Carbon Dioxide Supersaturation in the Surface Waters of Lakes

• Published in: Science (American Association for the Advancement of Science) 1994-09, Vol.265 (5178), p.1568-1570
• Main Authors: Cole, Jonathan J., Caraco, Nina F., Kling, George W., Kratz, Timothy K.
• Format: Article
• Language: English
• Subjects: Atmospherics; Carbon dioxide; Datasets; Direct measurement; Earth sciences; Earth, ocean, space; Exact sciences and technology; Freshwater; Geochemistry; Lake water; Lakes; Lentic systems; Marine and continental quaternary; Mineralogy; Silicates; Supersaturation; Surface water; Surficial geology; Temperate regions; Water geochemistry
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.265.5178.1568

Data on the partial pressure of carbon dioxide (CO$_2$) in the surface waters from a large number of lakes (1835) with a worldwide distribution show that only a small proportion of the 4665 samples analyzed (less than 10 percent) were within ±20 percent of equilibrium with the atmosphere and that most samples (87 percent) were supersaturated. The mean partial pressure of CO$_2$ averaged 1036 microatmospheres, about three times the value in the overlying atmosphere, indicating that lakes are sources rather than sinks of atmospheric CO$_2$. On a global scale, the potential efflux of CO$_2$ from lakes (about 0.14 × 10$^{15}$ grams of carbon per year) is about half as large as riverine transport of organic plus inorganic carbon to the ocean. Lakes are a small but potentially important conduit for carbon from terrestrial sources to the atmospheric sink.