INVESTIGATION OF SEA-SURFACE MICROLAYER AND PHYTOPLANKTON CULTURE SAMPLES BY MONOLAYER TECHNIQUES AND BREWSTER-ANGLE MICROSCOPY

Natural samples of sea-surface microlayer and phytoplankton culture sa mples have been studied by monolayer techniques and by Brewster angle microscopy (BAM). Surface pressure-area (pi-A) and surface potential-a rea (Delta V-A) isotherms have been measured. Simultaneously BAM video images have been recorded. The pi-A isotherms, as well as BAM images of monolayers of dipalmitoyl phosphatidylcholine (DPPC), dimyristoylph osphatidic acid (DMPA) and dioctadecyldimethyl ammonium bromide (DOMA) spread on an aqueous subphase containing a sample of phytoplankton cu lture show that surface active substances released by phytoplankton in fluence molecular organization as well as domain morphology of the lip id monolayers. The sea-surface microlayer sample spread at the air/wat er interface exhibits the characteristics of a liquid expanded phase w ithout undergoing a phase transition. The BAM images taken from this f ilm depend on surface pressure, showing at low surface pressures liqui d condensed domains surrounded by a liquid expanded phase, and at high er surface densities only a liquid condensed phase.