Particle cycling rates at Station P as estimated from the inversion of POC concentration data
Amaral, Vinícius J. (University of California Santa Cruz. Department of Ocean Sciences)
Lam, Phoebe J. (University of California Santa Cruz. Department of Ocean Sciences)
Marchal, Olivier (Woods Hole Oceanographic Institution. Department of Geology and Geophysics)
Roca Martí, Montserrat (Dalhousie University. Department of Oceanography)
Fox, James (Oregon State University. Department of Microbiology)
Nelson, Norman B. (University of California Santa Barbara. Earth Research Institute)

Fecha:	2022
Resumen:	Particle cycling rates in marine systems are difficult to measure directly, but of great interest in understanding how carbon and other elements are distributed throughout the ocean. Here, rates of particle production, aggregation, disaggregation, sinking, remineralization, and transport mediated by zooplankton diel vertical migration were estimated from size-fractionated measurements of particulate organic carbon (POC) concentration collected during the NASA EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) cruise at Station P in summer 2018. POC data were combined with a particle cycling model using an inverse method. Our estimates of the total POC settling flux throughout the water column are consistent with those derived from thorium-234 disequilibrium and sediment traps. A budget for POC in two size fractions, small (1-51 mm) and large (> 51 mm), was produced for both the euphotic zone (0-100 m) and the upper mesopelagic zone (100-500 m). We estimated that POC export at the base of the euphotic zone was 2. 2 ± 0. 8 mmol m-2 d-1, and that both small and large particles contributed considerably to the total export flux along the water column. The model results indicated that throughout the upper 500 m, remineralization leads to a larger loss of small POC than does aggregation, whereas disaggregation results in a larger loss of large POC than does remineralization. Of the processes explicitly represented in the model, zooplankton diel vertical migration is a larger source of large POC to the upper mesopelagic zone than the convergence of large POC due to particle sinking. Positive model residuals reveal an even larger unidentified source of large POC in the upper mesopelagic zone. Overall, our posterior estimates of particle cycling rate constants do not deviate much from values reported in the literature, i. e. , size-fractionated POC concentration data collected at Station P are largely consistent with prior estimates given their uncertainties. Our budget estimates should provide a useful framework for the interpretation of process-specific observations obtained by various research groups in EXPORTS. Applying our inverse method to other systems could provide insight into how different biogeochemical processes affect the cycling of POC in the upper water column.
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Materia:	EXPORTS ; North Pacific ; Ocean particle model ; Particle cycling rates in the ocean ; Particulate organic carbon ; Station P ; SDG 14 - Life Below Water
Publicado en:	Elementa (Washington DC), Vol. 10, Issue 1 (August 2022) , art. 00018, ISSN 2325-1026

DOI: 10.1525/elementa.2021.00018

29 p, 1.7 MB

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