TY - JOUR
T1 - Concurrent reductions in sinking particle flux and its ratios of opal and organic carbon to CaCO 3 in the oligotrophic western North Pacific Ocean during 2007–2014
AU - Jeong, Jin Hyun
AU - Kim, Dongseon
AU - Kim, Hyung Jeek
AU - Kim, Eung
AU - An, Soonmo
AU - Kim, Tae Wook
N1 - Funding Information:
This research was part of a project titled “Study on air-sea interaction and process of rapidly intensifying typhoon in the northwestern Pacific” funded by the Ministry of Oceans and Fisheries , Korea, and the KIOST project ( PE99665 ). Additional support was provided by the Basic Science Research Program (2017R1C1B2009189) funded by the Ministry of Education and the National Research Foundation of Korea , and a Korea University Grant .
Funding Information:
This research was part of a project titled “Study on air-sea interaction and process of rapidly intensifying typhoon in the northwestern Pacific” funded by the Ministry of Oceans and Fisheries, Korea, and the KIOST project (PE99665). Additional support was provided by the Basic Science Research Program (2017R1C1B2009189) funded by the Ministry of Education and the National Research Foundation of Korea, and a Korea University Grant.
PY - 2019/1
Y1 - 2019/1
N2 - Sediment trap data collected from the western North Pacific Ocean (NPO) revealed a reduction in sinking particle flux (SPF) to the mesopelagic zone (~1000 m) during 2012–2014 compared to levels during 2007–2011. Satellite-based net primary production (NPP) estimates showed no discernable decline with time, resulting in a decreasing SPF/NPP ratio. Based on a synchronized reduction in the opal/CaCO 3 ratio, the decline in SPF can be attributed to a shift in the relative composition of phytoplankton from a group with relatively high nutrient demand (i.e., diatoms) to those with low nutrient demand (i.e., coccolithophores and other small phytoplankton adapted to a more nutrient-depleted environment). This shift could result in a decline in particle export below the mixed layer depth (MLD) and an increase in regenerated production (or nutrient recycling) within the MLD, which could be reconciled with decreasing SPF and non-decreasing NPP, as shown by the significant correlation between SPF/NPP and the opal/CaCO 3 ratio. Environmental factors associated with nutrient availability were investigated, along with climate variability indices of the NPO. Using eddy kinetic energy, vertical Ekman transport, and vertical density profiles, the nutrient deficiency was partially explained during the seasons showing significant SPF reductions. An association between SPF and the Pacific Decadal Oscillation was identified. However, the 7-year data were not sufficient for verification. The results of this study indicate that particle fluxes to depth and ocean biological pumps are subject to interannual variability caused by various factors.
AB - Sediment trap data collected from the western North Pacific Ocean (NPO) revealed a reduction in sinking particle flux (SPF) to the mesopelagic zone (~1000 m) during 2012–2014 compared to levels during 2007–2011. Satellite-based net primary production (NPP) estimates showed no discernable decline with time, resulting in a decreasing SPF/NPP ratio. Based on a synchronized reduction in the opal/CaCO 3 ratio, the decline in SPF can be attributed to a shift in the relative composition of phytoplankton from a group with relatively high nutrient demand (i.e., diatoms) to those with low nutrient demand (i.e., coccolithophores and other small phytoplankton adapted to a more nutrient-depleted environment). This shift could result in a decline in particle export below the mixed layer depth (MLD) and an increase in regenerated production (or nutrient recycling) within the MLD, which could be reconciled with decreasing SPF and non-decreasing NPP, as shown by the significant correlation between SPF/NPP and the opal/CaCO 3 ratio. Environmental factors associated with nutrient availability were investigated, along with climate variability indices of the NPO. Using eddy kinetic energy, vertical Ekman transport, and vertical density profiles, the nutrient deficiency was partially explained during the seasons showing significant SPF reductions. An association between SPF and the Pacific Decadal Oscillation was identified. However, the 7-year data were not sufficient for verification. The results of this study indicate that particle fluxes to depth and ocean biological pumps are subject to interannual variability caused by various factors.
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U2 - 10.1016/j.dsr.2018.11.009
DO - 10.1016/j.dsr.2018.11.009
M3 - Article
AN - SCOPUS:85057961633
VL - 143
SP - 58
EP - 69
JO - Deep-Sea Research Part I: Oceanographic Research Papers
JF - Deep-Sea Research Part I: Oceanographic Research Papers
SN - 0967-0637
ER -