title: Refractory dissolved organic nitrogen accumulation in high-elevation lakes.
abstract: The role of dissolved organic matter (DOM) as either a sink for inorganic nutrients or an additional nutrient source is an often-neglected component of nutrient budgets in aquatic environments. Here, we examined the role of DOM in reactive nitrogen (N) storage in Sierra Nevada (California, USA) lakes where atmospheric deposition of N has shifted the lakes toward seasonal phosphorus (P)-limitation. Nuclear magnetic resonance (NMR) spectroscopy and isotope analyses performed on DOM isolated from Lake Tahoe reveal the accumulation of refractory proteinaceous material with a 100-200-year residence time. In contrast, smaller lakes in the same watershed contain DOM with typical terrestrial characteristics, indicating that proteins in Lake Tahoe are autochthonously produced. These data support the role of DOM as a possible sink for reactive N in these lake ecosystems and identify a potential role for DOM in affecting the inorganic nutrient stoichiometry of these environments.
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0244, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Goldberg
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0244, USA.
authors.forename: G I
authors.initials: GI
authors.lastname: Ball
authors.affiliation: Tahoe Environmental Research Center, University of California, Davis, 291 Country Club Drive, Incline Village, Nevada 89451, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Allen
authors.affiliation: 1] Tahoe Environmental Research Center, University of California, Davis, 291 Country Club Drive, Incline Village, Nevada 89451, USA [2] Department of Civil and Environmental Engineering, University of California, Davis, One Shields Avenue, Davis, California 95616, USA.
authors.forename: S G
authors.initials: SG
authors.lastname: Schladow
authors.affiliation: Environmental NMR Center and Chemistry Program, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, 1265 Military Trail, Ontario, Canada MIC 1A4.
authors.forename: A J
authors.initials: AJ
authors.lastname: Simpson
authors.affiliation: Environmental NMR Center and Chemistry Program, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, 1265 Military Trail, Ontario, Canada MIC 1A4.
authors.forename: H
authors.initials: H
authors.lastname: Masoom
authors.affiliation: Environmental NMR Center and Chemistry Program, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, 1265 Military Trail, Ontario, Canada MIC 1A4.
authors.forename: R
authors.initials: R
authors.lastname: Soong
authors.affiliation: Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: H D
authors.initials: HD
authors.lastname: Graven
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, California 92093-0244, USA.
authors.forename: L I
authors.initials: LI
authors.lastname: Aluwihare