The export flux of particulate organic carbon derived from <sup>210</sup>Po / <sup>210</sup>Pb disequilibria along the North Atlantic GEOTRACES GA01 (GEOVIDE) transect
Abstract. The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. The deficits of 210Po in the Iberian Basin and at the Greenland Shelf were strongly affected by vertical advection. Using the export flux of 210Po and the particulate organic carbon (POC) to 210Po ratio on total (> 1 µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10 mmol C m−2 d−1, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency