4. The Role and Influence of Biochemical Processes on the Chemical Nature of 

 Seawater. The objective of this component is to understand the chemical and biological 

 mechanisms that together control the nature of the marine environment. Development of this 

 major component of the Chemical Oceanography Program arose from advances in marine organic 

 chemistry and in microbiology, advances based on constantly developing instrumental 

 capabilities, most notably temperature-programmed capillary column gas chromatography- 

 mass spectrometry, flow cytometry, image analysis, and high-performance liquid 

 chromatography. New techniques and instrumentation continue to open up opportunitites for 

 study of organic matter distribution and reaction mechanisms in seawater and sediments. 



Isotopic tracers and organic source markers are new techniques for advancing marine organic 

 chemistry. It is now possible to determine carbon isotopic composition of functional groups on 

 individual organic compounds. This allows more specific information to be gained regarding 

 biosynthesis and sources of individual compounds as well as mechanisms of their transformation 

 reactions over time. Close collaboration with the Biological Oceanography Program will 

 continue and probably increase in these areas. 



5. Development and Use of Chemical Tracers to Study Large-Scale Temporal 

 Processes in the Ocean. This area of research has progressed rapidly during the last five 

 years due principally to increased precision in analyzing radio isotopes in seawater and 

 development of sampling and analytical techniques for measurement of new tracers that have 

 unique source functions (e.g., freons). Because geochemical and physical sampling strategies are 

 often incompatible, plans are now being devised for multiship coverage to accommodate 

 infrequent large-volume samples and a denser sampling grid for smaller samples. The latter 

 accommodates most physical oceanographic sampling and measurement schemes. New tracers 

 include pairs of constituents requiring tjoth small- and large-volume samples. For example, 

 freon and krypton complement each other as conservative tracers, with one of them, krypton, 

 decaying predictably so that the age of water parcels can be obtained. 



Activities in this area will proceed into the southern hemisphere incorporating higher precision 

 in analytical methods and more efficient sampling strategies that will combine large- and 

 small-volume samplers. Results from the South Atlantic will complement data already collected 

 for the North and Tropical Atlantic. This study will also complement efforts of other 

 projects such as SEAREX, VERTEX, Warm Core Rings, and future efforts concerned with 

 biogeochemical cycles/balances and ocean fluxes. International cooperation is expected to 

 continue along the pattern set during Geochemical Ocean Sections Study (GEOSECS) activities. 

 However, the ability of foreign laboratories to conduct extensive large-volume sample 

 processing, as for GEOSECS in the 1970's, is now paralleled by facilities supported in the United 

 States (e.g.. for ^^Kr, S^Ar. 228Ra. 90sr, I37cs and ^^C). 



Foreign ship-of-opportunity programs are essential for the tracer coverage required, but they 

 cannot substitute for well-designed and well-managed sampling programs using large dedicated 

 research vessels of the UNOLS fleet. Close collaboration with the Physical Oceanography 

 Program will be maintained to coordinate transient tracer studies with modeling efforts 

 conducted in WOCE. Tracer information is extremely useful to physical oceanographers to 

 provide additional constraints on circulation models. 



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