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Turnover and uptake of dissolved phosphate in freshwater. A study in Lake Kinneret 1
Author(s) -
Halmann M.,
Stiller M.
Publication year - 1974
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.1974.19.5.0774
Subject(s) - phosphate , nutrient , saturation (graph theory) , limiting , residence time (fluid dynamics) , hydrology (agriculture) , environmental chemistry , chemistry , plankton , zoology , environmental science , geology , biology , oceanography , mechanical engineering , mathematics , geotechnical engineering , organic chemistry , combinatorics , engineering
The residence times and turnover rates of dissolved phosphate in the surface water of Lake Kinneret and in the Jordan River above and below the lake were measured by adding 32 P‐HPO 4 2 − tracer to the unfiltered water and determining its disappearance from solution. Residence times varied from 9.1 to 0.2 hr in winter and summer at water temperatures of 14.5 to 30°C: the turnover rates ( V ) ranged from 0.02 to 0.20 µ M hr −1 . The rate of uptake by plankton ( V i ) of dissolved phosphate could be fitted to a Monod equation, V i = V m S /( K s + S ), in which V m and K 8 are the maximal rate and the half‐saturation constant. Values of V m were in the range of 0.04–1.1 µ M hr −1 for winter and summer; K s values ranged from 0.2–0.8 µ M, higher than the usual observed natural concentration of dissolved phosphate in Lake Kinneret. This supports the conclusion that in its water, phosphate is the primary limiting nutrient. In the Jordan River, upstream of Lake Kinneret, the dissolved phosphate concentration (0.44 µ M) was higher than the K s value (0.27 µ M) and therefore in its water, phosphate may not be the primary limiting nutrient.