title: Linking the Molecular Signature of Heteroatomic Dissolved Organic Matter to Watershed Characteristics in World Rivers.
abstract: Large world rivers are significant sources of dissolved organic matter (DOM) to the oceans. Watershed geomorphology and land use can drive the quality and reactivity of DOM. Determining the molecular composition of riverine DOM is essential for understanding its source, mobility and fate across landscapes. In this study, DOM from the main stem of 10 global rivers covering a wide climatic range and land use features was molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). FT-ICR mass spectral data revealed an overall similarity in molecular components among the rivers. However, when focusing specifically on the contribution of nonoxygen heteroatomic molecular formulas (CHON, CHOS, CHOP, etc.) to the bulk molecular signature, patterns relating DOM composition and watershed land use became apparent. Greater abundances of N- and S-containing molecular formulas were identified as unique to rivers influenced by anthropogenic inputs, whereas rivers with primarily forested watersheds had DOM signatures relatively depleted in heteroatomic content. A strong correlation between cropland cover and dissolved black nitrogen was established when focusing specifically on the pyrogenic class of compounds. This study demonstrated how changes in land use directly affect downstream DOM quality and could impact C and nutrient cycling on a global scale.
authors.affiliation: Florida International University , Southeast Environmental Research Center and Department of Chemistry and Biochemistry, Biscayne Bay Campus, North Miami, Florida 33181, United States.
authors.forename: Sasha
authors.initials: S
authors.lastname: Wagner
authors.affiliation: Carl von Ossietzky University of Oldenburg , Institute for Chemistry and Biology of the Marine Environment, Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), 26129 Oldenburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Riedel
authors.affiliation: Carl von Ossietzky University of Oldenburg , Institute for Chemistry and Biology of the Marine Environment, Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), 26129 Oldenburg, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Niggemann
authors.affiliation: University of Jyväskylä , Department of Biological and Environmental Sciences, 40500 Jyväskylä, Finland.
authors.forename: Anssi V
authors.initials: AV
authors.lastname: Vähätalo
authors.affiliation: Carl von Ossietzky University of Oldenburg , Institute for Chemistry and Biology of the Marine Environment, Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), 26129 Oldenburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Dittmar
authors.affiliation: Florida International University , Southeast Environmental Research Center and Department of Chemistry and Biochemistry, Biscayne Bay Campus, North Miami, Florida 33181, United States.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Jaffé
mesh_terms: D065928:Forests; D005583:Fourier Analysis; D013058:Mass Spectrometry / Q000379:methods*; D009584:Nitrogen / Q000032:analysis; D009792:Oceans and Seas; D045483:Rivers / Q000737:chemistry; D013455:Sulfur / Q000032:analysis
chemical_list: D013455:Sulfur; D009584:Nitrogen