Specific absorption coefficient and the phytoplankton package effect in Lake Taihu, China

Abstract

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-aspecific 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 a ph *(k) and TChl-a concentration. Four types of absorption spectra are identified by normalizing a ph *(k) to a ph *(440). The a ph *(k) 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 a ph *(440) to a ph *(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.

The variability of particle backscattering coefficient in an oligo-to-hypertrophic cascading reservoir system: implications to TSM bio-optical model development

“…These authors discovered that the chlorophyll-a specific absorption coefficient a à phy decreases with increasing [Chl-a] at 412, 443 and 490 nm and is lower at 675 nm. This inverse relationship was also reported in previous studies (Le et al 2009a) and may be explained by the fact that an increase in [Chl-a] lead to an increase in the concentration of intracellular pigment or in cell volume rather than in cell number, resulting in an absorption efficiency loss in the package effect. The phytoplankton backscattering efficiency tends to be higher in blue than in red wavelength (Brewin et al 2012), but can be masked due to the package effect.…”

Temporal and Spatial Dynamics of Phytoplankton Primary Production in Lake Taihu Derived from MODIS Data

“…Lake Taihu is a crucial water source for the Yangtze River Delta, located between 30°56′N-31°33′N and 119°54′E-120°36′E (Figure 1) [30]. In this article, Lake Taihu can be divided into six areas based on shoreline geometry, environmental factors, and human activities: Meiliang Bay, Zhushan Bay, Gonghu Bay, Xukou Bay, East Lake Taihu and the open area ( Figure 1) [32,33].…”

“…Besides, Lake Taihu Basin also contributes 11.6% of China's gross domestic product, despite accounting for only 0.38% of China's total area. With economic development, a lot of wastewater, sewage and polluted water surrounding urban and rural areas were discharged to Lake Taihu, resulting in phytoplankton blooms and then triggering a drinking water crisis in 2007 [30]. Phytoplankton are commonly the most important primary producer in lake ecosystems, strongly influencing nutrient concentrations and supporting higher trophic levels such as zooplankton and filter feeders.…”

Estimating specific inherent optical properties of tropical coastal waters using bio-optical model inversion and in situ measurements: case of the Berau estuary, East Kalimantan, Indonesia

“…For example, Prieur & Sathyendranath (1981), Sathyendranath et al (1987), and Gallegos & Correl (1990) found that a Chl * for oceanic and coastal waters varies from 0.01 to 0.047 m 2 mg -1 , whereas Smith & Baker (1981) found that a Chl * varied between 0.039 and 0.168 m 2 mg -1 . On the other hand, Heege , in Albert & Mobley, 2003 and Le et al (2009) Table 3). These results indicate that the Berau estuarine waters have a relative low trophic state.…”

“…This model has potential of providing accurate retrievals of several parameters because they attempt to model the physics of ocean color (Maritorena et al, 2002). Semi-analytical models have been developed to derive waters constituents such as chlorophyll a (Chl a) concentration, total suspended matter (TSM) concentration, and colored dissolved organic matter (CDOM) absorption (D'Sa et al, 2002;Maritorena et al, 2002;Haltrin & Arnone, 2003;Doerffer & Schiller, 2007;Van der Woerd & Pasterkamp, 2001;Le et al, 2009;Salama & Stein, 2009;Salama & Shen, 2010a).…”