Lake Constance: Yellow substance measurements in 1998

Abstract

The absorption properties of yellow substance (Gelbstoff) in Lake Constance (Bodensee) were studied during two campaigns in May and September 1998. Sampling covered all major water types of the lake. Absorption decreases in good approximation exponentially from short to long wavelengths with an average spectral slope of S = 0.0142 ± 0.0012 nm-1. The typical absorption at 440 nm in the pelagial, litoral and the Rhein mouth is 0.29 ± 0.05 m-1. Increased values were observed in the plume of the river Schussen, for which absorption at 440 nm can be as high as 3.7 m-1. Neither the spectral shape nor the concentration was changing significantly from May to September 1998, except for the river Schussen.