Open AccessAssessing carbon dynamics in natural and perturbed boreal aquatic systems
Author(s) -
Ouellet Alexandre,
Lalonde Karine,
Plouhinec JeanBaptiste,
Soumis Nicolas,
Lucotte Marc,
Gélinas Yves
Publication year - 2012
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2012jg001943
Subject(s) - biogeochemical cycle , environmental science , carbon cycle , dissolved organic carbon , greenhouse gas , environmental chemistry , water column , aquatic ecosystem , carbon fibers , carbon dioxide , organic matter , methane , total organic carbon , biogeochemistry , atmosphere (unit) , hydrology (agriculture) , ecosystem , ecology , chemistry , oceanography , geology , composite number , composite material , biology , materials science , geotechnical engineering , physics , thermodynamics
Most natural freshwater lakes are net greenhouse gas (GHG) emitters. Compared to natural systems, human perturbations such as watershed wood harvesting and long‐term reservoir impoundment lead to profound alterations of biogeochemical processes involved in the aquatic cycle of carbon (C). We exploited these anthropogenic alterations to describe the C dynamics in five lakes and two reservoirs from the boreal forest through the analysis of dissolved carbon dioxide (CO 2 ), methane (CH 4 ), oxygen (O 2 ), and organic carbon (DOC), as well as total nitrogen and phosphorus. Dissolved and particulate organic matter, forest soil/litter and leachates, as well as dissolved inorganic carbon were analyzed for elemental and stable isotopic compositions (atomic C:N ratios, δ 13 C org , δ 13 C inorg and δ 15 N tot ). We found links between the export of terrestrial organic matter (OM) to these systems and the dissolved CO 2 and O 2 concentrations in the water column, as well as CO 2 fluxes to the atmosphere. All systems were GHG emitters, with greater emissions measured for systems with larger inputs of terrestrial OM. The differences in CO 2 concentrations and fluxes appear controlled by bacterial activity in the water column and the sediment. Although we clearly observed differences in the aquatic C cycle between natural and perturbed systems, more work on a larger number of water bodies and encompassing all four seasons should be undertaken to better understand the controls, rates, and spatial as well as temporal variability of GHG emissions, and to make quantitatively meaningful comparisons of GHG emissions (and other key variables) from natural and perturbed systems.