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Effect of catchment characteristics on aquatic carbon export from a boreal catchment and its importance in regional carbon cycling
Author(s) -
Huotari Jussi,
Nykänen Hannu,
Forsius Martin,
Arvola Lauri
Publication year - 2013
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12333
Subject(s) - dissolved organic carbon , environmental science , tributary , hydrology (agriculture) , drainage basin , carbon cycle , terrestrial ecosystem , ecosystem , cycling , land cover , aquatic ecosystem , streams , peat , water quality , ditch , boreal , land use , ecology , environmental chemistry , chemistry , geology , forestry , geography , computer network , cartography , geotechnical engineering , computer science , biology
Inland waters transport and emit into the atmosphere large amounts of carbon (C), which originates from terrestrial ecosystems. The effect of land cover and land‐use practises on C export from terrestrial ecosystems to inland waters is not fully understood, especially in heterogeneous landscapes under human influence. We sampled for dissolved C species in five tributaries with well‐determined subcatchments (total size 174.5 km 2 ), as well as in various points of two of the subcatchments draining to a boreal lake in southern Finland over a full year. Our aim was to find out how land cover and land‐use affect C export from the catchments, as well as CH 4 and CO 2 concentrations of the streams, and if the origin of C in stream water can be determined from proxies for quality of dissolved organic matter ( DOM ). We further estimated the gas evasion from stream surfaces and the role of aquatic fluxes in regional C cycling. The export rate of C from the terrestrial system through an aquatic conduit was 19.3 g C m −2 (catchment) yr −1 , which corresponds to 19% of the estimated terrestrial net ecosystem exchange of the catchment. Most of the C load to the recipient lake consisted of dissolved organic carbon ( DOC , 6.1 ± 1.0 g C m −2 yr −1 ); the share of dissolved inorganic carbon ( DIC ) was much smaller (1.0 ± 0.2 g C m −2 yr −1 ). CO 2 and CH 4 emissions from stream and ditch surfaces were 7.0 ± 2.4 g C m −2 yr −1 and 0.1 ± 0.04 g C m −2 yr −1 , respectively, C emissions being thus equal with C load to the lake. The proportion of peatland in the catchment and the drainage density of peatland increased DOC in streams, whereas the proportion of agricultural land in the catchment decreased it. The opposite was true for DIC . Drained peatlands were an important CH 4 source for streams.