Attenuation of photosynthetically available radiation by chlorophyll, chromophoric dissolved organic matter, and tripton in lake Donghu, China

The attenuation coefficient of photosynthetically available radiation [Kd(PAR)] and three water quality parameters [chlorophyll a (chl a)], chromophoric dissolvedorganic matter (CDOM) and tripton) were measured at three stations in shallow, subtropical Lake Donghu from April 2003 to March 2004. The multiple regressionequation of &(PAR) versus chl a, CDOM, and tripton was: Kd(PAR) = 0.44 + 0.019 chla + 1.88 CDOM + 0.016 tripton, which revealed the relative contributions of the threeparameters to Kd(PAR). The effects of water and CDOM on Kd(PAR) were of minor importance (19-26%), while chl a and tripton were the two greatest contributors,accounting collectively for 74-8 1 %.