210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export

Estimating the particulate organic carbon (POC) export flux from the upper ocean is fundamental for understanding the efficiency of the biological carbon pump driven by sinking particles in the oceans. The downward POC flux from the surface ocean based on 210Po-210Pb disequilibria in seawater sample...

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Autores principales:	Qiangqiang Zhong, Tao Yu, Hui Lin, Jing Lin, Jianda Ji, Jialin Ni, Jinzhou Du, Dekun Huang
Formato:	article
Lenguaje:	EN
Publicado:	Frontiers Media S.A. 2021
Materias:	210Po deficiency POC export flux marine biological carbon pump Western North Pacific Ocean euphotic zone Science Q General. Including nature conservation, geographical distribution QH1-199.5
Acceso en línea:	https://doaj.org/article/5a2d47d78c5247dbb869643a9a269e9b
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spelling	oai:doaj.org-article:5a2d47d78c5247dbb869643a9a269e9b2021-12-02T09:34:42Z210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export2296-774510.3389/fmars.2021.700524https://doaj.org/article/5a2d47d78c5247dbb869643a9a269e9b2021-12-01T00:00:00Zhttps://www.frontiersin.org/articles/10.3389/fmars.2021.700524/fullhttps://doaj.org/toc/2296-7745Estimating the particulate organic carbon (POC) export flux from the upper ocean is fundamental for understanding the efficiency of the biological carbon pump driven by sinking particles in the oceans. The downward POC flux from the surface ocean based on 210Po-210Pb disequilibria in seawater samples from the western North Pacific Ocean (w-NPO) was measured in the early summer (May-June) of 2018. All the profiles showed a large 210Po deficiency relative to 210Pb in the euphotic zone (0–150 m), while this 210Po deficiency vanished below ∼500 m (with 210Po/210Pb ∼1 or > 1). A one-dimensional steady-state irreversible scavenging model was used to quantify the scavenging and removal fluxes of 210Po and 210Pb in the euphotic zone of the w-NPO. In the upper ocean (0–150 m), dissolved 210Po (D-Po) was scavenged into particles with a residence time of 0.6–5.5 year, and the 210Po export flux out of the euphotic zone was estimated as (0.33–3.49) × 104 dpm/m2/year, resulting in a wide range of particulate 210Po (P-Po) residence times (83–921 days). However, in the deep ocean (150–1,000 m), 210Po was transferred from the particulate phase to the dissolved phase. Using an integrated POC inventory and the P-Po residence times (Eppley model) in the w-NPO euphotic zone, the POC export fluxes (mmol C/m2/d) varied from 0.6 ± 0.2 to 8.8 ± 0.4. In comparison, applying the POC/210Po ratio of all (>0.45 μm) particles to 210Po export flux (Buesseler model), the obtained POC export fluxes (mmol C/m2/d) ranged from 0.7 ± 0.1 to 8.6 ± 0.8. Both Buesseler and Eppley methods showed enhanced POC export fluxes at stations near the continental shelf (i.e., Luzon Strait and the Oyashio-Kuroshio mixing region). The Eppley model-based 210Po-derived POC fluxes agreed well with the Buesseler model-based fluxes, indicating that both models are suitable for assessing POC fluxes in the w-NPO. The POC export efficiency was < 15%, suggesting a moderate biological carbon pump efficiency in the w-NPO. These low export efficiencies may be associated with the dominance of smaller particles and the processes of degradation and subsequent remineralization of these small particles in the euphotic zone of oligotrophic regions in the w-NPO.Qiangqiang ZhongQiangqiang ZhongTao YuHui LinJing LinJianda JiJialin NiJinzhou DuDekun HuangFrontiers Media S.A.article210Po deficiencyPOC export fluxmarine biological carbon pumpWestern North Pacific Oceaneuphotic zoneScienceQGeneral. Including nature conservation, geographical distributionQH1-199.5ENFrontiers in Marine Science, Vol 8 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	210Po deficiency POC export flux marine biological carbon pump Western North Pacific Ocean euphotic zone Science Q General. Including nature conservation, geographical distribution QH1-199.5
spellingShingle	210Po deficiency POC export flux marine biological carbon pump Western North Pacific Ocean euphotic zone Science Q General. Including nature conservation, geographical distribution QH1-199.5 Qiangqiang Zhong Qiangqiang Zhong Tao Yu Hui Lin Jing Lin Jianda Ji Jialin Ni Jinzhou Du Dekun Huang 210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
description	Estimating the particulate organic carbon (POC) export flux from the upper ocean is fundamental for understanding the efficiency of the biological carbon pump driven by sinking particles in the oceans. The downward POC flux from the surface ocean based on 210Po-210Pb disequilibria in seawater samples from the western North Pacific Ocean (w-NPO) was measured in the early summer (May-June) of 2018. All the profiles showed a large 210Po deficiency relative to 210Pb in the euphotic zone (0–150 m), while this 210Po deficiency vanished below ∼500 m (with 210Po/210Pb ∼1 or > 1). A one-dimensional steady-state irreversible scavenging model was used to quantify the scavenging and removal fluxes of 210Po and 210Pb in the euphotic zone of the w-NPO. In the upper ocean (0–150 m), dissolved 210Po (D-Po) was scavenged into particles with a residence time of 0.6–5.5 year, and the 210Po export flux out of the euphotic zone was estimated as (0.33–3.49) × 104 dpm/m2/year, resulting in a wide range of particulate 210Po (P-Po) residence times (83–921 days). However, in the deep ocean (150–1,000 m), 210Po was transferred from the particulate phase to the dissolved phase. Using an integrated POC inventory and the P-Po residence times (Eppley model) in the w-NPO euphotic zone, the POC export fluxes (mmol C/m2/d) varied from 0.6 ± 0.2 to 8.8 ± 0.4. In comparison, applying the POC/210Po ratio of all (>0.45 μm) particles to 210Po export flux (Buesseler model), the obtained POC export fluxes (mmol C/m2/d) ranged from 0.7 ± 0.1 to 8.6 ± 0.8. Both Buesseler and Eppley methods showed enhanced POC export fluxes at stations near the continental shelf (i.e., Luzon Strait and the Oyashio-Kuroshio mixing region). The Eppley model-based 210Po-derived POC fluxes agreed well with the Buesseler model-based fluxes, indicating that both models are suitable for assessing POC fluxes in the w-NPO. The POC export efficiency was < 15%, suggesting a moderate biological carbon pump efficiency in the w-NPO. These low export efficiencies may be associated with the dominance of smaller particles and the processes of degradation and subsequent remineralization of these small particles in the euphotic zone of oligotrophic regions in the w-NPO.
format	article
author	Qiangqiang Zhong Qiangqiang Zhong Tao Yu Hui Lin Jing Lin Jianda Ji Jialin Ni Jinzhou Du Dekun Huang
author_facet	Qiangqiang Zhong Qiangqiang Zhong Tao Yu Hui Lin Jing Lin Jianda Ji Jialin Ni Jinzhou Du Dekun Huang
author_sort	Qiangqiang Zhong
title	210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
title_short	210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
title_full	210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
title_fullStr	210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
title_full_unstemmed	210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export
title_sort	210po-210pb disequilibrium in the western north pacific ocean: particle cycling and poc export
publisher	Frontiers Media S.A.
publishDate	2021
url	https://doaj.org/article/5a2d47d78c5247dbb869643a9a269e9b
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210Po-210Pb Disequilibrium in the Western North Pacific Ocean: Particle Cycling and POC Export

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