Ocean microlayer

At the upper ocean microlayer and at the boundary layer confining the air bubbles, among other various physical and chemical effects, organic materials significantly alter the surface tension of water, y. In slick covered sea surfaces, depressions of y exceeding 20 mN m"1 have been observed. 

Korenowski GM (1997) Applications of laser technology and laser spectroscopy in studies of the ocean microlayer. In The Sea Surface and Global Change, ed. P. S. Liss and R. A. Duce, pp.445-470. Cambridge, U K. 

Because 03 does not penetrate the ocean microlayer from the atmosphere, its reactions are significant only in the microlayer. The reaction of iodide with ozone has been documented at the surface microlayer of the ocean... 

Chesselet, R., Buat-Menard, P., Lesty, M. and Jehanno, C., 1976. Heavy metals in oceanic microlayer-derived aerosols. Abstracts of papers. Joint Oceanographic Assembly, Edinburgh, September, 1976. FAO, Rome. 

Heussner S, Cherry RD, Heyraud M (1990) Po-210 and Pb-210 in sediment trap particles on a Mediterranean continental margin. Cont. Shelf Res 10 989-100 Heyraud M, Cherry RD (1983) Correlation of Po-210 and Pb-210 enrichments in the sea-surface microlayer with neuston biomass. Cont Shelf Res 1 283-293 Honeyman BD, Santschi PH (1989)The role of particles and colloids in the transport of radionuclides and trace metals in the oceans. In Environmental particles. Buffle J, van Leewen HP (eds) Lewis Publishers, Boca Raton, p 379-423... 

SauerTC Jr, Durell GS, Brown JS, et al. 1989. Concentrations of chlorinated pesticides and PCBs in microlayer and seawater samples collected in open-ocean waters off the U.S. East Coast and in the Gulf of Mexico. Mar Chem 27 235-257. 

There are very few measurements of the DMS concentration in the sea surface microlayer. The first report (44) indicated an enrichment of 5 times relative to underlying water samples. Other reports indicate that no enrichment was observed in tne microlayer DMS concentration (23.47.511. These differences may be related to the sampling techniques used. It is possible that chemical and biological processes in tne sea surface microlayer may affect the transfer of DMS from the bulk ocean to the atmosphere. However, at present, very little is known about the processes affecting the chemistry of DMS in the microlayer. 

C, microlayer, subsurface water of salinity 32%, TOC 2.2 46 ppm, ocean water from Bering/Chukchi Sea estimated value adjusted to salinity, Rice et al. 1997b)... 

Available data in the literature (12) show that the primary oxidants in the photic zone of the ocean other than I03" (<470 nM) are 02 (about 250 p,M) and H202 (100 nM). Ozone does not penetrate the surface microlayer, and its depletion has been estimated to occur within the first few micrometers (13). Nitrate, which is present in seawater (up to 50 xM in deep waters), is not considered to be an oxidant at seawater pH because as an anion it has Lewis base properties like I". In fact, the energies of the donor orbitals for NOa" and I" are within 0.05 eV (14, 15). 

The world s oceans have also been monitored for PCB concentrations. PCB levels reported in sea water from various oceans include 0.04—0.59 ng/L in the north Pacific, 0.02-0.20 ng/L in the north Atlantic, and 0.035-0.069 ng/L in the Antarctic (Giam et al. 1978 Tanabe et al. 1983, 1984). PCB levels were several orders of magnitude higher in sea-surface microlayer samples taken from industrial areas, compared to sites further offshore (Cross et al. 1987). PCB concentrations of 0.3-3 ng/L, have been detected in sea water from the North Sea (Boon and Duinker 1986). 

R. Conrad, W. Seiler (1988). Influence of the surface microlayer on the flux of nonconservative trace gases (CO, H2, CH4, N2O) across the ocean-atmosphere interface. J. Atmos. Chem., 6, 83-94. 

Other experimental efforts focused on the collection of ocean surface samples in order to investigate properties of the marine microlayer in the laboratory. Samples were retrieved using either inert screens (Garrett 1965) or drum-type samplers (Carlson et al. 1988, Frew and Nelson 1992). 

Thus the surface chemistry of the ocean consists essentially of the chemistry of that part of the uncharacterised and complex part of the DOM in seawater which is surface active. Apart from other effects, this can lead to the entrainment of trace elements in the surface layer by complex formation with the surface active polymers and their enrichment in the microlayer (Barker and Zeitlin, 1972 Duce et al., 1972 Piotrowicz et al., 1972, Hunter, 1977) and possible enrichment of the atmospheric aerosol (Duce et al., 1972,1976), at least near the ocean surface (Chesselet et al., 1976). 

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