Raja M, Rosell-Melé A
Institut de Ciència i Tecnologia Ambientals (ICTA-UAB) Universitat Autònoma de Barcelona Bellaterra Spain.
Present at: University of Nottingham GSK Centre for Sustainable Chemistry Nottingham UK.
J Geophys Res Biogeosci. 2022 May;127(5):e2021JG006514. doi: 10.1029/2021JG006514. Epub 2022 Apr 25.
Primary productivity in the ocean plays a major role in the global carbon cycle. To estimate its changes through geological time, different sedimentary proxies are used. However, the relative weights of the various processes driving the sedimentary accumulation of organic matter are not fully constrained or represent the flux of specific algal classes. Here, we compare sea-surface chlorophyll- (SSchla) abundance estimated from remote sensing data over the last 20 years with the sedimentary concentration of its derivatives (i.e., chlorin) on a suite of 140 core-top sediments from different biogeochemical regions. We estimate with field data that only 0.33% of SSchla in tropical and subtropical regions is transferred to surface sediments in the form of chlorin. Despite the small fraction of chlorin that arrive to the sea-floor, the sedimentary spatial distribution of chlorin is driven primarily by SSchla concentration in high and moderate productivity locations (SSchla > 0.20 mg·m). Our calibration paves the way for the use of chlorin as quantitative proxies of primary productivity in paleoreconstructions and cautions on their use in low primary productivity settings.
海洋中的初级生产力在全球碳循环中起着重要作用。为了估算其在地质时期的变化，人们使用了不同的沉积指标。然而，驱动有机质沉积积累的各种过程的相对权重尚未得到充分限制，也不能代表特定藻类类群的通量。在这里，我们将过去20年从遥感数据估算的海表叶绿素（SSchla）丰度与其衍生物（即二氢卟吩）在一组来自不同生物地球化学区域的140个岩芯顶部沉积物中的沉积浓度进行了比较。我们根据实地数据估计，在热带和亚热带地区，只有0.33%的海表叶绿素以二氢卟吩的形式转移到表层沉积物中。尽管到达海底的二氢卟吩比例很小，但在高生产力和中等生产力地区（海表叶绿素>0.20mg·m），二氢卟吩的沉积空间分布主要受海表叶绿素浓度驱动。我们的校准为在古重建中使用二氢卟吩作为初级生产力的定量指标铺平了道路，并提醒人们在初级生产力较低的环境中使用时要谨慎。
