A carbon budget for the Barents Sea

The first carbon budget constructed for the Barents Sea to study the fluxes of carbon into, out of, and within the region is presented. The budget is based on modelled volume flows, measured dissolved inorganic carbon (DIC) concentration, and literature values for dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations. The results of the budget show that ∼5600±660×106 t C yr−1 is exchanged through the boundaries of the Barents Sea. If a 40% uncertainty in the volume flows is included in the error calculation it resulted in a total uncertainty of ±1600×106 t C yr−1. The largest part of the total budget flux consists of DIC advection (∼95% of the inflow and ∼97% of the outflow). The other sources and sinks are, in order of importance, advection of organic carbon (DOC+POC; ∼3% of both in- and outflow), total uptake of atmospheric CO2 (∼1% of the inflow), river and land sources (∼0.2% of the inflow), and burial of organic carbon in the sediments (∼0.2% of the outflow). The Barents Sea is a net exporter of carbon to the Arctic Ocean; the net DIC export is ∼2500±660×106 t C yr−1 of which ∼1700±650×106 t C yr−1 (∼70%) is in subsurface water masses and thus sequestered from the atmosphere. The net total organic carbon export to the Arctic Ocean is ∼80±20×106 t C yr−1. Shelf pumping in the Barents Sea results in an uptake of ∼22±11×106 t C yr−1 from the atmosphere which is exported out of the area in the dense modified Atlantic Waters. The main part of this carbon was channelled through export production (∼16±10×106 t C yr−1).