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Research article2018Peer reviewedOpen access

Pipes or chimneys? For carbon cycling in small boreal lakes, precipitation matters most

de Wit, Heleen A.; Couture, Raoul-Marie; Jackson-Blake, Leah; Futter, Martyn N.; Valinia, Salar; Austnes, Kari; Guerrero, Jose-Luis; Lin, Yan


Are small lakes passive pipes transporting terrigenous organic carbon (dissolved organic carbon [DOC]), or chimneys for CO2 release in the landscape? Using a unique combination of 30-yr measurements, sediment dating and modeling of a small humic lake and its catchment in southeast Norway, we calculated lateral DOC fluxes and in-lake retention. Concentrations and fluxes rose significantly, driven by declining sulfur deposition and increased precipitation. In-lake retention (% of inputs) declined because of higher discharge and lower residence times. DOC removal rates were not sensitive to residence time. Modeled in-lake DOC removal was driven primarily by microbial metabolism and, secondarily, by flocculation, suggesting that the likely fate of lake-retained DOC is CO2 evasion to the atmosphere. Precipitation was the overriding landscape control on DOC fluxes and retention. In a wetter climate, small northern lakes will, on balance, function more as pipes than chimneys, with increasing lateral DOC fluxes but little change in CO2 production.

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Limnology and Oceanography Letters
2018, Volume: 3, number: 3, pages: 275-284
Publisher: WILEY

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      Oceanography, Hydrology, Water Resources

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