1980 - National Institute of Oceanography

3.2
Chemical Oceanography
3.2.1 Chemical studies in the coastal and offshore waters of the Arabian
Sea and Bay of Bengal
3.2.2 Drugs from the sea
3.2.3 Protection of marine environment and monitoring of pollutants along
the Indian coast
3.2.4 Characteristics of the estuarine regions of major rivers of India
The major concern of chemical oceanographers is to determine the chemistry
of the marine environment and the changes therein induced by natural and man
made activities. Studies on the marine environment also include the determination
of the amount of organic carbon present in the surface waters, the distribution,
nature and biochemistry of marine compounds in marine fauna and flora thereby
identifying new drug resources, and pollution and related aspects like the protection
and control of oil pollution, sewage and industrial discharge. These studies were
carried out under four projects and the summary of each is given below.
3.2.1 Chemical studies in the coastal and offshore waters of the Arabian Sea and Bay
of Bengal
The work under this project was carried out at headquarters as well as at
Regional Centre, Cochin.
1. Chemical characteristics of the Andaman Sea and Bay of Bengal
During the cruises in the southern Bay of Bengal from 78°E to 98°30'E, hydrographic
stations were worked at 1 degree intervals. In the Andaman Sea almost all the
stations worked during the cruises 51 and 52 in 1979 were repeated in 1980 and in addition
70 new stations were occupied to study the changes that might have taken place during
the course of the year. A total number of 4152 analyses were carried out on board and
317 samples were collected for the analysis of major ions in the shore laboratory.
In the upper 50-75 m, of the entire Andaman Seas the concentrations of nitrates,
phosphates and silicates were low. These were associated with high oxygen and pH-
Nitrite was detected only between 50 and 75 m depth. A thick oxygen minimum layer
extended from 100 m to 1000 m. In 1980, the concentrations of nutrients increased with
simultaneous decrease in the oxygen and pH. At a station in the Malacca Strait, north of
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