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234 Th ‐Derived Particle Fluxes and Seasonal Variability: When Is the SS Assumption Reliable? Insights From a Novel Approach for Carbon Flux Simulation
Author(s) -
CeballosRomero E.,
De Soto F.,
Le Moigne F. A. C.,
GarcíaTenorio R.,
VillaAlfageme M.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079968
Subject(s) - flux (metallurgy) , sediment trap , atmospheric sciences , environmental science , range (aeronautics) , carbon fibers , carbon flux , temperate climate , particle (ecology) , climatology , oceanography , geology , chemistry , biology , mathematics , ecosystem , ecology , materials science , organic chemistry , algorithm , composite number , composite material
234 Th measurements are widely used to estimate the downward carbon flux of particles via the oceanic Biological Pump. Carbon export is evaluated from 234 Th‐ 238 U disequilibrium assuming either steady state (SS) conditions, or including a non‐SS (NSS) correction. We use a novel stochastic simulation to quantify the temporal variation of vertical carbon and 234 Th (dissolved and particulate) concentration profiles with high temporal resolution. We calculate seasonal export as if in situ measured with sediment trap and SS‐ and NSS‐ 234 Th approaches and quantify the periods of validity for SS/NSS conditions defined in previous works. The SS approach is valid throughout the entire season in oligotrophic regions. In temperate regions, the SS introduces a bias in the export if sampling takes place outside specific temporal windows. Windows of validity range from days in short blooms of ~15‐day duration to weeks in blooms longer than ~30 days.