Elevated particulate organic carbon export flux induced by internal waves in the oligotrophic northern South China Sea

Dewang Li,Wen-Chen Chou,Yung-Yen Shih,Guan-Yu Chen,Yi Chang,Tsang-Yuh Lin,Chin-Chang Hung,Chun Hoe Chow

doi:10.1038/s41598-018-20184-9

Abstract

To understand the biogeochemical response to internal waves in the deep basin of the northern South China Sea (NSCS), particulate organic carbon (POC) export fluxes were quantified for the first time during the passage of large internal waves using drifting sediment traps attached with hydrographic sensors. Results revealed large variations in temperature, nitrate and chlorophyll a (Chl a) concentrations during and after internal waves, suggesting that cold nutrient-replete waters may be brought to the euphotic zone in the dissipation zone during and after the passage of internal wave packets, resulted in phytoplankton flourished. Most importantly, POC export fluxes (110.9 ± 10.7 mg C m−2 d−1) were significantly enhanced after internal waves compared to non-internal wave area (32.6–73.0 mg C m−2 d−1) in the NSCS. Such elevated POC fluxes may be induced by downward flourished biogenic particles, particle aggregation or converged particles from mixed layer triggered by internal waves.

Highlights

In density-stratified ocean, lake, and atmosphere, distortions of density feel the restoring of gravity and propagating as internal waves
Previous results suggest that the NSCS produces particulate carbon and sinking particulate organic matter in the deep water of the northern South China Sea is predominately marine origin[21,22]
Hydrographic settings influenced by internal waves

Summary

Introduction

In density-stratified ocean, lake, and atmosphere, distortions of density feel the restoring of gravity and propagating as internal waves. Large variations of time series temperature, salinity, and Chl a concentration were observed at stations K1 and K2 (Fig. 2).

Results

Conclusion