Dissolved organic matter in Chascomus pond (Argentina). Influence of calcium carbonate in humic acid concentration

Supersaturation of calcium carbonate up to a saturation index of 20 was observed during a water chemistry study of Chascomus pond from April 1988 to May 1989, when precipitation was lower than average. Supersaturation occurred in spring and summer and in the same period there was a reduction in dissolved organic matter, including the humic substances component. The reduction of humic substances could be attributed to an association between calcium carbonate and organic matter. Gel permeation chromatography showed that higher molecular weight humic material was preferentially removed.