Pine pollen grains in coastal waters of the Baltic Sea

Measurements relating to a yellow deposit covering large areas of the Baltic Sea in spring are reported. Analysis of water samples showed it to be of terrestrial origin and to consist mainly of pine pollen grains. The equivalent spherical diameter (ESD) of these grains ranged from 29.1 to 78.4 μm, with a maximum between 47.7 and 56.3 μm. Surface water concentrations of pollen in the coastal zone near Ustka showed that its proportion in the total suspended particulate matter (SPM) might be as high as 30-40%. Such high surface water concentrations of hitherto neglected substances critical to water color formation can give rise to serious errors in remote measurements of water composition and properties.