Fluxes of clay minerals in the South China Sea

Schroeder, Annette; Wiesner, Martin G.; Liu, Zhifei

doi:10.1016/j.epsl.2015.08.001

Cited by 54 publications

(42 citation statements)

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“…[] also observed such a downward increasing pattern of TMF in the same area although their values were slightly lower than our results. In fact, similar phenomena were reported in the central (the SEATS, SCS‐NE, SCS‐NC, and SCS‐C sites) and southern (the SCS‐SW, SCS‐SC, and SCS‐S sites) SCS basins (see Figure ) [ Gaye et al ., ; Lahajnar et al ., ; Schroeder et al ., ]. Moreover, there is no consistency in the seasonal pattern at different depths from subsurface to deep waters in our study regions (Figure ), as well as in the central SCS basin reported by Gaye et al .…”

Section: Discussionmentioning

confidence: 99%

“…The isotopic indicators point to an endmember of surface sediment around the Kaoping Canyon (SSKC, Table ), which is verified to be a mixture of marine primary production and Taiwanese river inputs [ Kao et al ., ]. Thus, from isotopic mixing plots we conclude that the SSKC is the most likely source of POM transported laterally to the SCS deep basin by deep contour current and possibly mesoscale eddies [ Z. F. Liu et al ., ; Liu et al ., ; Schroeder et al ., ]. Note that some data points apparently fall out of the mixing field with known endmembers in Figure b and these samples point toward higher C/N ratios and lower δ 15 N values, which are very likely terrigenous organics in/on surface soil.…”

Section: Discussionmentioning

confidence: 99%

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Examining N cycling in the northern South China Sea from N isotopic signals in nitrate and particulate phases

et al. 2017

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Nitrogen sources and dynamics, one of the key issues in marine biogeochemical cycles, remain poorly constrained in marginal seas. Here we examine the nitrogen cycle in the northern South China Sea (SCS) by combining data from previous reports with a new data set of N isotopic compositions (δ15N) of nitrate, zooplankton, and sinking particles. Average δ15N in subsurface nitrate is 4.8 ± 0.3‰, similar to that of sinking particles (δ15Nsink of 4.4‰) through the euphotic zone (EZ) collected by floating traps and to documented mean (4.6‰) for long‐term mooring traps at 200 m. This along with oft‐observed shallow nitracline (<100 m) suggests that subsurface nitrate is the primary source of new N to support export production. Moreover, δ15Nsink at the bottom of the EZ resembles those of suspended particles (4.2 ± 1.0‰) and zooplankton (5.4 ± 1.0‰) inside the EZ. High similarity in δ15N among various types of particles including zooplankton in different size fractions in the EZ implies rapid N turnover in the ecosystem. In deep waters at 2000–3000 m, however, additional particulate N fluxes are found due to lateral transport, which contain 15N‐depleted particles, resulting in a downward decreasing trend of δ15Nsink. Incorporation of lighter N by bacteria and selective export of picoplankton are proposed as alternative mechanisms contributing to low δ15Nsink in the deep waters. The significant δ15Nsink change in the deep water column makes the SCS different from most other marginal seas; thus, caution should be made when using sedimentary δ15N to reconstruct paleonitrogen processes.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Examining N cycling in the northern South China Sea from N isotopic signals in nitrate and particulate phases

et al. 2017

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“…Sediment trap locations and current patterns in the northern South China Sea. Black and purple stars are sampling locations of this article and Schröder et al (), respectively. The surface and intermediate currents are basically depicted by Zhu et al () and Hu et al (): The surface currents are indicated by light blue arrows (winter) and yellow arrows (summer); the intermediate currents are indicated by dark blue arrows (winter) and orange arrows (summer).…”

Section: Regional Backgroundmentioning

confidence: 99%

“…No seasonal change has been observed in the clay mineral assemblages of the particles collected by the XI sediment trap in the Xisha Trough (J. G. Liu et al, ), suggesting a steady input pattern for clay minerals in this region. Schröder et al () analyzed data from sediment traps in the SCS and reported that clay minerals sinking to the shallow traps are probably controlled by surface currents. However, particles collected by deep traps are less variable and display increasing smectite content with water depth, which indicates complicated transportation processes including lateral advection and resuspension of shelf sediments (Schröder et al, ); other factors such as authigenic smectite may also be relevant.…”

Section: Introductionmentioning

confidence: 99%

Elemental and Sr‐Nd Isotope Geochemistry of Sinking Particles in the Northern South China Sea: Implications for Provenance and Transportation

et al. 2018

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Major and trace elements, Sr and Nd isotopes of bulk particles from the SCS‐NW and SCS‐N‐03 traps were studied to trace the provenance of sinking particles in the northern South China Sea (SCS). About 63% of biogenic materials and most of lithogenic materials from the SCS‐NW trap may be contributed from resuspended sediments, and more biogenic materials are collected in winter than in summer. The immobile‐element discrimination diagrams also indicate that the lithogenic materials of particles are, to a large degree, from local seafloor sediments, and that the lithogenic materials of particles from SCS‐N and SCS‐W traps have seasonal variations. Sr isotopes (87Sr/86Sr and δ88Sr) of bulk particles are significantly influenced by biogenic materials and cannot be used in provenance tracing. In contrast, Nd isotopes are ideal tools to trace particle provenance. However, the traditional Nd isotope (143Nd/144Nd) shows no statistical difference on the particles of the SCS‐NW and SCS‐N‐03 traps, making it unable to identify their provenance. Fortunately, the stable Nd isotope, ε146Nd, shows different correlation trends to ε143Nd in these two traps, suggesting that stable Nd isotope can potentially identify the sources of lithogenic materials in the northern SCS. Our results indicate that distribution and transportation of sinking particles are controlled by currents of the SCS mainly driven by the East Asian Monsoon.

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“…They can interact with the organic contaminants and interfere with the extraction process. 63,64 In Table 7, it can be seen the significance of the matrix effect in the aqueous matrices based on the statistical tests F and t. The marine water and weir water promoted matrix effects in pesticide at all concentration levels. The chlorpyriphos and cypermethrin were the most affected by the matrix interferences.…”

Section: Recovery and Matrix Effectmentioning

confidence: 99%

Strategy for Correction of Matrix Effect on the Determination of Pesticides in Water Bodies Using SPME-GC-FID

Silva

Paz

Cavalcante

et al. 2016

J. Braz. Chem. Soc.

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This paper investigates a strategy as a quality control parameter, using standard surrogate and determination of a relation factor for determination of parathion-methyl, chlorpyriphos and cypermethrin pesticides in environmental aqueous matrices with distinct characteristics (river water, estuarine, seawater and weir water), using the technique of solid phase microextraction gas chromatography with flame ionization detector (SPME-GC-FID). Pesticides were very susceptible to matrix effects promoted by environmental samples. The salinity and the organic matter seem to have been the main sources of interference in the method. For chlorpyriphos, in middle and high levels, the values of relation factor (R f ) for estuarines, seawater and weir matrices were statistically similar. For cypermethrin, the statistical equality occurred in estuarine matrices in medium and high levels of concentration. That indicates proportional behavior between the pesticide and the surrogate recovery, suggesting that a single value of R f can be used as correction factor recovery for any of these matrices.

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Fluxes of clay minerals in the South China Sea

Cited by 54 publications

References 49 publications

Examining N cycling in the northern South China Sea from N isotopic signals in nitrate and particulate phases

Examining N cycling in the northern South China Sea from N isotopic signals in nitrate and particulate phases

Elemental and Sr‐Nd Isotope Geochemistry of Sinking Particles in the Northern South China Sea: Implications for Provenance and Transportation

Strategy for Correction of Matrix Effect on the Determination of Pesticides in Water Bodies Using SPME-GC-FID

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