Biogeochemical characteristics of settling particulate organic matter in Lake Superior: A seasonal comparison |
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| Affiliation: | 1. Hydrogeology Group, Institute for Regional Development (IDR), University of Castilla–La Mancha (UCLM), Campus Universitario s/n, 02071 Albacete, Spain;2. Grup d’Mineralogia Aplicada i Medi Ambient, Dep. Cristal·lografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona, C/ Martí i Franquès s/n, 08028, Barcelona, Spain;3. Grup d''Hidrologia Subterrània (GHS), Institut de Diagnóstic Ambiental i Estudis de l''Aigua (IDAEA-CSIC), C/Jordi Girona 18, 08028 Barcelona, Spain;4. Applied Tectonophysics Group, Departamento de Geodinámica, Universidad Complutense de Madrid, C/José Antonio Novais 2, 28040 Madrid, Spain;5. Stable Isotope Laboratory, University of Salamanca, Plz. De los Caídos s/n, 37008 Salamanca, Spain;1. Department of Biology & Institute for Great Lakes Research, Central Michigan University Biological Station, Central Michigan University, Mount Pleasant, MI 48859, USA;2. Great Lakes Research Center and Michigan Technological Research Institute, Michigan Technological University, Houghton, MI 49931, USA;3. Water Center, University of Michigan, Ann Arbor, MI 48105, USA;4. Great Lakes Environmental Research Laboratory, National Oceanic and Atmospheric Administration, Ann Arbor, MI 48104, USA;1. State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China;2. State Environmental Protection Key Laboratory For Lake Pollution Control, Research Center of Lake Environment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China;3. Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming, 650000, China;4. Dongting Lake Ecological Observation and Research Station, Yueyang, 414000, China;1. Department of Biology, Clarkson University, Potsdam 13699, NY, USA;2. Department of Biology, Central Michigan University, Mount Pleasant 48859, MI, USA;3. Institute for Great Lakes Research, Central Michigan University, Mount Pleasant 48859, MI, USA |
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| Abstract: | To assess settling particulate organic matter (POM) seasonality and its availability to the benthic community, settling particulate matter was studied in terms of mass fluxes and main biogeochemical characteristics (including organic carbon (OC), nitrogen, and stable carbon and nitrogen isotopic values) at two Lake Superior offshore sites over the course of a year. Fourier transform infrared spectroscopy (FTIR) and hydrolysis, extraction, and derivatization were used to provide further compositional information. Carbon and nitrogen content, isotopic and wet chemical data, and FTIR spectra show that summer particulate material is mainly autochthonous, with higher proportions of amide and carbohydrate. FTIR shows that spring particulate material contains relatively high proportions of clay minerals, indicating major sources from sediment resuspension and/or spring runoff. Distinct amino acid distributions at the two sites, revealed by principal component analysis (PCA) based on amino acid mol% composition, possibly result from differences in OM sources and the degree of degradation occurring at the two sites. Carbohydrate (PCHO), total hydrolyzable amino acid (THAA) and FTIR data suggest that the nutritional value of bulk POM to benthic heterotrophs should be lower in spring than summer-fall, although both periods exhibited high sinking fluxes of total mass and OC. Due to sediment resuspension events and an oxic water column, organic matter eventually buried in Lake Superior’s sediments has probably experienced extensive alteration due to several cycles through the water column and the bacterially-active sediment-water interface. |
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| Keywords: | Particulate organic matter (POM) Lake Superior Fourier transform infrared spectroscopy (FTIR) Biogeochemical characteristics |
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