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The p CO 2 in boreal lakes: Organic carbon as a universal predictor?
Author(s) -
Larsen Søren,
Andersen Tom,
Hessen Dag O.
Publication year - 2011
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2010gb003864
Subject(s) - dissolved organic carbon , total organic carbon , environmental science , carbon cycle , pco2 , groundwater , hydrology (agriculture) , drainage basin , carbon fibers , environmental chemistry , ecosystem , ecology , chemistry , geology , geography , biology , mathematics , psychology , geotechnical engineering , cartography , algorithm , psychiatry , composite number
During the past two decades, it has become evident that a majority of lakes are net conduits of CO 2 to the atmosphere. This insight has implications both for lake metabolism per se and for assessing the role of lakes in the global C cycle. The concentration of dissolved organic carbon (DOC), which constitutes >90% of the total organic carbon (TOC), has been identified as a key driver of partial pressure of CO 2 ( p CO 2 ). A crucial question is whether one may identify global relationships in the DOC‐ p CO 2 relationship in lakes or whether this has to be determined regionally or locally. A second major aspect is how to best predict CO 2 as a function of DOC. Based on a survey of p CO 2 and a range of lake and catchment variables in 112 lakes, we support the view that DOC is by far the most important determinant of p CO 2 while groundwater influx has a minor contribution. Contrary to expectations, total phosphorus (P) also apparently contributed positively to p CO 2 , owing to the fact that most P in these lakes is on the form of allochthonously organic P, and thus correlates strongly with DOC. Physical principles dictate that even a lake completely devoid of DOC should have a nonzero p CO 2 . This is not reflected in power models, which imply that the p CO 2 approaches zero with zero DOC. Based on this study as well as published data on DOC‐ p CO 2 relationships, we argue that identity link gamma–generalized linear models are appropriate for predicting p CO 2 in lakes and that their application makes it possible to reach reasonably accurate global models for how p CO 2 relates to DOC and other environmental factors.