Lake-organics, complexation

The K1/K3 ratios divide these natural waters into three groups. Okeefenokee Swamp and Volo Bog have ratios of about 3 a group of small lakes and two coastal marine waters show a somewhat weaker binding with K1/K3 ranging from 0.16 to 0.56 Lake Michigan exhibits much weaker organic complexes with a K]VK3 of 0.03. 

Complexation of Cu at Varying pH. In order to compare the effects of complexation by lake organics at different pH s, the fraction (a) of total dissolved copper (Cu ) was... 

Organic matter exuded by the plankters could have complexed with the metals and made them more diflBcult to reduce at the electrode. The presence of organically complexed trace metals in lake water has been shown (15,16), If the added standard did not fully equilibrate with the organic matter, apparently low concentrations would have been obtain. ... 

Barsdate, R.J. and Matson, W.R., 1967. Trace metals in arctic and sub-arctic lakes with reference to the organic complexes of metals. In B. Aberg and F.P. Hungate (Editors), Radioecological Concentration Processes. Pergamon Press, London, pp. 711—719. 

Matson, W.R., Allen, H.E. and Reksham, P., 1969. Trace—Metal Organic Complexes in the Great Lakes. Presented before the Division of Water, Air and Waste Chemistry, A.C.S., Minnesota, 1969. 

The effect of pH on the mobilization of zinc in a few highly acidic clean lakes has been studied (Sprenger et al. 1987 White and Driscoll 1987). In these lakes, in which the pH was <3.6, concentrations of zinc were elevated in the water column, and the concentration of zinc in the upper layer of sediment was substantially lower than values reported for other lakes at higher pH values. The relatively higher concentration of zinc in the water column compared to the sediment may be the result of lower adsorption of zinc on oxide surfaces due to low pH, solubilization of inorganic zinc from the sediment layer, and the dissociation of bound organic complexes of zinc present in the sediment and their subsequent release into the water phase. 

There are now enormous data sets on Al concentrations in lakes and streams, from those areas where acid deposition has important effects on hydrogeochemistry, that is eastern Canada and northeast USA, north and west of Britain, and Scandanavia. A number of these are summarised by Schecher and Driscoll (1990). Rarely do concentrations of total Al exceed about lO M (roughly 300ug/l), except where very acid snowmelt is involved, in contrast to the much higher concentrations often found in soil solutions. Al fractionation and speciation studies show that organically-complexed Al seems to be a greater proportion of the... 

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