solubility of Salts ............................................................................................................................................................. 35
Effects on Solubility: ........................................................................................................................................................ 37
Sources of gasses: ............................................................................................................................................................. 39
Atmospheric exchange by diffusion: .............................................................................................................................. 40
Alkalinity and control of pH ...................................................................................................................................... 42
Rates of Oxygen consumption: ................................................................................................................................. 44
Air-sea interaction: ....................................................................................................................................................... 45
Nutrients ............................................................................................................................................................................ 46
Phosphorus ....................................................................................................................................................................... 46
Nitrogen: ........................................................................................................................................................................... 49
Silicon ................................................................................................................................................................................ 52
Other nutrients ................................................................................................................................................................. 53
,DISSOLVED AND PARTICULATE ORGANIC COMPOUNDS IN SEAWATER ....................................... 54
Distribution of organic matter ........................................................................................................................................ 55
Marine Snow .................................................................................................................................................................... 56
Radioactivity .................................................................................................................................................................... 58
Reaction Kinetics of radioactivity .................................................................................................................................. 61
Carbon-14 and carbon dating ......................................................................................................................................... 62
CHEMICAL EXTRACTION OF USEFUL SUBSTANCES FROM THE SEA ................................................ 63
Salt from seawater ........................................................................................................................................................... 63
Extraction of metals from seawater ............................................................................................................................... 63
Fresh water from sea ....................................................................................................................................................... 64
Indian Ocean (Bay of Bengal and Arabian sea) ................................................................................................. 66
,History
1. What is Challenger expedition? What were the goals of it?
2. Antoine Laurent Lavoisier was reported to be the first chemist to analyze the major constituents of seawater -
describe his experiment and also the results.
key figures and their contributions:
1. Aristotle (384–322 BCE): Aristotle was an ancient philosopher and scientist who explored the origin and
nature of seawater. He considered various explanations, such as the metaphorical idea that the sea is "the sweat
of the earth" and believed water became salty due to the mixing of an earthy substance. Aristotle also noted the
bitter taste of seawater and conducted experiments highlighting the relative density difference between seawater
and fresh water. He made early observations on the organic chemistry of seawater, noting the presence of a fatty,
oily substance on its surface.
2. Robert Boyle (1627–1691): Known as the "father of modern chemistry," Boyle published a tract in 1673
titled "Observations and Experiments about the Saltness of the Sea." He conducted experiments on the
chemistry of seawater, including evaporation and residue weighing. Boyle recognized that even freshwater
sources contained small amounts of salt, indicating that ocean salt might accumulate from land runoff.
3. Edmond Halley (1656–1742): A versatile English natural scientist, Halley measured the rate of water
evaporation in the ocean and estimated the water exchange in the Mediterranean. He understood that variations
in seawater salinity were influenced by factors like river runoff, evaporation, precipitation, and ocean currents.
4. Luigi Ferdinando Marsili (1658–1730): Marsili is considered one of the early pioneers of oceanography. He
published the first book entirely dedicated to oceanography, covering various aspects, including seawater
properties and marine life. Marsili conducted measurements of seawater salinity, temperature, and seasonal
thermoclines. He was among the first to apply color tests to determine seawater acidity and recognized the
challenges in determining seawater salinity by residue weighing.
5. Antoine Laurent Lavoisier (1743–1794): Lavoisier, a renowned chemist, rejected the phlogiston theory and
introduced the concepts of oxidation and reduction. He conducted experiments on the major components of sea
salt and identified various salts in seawater, contributing to the understanding of its composition
Lavoisier (1772) attempted to analyze the major components of sea salt. He evaporated seawater, and extracted
the dried residue with alcohol and with alcohol–water mixtures and recrystallized the salts from the resulting
solutions. By this approach he was able to identify several products
CaCO3 - calcium carbonate
CaSO4·2H2O - gypsum, calcium sulfate
NaCl - sodium chloride
Na2SO4·xH2O - Glauber’s salt, sodium sulfate
MgSO4 - Epsom salt, magnesium sulfate
MgCl2 - magnesium chloride
This early attempt to analyze such a mixture of salts showed the complexity of seawater as a chemical system
and defined the approximate amounts of the major components.
6. Joseph Louis Gay-Lussac (1778–1850): Gay-Lussac is known for Gay-Lussac's law and significant
contributions to stoichiometry. He conducted experiments related to seawater composition and analyzed the
, concentration of total salt. His work contributed to understanding the relative constancy of seawater
composition and the concept of the "water column."
7. Alexander Marcet (1819): Marcet's analyses of seawater from various locations led to the observation that
seawater from around the world had nearly identical constituents and proportions. This insight laid the
foundation for the Principle of Constant Composition.
Challenger Expedition:
The Challenger Expedition was a significant scientific voyage undertaken from 1872 to 1876. It was the first
major oceanographic expedition organized specifically to gather data on the ocean and marine life. The
expedition was named after its ship, HMS Challenger, a British Royal Navy vessel. This was not the first
oceanographic expedition, but it was the biggest and most comprehensive up until that time. It was the most
scientifically well-conceived and it is often held to have marked the beginning of oceanography as a scientific
discipline. In 1871, a committee of the Royal Society formulated the goals of what was to become the
Challenger expedition, as follows (Yonge 1972):
(1) To investigate the Physical Conditions of the Deep Sea, in the Great Ocean-basins... in regard to Depth,
Temperature, Circulation, Specific Gravity and Penetration of Light ... at various ranges of depth from the
surface to the bottom.
(2) To determine the Chemical Composition of Sea Water ... at surface and bottom ... [and] various intermediate
depths... to include the Saline Constituents, the Gases, and the Organic Matter in solution, and the nature of any
particles found in suspension.
(3) To ascertain the Physical and Chemical characters of the Deposits everywhere in progress on the Sea-
bottom, and to trace, so far as may be possible, the sources of these deposits.
(4) To examine the Distribution of Organic Life throughout the areas traversed, especially in the deep Ocean-
bottoms and at different depths; with especial reference to the Physical and Chemical conditions already
referred to, and to the connection of the present with the past condition of the Globe.
