Carotenoids are the likely precursor of a significant fraction of marine dissolved organic matter
Journal
Science Advances
Journal Volume
3
Journal Issue
9
Start Page
1602976
ISSN
2375-2548
Date Issued
2017-01-01
Author(s)
Arakawa, Neal
Aluwihare, Lihini I.
Simpson, Andre J.
Soong, Ronald
Lane-Coplen, Daniel
Abstract
The ocean’s biota sequester atmospheric carbon dioxide (CO2) in part by producing dissolved organic matter (DOM) that persists in the ocean for millennia. This long-term accumulation of carbon may be facilitated by abiotic and biotic production of chemical structures that resist degradation, consequently contributing disproportionately to refractory DOM. Compounds that are selectively preserved in seawater were identified in solid-phase extracted DOM (PPL-DOM) using comprehensive gas chromatography (GC) coupled to mass spectrometry (MS). These molecules contained cyclic head groups that were linked to isoprenoid tails, and their overall structures closely resembled carotenoid degradation products (CDP). The origin of these compounds in PPL-DOM was further confirmed with an in vitro b-carotene photooxidation experiment that generated water-soluble CDP with similar structural characteristics. The molecular-level identification linked at least 10% of PPL-DOM carbon, and thus 4% of total DOM carbon, to CDP. Nuclear magnetic resonance spectra of experimental CDP and environmental PPL-DOM overlapped considerably, which indicated that even a greater proportion of PPL-DOM was likely composed of CDP. The CDP-rich DOM fraction was depleted in radiocarbon (14C age 1500 years), a finding that supports the possible long-term accumulation of CDP in seawater. By linking a specific class of widespread biochemicals to refractory DOM, this work provides a foundation for future studies that aim to examine how persistent DOM forms in the ocean.
Subjects
Aquatic Organisms
Carbon Dioxide
Carbon Isotopes
Carotenoids
Environmental Monitoring
Gas Chromatography-Mass Spectrometry
Magnetic Resonance Spectroscopy
Oceans and Seas
Organic Chemicals
Seawater
Atmospheric chemistry
Biogeochemistry
Carbon dioxide
Chromatography
Degradation
Gas chromatography
Magnetic resonance spectroscopy
Mass spectrometry
Organic compounds
Photooxidation
Pigments
Refractory materials
carbon
carbon dioxide
carotenoid
organic compound
sea water
Atmospheric carbon dioxide
Degradation products
Dissolved organic matters
Isoprenoids
Molecular levels
Specific class
Structural characteristics
Watersoluble
aquatic species
chemistry
environmental monitoring
mass fragmentography
nuclear magnetic resonance spectroscopy
sea
Biological materials
SDGs
Publisher
American Association for the Advancement of Science (AAAS)
Type
journal article