Particle cycling rates at Station P as estimated from the inversion of POC concentration data

Bibliographic Data

ID19568427
AuthorsVinícius J Amaral (0000-0001-8178-5695, University of California, Santa Cruz), Phoebe J Lam (0000-0001-6609-698X, University of California, Santa Cruz), Olivier Marchal (0000-0001-9360-4687, Woods Hole Oceanographic Institution), Montserrat Roca-Martí, Montserrat Roca‐Martí (0000-0002-4719-9358, Dalhousie University), James Fox (0000-0003-1485-2995, Oregon State University), Norman B Nelson (University of California, Santa Barbara)
Year2022
Volume10
Issue1
Publication date2022-08-16
Open AccessYes
TypeARTICLE
VenueElementa Science of the Anthropocene (JOURNAL)
Journal identifiersISSN: 2325-1026 • E-ISSN: 2325-1026
PublisherUniversity of California Press (PUBLISHER • US)
DOI10.1525/elementa.2021.00018
OpenAlexW4292181077
LanguageEN
References cited103

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 μm) and large (> 51 μm), 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

Atmospheric sciences · Biological pump · Diel vertical migration · Marine snow · Mesopelagic zone · Nutrient · Pelagic zone · Photic zone · Phytoplankton · Settling · Water column · Zooplankton · Chemistry · Environmental Science · Isotope Analysis in Ecology · Marine and coastal ecosystems · Marine Biology and Ecology Research · Geology · Oceanography

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