Estimates of the remineralization and burial of organic carbon in Lake Baikal sediments |
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| Affiliation: | 1. Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China/Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, China;2. Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Qinzhou University, Qinzhou 535011, China;3. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062,China;1. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, China;2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210023, China;3. Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China;4. School of geography science, Nanjing Normal University, Nanjing 210023, China;5. Department of Geography, University of Wisconsin, Madison, Wisconsin 53706, USA;6. School of Biochemical and Environmental Engineering, Nanjing Xiao Zhuang University, Nanjing 210046, China;1. Limnological Institute SB RAS, 3, Ulan-Batorskaya St., Irkutsk 664033, Russia;2. Sorbonne Université, CNRS, Institut des Sciences de la Terre de Paris, ISTeP, 4 place Jussieu, Paris 75005, France;3. Institut de Physique du Globe de Paris, Sorbonne Paris Cité, UMR 7154 CNRS, 1, rue Jussieu, Paris 75005, France;4. Irkutsk National Research Technical University, Irkutsk 664074, Russia |
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| Abstract: | Sediment cores collected from several stations throughout Lake Baikal in water depths from 100 m off the Selenga River delta to the deepest basin of the lake (~1640 m), have been analyzed for sedimentary organic carbon, nitrogen, and the remineralized components in pore water. The organic carbon content of surface sediments generally varied from 2.3 to 3.2% by weight, and profiles typically showed an exponential decrease in both organic carbon and nitrogen in the upper 20–30 cm of the sediment column. Steady state models of organic matter diagenesis yield first order decomposition rate constants which range from 0.0009 to 0.022 y?1. The calculated residence times for the metabolizable fraction of the organic matter in these sediments increases roughly with increasing water depth and is on the order of 50–300 years. Pore water concentration profiles were determined for dissolved inorganic carbon, dissolved organic carbon (DOC), methane, and dissolved ammonium. At depth (25–30 cm) methane concentrations ranged from 50 to 800 μmol Lpw?1 and DOC from 400 to 900 μmol Lpw?1. Estimation of carbon recycling rates based upon diffusion along pore water concentration gradients at the sediment-water interface, indicate that combined DOC and methane fluxes generally contribute <15% of the overall turnover of sedimentary organic carbon. Comparisons to Laurentian Great Lakes environments show trends in sediment deposition, organic matter remineralization, and the time scales of carbon recycling across nearly two orders of magnitude with the fraction of organic content buried generally decreasing with decreasing sedimentation rates. |
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| Keywords: | Lake Baikal Sedimentation Great Lakes Carbon and nitrogen cycling Communicated by Noel Urban |
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