In situ determination of sun-induced chlorophyll a fluorescence quantum yield in the North China Sea

摘要

Sun-induced chlorophyll a fluorescence signals were measured in the North China Sea using an underwater hyperspectral spectroradiometer. We combined these signals with other apparent and inherent optical properties to derive the quantum yield of chlorophyll a fluorescence in vivo, and determined that the maximum was around 0.06 and the average value reached 0.017, with most values ranging from 0.001 to 0.02, consistent with results obtained in other sea areas. In addition, we validated some empirical relationships with in situ measurements, and compared them with the former results. We found that the correlations between inherent optical properties and chlorophyll a concentration in this area are very different from those in other seas; however, the relationship between the diffuse attenuation coefficient for the instantaneous photosynthe-tically available radiation (IPAR) and that at 490 nm is comparatively stable.