title: Turnover time of fluorescent dissolved organic matter in the dark global ocean.
abstract: Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (>200 m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, which persist significantly longer than the ~350 years that the dark global ocean takes to renew. In parallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is also detected. We propose the use of DOM fluorescence to study the cycling of resistant DOM that is preserved at centennial timescales and could represent a mechanism of carbon sequestration (humic-like fraction) and the decaying DOM injected into the dark global ocean, where it decreases at centennial timescales (tyrosine-like fraction).
authors: Departamento de Ecología and Instituto del Agua, Universidad de Granada, 18071 Granada, Spain.
authors: Teresa S
authors: TS
authors: Catalá
authors: Departamento de Ecología and Instituto del Agua, Universidad de Granada, 18071 Granada, Spain.
authors: Isabel
authors: I
authors: Reche
authors: Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, 36208 Vigo, Spain.
authors: Antonio
authors: A
authors: Fuentes-Lema
authors: 1] CSIC Instituto de Investigacións Mariñas, 36208 Vigo, Spain [2] CSIC Institut de Ciencies del Mar, 08003 Barcelona, Spain.
authors: Cristina
authors: C
authors: Romera-Castillo
authors: CSIC Instituto de Investigacións Mariñas, 36208 Vigo, Spain.
authors: Mar
authors: M
authors: Nieto-Cid
authors: CSIC Institut de Ciencies del Mar, 08003 Barcelona, Spain.
authors: Eva
authors: E
authors: Ortega-Retuerta
authors: CSIC Institut de Ciencies del Mar, 08003 Barcelona, Spain.
authors: Eva
authors: E
authors: Calvo
authors: IEO Centro Oceanográfico de A Coruña, 15006 A Coruña, Spain.
authors: Marta
authors: M
authors: Álvarez
authors: CSIC Institut de Ciencies del Mar, 08003 Barcelona, Spain.
authors: Cèlia
authors: C
authors: Marrasé
authors: National Institute of Aquatic Resources, Technical University of Denmark, 2920 Charlottenlund, Denmark.
authors: Colin A
authors: CA
authors: Stedmon
authors: CSIC Instituto de Investigacións Mariñas, 36208 Vigo, Spain.
authors: X Antón
authors: XA
authors: Álvarez-Salgado
mesh_terms: D003624:Darkness; D005453:Fluorescence; D038622:Internationality; D009792:Oceans and Seas; D009930:Organic Chemicals / Q000032:analysis*; D010100:Oxygen / Q000032:analysis; D012767:Ships; D012995:Solubility; D013997:Time Factors; D014867:Water
chemical_list: D009930:Organic Chemicals; D014867:Water; D010100:Oxygen