210Po-210Pb distribution and carbon export in the northern Gulf of Mexico continental slope

An important pathway for CO2 sinking in the ocean is via “biological pump”, driven by production of particulate organic carbon (POC) surface and its subsequent export to deeper vertical settling. Here we examine fluxes POC continental slope northern Gulf Mexico utilizing short-lived radionuclide pair 210Po - 210Pb. The total activities 210Pb ranged from 2.5 ± 0.35 16.52 1.98 dpm 100 L-1 3.47 0.45 24.49 3.42 respectively with exception higher (87.36 11.38 L-1) (32.25 4.35 near bottom water hypersaline anoxic Orca basin. In upper 150 m column, inventories were consistently greater than those while overall column found be equilibrium. varied between 9.8 6.34 m-2 d-1 30.7 12.06 corresponding 8.6 mg C 37.65 d-1. showed a general decreasing trend further offshore, closely following similar net primary productivity across slope. efficiency ratios “e-ratios” biological pump over this region was vary 0.027 0.11 averaging at 0.05 0.01, which low. based model-based e-ratio estimates different but within range previous estimates.