The biological pump supplies carbon to the oceans’ interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems^1,2. Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes³. Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes^4,5. Nevertheless, it continues to be mainly parameterized using an empirically derived relationship, the ‘Martin curve’⁶. The derived power-law exponent is the standard metric used to compare flux attenuation patterns across oceanic provinces^7,8. Here we present in situ experimental findings from C-RESPIRE⁹, a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7–29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces.

生物泵向海洋内部供应碳，推动长期碳封存，并为深海生态系统提供能量^1,2 。其效率由透光带中新形成的颗粒的转变决定，随后通过中层过程进行垂直通量衰减³ 。颗粒有机碳 (POC) 通量的深度衰减由涉及浮游动物和/或微生物的多个过程调节^4,5 。尽管如此，它仍然主要使用经验导出的关系“马丁曲线” ⁶进行参数化。导出的幂律指数是用于比较跨海洋省份的通量衰减模式的标准度量^7,8 。在这里，我们展示了 C-RESPIRE ⁹的原位实验结果，C-RESPIRE 9 是一种部署在多个中层深度的双粒子拦截器和孵化器，用于测量微生物介导的 POC 通量衰减。我们发现，在代表 POC 通量 30 倍范围的 6 个对比海洋区域中，颗粒附着微生物的降解占通量衰减的 7-29%，这意味着浮游动物在通量衰减中的影响更大。微生物再矿化（按 POC 通量标准化）在不同地点和深度范围内变化 20 倍，在高 POC 通量时速率最低。高达三倍变化的垂直趋势与低纬度地区的强烈温度梯度有关。相比之下，温度在中高纬度地区的作用较小，其中垂直趋势可能是由颗粒生物化学、碎片化和微生物生态生理学共同决定的。 对马丁曲线的解构揭示了驱动微生物介导的跨海洋省份 POC 通量衰减的基础机制。