title: Two chemically distinct pools of organic nitrogen accumulate in the ocean.
abstract: The chemical dynamics of marine dissolved organic nitrogen (DON), a reservoir featuring surface accumulations even in areas where nitrogen limits productivity, have yet to be resolved. We exploited differences in the acid lability of amide bonds within high-molecular-weight (HMW) DON to show that vertical DON profiles result in part from the presence of two chemically distinct pools of amide. Half of HMWDON in surface waters is present as N-acetyl amino polysaccharides. In contrast, nearly all deep-sea HMWDON, and therefore, most HMWDON, is present in amides that resist both chemical hydrolysis and biological degradation.
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093, USA. laluwihare@ucsd.edu
authors.forename: Lihini I
authors.initials: LI
authors.lastname: Aluwihare
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Repeta
authors.forename: Silvio
authors.initials: S
authors.lastname: Pantoja
authors.forename: Carl G
authors.initials: CG
authors.lastname: Johnson
mesh_terms: D000577:Amides / Q000032:analysis* / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis / Q000378:metabolism; D001267:Atlantic Ocean; D001419:Bacteria / Q000378:metabolism; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D009112:Muramic Acids / Q000032:analysis / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis* / Q000378:metabolism; D010457:Peptidoglycan / Q000032:analysis / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism; D011506:Proteins / Q000032:analysis / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*
chemical_list: D000577:Amides; D000596:Amino Acids; D009112:Muramic Acids; D010457:Peptidoglycan; D011134:Polysaccharides; D011506:Proteins; D009584:Nitrogen