title: Major structural components in freshwater dissolved organic matter.
abstract: Dissolved organic matter (DOM) contains a complex array of chemical components that are intimately linked to many environmental processes, including the global carbon cycle, and the fate and transport of chemical pollutants. Despite its importance, fundamental aspects, such as the structural components in DOM remain elusive, due in part to the molecular complexity of the material. Here, we utilize multidimensional nuclear magnetic resonance spectroscopy to demonstrate the major structural components in Lake Ontario DOM. These include carboxyl-rich alicyclic molecules (CRAM), heteropolysaccharides, and aromatic compounds, which are consistent with components recently identified in marine dissolved organic matter. In addition, long-range proton-carbon correlations are obtained for DOM, which support the existence of material derived from linear terpenoids (MDLT). It is tentatively suggested that the bulk of freshwater dissolved organic matter is aliphatic in nature, with CRAM derived from cyclic terpenoids, and MDLT derived from linear terpenoids. This is in agreement with previous reports which indicate terpenoids as major precursors of DOM. At this time it is not clear in Lake Ontario whether these precursors are of terrestrial or aquatic origin or whether transformations proceed via biological and/ or photochemical processes.
authors.affiliation: Department of Chemistry, University of Toronto Scarborough, Toronto, Ontario, Canada M1C 1A4.
authors.forename: Buuan
authors.initials: B
authors.lastname: Lam
authors.forename: Andrew
authors.initials: A
authors.lastname: Baer
authors.forename: Mehran
authors.initials: M
authors.lastname: Alaee
authors.forename: Brent
authors.initials: B
authors.lastname: Lefebvre
authors.forename: Arvin
authors.initials: A
authors.lastname: Moser
authors.forename: Antony
authors.initials: A
authors.lastname: Williams
authors.forename: André J
authors.initials: AJ
authors.lastname: Simpson
mesh_terms: D005618:Fresh Water / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009930:Organic Chemicals / Q000737:chemistry*; D012995:Solubility
chemical_list: D009930:Organic Chemicals