Introduction of Marine Chemistry


A boundary less body of saline water that composes a large part of planet’s hydrosphere.


Scientific discipline concerned with all aspects of the world’s oceans, including their physical and chemical properties, origin and geology, and life forms.

Oceanography is divided into four general categories:

Physical Oceanography: Studying the physics of the ocean.

Chemical Oceanography: Study of the chemistry of the sea water and sediment.

Biological Oceanography: Study of marine biota and their interactions.

Geological Oceanography: Which studies the geological makeup of the ocean floor.


Chemical Oceanography

Concerned with the study of chemical properties and interactions of substances present in the marine environment.

Chemical oceanography can be further divided into focused areas of study. For example:

Marine chemistry:

Concerned with the composition of sea water.

Marine Geochemistry:

Concerned with the chemistry of the precipitated rocks and sediment found on the sea floor.

Marine Bio-geochemistry:

Concerned with the role of organisms (particularly microorganisms) in the alteration or formation of geological features in the oceans.

There are several diverse areas of investigations by which marine chemistry or chemical oceanography can claim its rights as an emerging discipline. These include:

  1. Chemical composition and its variation in sea water, biomass and sediments.
  2. Biological utilization of chemicals as well as their regeneration (cycling) in the water column and in sediments.
  1. Chemical aspects of pollution and its prevention.
  2. Extraction and economic recovery of chemicals, pharmaceuticals, minerals, oil and gas and energy from the sea.
  1.    Applications of radioisotopes in oceanography.
  2.    Development of reliable new analytical techniques and methods.

Early Developments in Chemical Oceanography

Development of Volumetric Analytical methods

Joseph Louis Gay-Lussac (1824-1836).

The salt content of seawater is nearly geographically constant.

Development of Marcet’s Principle

Alexander Marcet’s proposed, seawater contained small quantities of all soluble substances and that the relative abundances of some were constant.

Concept of Salinity

Georg Forchhammer in 1865 introduced the concept of salinity and demonstrated the validity of Marcet’s Principle for the most abundant salt ions: Chloride, Sodium, Potassium, Magnesium and Sulfate.

Martin Knudsen, Carl Forch and S.P.L. Sorenson (between 1899 and 1902) proposed the relationship between chlorinity and salinity by

S‰ = 1.805C‰+ 0.030

Challenger Expedition (1872-1876):

Distance covered: 68,000 nautical miles (1,25,336 km).

Collections: 133 loads of rocks and sediments.

Collected species: 4717

German Atlantic Ocean Expedition (1925-1927)

Research Vessel Meteor.

Introduced eco sounding to map seafloor topography.

International Council of Scientific Unions (ICSU)

Organized the International Geophysical Year (IGY) during 1957 to 1958.

Participating Nations: 67

Studies were conducted on tides, currents, earth heat flow, gravity, magnetic fields and ocean basin topography.

These studies led to the sea floor spreading theory of Alfred Weginer.

International Indian Ocean Expedition (1959-1965)

Organized by Scientific Committee on Ocean Research (SCOR) and Inter-Governmental Oceanographic Commission (IOC) of UNESCO.

Involving Countries: 23

Research Vessels: 40


In 1974, UN convened a Conference on the Law of Sea.

Established Exclusive Economic Zone (EEZ) concept.

Global Earth Observation System (GEOS)

Established in July 2003.

Current members 89 with European Commission.

The Global Ocean Observing System (GOOS) is an important component of GEOS.





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