A Preliminary Study of Chromophoric Dissolved Organic Matter (CDOM) in Lake Taihu, a Shallow Subtropical Lake in China

• Published in: Acta Hydrochimica et Hydrobiologica 2005-09, Vol.33 (4), p.315-323
• Main Authors: Zhang, Yun Lin, Qin, Bo Qiang, Chen, Wei Min, Zhu, Guang Wei
• Format: Article
• Language: English
• Subjects: Absorption Coefficient; Absorptionskoeffizient; Determination Coefficient; Dissolved Organic Carbon; DOC; DOC-specific Absorption Coefficient; DOC-spezifischer Absorptionskoeffizient; Freshwater; Gelöster organisch gebundener Kohlenstoff; Spectral Slope Coefficient; Spektraler Verlauf
• ISSN: 0323-4320; 1521-401X
• DOI: 10.1002/aheh.200400585

The optical properties and spatial distribution of chromophoric dissolved organic matter (CDOM) in Meiliang Bay of Lake Taihu were evaluated and compared to the results in literature. Concentrations of dissolved organic carbon (DOC) ranged from 8.75 to 20.19 mg L−1 with an average of (13.10 ± 3.51) mg L−1. CDOM absorption coefficients a(λ) at 280 nm, 355 nm, and 440 nm were in the range 11.28...33.46 m−1 (average (20.95 ± 5.52) m−1), 2.42...7.90 m−1 (average (4.92 ± 1.29) m−1), and 0.65...2.44 m−1 (average (1.46 ± 0.44) m−1), respectively. In general, CDOM absorption coefficient and DOC concentration were found to decrease away from the river inflow to Meiliang Bay towards the lake center. The values of the DOC‐specific absorption coefficients a*(λ), given as absorption coefficient related to mass concentration of organic carbon (C) ranged from 0.28 to 0.47 L mg−1 m−1 at 355 nm. The determination coefficients between CDOM absorption and DOC concentration decreased with the increase of wavelength from 280 to 550 nm. The linear regression relationship between CDOM absorption at 280 nm and DOC concentration was following: a(280 nm) = 1.507 L mg−1 m−1 · DOC + 1.215 m−1. The spectral slope S values were dependent on the wavelength range used in the regression. The estimated S values decreased with increasing wavelength range used. A significant negative linear relationship was found between CDOM absorption coefficients, DOC‐specific absorption coefficients and estimated S values especially in longer wavelength range. The linear regression relationship between DOC‐specific absorption coefficients at 440 nm and estimated S values during the wavelength range from 280 to 500 nm was following: a*(440 nm) = (–0.021 μm · S + 0.424) L mg−1 m−1. Chromophore gelöste organische Wasserinhaltsstoffe (CDOM) im subtropischen Flachsee Lake Taihu in China – eine vorläufige Studie Optische Eigenschaften und räumliche Verteilung der chromophoren gelösten organischen Wasserinhaltsstoffe (chromophoric dissolved organic matter – CDOM) in der Meiliang‐Bucht des Lake Taihu wurden untersucht und mit Literaturdaten verglichen. Für den gelösten organisch gebundenen Kohlenstoff (DOC) wurden Konzentrationen zwischen 8.75 mg L−1 und 20.19 mg L−1 gefunden, mit einem Mittelwert von (13.10 ± 3.51) mg L−1. Die Absorptionskoeffizienten der CDOM bei 280 nm, 355 nm und 440 nm bewegten sich im Bereich von 11.28...33.46 m−1 (Mittelwert: (20.95 ± 5.52) m−1), 2.42...7.90 m−1 (Mittelwert: (4.92 ± 1.29)