法国索邦大学Bressac, M.团队的一项最新研究对海洋生物泵中碳通量衰减的驱动因素进行了分析。2024年9月11日，国际知名学术期刊《自然》发表了这一成果。

据悉，生物泵向海洋内部提供碳，推动长期的碳固存，为深海生态系统提供能量。其效率取决于新形成的粒子在透光带的转换，随后是通过介层过程的垂直通量衰减。颗粒有机碳(POC)通量的深度衰减，是受涉及浮游动物和/或微生物的多个过程所调节。尽管如此，它仍然主要使用经验推导关系“马丁曲线”进行参数化。推导出的幂律指数是用于比较海洋通量衰减模式的标准度量。

研究人员展示了C-RESPIRE的原位实验结果，C-RESPIRE是部署在多个中层深度的双重粒子拦截器和培养箱，测量微生物介导的POC通量衰减。研究发现，在6个对比鲜明的海洋体系中，即POC通量的30倍范围内，颗粒附着微生物的降解为通量衰减的百分之7％-29％，这意味着浮游动物在通量衰减中发挥更大的影响作用。

微生物再矿化，标准化到POC通量，在不同的地点和深度范围内相差20倍，在高POC通量下速率最低。高达三倍的变化的垂直趋势与低纬度地区强温度梯度有关。在中高纬度地区，温度的影响较小，垂直趋势可能由颗粒生物化学、破碎化和微生物生态生理共同决定。马丁曲线的解构揭示了驱动微生物介导的POC通量衰减的基本机制。

附：英文原文

Title: Decoding drivers of carbon flux attenuation in the oceanic biological pump

Author: Bressac, M., Laurenceau-Cornec, E. C., Kennedy, F., Santoro, A. E., Paul, N. L., Briggs, N., Carvalho, F., Boyd, P. W.

Issue&Volume: 2024-09-11

Abstract: The biological pump supplies carbon to the oceans’ interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems. Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes. Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes. Nevertheless, it continues to be mainly parameterized using an empirically derived relationship, the ‘Martin curve’. The derived power-law exponent is the standard metric used to compare flux attenuation patterns across oceanic provinces. Here we present in situ experimental findings from C-RESPIRE, 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 7–29per 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.

DOI: 10.1038/s41586-024-07850-x

Source: https://www.nature.com/articles/s41586-024-07850-x