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DISTRIBUTION OF NATURAL ISOTOPES OF CARBON IN LINSLEY POND AND OTHER NEW ENGLAND LAKES 1
Author(s) -
Deevey Edward S.,
Stuiver Minze
Publication year - 1964
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1964.9.1.0001
Subject(s) - groundwater , environmental science , carbonate , hydrology (agriculture) , total organic carbon , surface water , isotopes of carbon , outflow , carbon fibers , environmental chemistry , groundwater flow , chemistry , geology , oceanography , aquifer , environmental engineering , geotechnical engineering , materials science , organic chemistry , composite number , composite material
One product of lake metabolism, the CO 2 that is produced anaerobically, is naturally labeled by its high C 13 content, but in the presence of carbonates, even the modest amounts found in medium‐hard Linsley Pond, such enrichment is not distinctive. Groundwater near the lake is highly charged (175 ml/liter) with CO 2 ; because its source includes ancient carbonate, it is naturally labeled as C 14 ‐poor (Δ=‒87.5‰). Combining these data with estimates of surface inflow, outflow, and other gains and losses of water and carbon, we can account for the C 14 deficiency observed in hypolimnetic water (Δ = ca. ‒100‰) by a groundwater contribution of the order of 1 liter/(m 2 × day), perhaps less than 1% of the flow expected if the lake were not well insulated by a clay basin seal. Under ice, during the winter of 1961–62, C 14 depletion of the deep water developed so rapidly as to suggest direct injection of groundwater and its accumulation by gravitational flow; however, groundwater carbon is ordinarily cycled metabolically, as shown by the fact that organic surface mud has an apparent age of ca. 1,000 years ( δ C 14 = ‒133‰). Inadequate knowledge of the hydrology of Linsley Pond interferes with rigorous description of the carbon balance, as does recent strong but irregular contamination of air by artificial (hydrogen‐bomb) C 14 . By 1960, submerged pondweeds and surface waters of several lakes were enriched in artificial C 14 by less than 5%, while water‐lily leaves, which use atmospheric rather than aquatic sources of carbon, were enriched by ca. 22%. Using the enrichment of Linsley Pond, 1.9% per year, as a tracer, we find the invasion of atmospheric CO 2 to be slow, ca. 1.2 moles/(m 2 × yr) [1.4 mg/(cm 2 × yr)]. Contributions from groundwater and from air being small, and metabolism being an internal cycle that is nearly closed, the carbon balance of a small lake is seen as part of the hydrologic cycle and as dominated by bicarbonate in surface runoff.