title: Compositions and constituents of freshwater dissolved organic matter isolated by reverse osmosis.
abstract: Dissolved organic matter (DOM) from riverine and lacustrine water was isolated using a reverse osmosis (RO) system. Solid-state (13)C nuclear magnetic resonance ((13)C NMR) was used to quantitatively evaluate the compositions and constituents of DOM, which are compared with previous investigations on marine DOM. Results indicated that concentration factor (CF) was a key metric controlling yield and sorption of DOM on the RO system. The sorption was likely non-selective, based on the (13)C NMR and δ(13)C analyses. Carbohydrates and lipids accounted for 25.0-41.5% and 30.2-46.3% of the identifiable DOM, followed by proteins (18.2-19.8%) and lignin (7.17-12.8%). The freshwater DOM contained much higher alkyl and aromatic C but lower alkoxyl and carboxyl C than marine DOM. The structural difference was not completely accounted for by using structure of high molecular weight (HMW) DOM, suggesting a size change involved in transformations of DOM during the transport from rivers to oceans.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. Electronic address: yran@gig.ac.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ran
authors.affiliation: Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, United States.
authors.forename: Jingdong
authors.initials: J
authors.lastname: Mao
mesh_terms: D002241:Carbohydrates / Q000737:chemistry; D002412:Cations; D005374:Filtration; D005618:Fresh Water / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009792:Oceans and Seas; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry; D009995:Osmosis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002241:Carbohydrates; D002412:Cations; D008055:Lipids; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical
keywords: (13)C NMR; Composition; Dissolved organic matter; Isolation; Reverse osmosis; Stable carbon isotope