The estimated errors of approximation are given in Table 1. The broad range of concentrations of the optically active components (OACs) contained in the

waters of the investigated lakes (e.g. chlorophyll a concentration Ca from ca 1 mg m−3 to 336 mg m−3) enables the influence of each group of these OACs on the reflectance spectra Rrs(λ) of these waters to be established. Three types of reflectance spectra with quite different shapes and values were distinguished. The first one, for waters with intermediate (or low) concentrations of all three OACs, has a conspicuous, broad peak in the 560–580 nm band (with maximum values of Rrs very much less than 0.01 sr−1), and two very weak, scarcely discernible peaks in the longwave bands. These type I spectra Rrs(λ) of the lake waters resemble those commonly observed for the Baltic Proper. The second type, for lake waters with very high CDOM concentrations AZD6244 (aCDOM(440 nm)> 10 m−1), has very low reflectance values (Rrs < 0.001 sr−1) over the entire spectral range, with two visible see more reflectance spectra peaks: a very weak one at ca 650 and a somewhat stronger one at 690–710 nm. The third type of spectrum Rrs(λ), for lake

waters with low CDOM concentrations (aCDOM(440 nm)< 5 m−1) and high chlorophyll a levels (Ca > 4 mg m−3, up to 336 mg m−3) exhibits three peaks (Rrs > 0.005 sr−1): a broad one at 560–580 nm, a smaller one at ca 650 nm and a well-pronounced one at 690–720 nm. The correlations of the relevant spectral reflectance bands with the chlorophyll a concentration and with the total SPM concentration for the lake waters have high coefficients of determination: R2 = 0.95 and 0.90 respectively. The correlation of the coloured dissolved organic matter absorption coefficient aCDOM(440 nm) with the spectral reflectance band ratio Rrs(570)/Rrs(655) is somewhat weaker, with a coefficient of determination R2 = 0.85. As expected, the errors in determining optically active components (OAC) with the new equations are also quite satisfactory. The standard error factors are as follows: for the estimated chlorophyll a

concentration x = 1.36, for the estimated total SPM concentration x = 1.56 and for the estimated coloured dissolved organic matter absorption coefficient x = 1.46. Adenosine triphosphate “
“The high phytoplankton productivity in the Baltic (Hagström et al. 2001) makes it a key area on the European shelf as regards atmospheric CO2 uptake (Thomas et al. 2003, 2005). Since particulate organic matter (POM) is a carrier of carbon to the sediments, it plays an important role in the biological pump mechanism (e.g. Pempkowiak et al. 1984, Chisholm 2000, Turnewitsch et al. 2007). The measure of particulate organic matter is particulate organic carbon (POC). POC concentrations depend on the equilibrium between the sources and sinks of organic substances.