Specific absorption coefficient and the phytoplankton package effect in Lake Taihu, China
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- Le, C., Li, Y., Zha, Y. et al. Hydrobiologia (2009) 619: 27. doi:10.1007/s10750-008-9579-6
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In order to investigate variations of absorption and total chlorophyll-a (TChl-a)-specific absorption coefficient of phytoplankton in Lake Taihu, 57 water samples obtained from Lake Taihu during November 8–22, 2007 were used in this study. Package effect and accessory pigments’ influences on the absorption spectra were also examined. Phytoplankton absorption was measured by quality filter technical, and TChl-a concentration was measured by “hot ethanol” method. Results yielded significant variations in phytoplankton absorption and TChl-a-specific absorption coefficient. Phytoplankton absorption coefficient at 675 nm is highly correlated to TChl-a concentration, while absorption at 440 nm is less correlated to TChl-a concentration because of great package effect and accessory pigments’ influence. There was an inverse relationship between aph*(λ) and TChl-a concentration. Four types of absorption spectra are identified by normalizing aph*(λ) to aph*(440). The aph*(λ) variation is mainly due to accessory pigments and package effect, whose influence at 675 nm ranges from 83.2% to 28%, with an average of 65.3%. Meanwhile, the wide varying ratio of aph*(440) to aph*(675) indicates a large variation range in the ratio of accessory pigment to TChl-a concentration. Those findings are significant to estimate Chl-a concentration based on bio-optical model, estimate primary production from remote sensing, and plan further ecological restoration measures for Lake Taihu.