Particle-reactive radionuclides (&amp;lt;sup&amp;gt;234&amp;lt;/sup&amp;gt;Th, &amp;lt;sup&amp;gt;210&amp;lt;/sup&amp;gt;Pb, &amp;lt;sup&amp;gt;210&amp;lt;/sup&amp;gt;) as tracers for the estimation of export production in the South China Sea

Wei, Ching-Ling; Lin, Shih-Ting; Sheu, David D.; Chou, Wei‐Lung; Yi, Mingqiang; Santschi, Peter H.; Wen, Liang

doi:10.5194/bg-8-3793-2011

Cited by 72 publications

(40 citation statements)

References 66 publications

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“…In addition, an average ratio of 4.0 ± 1.6 (1SD, n = 77) μmol dpm −1 for suspended particle POC/ 234 Th was determined at the depth of 150 m in the basin regime. This ratio is remarkably close to the trap‐derived POC/ 234 Th ratios of 4.8 ± 1.8 μmol dpm −1 reported at the same depth horizon in this region [ Wei et al ., ], despite that dissolved 234 Th preferentially absorbs to QMA filters during particle filtration and thus may cause a bias in POC/ 234 Th ratio reported here [e.g., Benitez‐Nelson et al ., ; Rutgers van der Loeff et al ., ].Overall, POC export fluxes in the basin area are low and relatively uniform (Figure ). The average POC export fluxes in the four surveys are 7.7 ± 2.7 (n = 22), 4.3 ± 1.4 (n = 26), 9.7 ± 4.0 (n = 12), and 4.5 ± 2.0 (n = 20) mmol m −2 d −1 , respectively.…”

Section: Discussionmentioning

confidence: 94%

“…The average POC export fluxes in the four surveys are 7.7 ± 2.7 (n = 22), 4.3 ± 1.4 (n = 26), 9.7 ± 4.0 (n = 12), and 4.5 ± 2.0 (n = 20) mmol m −2 d −1 , respectively. These values are within the range of POC export flux that was reported in the same region [e.g., Chen et al ., ; Wei et al ., ; Hung et al ., ]. In addition, they are also comparable to the POC export rates reported in the open oceans [e.g., Rutgers van der Loeff et al ., ].…”

Section: Discussionmentioning

confidence: 97%

“…In contrast, the coastal area and the continental shelf are highly productive [ Chen , ]. POC export and plankton community structure studies, although sparse, also indicated a strong contrast between the coastal area and the basin [ Ning et al ., ; Chen , ; Wei et al ., ].…”

Section: Introductionmentioning

confidence: 99%

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Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

et al. 2015

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In this study, we utilize 234 Th/ 238 U disequilibrium to determine particulate organic carbon (POC) export from the euphotic zone in the South China Sea. Depth profiles of 234 Th, total chlorophyll, pigments, and POC were collected during four cruises from August 2009 to May 2011, covering an entire seasonal cycle of spring, summer, autumn, and winter. The extensive data set that was acquired allows for an evaluation of the seasonal variability of upper ocean POC export and its controls in a large marginal sea. The results show that 234 Th fluxes from the euphotic zone fall in the range of 52821550, 34022694, and 302-2647 dpm m 22 d 21 for the coastal, shelf, and basin regimes, respectively. In these regimes, POC/ 234 Th ratios at the base of the euphotic zone fall in the range of 5.7-58.2, 4.6-44.0, and 2.5-15.5 lmol dpm 21 , respectively. Accordingly, for the coastal, shelf, and basin regimes, the mean POC export fluxes from the euphotic zone are 24.3, 18.3, and 6.3 mmolC m 22 d 21 , respectively. Seasonal variations in POC export flux are remarkable in the study area, and POC export peaks were generally observed in autumn. We use a simple linear regression (LLS) method to examine the correlation of POC export versus POC stock and versus plankton community structure. We found a strong correlation (R 2 5 0.73, p < 0.005) between POC export flux and the fraction of diatom in the coastal area, indicating that POC export flux in this province is driven by large phytoplankton, in particular, diatoms. In the shelf area, a relatively strong correlation (R 2 5 0.54, p < 0.0001) was noted for POC export flux and POC stock in the euphotic zone. This indicates that POC export flux in the South China Sea shelf is primarily controlled by POC stock. In contrast, in the South China Sea basin, we identified a weak but intriguing correlation (R 2 5 0.26, p < 0.0001) between POC export flux and the fraction of haptophytes and prasinophytes that are typically < 5 lm in size. This suggests that mechanisms controlling POC export flux in the South China Sea basin are complicated. However, small phytoplankton may play a significant role in controlling POC export flux since they dominate the phytoplankton community structure in this region. (2015), Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea, Journal of Geophysical Research: Oceans PUBLICATIONS 1. Detailed information about the sampling stations is provided in Table A1. A total of 123 stations were occupied during the four survey cruises. Depth profiles of 234 Th, total chlorophyll, pigments, and POC were collected at 33 stations during the spring survey, 41 stations during the summer survey, 19 stations during the autumn survey, and 30 stations during the winter survey. For most of the stations in the basin (water depth > 200 m), water samples were collected throughout the upper 150 m at 5, 25, 50, 75, 100, 125, and

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 97%

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Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

et al. 2015

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“…At station 91 with a deeper seafloor than 105A, the TPM contents showed the same value in euphotic and mesopelagic water, averaging 0.52 6 0.01 mg L 21 (Table 1). It has been revealed that particulate matter in the euphotic zone is rich in biogenic components (i.e., organic matter and biogenic silica) in the western SCS [Wei et al, 2011;Cai et al, 2015;Yang et al, 2015b]. During settling below the euphotic zone, organic components degrade up to >50% in the SCS [Chen et al, 1998;Yang et al, 2009]; the TPM contents would decrease in the mesopelagic layer if there were no additional inputs of particulate matter.…”

Section: Po Deficiency In Mesopelagic Watermentioning

confidence: 99%

Utilizing ²¹⁰Po deficit to constrain particle dynamics in mesopelagic water, western South China Sea

Yang

Zhang

et al. 2017

Geochem Geophys Geosyst

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The 210Po‐210Pb pair is increasingly used as a proxy of quantifying organic carbon export from the euphotic zone. However, disequilibria between 210Po and 210Pb in mesopelagic water have been poorly studied. Here we present unusual deficiencies of 210Po with respect to 210Pb in mesopelagic water (200–1000 m) in the South China Sea (SCS). The total particulate matter (TPM) increased by up to 32% in the mesopelagic layer comparing with the euphotic zone. The total 210Po/210Pb ratio varied from 0.41 to 0.98 with an average of 0.72 ± 0.19, showing an enhanced removal of 210Po in mesopelagic water. On average, particulate 210Po and 210Pb increased by 23% and 32% at the slope stations, respectively. These results indicated that the 210Po deficits result from lateral transport, probably via benthic nepheloid layer. Based on the deficiency of 210Po, the residence times of particulate 210Po were estimated to range from 0.11 to 0.25 year (avg. 0.17 ± 0.07 year), allowing resuspended sediment to disperse over a long range. The export fluxes of 210Po varied from 68 to 121 dpm m−2 d−1 with an average of 96 ± 27 dpm m−2 d−1, which was 6 times that out of the euphotic zone. Using the 210Po deficits, the export fluxes of TPM out of the mesopelagic layer were quantified to vary from 4.19 to 10.20 g m−2 d−1, revealing a large amount of particles from the shelf to the SCS basin. This study suggests that 210Po‐210Pb could be an effective tracer of tracking particle cycling in mesopelagic water.

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“…In the coastal NSCS, biological production is controlled by river plume and coastal upwelling leading to a large variability of export flux over the shelf (Gan et al, 2010(Gan et al, , 2014. There is higher export flux during winter-spring in the central NSCS (Wei et al, 2011) due to the increase of nutrient fluxes by turbulent mixing and Ekman pumping . In addition, mesoscale eddies might account for some high particle fluxes in the central NSCS (Zhou et al, 2013).…”

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confidence: 99%

Temporal Change of Export Production at Xisha of the Northern South China Sea

Chen

2018

JGR Oceans

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Physical‐biological interaction within the upper ocean influences fixed organic carbon with various efficiencies leading to spatial and temporal change of carbon export in the ocean, which is important for global biogeochemical dynamics but is inadequately understood in the northern South China Sea (NSCS). Here the temporal variations of primary and export production are investigated using a 1‐D physical‐biogeochemical coupling model at a pelagic station of Xisha (XS) in the NSCS. At this station, the model reproduces the satellite sea surface observations, the depth‐integrated primary production, and the sinking flux of particulate organic carbon at 500 m from a moored sediment trap. By synthesizing these results, we investigate the long‐term dynamics of the biological pump with the focus on export production. We compared our results at XS with that at A Long‐Term Oligotrophic Habitat Assessment (ALOHA) in the North Pacific subtropical gyre. While the surface export at XS is greater than ALOHA, the stronger subsurface remineralization at XS has resulted in a similar week biological pump as ALOHA. The high surface export and subsurface flux attenuation at XS are caused by its physical dynamics that support a stronger upward nitrate flux than ALOHA. We also find a time lag of about 20 days between primary production and export production at XS, which has led to the large variability of export ratios in the subsurface layers. Further analyses suggest that the temporal variations of primary and export productions are largely driven by the change of turbulent mixing and Ekman pumping that control the vertical nutrient fluxes into the upper ocean.

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Particle-reactive radionuclides (<sup>234</sup>Th, <sup>210</sup>Pb, <sup>210</sup>) as tracers for the estimation of export production in the South China Sea

Cited by 72 publications

References 66 publications

Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

Utilizing ²¹⁰Po deficit to constrain particle dynamics in mesopelagic water, western South China Sea

Temporal Change of Export Production at Xisha of the Northern South China Sea

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Particle-reactive radionuclides (&lt;sup&gt;234&lt;/sup&gt;Th, &lt;sup&gt;210&lt;/sup&gt;Pb, &lt;sup&gt;210&lt;/sup&gt;) as tracers for the estimation of export production in the South China Sea

Cited by 72 publications

References 66 publications

Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea

Utilizing 210Po deficit to constrain particle dynamics in mesopelagic water, western South China Sea

Temporal Change of Export Production at Xisha of the Northern South China Sea

Contact Info

Product

Resources

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Particle-reactive radionuclides (<sup>234</sup>Th, <sup>210</sup>Pb, <sup>210</sup>) as tracers for the estimation of export production in the South China Sea

Utilizing ²¹⁰Po deficit to constrain particle dynamics in mesopelagic water, western South China Sea