measure ingestion of small copepods associated with snow particles with the objective of 

 quantifying the total impact of these processes on the degradation of sinking particles in the 

 depths immediately beneath the photic zone are being developed. 



H. Mineral Dissolution and Precipitation Reactions Rates 



One of the commonly overlooked components of benthic carbon cycles in shelf sediments 

 is the formation and dissolution of CaC03. At a global scale, CaC03 is more important than 

 organic carbon as a burial mechanism for carbon. A variety of studies have demonstrated 

 extensive dissolution of sedimentary carbonates in shelf depth environments despite 

 supersatmated overiying waters. 



The decomposition of organic matter or oxidation of anaerobic metabolites drives 

 dissolution. Substantial, and perhaps the greatest, dissolution apparently occurs during the 

 spring bloom recruitment which is timed to the spring bloom delivery of carbon to the bottom. 

 The recruitment of benthos, including shell-bearing bivalves, is often greatest during spring 

 bloom periods in this type of environment. The dynamics of recruitment and loss of small 

 carbonate-bearing species of benthic forams and bivalves must be assessed during the spring 

 bloom period. Patterns of live/dead/total abundances during this time should allow estimates 

 of net dissolution or precipitation of benthic carbonate. This information will be factored into 

 the interpretation of the time dependent CO2/O2 flux balances. Other mineral groups that may 

 play an important role in the interpretation of the cycling of organic carbon in the BBL 

 include sulfide and iron and manganese oxide minerals. 



m. METHODOLOGY 



Most measurements of carbon transformation in aquatic systems cannot, at this time, be 

 made remotely. The exceptions are primary production and total community respiration, for 

 which the capability for moored-instrument measurements is under development (FRR 

 fluorometer and oxygen sensors). Therefore shipboard work is essential for this component of 

 the OMP program. Because transformation studies tend to require lengthy experiments by 

 numerous investigators, a few, relatively intensive investigations of representative inner, mid 

 and outer shelf stations are indicated. The number of investigators involved in making 

 transformation measurements (approximately 50) requires the use of two ships; we anticipate 

 that one of these will be "cold", (no radioisotopes on board) for natural abundance work. 



Transformation studies should be conducted during seasons that are expected to represent 

 key periods of biological, chemical and physical activity: Dec/Jan (coldest temperatures, 

 formation and transport of bottom nepheloid layer); Feb/Mar (strongest storm effects, spring 

 bloom); May/June (beginning of water column stratification); Aug/Sep (highest water 

 temperatures, strong stratification, potentially high rates of microbial activity). Each cruise 

 should combine limited transport sampling, using tow-yo (e.g. SeaSoar) mapping, with water- 

 column and sea floor sampling at closely- spaced stations along transects coordinated with the 

 mooring array. The transect mapping data will be used to provide a larger- scale, high- 

 resolution framework for both planning and interpreting transect data, and will be supported by 

 real-time acquisition of remote sensing data (e.g. SeaWifs and AVHRR images). Cruise 



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