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Seasonal changes in the spectral composition of downwelling irradiance in Lake Kinneret (Israel) 1, 2
Author(s) -
Dubinsky Zvy,
Berman Thomas
Publication year - 1979
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.1979.24.4.0652
Subject(s) - downwelling , photic zone , irradiance , photosynthetically active radiation , extinction (optical mineralogy) , radiometer , atmospheric sciences , chlorophyll a , chlorophyll , oceanography , photosynthesis , phytoplankton , environmental science , upwelling , chemistry , biology , physics , geology , mineralogy , ecology , optics , botany , nutrient
A submersible scanning radiometer was used to measure seasonal variations in the intensity and spectral characteristics of downwelling irradiance in Lake Kinneret, Israel. Extinction coefficients for photosynthetically active radiation (350–750 nm) varied from 0.2 to 3.3 ln units·m −1 , the euphotic zone (1% of light energy at surface) ranged from 1.7 to 11 m. Specific extinction coefficients of chlorophyll, k c (ln units mg −1 ·n −2 ), and water k w (ln units·m −1 ) were dependent on the wavelength at which they were measured (at 650 nm, k c = 0.011, k w = 0.693; for 350 to 750 nm, k c = 0.007, k w = 0.489). High concentrations of chlorophyll and other cell pigments during the annual Peridinium bloom strongly attenuated light penetrance and caused a spectral shift toward the red to give elevated quantum to joule (Q:W) ratios (2.96 × 1018)