Publication Date:
2013-02-28
Description:
[1] AbstractAccurate quantification of CO 2 flux across the air-water interface and identification ofthe mechanisms driving CO 2 concentrations in lakes and reservoirs is critical to integrating aquatic systems into large-scale carbon budgets, and to predicting the response of these systems to changes in climate or terrestrial carbon cycling. Large-scale estimates of the role of lakes and reservoirs in the carbon cycle, however, typically must rely on aggregation of spatially and temporally inconsistent data from disparate sources.We performed a spatially comprehensive analysis of CO 2 concentration and air-water fluxes in lakes and reservoirs of the contiguous United States using large, consistent data sets, and modeled the relative contribution of inorganic and organic carbon loading to vertical CO 2 fluxes. Approximately 70% of lakes and reservoirs are supersaturated with respect to the atmosphere during the summer (June–September). Although there is considerable inter- and intraregional variability, lakes and reservoirs represent a net source of CO 2 to the atmosphere of approximately 40Gg C d -1 during the summer. While in-lake CO 2 concentrations correlate with indicators of in-lake net ecosystem productivity (NEP), virtually no relationship exists between dissolved organic carbon (DOC) and p CO 2,aq . Modeling suggests that hydrologic dissolved inorganic carbon (DIC) supports p CO 2,aq in most supersaturated systems (to the extent that 12% of supersaturated systems simultaneously exhibit positive NEP), and also supports primary production in most CO 2 -undersaturated systems. DIC loading appears to be an important determinant of CO 2 concentrations and fluxes across the air-water interface in the majority of lakes and reservoirs in the contiguous United States.
Print ISSN:
0886-6236
Electronic ISSN:
1944-9224
Topics:
Biology
,
Chemistry and Pharmacology
,
Geography
,
Geosciences
,
Physics
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