Technical Note: Comparison of storage strategies of sea surface microlayer samples

The sea surface microlayer (SML) is an important biogeochemical system whose physico-chemical analysis often necessitates some degree of sample storage. However, many SML components degrade with time so the development of optimal storage protocols is paramount. We here briefly review some commonly used treatment and storage protocols. Using freshwater and saline SML samples from a river estuary, we investigated temporal changes in surfactant activity (SA) and the absorbance and fluorescence of chromophoric dissolved organic matter (CDOM) over four weeks, following selected sample treatment and storage protocols. Some variability in the effectiveness of individual protocols most likely reflects sample provenance. None of the various protocols examined performed any better than dark storage at 4 °C without pre-treatment. We therefore recommend storing samples refrigerated in the dark.