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Effects of lake size, water clarity, and climatic variability on mixing depths in Canadian Shield lakes
Author(s) -
Fee E. J.,
Hecky R. E.,
Kasian S. E. M.,
Cruikshank D. R.
Publication year - 1996
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.1996.41.5.0912
Subject(s) - environmental science , extinction (optical mineralogy) , hydrology (agriculture) , shield , surface water , atmospheric sciences , physical geography , geology , geography , mineralogy , petrology , geotechnical engineering , environmental engineering
The depth of the summer mixed ( E d ) of 21 Canadian Shield lakes in northwestern Ontario was examined in relation to lake size (surface area, A o ) and water clarity (extinction coefficient, K d ) for periods ranging from 2 to 23 yr ( n = 1,408). The lakes range in A o from 4 to 4.9 × 10 5 ha, and midsummer (mid‐June through mid‐August mean) K d varied from <0.2 to >2.5 m ‒1 with greatest variation in small lakes that were experimentally eutrophicated or acidified or whose terrestrial basins were burned. Over the full spectrum of lake sizes, A o was the primary determinant of E d ; transparency significantly modified this relationship but only in small lakes ( A o <500 ha). In noneutrophic shield lakes, transparency is controlled by the concentration of dissolved organic C (DOC). Lower DOC concentrations (a likely consequence of 2 × CO 2 climate change) would cause transparency to increase, resulting in 1–2‐m‐deeper epilimnia in small lakes; there would be no similar effect in large lakes.