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Using rare earth elements to constrain particulate organic carbon flux in the East China Sea

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ABSTRACT

Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare earth elements (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82–94% using the OC mixing model, and 30–80% using the REEs mixing model, respectively. These results suggest that REEs may be better proxies for sediment resuspension than OC in high turbidity marginal seas because REEs do not appear to undergo degradation during particle sinking as compared to organic carbon. Our results suggest that REEs can be used as tracers to provide quantitative estimates of POC fluxes in marginal seas.

No MeSH data available.


Depth profiles for temperature (Temp), salinity, nitrate (NO3), chlorophyll (Chl a), particulate organic carbon (POC) and total suspended matter (TSM) concentrations in the inner shelf (E1, E5) and the outer shelf (E34 and E14) of the East China Sea.Note: POC data are not available at station E1.
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f2: Depth profiles for temperature (Temp), salinity, nitrate (NO3), chlorophyll (Chl a), particulate organic carbon (POC) and total suspended matter (TSM) concentrations in the inner shelf (E1, E5) and the outer shelf (E34 and E14) of the East China Sea.Note: POC data are not available at station E1.

Mentions: Vertical distributions of temperature, salinity, nitrate, chlorophyll-a (Chl a), POC and total suspended matter (TSM) concentrations in the inner (e.g., stations E1 and E5) and outer shelf of the ECS (e.g., stations E14 and E34) are shown in Fig. 2. The hydrographic settings are similar to previous studies with low salinity, high nutrient, high surface Chl a and high TSM concentrations occurring on the inner shelf, and high salinity, low nutrient and low surface Chl a, POC and TSM on the outer shelf (stations E14 and E34)1511. In summer the water column at stations E5, E14 and E34 was stratified, with sub-surface maximum concentrations of Chl a and POC within the depth of the euphotic zone (E5:35 m, E14:72 m, E34:70 m, Fig. 2). A pronounced feature in the inner shelf is that TSM concentrations increased with increasing depth, suggesting the possible occurrence of sediment resuspension in the bottom waters.


Using rare earth elements to constrain particulate organic carbon flux in the East China Sea
Depth profiles for temperature (Temp), salinity, nitrate (NO3), chlorophyll (Chl a), particulate organic carbon (POC) and total suspended matter (TSM) concentrations in the inner shelf (E1, E5) and the outer shelf (E34 and E14) of the East China Sea.Note: POC data are not available at station E1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037389&req=5

f2: Depth profiles for temperature (Temp), salinity, nitrate (NO3), chlorophyll (Chl a), particulate organic carbon (POC) and total suspended matter (TSM) concentrations in the inner shelf (E1, E5) and the outer shelf (E34 and E14) of the East China Sea.Note: POC data are not available at station E1.
Mentions: Vertical distributions of temperature, salinity, nitrate, chlorophyll-a (Chl a), POC and total suspended matter (TSM) concentrations in the inner (e.g., stations E1 and E5) and outer shelf of the ECS (e.g., stations E14 and E34) are shown in Fig. 2. The hydrographic settings are similar to previous studies with low salinity, high nutrient, high surface Chl a and high TSM concentrations occurring on the inner shelf, and high salinity, low nutrient and low surface Chl a, POC and TSM on the outer shelf (stations E14 and E34)1511. In summer the water column at stations E5, E14 and E34 was stratified, with sub-surface maximum concentrations of Chl a and POC within the depth of the euphotic zone (E5:35 m, E14:72 m, E34:70 m, Fig. 2). A pronounced feature in the inner shelf is that TSM concentrations increased with increasing depth, suggesting the possible occurrence of sediment resuspension in the bottom waters.

View Article: PubMed Central - PubMed

ABSTRACT

Fluxes of particulate organic carbon (POC) in the East China Sea (ECS) have been reported to decrease from the inner continental shelf towards the outer continental shelf. Recent research has shown that POC fluxes in the ECS may be overestimated due to active sediment resuspension. To better characterize the effect of sediment resuspension on particle fluxes in the ECS, rare earth elements (REEs) and organic carbon (OC) were used in separate two-member mixing models to evaluate trap-collected POC fluxes. The ratio of resuspended particles from sediments to total trap-collected particles in the ECS ranged from 82–94% using the OC mixing model, and 30–80% using the REEs mixing model, respectively. These results suggest that REEs may be better proxies for sediment resuspension than OC in high turbidity marginal seas because REEs do not appear to undergo degradation during particle sinking as compared to organic carbon. Our results suggest that REEs can be used as tracers to provide quantitative estimates of POC fluxes in marginal seas.

No MeSH data available.