CHEMICAL OCEANOGRAPHY/CHEMISTRY

Marine chemists and chemical oceanographers study the dissolved and particle-bound materials in marine organisms and the marine environment. An understanding of marine chemistry is essential for pure and applied research across many disciplines, including the biological and physical sciences.

Marine chemists measure the amounts of individual elements or compounds in the sea and determine their physical properties and reactions. This often involves the development of analytical procedures that can be used at sea and in the laboratory. Examples include instruments for measuring levels of carbon dioxide (CO2), dissolved organic carbon, and volatile compounds in sea water. The dynamics of some of these compounds is important to understanding climate.

Determining the amounts of compounds in the sea is not always an easy task, even for commonly occurring substances. For example, analysis of iron levels in sea water is difficult because although iron is essential for all forms of life, it is present at concentrations that may be less than one part per hundred billion. Other important elements and compounds such as magnesium, bromine and sodium sulphate are also obtained from the sea. One cubic kilometre of sea water contains five kg of gold and 1.5 tonnes of uranium, but great advances in chemical techniques are required to make commercial use of these relatively small concentrations. Indeed, the future exploitation of minerals from the sea depends on significant advances in technology. Another important area of chemical research is the production of value-added organic substances such as drugs and oils derived from fish and other organisms.

In recent years much interest has centred on the disposal of radioactive, industrial, and domestic wastes in the ocean. While it might seem very convenient to dump these wastes in the deep ocean, careful chemical analysis has shown that these materials often find their way into surface waters or into living creatures consumed by man. Pollution of beaches by oil wastes, sewage and other materials dumped at sea continues to occur and is a significant problem. It has been suggested that chemical dispersants used on oil spills may create a worse problem than the one they are intended to alleviate. Also, many pollutants such as metals or hydrocarbons (oil and pesticides) accumulate in plants and animals at levels many times their concentration in sea water. Addressing these problems is a challenge currently facing marine chemists and chemical oceanographers.

Recent advances in technology have increased the amount of data that can be gathered at sea. However, marine chemists spend most of their time in a laboratory conducting chemical analyses and interpreting results. Career opportunities exist mainly in publicfunded research and management organisations, although there are some opportunities for applied careers in private enterprise.

Photo: Chemical oceanographers using recently developed technology to record vertical profiles of temperature, depth, salinity, chlorophyll and other parameters.