Primary Productivity and Carbon Export During the Southern Ocean Gas Exchange (SOGasEx) Lagrangian Tracer Experiments

Biological uptake rates of inorganic carbon were measured during two gas exchange tracer experiments in the Southern Ocean, Atlantic sector near 51°S, 38°W (SOGasEx). Primary productivity estimated from radiocarbon incubations ranged from 12 to 40 mmol C m-2 d-1. Time integrated primary production was estimated to be 355 and 487 mmol C m-2 during the first experiment and second experiments respectively. New productivity (primary productivity associated with nitrate uptake) and time integrated new production, will be calculated from 15N-nitrate incubations. Over large enough temporal and spatial scales, new productivity is expected to be coupled with carbon export out of the surface, euphotic zone into the deep ocean. Particulate organic carbon distribution through the water column and over the time course of the experiments was measured in discrete samples and estimated in situ by beam transmission and will also be used to estimate the balance between carbon production and export. Primary productivity and export rates determined here will be incorporated into a carbon budget and CO2 air- sea flux models for the SOGasEx experiments.