The enzyme carbonic anhydrase (CA) is crucial to many physiological processes involving CO₂, from photosynthesis and respiration, to calcification and CaCO₃ dissolution. We present new measurements of CA activity along a North Pacific transect, on samples from in situ pumps, sediment traps, discreet plankton samples from the ship's underway seawater line, plankton tows, and surface sediment samples from multicores. CA activity is highest in the surface ocean and decreases with depth, both in suspended and sinking particles. Subpolar gyre surface particles exhibit 10× higher CA activity per liter of seawater compared to subtropical gyre surface particles. Activity persists to 4700 m in the subpolar gyre, but only to 1000 m in the subtropics. All sinking CA activity normalized to particulate organic carbon (POC) follows a single relationship (CA/POC = 1.9 ± 0.2 × 10⁻⁷ mol mol⁻¹). This relationship is consistent with CA/POC values in subpolar plankton tow material, suspended particles, and core top sediments. We hypothesize that most subpolar CA activity is associated with rapidly sinking diatom blooms, consistent with a large mat of diatomaceous material identified on the seafloor. Compared to the basin‐wide sinking CA/POC relationship, a lower subtropical CA/POC suggests that the inventory of subtropical biomass is different in composition from exported material. Pteropods also demonstrate substantial CA activity. Scaled to the volume within pteropod shells, first‐order CO₂ hydration rate constants are elevated ≥ 1000× above background. This kinetic enhancement is large enough to catalyze carbonate dissolution within microenvironments, providing observational evidence for CA‐catalyzed, respiration‐driven CaCO₃ dissolution in the shallow North Pacific.

中文翻译：

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北太平洋下沉和悬浮颗粒的碳酸酐酶活性

碳酸酐酶 (CA) 对涉及 CO2 的许多生理过程至关重要，从光合作用和呼吸作用到钙化和 CaCO₃ 溶解。我们展示了沿北太平洋横断面的 CA 活动的新测量结果，这些样本来自原位泵、沉积物捕集器、来自船舶航行海水线的谨慎浮游生物样本、浮游生物拖带和来自多核的表层沉积物样本。CA 活动在表层海洋中最高，并随深度降低，无论是悬浮颗粒还是下沉颗粒。与亚热带环流表面颗粒相比，亚极环流表面颗粒每升海水的 CA 活性高 10 倍。活动在副极地环流持续到 4700 m，但在亚热带仅持续到 1000 m。归一化为颗粒有机碳 (POC) 的所有下沉 CA 活动遵循单一关系（CA/POC = 1.9 ± 0.2 × 10⁻⁷ mol mol⁻¹）。这种关系与次极地浮游生物丝束材料、悬浮颗粒和核心顶部沉积物的 CA/POC 值一致。我们假设大多数次极地 CA 活动与快速下沉的硅藻华有关，这与在海底发现的大量硅藻材料一致。与整个盆地下沉的 CA/POC 关系相比，较低的亚热带 CA/POC 表明亚热带生物量的清单与出口材料的成分不同。翼足类动物也表现出大量的 CA 活动。缩放到翼足类外壳内的体积，一级 CO₂ 水合速率常数升高 ≥ 1000 倍于背景。