Abstract

The last 15 years has seen a considerable increase in our understanding of the chemical composition of the sea-surface microlayer. However, many new developments in methods of chemical analysis have yet to be applied systematically to the microlayer. The development of continuous microlayer samplers coupled to UV absorbance or fluorescence detectors now allows much greater temporal and spatial resolution to be achieved in field measurements, and will have great application with the development of new chemical sensing technology. These techniques, and a greater range of studied environments, indicate that microlayer enrichment of the major classes of organic compounds (protein, carbohydrate) or of organic parameters such as dissolved organic carbon, is less than earlier studies might have indicated. Enrichment factors larger than 1.5 are relatively rare, and depletion is often observed. Improvements in the analysis of specific organic compounds, including better sample blanks, sensitivity and improved identification of individual compounds, have all been seen. Recently-reported concentrations of PCB and organochlorine insecticides in low latitude regions are extremely low, although microlayer samples enriched in these components are found at high latitudes. Organotin species have also been reported in microlayers. For trace elements passively associated with surface-layer organic material such as trace metals, a confusing picture exists.