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

CO ₂在海洋中下沉的重要途径是通过“生物泵”，这是由表层海洋中颗粒有机碳（POC）的产生以及随后通过垂直沉降向深海的出口驱动的。在这里，我们利用短寿命放射性核素对²¹⁰ Po- ²¹⁰ Pb研究了墨西哥湾北部大陆坡上POC的垂直通量。的总活动²¹⁰宝和²¹⁰的Pb范围为2.5±0.35至16.52±1.98 DPM 100升^-1和从3.47±0.45至24.49±3.42 DPM 100升^-1分别与较高活动除外²¹⁰宝（87.36± 11.38 dpm 100公升^-1）和高盐缺氧Orca盆地近底部水的²¹⁰ Pb（32.25±4.35 dpm 100 L ^-1）。在水柱的上方150 m，²¹⁰ Pb的存量始终大于²¹⁰ Po的存量，而²¹⁰ Po和²¹⁰ Pb的总水柱总存量接近平衡。在²¹⁰宝通量9.8±6.34 DPM米之间变化^-2 d ^-1和30.7±12.06 DPM米^-2 d ^-1与对应POC通量之间8.6毫克C M ^-2 d ^-1和37.65毫克C M ^-2 d^-1。通量在离岸更远的地方表现出总体下降的趋势，紧跟在整个斜坡上的净初级生产力的类似趋势之后。发现生物泵在该倾斜区域上的出口效率比“ e-比率”在0.027和0.11之间变化，平均值为0.05±0.01，这很低。基于²¹⁰ Po的电子比率估计值不同，但在先前估计值的范围内。