Geographic Variation of Particle Size Distribution in the Kuroshio Region: Possible Causes in the Upper Water Column

Yamada, Yosuke; Fukuda, Hideki; Umezawa, Yu; Nagata, Toshi

doi:10.3389/fmars.2021.768766

Cited by 2 publications

(7 citation statements)

References 68 publications

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“…accumulation of larger particles detectable by LISST-100X in the presence of a high concentration of TEP, which has a porous, gel-like structure, in the subtropical northwest Pacific along the Kuroshio Current (Yamada et al, 2021). Therefore, porous gellike materials may be a determinant of particle dynamics in subtropical environments.…”

Section: Discussionmentioning

confidence: 99%

“…Among particle properties (POC/PON, Chl a/TPV, POC/TPV, and PON/TPV) within the euphotic layer, only Chl a/TPV showed a significant difference between the two areas (Table 4). Yamada et al (2021) reported that the ratio of TEP concentration, which has a porous gel like structure, to Chl a concentration was elevated in oligotrophic areas along the Kuroshio Current. Low Chl a/TPV in the subtropical gyre may indicate a smaller contribution of phytoplankton to TPV and lower food quality relative to the slope.…”

Section: Discussionmentioning

confidence: 99%

“…The volumetric particle concentration in each size class is estimated by inversion modeling based on Mie theory (Agrawal and Pottsmith, 2000). To minimize overestimation in the upper size bins driven by salinity fluctuation (Styles, 2006) and underestimation in the lower size bins due to low particulate concentrations or high ambient light conditions (Andrews et al, 2011), we used a size class range of 5.2-119 mm (20 LISST bins) (Yamada et al, 2015;Yamada et al, 2021). The LISST-100X was mounted on a winch wire with a protective frame, and the volume of particles at a given depth was measured for 10 min at a 1-s measurement interval (totaling 600 counts).…”

Section: Water Sampling and Determination Of Environmental Variablesmentioning

confidence: 99%

“…Volumetric size distribution data were used to calculate the PSD in numerical terms, assuming that particles are spheres. Then, the numerical PSD was determined using the following power-law equation (Bader, 1970;Kostadinov et al, 2009;Buonassissi and Dierssen, 2010;Yamada et al, 2015;Yamada et al, 2021):…”

Section: Water Sampling and Determination Of Environmental Variablesmentioning

confidence: 99%

“…Several studies in subtropical areas have reported that the particle size distribution (PSD) in the mixed layer exhibits spatial and temporal variations (Buonassissi and Dierssen, 2010;White et al, 2015;Fender et al, 2019). Yamada et al (2021) reported that the contribution of larger particles increased with the concentration of transparent exopolymer (TEP) particles in an oligotrophic area along the Kuroshio Current in the subtropical Pacific Ocean. The porous structure and sticky nature of TEP stimulate rapid accumulation of large aggregates (Passow, 2002;Mari et al, 2017;Nagata et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

et al. 2022

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The biological pump that transports carbon from the surface ocean to the ocean interior is an important determinant of ocean carbon absorption from the atmosphere, and of biological activity beneath the euphotic zone. Various factors influence the magnitude and efficiency of this biological pump, such as primary production, particle size, and the composition of consumers of particulate organic carbon (POC). The complex factors influencing the biological pump induce high regional and temporal variability; however, the mechanisms of this variability are not understood and its causes remain unclear. The size of sinking particles has been hypothesized to affect the attenuation of POC flux via reduction of residence time within the water column. Here, we conducted sediment trap experiments in slope and subtropical gyre areas along the Kuroshio in the subtropical North Pacific. The ratio of POC flux at a depth 100 m below the base of the euphotic zone to that at the base of the euphotic zone (T100) varied from 0.307 to 0.646 and from 0.090 to 0.958 in the slope and subtropical gyre areas, respectively, and was positively correlated with variations in the volume-weighted mean particle diameter (Spearman rank order correlation coefficient: 0.700, p< 0.05, n = 9). However, the variation in T100 was not correlated with ambient water temperature (p > 0.05). The results support the hypothesis that attenuation of POC flux is influenced by the size of sinking particles in oligotrophic oceanic areas.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Water Sampling and Determination Of Environmental Variablesmentioning

confidence: 99%

Section: Water Sampling and Determination Of Environmental Variablesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

et al. 2022

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Functions of extracellular polymeric substances in partitioning suspended and sinking particles in the upper oceans of two open ocean systems

Yamada,

Ebihara,

Fukuda

et al. 2024

Limnology & Oceanography

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Marine particle dynamics and carbon export, involving extracellular polymeric substances (EPS) like transparent exopolymer particles (TEP) and Coomassie Brilliant Blue‐stained particles (CSP), are poorly understood. Although TEP adhesive properties may enhance carbon export by facilitating aggregate formation, their low density can also enhance particle suspension. Factors influencing TEP regulation of particle dynamics remain unclear. To investigate EPS contributions to particle dynamics, we investigated ratios of TEP to particulate organic carbon (POC) and of CSP to POC in suspended and sinking particles collected with marine snow catchers. Samples were collected in a subarctic region near Hokkaido during a spring phytoplankton bloom and in the oligotrophic, subtropical Kuroshio region. At Hokkaido, the mean TEP : POC ratio of sinking particles (0.075 μg Xeq. : μg C) was > 30× lower than in suspended particles (2.3), consistent with a model prediction of selective retention of buoyant TEP‐rich particles in the upper water column. In the Kuroshio region, sinking particles also contained fewer TEP than suspended particles; however, the TEP : POC ratio of sinking particles (1.0) was > 10× higher than at Hokkaido, suggesting that TEP constitute a significant carbon component of sinking particles. These findings indicate that TEP facilitate aggregation of high‐density particles and particle sinking in the Kuroshio region. Distributions of CSP : POC ratios between suspended and sinking particles resembled TEP : POC ratios in both regions, implying a significant contribution of CSP to particle dynamics. We propose that EPS have divergent effects on suspension and sinking of marine particles, which vary with particle composition and biogeochemical conditions.

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Geographic Variation of Particle Size Distribution in the Kuroshio Region: Possible Causes in the Upper Water Column

Cited by 2 publications

References 68 publications

Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

Functions of extracellular polymeric substances in partitioning suspended and sinking particles in the upper oceans of two open ocean systems

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