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Sea surface microlayer: a field evaluation of teflon plate, glass plate and screen sampling techniques. Part 1. Thickness of microlayer samples and relation to wind speed

Falkowska L.

Oceanologia

1999

No. 41 (2)

211-221

Surface microlayer samples were collected in the open sea with the simultaneous use of three different techniques. The thinnest water layer, 10 žm on average was collected with a teflon plate (TPM), 90 žm thick samples were collected with a glass plate (GPM) and 250 žm samples with a screen (SM). The sampling was performed under variable weather conditions. The microlayer thickness was found to increase with increasing wind speed. Glass plate and screen samples were influenced by the sea state. The intensification of turbulence in the surface layer was responsible for increased advective transport of organic matter and its accumulation near the sea surface and the greater thickness of the microlayer. When the wind speed exceeded 8 ms-1 (5oB), the microlayer thickness was observed to decrease gradually. The thickness of a microlayer collected by teflon plate was found to be inversely proportional to the wind speed. The classic screen method turned out to be the most useful of the techniques examined because of its relatively short sampling time and large sample volume. This technique is also applicable in inclement weather, when mechanical samplers are useless.

Sea surface microlayer: a field evaluation of teflon plate, glass plate and screen sampling techniques. Part 2. Dissolved and suspended matter

Falkowska L.

Oceanologia

1999

No. 41 (2)

223-240

The similarities and differences in chemical composition of particular sub-layers of the sea microlayer are discussed on the basis of data obtained from the open sea region of the Gdansk Basin. Three methods of microlayer sampling were tested simultaneously, resulting in sub-samples of different mean thickness (10, 90, 250 žm). Samples were analysed to determine dissolved NO3-, NH4+, PO43-, Ptot and DOC, as well as suspended components (chl a, phae a, ATP, POC, particle size distribution and algae). It was found that the stratified microlayer forms a medium extremely diversified chemically and biologically. Variable ranges of concentration as well as varying frequencies of the depletion or enrichment coefficient in each measurement period indicate disparate conditions in the microlayers, which are related to the intensity of primary production and the destruction of organic matter. Comparative studies provided no evidence for the preferential application of any of the sampling techniques to obtain the most accurate picture of dissolved organic and inorganic substances in the sea surface microlayer. In the case of particulate organic matter, satisfactory results were obtained with the classic screen technique. The article highlights the merit of simultaneous studies by various sampling techniques in answering questions related to the sea surface microstructure and the momentum of photochemical and biological processes at its different levels