Calcium carbonate (CaCO₃) minerals secreted by marine organisms are abundant in the ocean. These particles settle and the majority dissolves in deeper waters or at the seafloor. Dissolution of carbonates buffers the ocean, but the vertical and regional distribution and magnitude of dissolution are unclear. Here we use seawater chemistry and age data to derive pelagic CaCO₃ dissolution rates in major oceanic regions and provide the first data-based, regional profiles of CaCO₃ settling fluxes. We find that global CaCO₃ export at 300 m depth is 76 ± 12 Tmol yr⁻¹, of which 36 ± 8 Tmol (47%) dissolves in the water column. Dissolution occurs in two distinct depth zones. In shallow waters, metabolic CO₂ release and high-magnesium calcites dominate dissolution while increased CaCO₃ solubility governs dissolution in deeper waters. Based on reconstructed sinking fluxes, our data indicate a higher CaCO₃ transfer efficiency from the surface to the seafloor in high-productivity, upwelling areas than in oligotrophic systems. These results have implications for assessments of future ocean acidification as well as palaeorecord interpretations, as they demonstrate that surface ecosystems, not only interior ocean chemistry, are key to controlling the dissolution of settling CaCO₃ particles.

海洋生物分泌的碳酸钙（CaCO _{3 ）矿物质在海洋中含量丰富。}这些颗粒沉降，大部分溶解在更深的水域或海底。碳酸盐的溶解缓冲了海洋，但溶解的垂直和区域分布和幅度尚不清楚。在这里，我们使用海水化学和年龄数据来推导主要海洋区域的远洋 CaCO ₃溶解速率，并提供第一个基于数据的 CaCO ₃沉降通量的区域剖面。我们发现在 300 m 深度处的全球 CaCO ₃输出量为 76 ± 12 Tmol yr ^-1，其中 36 ± 8 Tmol (47%) 溶解在水柱中。溶解发生在两个不同的深度区域。在浅水区，代谢 CO₂释放和高镁方解石主导溶解，而增加的 CaCO ₃溶解度控制在更深水域的溶解。基于重建的下沉通量，我们的数据表明，在高产、上升流区域， CaCO _{3从地表到海底的转移效率高于贫营养系统。}这些结果对评估未来海洋酸化以及古记录解释具有重要意义，因为它们表明，表面生态系统，不仅是内部海洋化学，是控制沉降 CaCO ₃颗粒溶解的关键。