ROLE OF AQUATIC SURFACE MICROLAYER IN THE DYNAMICS OF NUTRIENTS AND ORGANIC-COMPOUNDS IN LAKES, WITH IMPLICATIONS FOR THEIR ECOTONES

The origin and mechanisms of formation of aquatic surface microlayers are reviewed, and processes within the layer responsible for enrichmen t of inorganic and organic substances, particles, and microorganisms a re discussed. In a study of the chemical and biological composition of microlayers in three lakes of different levels of productivity, surfa ce slicks were sampled with a revolving cylinder coated with hydrophil ic Teflon. DOC, POC, DON and various forms of phosphorus were enriched in the microlayer compared to those in the subsurface water. In eutro phic and oligotrophic lakes the DOC:DON ratio shows that the slicks we re more influenced by allochtonous sources than was the subsurface wat er, which indicates that processes in the ecotone influence the microl ayer composition.