Quantifying the relative importance of lake emissions in the carbon budget of a subarctic catchment

Abstract

[1] Climate change and thawing of permafrost will likely result in increased decomposition of terrestrial organic carbon and subsequent carbon emissions to the atmosphere from terrestrial and aquatic systems. The quantitative importance of mineralization of terrestrial organic carbon in lakes in relation to terrestrial carbon fluxes is poorly understood and a serious drawback for the understanding of carbon budgets. We studied a subarctic lake in an area of discontinuous permafrost to assess the quantitative importance of lake carbon emission for the catchment carbon balance. Estimates of net ecosystem production and stable carbon-isotope composition of dissolved organic carbon in the lake water suggest substantial input and respiration of terrestrial organic carbon in the lake. The lake was a net source of CO 2 and CH 4 to the atmosphere at ice breakup in spring and during the whole ice-free period. The carbon emission from the lake was similar in magnitude to the terrestrial net release of carbon to the atmosphere. The results indicate that lakes are important sources of catchment carbon emission, potentially increasing the positive feedback from permafrost thawing on global warming.Citation: Karlsson, J., T. R. Christensen, P. Crill, J. Förster, D. Hammarlund, M. Jackowicz-Korczynski, U. Kokfelt, C. Roehm, and P. Rosén (2010), Quantifying the relative importance of lake emissions in the carbon budget of a subarctic catchment,

Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques

“…In terms of the CO 2 fluxes the influence of the lake is probably less pronounced. However, the lake is during the growing season a continuous source of CO 2 (Karlsson et al 2010) increasing the respiration term during the night time and possibly lowering the total uptake during the day. The lake influence on the CO 2 fluxes, although marginal, may only have lowered the estimates for the potential CO 2 uptake by the terrestrial parts of the mire complex.…”

“…Annual total C budgets have been documented for individual palsa ecosystem components based on automatic chamber measurements and recently the annual dissolved organic carbon (DOC) export terms have been documented from the same parts of the palsa complex . Also the lakes in the area have been subjects to recent studies both in the terms of general organic carbon supply (Karlsson et al 2010) and in terms of their methane dynamics (Wik et al 2012). Initial attempts to synthesize the mass balance of the entire Torneträsk catchment have also been conducted (Christensen et al 2007) pointing at the needs for better data coverage.…”

Environmental Monitoring and Research in the Abisko Area—An Overview

“…Both the large-scale initial estimations of the whole Torneträsk catchment have been documented (Christensen et al 2007) but also more detailed sub-catchment analysis in the Stordalen catchment . All of these efforts show an interconnectivity in the landscape where it becomes clear that carbon cycling in one part of the system is deeply dependent on processes in neighboring ecosystems (e.g., lakes and birch forest/palsa-mire ecosystems; Karlsson et al 2010). Change in the permafrost environment is one of the most significant examples in the circumpolar North of how permafrost thaw affects ecosystem functioning with implications for feedback mechanisms in a changing climate.…”

Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta

“…Thermokarst has important effects on the ecology, geomorphology, hydrology, and local climate of affected landscapes (Osterkamp et al, 2000;Grosse et al, 2011a). Various recent studies have investigated thermokarst lakes as sources of carbon release to the atmosphere (Zimov et al, 1997;Walter et al, 2006Walter et al, , 2007Schuur et al, 2009;Zona et al, 2009;Karlsson et al, 2010) or as indicators of a changing water balance in permafrost regions by 850 A. Morgenstern et al: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta analyzing changes in lake area using remote-sensing methods (Payette et al, 2004;Smith et al, 2005;Riordan et al, 2006;Kravtsova and Bystrova, 2009).…”