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The role of sediments in the carbon budget of a small boreal lake
Author(s) -
Chmiel Hannah E.,
Kokic Jovana,
Denfeld Blaize A.,
Einarsdóttir Karólína,
Wallin Marcus B.,
Koehler Birgit,
Isidorova Anastasija,
Bastviken David,
Ferland MarieÈve,
Sobek Sebastian
Publication year - 2016
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.1002/lno.10336
Subject(s) - mineralization (soil science) , water column , sediment , total organic carbon , hydrology (agriculture) , groundwater , carbon cycle , methane , sink (geography) , drainage basin , geology , water table , environmental science , geochemical cycle , carbon dioxide , environmental chemistry , oceanography , ecosystem , soil science , geomorphology , ecology , chemistry , soil water , geotechnical engineering , cartography , biology , geography
We investigated the role of lake sediments as carbon (C) source and sink in the annual C budget of a small (0.07 km 2 ) and shallow (mean depth, 3.4 m), humic lake in boreal Sweden. Organic carbon (OC) burial and mineralization in the sediments were quantified from 210 Pb‐dated sediment and laboratory sediment incubation experiments, respectively. Burial and mineralization rates were then upscaled to the entire basin and to one whole year using sediment thickness derived from sub‐bottom profiling, basin morphometry, and water column monitoring data of temperature and oxygen concentration. Furthermore, catchment C import, open water metabolism, photochemical mineralization as well as carbon dioxide (CO 2 ) and methane (CH 4 ) emissions to the atmosphere were quantified to relate sediment processes to other lake C fluxes. We found that on a whole‐basin and annual scale, sediment OC mineralization was three times larger than OC burial, and contributed about 16% to the annual CO 2 emission. Other contributions to CO 2 emission were water column metabolism (31%), photochemical mineralization (6%), and catchment imports via inlet streams and inflow of shallow groundwater (22%). The remainder (25%) could not be explained by our flux calculations, but was most likely attributed to an underestimation in groundwater inflow. We conclude that on an annual and whole‐basin scale (1) sediment OC mineralization dominated over OC burial, (2) water column OC mineralization contributed more to lake CO 2 emission than sediment OC mineralization, and (3) catchment import of C to the lake was greater than lake‐internal C cycling.