Dissolved organic carbon export and internal cycling in small, headwater lakes

Global Biogeochemical Cycles
By: , and 

Links

Abstract

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−1 in 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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Dissolved organic carbon export and internal cycling in small, headwater lakes
Series title Global Biogeochemical Cycles
DOI 10.1029/2010GB003815
Volume 24
Issue 4
Year Published 2010
Language English
Publisher Academic Press
Publisher location San Diego, CA
Contributing office(s) National Research Program - Central Branch, Toxic Substances Hydrology Program
Description 12 p.
First page 1
Last page 12
Online Only (Y/N) N
Additional Online Files (Y/N) N