Allochthonous influences

In Lake Michigan (31), diatoms appear to play an important role in the sedimentation of Cu and Zn. In Lake Windermere (32), the influence of allochthonous material may be more important. A recent study of Lake Windermere (33) indicated a Zn P ratio of 0.03 from the regression analysis of dissolved concentrations during a diatom bloom. Mountain Lake (34) is a small acidic lake. 

Lake Plussee (Muenster, in preparation) is a eutrophic hardwater lake of the Plon lake district. During the summer, concentrations of dissolved combined phenolic compounds oscillate drastically over short periods of time (as shown in Fig. 17 for epilimnetic waters), although DOC concentrations (measured as COD in glucose-carbon equivalents) were much more stable. Fluctuations in combined phenolic compounds correlate poorly with phytoplankton standing crop (Fig. 17, lowermost panel). Thus, distribution patterns of free phenols and phenolic compounds may result primarily from abiotic factors (e.g., photolysis, allochthonous inputs by rainstorms, or adsorption onto autochthonous calcite) or biotic ones other than release by phytoplankton (e.g., biodegradation after photolysis). These processes, which have not yet been quantified, obviously influence the upper water layers most, since absolute concentrations of phenolic compounds (as well as oscillations within the concentrations) are significantly lower in the deeper-water layers. Perhaps many of the phenols in the deeper strata occur in a particulate state, adsorbed onto sedimentary matter. Alternatively, total phenolic concentrations are really lower in the deeper strata if true, the reasons remain obscure. 

---