The OMZ and Its Influence on POC in the Tropical Western Pacific Ocean: Based on the Survey in March 2018

Abstract

The hypoxia problem in the ocean is worsening, and the oxygen minimum zone (OMZ) continues to expand. The Tropical Western Pacific Ocean is one of the most sensitive areas in response to climate change and human activities, and the OMZ in this area has also expanded significantly. Based on a survey conducted in March 2018, the characteristics of OMZ in the Kocebu seamount area of the Tropical Western Pacific Ocean and its biogeochemical effects are discussed. The results showed that DO in the Kocebu seamount area first decreased and then increased, and the lowest value was 2.49 mg/L at a water depth of 750 m. Based on the oxycline and the threshold of 3.20 mg/L, OMZ in this area was located in the water column of 590–1,350 m. With the increase in water depth, the POC concentration decreased gradually and remained stable in the water column deeper than 1,000 m. The presence of OMZ reduced the decomposition rate of POC, causing more POC to sink into deeper waters. 38.77% of POC was decomposed in the water column of 150–300 m, whereas only 16.25% of POC was decomposed in the OMZ. In contrast to the vertical distribution of POC, δ13C-POC decreased rapidly in the water columns of 100–150 and 300–500 m, indicating the rapid decomposition of POC. This result suggests that POC and δ13C-POC should be combined in the evaluation of POC decomposition.

Particulate Organic Matter in the Atacama Trench: Tracing Sources and Possible Transport Mechanisms to the Hadal Seafloor

“…Our discrete measurements at the same depth (∼16.3% POC; Figure 7b) are consistent with the POCsat results. Similar POC percentages in the mesopelagic zone have been reported in other high-productivity systems, which has been attributed to the presence of ODZ waters that could reduce the decomposition rate of POC and increase its sink into deeper waters (Ma et al, 2021;Weber & Bianchi, 2020).…”

Caracterización de la Materia Orgánica Particulada de la Fosa de Atacama Mediante Lípidos Polares Intactos e Isótopos Estables.

“…7B) are consistent with the POCsat results. Similar POC percentages in the mesopelagic zone have been reported in other high-productivity systems, which has been attributed to the presence of ODZ waters that could reduce the decomposition rate of POC and increase its sink into deeper waters (Weber & Bianchi, 2020;Ma et al, 2021).…”

“…Porcentajes similares de POC en la zona mesopelágica han sido reportados en otros sistemas de alta productividad, lo que se ha atribuido a la presencia de aguas ODZ que podrían reducir la tasa de descomposición de POC y aumentar su hundimiento en aguas más profundas (Weber & Bianchi, 2020;Ma et al, 2021).…”

“…March 2018) to evaluate the dynamics of POC in surface (0 m) and subsurface (1000 m) waters over the Atacama Trench (Fig.6A-D). Our rationale assumes that particles found at 1,000 m must have originated in surface waters within that time.…”

The diel vertical distribution and carbon biomass of the zooplankton community in the Caroline Seamount area of the western tropical Pacific Ocean

“…With the increasing global ocean deoxidation and the global expanding of the OMZs 42 , the OMZs were found in the western Pacific Ocean 25 and seamount areas of the WTPO [43][44][45] , including the Caroline Seamount. The presence of an OMZ is an important physiological limitation for zooplankton with DVM behaviour.…”