Satellite Observed Spatial and Temporal Variabilities of Particulate Organic Carbon in the East China Sea

Abstract

In this study, we investigate spatial and temporal variabilities of particulate organic carbon (POC) in the East China Sea (ECS) and explore the dominant influencing factors for its three subregions—coastal, continental shelf and open sea—by analyzing satellite derived POC from 2001 to 2011 after calibration against in situ samplings. The analysis reveals that the largest POC occurs in spring at the coastal region with a value of 297.5 mg m−3, and the smallest in summer at the open sea region with a value of 108.9 mg m−3. POC in the coastal region is dominated by biological activity related to river discharge of nutrients and organic matter, and is regulated by sediment discharge variation due to the Three Gorge Project and chemical fertilizer application along the Changjiang River watershed; the open sea region is dominated by water exchange with the Kuroshio current, which results in the highest sea surface temperature and the lowest chlorophyll and POC among the three subregions; POC in the continental shelf region is driven by the seasonal competition between the influence of the coastal ocean and the Kuroshio current through biological activity and water exchange. A method to estimate the organic matter reserve in the ECS was developed based on satellite data and in situ samplings. Organic carbon storage was estimated at 4.08 × 1013 g, which could be used as a baseline for future estimates. An improved estimation could be found with additional in situ data and with the use of a more sophisticated algorithm for satellite POC analysis.

Absorption-based algorithm for satellite estimating the particulate organic carbon concentration in the global surface ocean

“…The ocean is a vast carbon reservoir, and the ocean carbon cycle is crucial in studying global climate change and environmental evolution (Hedges, 1992;Siegenthaler and Sarmiento, 1993). Particulate organic carbon (POC) and dissolved organic carbon (DOC) are two kinds of oceanic organic carbon (Amon and Benner, 1996;Jahnke, 1996;Chen et al, 2022). Although the stock of POC is small, its importance depends on its constituents (phytoplankton, bacteria, zooplankton, and organic detritus), which are responsible for relatively large carbon fluxes and short turnaround times (Stramska, 2009;Evers-King et al, 2017).…”

Plankton Community Respiration and Particulate Organic Carbon in the Kuroshio East of Taiwan

“…POC is normally treated as a proxy for phytoplankton in the oligotrophic ocean, such as in the Kuroshio east of Taiwan [ 3 , 20 , 21 ]. In this study, the lowest and highest POC concentrations were 1.8 and 77.1 μg C L −1 , respectively, with mean depth-normalized integrated values ranging from 12.7 (±2.3) to 21.6 (±5.2) μg C L −1 ( Figure 4 c).…”

“…On average, the carbon ratio of Chl a to POC was 102.6 (±83.5)% using all data in this study. This suggests that the POC is mainly attributed to phytoplankton biomass in the oligotrophic KW [21]. In the oligotrophic ocean POC is normally treated as a proxy for phytoplankton in the oligotrophic ocean, such as in the Kuroshio east of Taiwan [3,20,21].…”

“…However, its biological components have not been examined. POC can also serve as a fundamental nutrition source for higher trophic levels (e.g., nekton), although it is surprising that data on this in the Kuroshio are scarce (e.g., [ 20 , 21 ]). As for organic carbon consumption (i.e., plankton CR), an even rarer dataset has been reported in the Kuroshio and the western Pacific Ocean [ 22 , 23 , 24 ].…”

The influence of increasing sea surface temperature on particulate organic carbon in Indonesian waters based on MODIS Aqua satellite

“…However, the correlation analysis during these nineteen years also reveals that SST does not always significantly influence POC (e.g., February and March). Another factor may induce seasonal POC variations in Indonesian waters, such as fresh water fluxes [16,23], currents [24] or winds [25]. Besides that, biological processes are also largely responsible for the higher levels of POC [18].…”