Wilford D. Gardner, M.J. Richardson, Ian D. Walsh; Texas A&M University

"The Role of POC, Small Particles and Aggregates in Biogeochemical Cycles in the Southern Ocean"

To help identify the factors and quantify the processes which regulate the magnitude and variability of primary productivity and fate of biogenic materials, we will optically measure the in situ distribution of particles from sizes of a micron to millimeters (large aggregates).

OPTICAL MEASUREMENTS:

Shipboard CTD: beam attenuation (transmissometer) and light scattering (LSS)

Shipboard Inline Seawater: beam attenuation (transmissometer or ac3 to ship's DAS.

LAPS (Large Aggregate Profiling System) Aggregate video camera, CTD, optics (transmissometer and fluorometer or ac9 with data logger), insitu particle size distribution (LISST), LSS

DISCRETE WATER MEASUREMENTS:

POC particulate organic carbon concentrations, PM particulate matter concentrations

Our optical data will be correlated with our POC and PM measurements, and with discrete microplankton, chlorophyll and primary productivity measurements made by others in the program. We are also interested in other PIs' measurements of fluorescence, CO2, microplankton, mixed layer dynamics, diel variations, frontal dynamics, nutrients, oxygen, light levels, wind mixing, and dissolved/particulate radioisotope distributions in order to evaluate the role of particles in the packaging and export of carbon and particulate matter from the euphotic zone and the exchange between the large and small particle pools.

PROPOSED CRUISE PARTICIPATION:

PFZ Process cruises 1 and 2 on Thompson doing all of the above measurements, possibly Process cruise 2 in the Ross Sea