Dissolved organic carbon export and internal cycling in small, headwater lakes
Article first published online: 27 OCT 2010
Copyright 2010 by the American Geophysical Union.
Global Biogeochemical Cycles
Volume 24, Issue 4, December 2010
How to Cite
2010), Dissolved organic carbon export and internal cycling in small, headwater lakes, Global Biogeochem. Cycles, 24, GB4008, doi:10.1029/2010GB003815., , and (
- Issue published online: 27 OCT 2010
- Article first published online: 27 OCT 2010
- Manuscript Accepted: 1 JUN 2010
- Manuscript Revised: 14 MAY 2010
- Manuscript Received: 1 MAR 2010
 Carbon (C) cycling in freshwater lakes is intense but poorly integrated into our current understanding of overall C transport from the land to the oceans. We quantified dissolved organic carbon export (DOCX) and compared it with modeled gross DOC mineralization (DOCR) to determine whether hydrologic or within-lake processes dominated DOC cycling in a small headwaters watershed in Minnesota, USA. We also used DOC optical properties to gather information about DOC sources. We then compared our results to a data set of approximately 1500 lakes in the Eastern USA (Eastern Lake Survey, ELS, data set) to place our results in context of lakes more broadly. In the open-basin lakes in our watershed (n = 5), DOCX ranged from 60 to 183 g C m−2 lake area yr−1, whereas DOCR ranged from 15 to 21 g C m−2 lake area yr−1, emphasizing that lateral DOC fluxes dominated. DOCX calculated in our study watershed clustered near the 75th percentile of open-basin lakes in the ELS data set, suggesting that these results were not unusual. In contrast, DOCX in closed-basin lakes (n = 2) was approximately 5 g C m−2 lake area yr−1, whereas DOCR was 37 to 42 g C m−2 lake area yr−1, suggesting that internal C cycling dominated. In the ELS data set, median DOCX was 32 and 12 g C m−2 yr−1in open-basin and closed-basin lakes, respectively. Although not as high as what was observed in our study watershed, DOCX is an important component of lake C flux more generally, particularly in open-basin lakes.