Turnover time of fluorescent dissolved organic matter in the dark global ocean

10,0150

English. Research article

English. Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon onEarth. In the dark ocean (4200 m), most of this carbon is refractory DOM. This refractoryDOM, largely produced during microbial mineralization of organic matter, includes humic-likesubstances generated in situ and detectable by fluorescence spectroscopy. Here we show twoubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, whichpersist significantly longer than the B350 years that the dark global ocean takes to renew. Inparallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is alsodetected. We propose the use of DOM fluorescence to study the cycling of resistant DOMthat is preserved at centennial timescales and could represent a mechanism of carbonsequestration (humic-like fraction) and the decaying DOM injected into the dark globalocean, where it decreases at centennial timescales (tyrosine-like fraction).

Spanish; Castilian. Versión del editor