Investigating Particle Size-Flux Relationships and the Biological Pump Across a Range of Plankton Ecosystem States From Coastal to Oligotrophic
Investigating Particle Size-Flux Relationships and the Biological Pump Across a Range of Plankton Ecosystem States From Coastal to Oligotrophic
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DOI：
10.3389/fmars.2019.00603
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发表时间：
2019-10-01
影响因子：
3.7
通讯作者：
Stukel, Michael R.
中科院分区：
文献类型：
--
作者：
Fender, Christian K.;Kelly, Thomas B.;Stukel, Michael R.
下沉的颗粒将表层海洋中产生的有机碳输送到海洋内部，导致大气二氧化碳在深海中的净储存。原位成像技术的快速发展有可能彻底改变我们对海洋中颗粒通量衰减的理解；然而，根据颗粒大小和丰度(直接由原位相机测量)估计颗粒通量是具有挑战性的。沉降率取决于几个因素，包括颗粒过量密度和孔隙率，这些因素因颗粒来源和类型而异。此外，粒子特征在下沉时会发生变化。我们比较了光学测量的颗粒尺寸谱轮廓(水下视觉剖面仪5，UVP)与使用沉积物陷阱和Th-234：U-238不平衡在加州电流生态系统(CCE)LTER计划的六个过程游轮上同时测量的颗粒通量。这些测量使我们能够评估尺寸-通量关系在从光学颗粒尺寸测量中估计通量的有效性。我们发现，以前发表的从UVP廓线估计碳通量的参数不太适合在CCE中直接测量通量。这种差异被发现主要是由于粪便颗粒在颗粒通量中的重要作用。这些颗粒主要在一个大小范围内(即100-400米)，由于传感器的分辨率，UVP不能很好地将其分解为图像。我们开发了新的CCE优化参数，用于从南加州海流UVP数据估计碳通量(通量=Sigma(X)(i=1)n(I)Ad(I)(B)Delta di())，其中A=15.4，B=1.05，d=颗粒直径(Mm)，通量以mg Cm(-2)d(-1)为单位。然而，我们警告说，要提高从光学仪器得出的通量估计的准确性，将需要具有更高分辨率的设备、区分粪便颗粒和低孔隙率海洋雪团的能力，以及改进对快速下沉的粪便颗粒的采样。我们还发现，在真光区内的颗粒尺寸-通量关系可能不同于浅黄光区，并假设在研究海洋中下沉颗粒的再矿化长度尺度时，必须考虑下沉颗粒随深度的变化性质。
Sinking particles transport organic carbon produced in the surface ocean to the ocean interior, leading to net storage of atmospheric CO2 in the deep ocean. The rapid growth of in situ imaging technology has the potential to revolutionize our understanding of particle flux attenuation in the ocean; however, estimating particle flux from particle size and abundance (measured directly by in situ cameras) is challenging. Sinking rates are dependent on several factors, including particle excess density and porosity, which vary based on particle origin and type. Additionally, particle characteristics are transformed while sinking. We compare optically measured particle size spectra profiles (Underwater Vision Profiler 5, UVP) with contemporaneous measurements of particle flux made using sediment traps and Th-234:U-238 disequilibrium on six process cruises from the California Current Ecosystem (CCE) LTER Program. These measurements allow us to assess the efficacy of size-flux relationships for estimating fluxes from optical particle size measurements. We find that previously published parameterizations that estimate carbon flux from UVP profiles are a poor fit to direct flux measurements in the CCE. This discrepancy is found to result primarily from the important role of fecal pellets in particle flux. These pellets are primarily in a size range (i.e., 100-400 m m) that is not well-resolved as images by the UVP due to the resolution of the sensor. We develop new, CCE-optimized parameters for use in an algorithm estimating carbon flux from UVP data in the southern California Current (Flux = Sigma(x)(i=1)n(i)Ad(i)(B)Delta di()), with A = 15.4, B = 1.05, d = particle diameter (mm) and Flux in units of mg C m(-2) d(-1). We caution, however, that increased accuracy in flux estimates derived from optical instruments will require devices with greater resolution, the ability to differentiate fecal pellets from low porosity marine snow aggregates, and improved sampling of rapidly sinking fecal pellets. We also find that the particle size-flux relationships may be different within the euphotic zone than in the shallow twilight zone and hypothesize that the changing nature of sinking particles with depth must be considered when investigating the remineralization length scale of sinking particles in the ocean.