mooring-based measurements will be combined with periodic ship surveys to obtain a regional 

 map of CO2 fluxes during the field year. 



Sediment traps are to be placed on the moorings (6 total) deployed off the shelf in the 

 deep-slope/rise region to quantify the vertical POC fluxes occurring in the offshore, organic 

 carbon depocenters. Horizontal velocities are expected to be low in the deep-slope/rise region, 

 and therefore in contrast to the shelf, trap biases for quantitative flux estimates are expected to 

 be minimal. For the moorings located at the deep-slope carbon depocenter, two sediment traps 

 per mooring are required. A trap at 500 m will be deployed to quantify POC fluxes and 

 characterize sinking particulates; 500 m represents the base of a mid-water zone of POC 

 regeneration, high biogenic particle production, and high marine aggregate density. A near- 

 bottom trap will be deployed for the purpose of comparing deep-water geochemical fluxes to 

 measured benthic fluxes, in order to estimate degree of lateral/advective input to the 

 depocenter and calculate benthic remineralization rates. The exact location of the slope/rise, 

 deep-water trap moorings will depend upon information acquired from benthic studies on the 

 deep slope and rise. 



B. Cruise-based Measurements 



1. Water column hydrographic measurements 



Time-series flow parameters (current meters, ADCPs), particle abundance 

 (transmissometers), primary production (FRR fluorometer) and deep-water particulate fluxes 

 (sediment traps) will be obtained from moorings. All other listed measurements in Table 1 

 must be obtained on cruises. Some of these are essential background data for transformation 

 studies and are described in detail in the Transformation Studies section. 



Repeated cruises in the near vicinity of the mooring transect lines are required in order to 

 address the expected temporal variability. Sampling and measurements wiU be made 

 throughout the water column at all stations (0-2000 m depth range). Samples will be obtained 

 from standard CTD/rosette casts, as well as from a towed SeaSoar-style system. The bottle 

 casts also will provide an opportunity to acquire additional samples for measurements not 

 listed in this section (e.g. water samples for plankton taxonomy analyses). The ship cruises 

 will also be used to investigate offshelf transport processes such as frontal eddies, filaments, 

 and warm-ring and Gulf Stream interactions with the outer shelf. These special investigations 

 will be carried out with a combination of standard hydrographic stations with which the entire 

 suite of variables can be measured, and underway surveying using towed instruments. These 

 specific studies will be directed toward processes of opportunity identified in realtime with 

 satellite data transmitted to the ships. 



i. Dissolved inorganic and organic carbon species 



Die represents the sum of three major CO2 species present in seawater: (C02)aq, 

 (HCOJ") and (C03~). The relative proportions of these species depend primarily on the 

 alkalinity and temperature of the water. Changes in DIC concentration reflect the net amount 

 of CO2 gained or lost through air-sea gas exchange, calcium carbonate formation or 

 dissolution, photosynthesis and respiration within the water column or underlying sediments, as 

 well as mixing with waters of different DIC concentration. DIC is measured routinely with a 



13 



