Diapycnal Mixing and Vertical Circulation on the Continental Shelf of the Northern South China Sea

AbstractSpatiotemporal variations in internal solitary wave (ISW) polarity over the continental shelf of the northern South China Sea (SCS) were examined based on mooring-array observations from October 2013 to June 2014. Depression ISWs were observed at the easternmost mooring, where the water depth is 323 m. Then, they evolved into elevation ISWs at the westernmost mooring, with a depth of 149 m. At the central mooring, with a depth of 250 m, the ISWs generally appeared as depression waves in autumn and spring but were elevation waves in winter. Seasonal variations in stratification caused this seasonality in polarity. On the intraseasonal time scales, anticyclonic eddies can modulate ISW polarity at the central mooring by deepening the thermocline depth for periods of approximately 8 days. During some days in autumn and spring, depression ISWs and ISWs in the process of changing polarity from depression to elevation appeared at time intervals of 10–12 h because of the thermocline deepening caused by internal tides. Isotherm anomalies associated with eddies and internal tides have a more significant contribution to determining the polarity of ISWs than do the background currents. The observational results reported here highlight the impact of multiscale processes on the evolution of ISWs.

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Seasonal Dynamics of Dissolved Organic Carbon Under Complex Circulation Schemes on a Large Continental Shelf: The Northern South China Sea

Journal of Geophysical Research Oceans ◽

10.1002/2017jc013325 ◽

2017 ◽

Vol 122 (12) ◽

pp. 9415-9428 ◽

Cited By ~ 7

Author(s):

Feifei Meng ◽

Minhan Dai ◽

Zhimian Cao ◽

Kai Wu ◽

Xiaozheng Zhao ◽

...

Keyword(s):

Organic Carbon ◽

South China Sea ◽

Dissolved Organic Carbon ◽

Continental Shelf ◽

South China ◽

Seasonal Dynamics ◽

Northern South China Sea ◽

China Sea

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Rare Earth Element Distributions in Continental Shelf Sediment, Northern South China Sea

Water ◽

10.3390/w12123540 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3540

Author(s):

Qian Ge ◽

Z. George Xue ◽

Fengyou Chu

Keyword(s):

Rare Earth ◽

South China Sea ◽

Continental Shelf ◽

South China ◽

Northern South China Sea ◽

Hainan Island ◽

Sediment Provenance ◽

Adjacent Area ◽

China Sea ◽

Qiongzhou Strait

A total of 388 surface sediment samples taken from the northern South China Sea (SCS) continental shelf were analyzed to characterize the signature of their rare earth elements (REEs). The average REEs concentration was 192.94 μg/g, with a maximum of 349.07 μg/g, and a minimum of 32.97 μg/g. The chondrite-normalized REEs pattern exhibits a remarkably light REEs accumulation, a relatively flat heavy REEs pattern, and a negative Eu anomaly. We subdivided the study area into three zones using the characteristics of REEs and statistical characteristics. Zone I: continental shelf off western Guangdong Province. Here, the sediment provenance is mainly river-derived from the Pearl River, Taiwanese rivers, and those in the adjacent area. Zone II: Qiongzhou Strait and Leizhou Peninsula. Here, the sediment provenance consists of the Qiongzhou Strait and the Hainan Island. Zone III: Hainan Island and SCS slope sediments are dominated. The REEs compositions are mainly controlled by source rock properties, hydrodynamic conditions, and an intensity of chemical weathering. We reconstructed the sediment dispersal and transport route using the REEs compositions, grain size, and other geochemical characteristics throughout the study area.

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