U. Brockmann, H. Hühnerfuss, G. Kattner
Nov 1, 1982
Citations
2
Influential Citations
32
Citations
Journal
Limnology and Oceanography
Abstract
An artificial surface fihn of oleyl alcohol was produced in the North Sea off Sylt Island to investigate the chemical uniformity of the surface filrn and its influence on gas exchange. Oleyl alcohol concentrations found at the sea surface were in good agreement with previously calculated values. Significant differences between fatty acid concentrations before and after production of the artificial film indicated that the natural surface-active substances were pushed aside by the spreading oleyl alcohol, with small amounts replenished from the underlying water later. The same displacement effect was inferred from the strong reduction in the number of colony-forming units of organotrophic bacteria in the presence of an oleyl alcohol slick. Gas exchange, in this cast dcsorption of CO,, was determined before and after formation of the artificial surface film. In the one experiment performed inhibition of exchange was significant when the film was present: without the film cquilibril~m was achieved after 3.7 Inin, whereas lmder the influence of the film, it took 5.7 min to reach equilibrium. Organic surface-active compounds and particulate matter accumulate at the ocean-atmosphere boundary, influencing several air-sea interaction processes (Garrett 1969; Hiihnerfuss and Garrett 1981). In coastal areas with high biological activity, but also on the open ocean, this accumulation frequently becomes visible as mirrorlike patches (“slicks”) on the sea surface (Garrett 1972; Barger et al. 1974; Hiihnerfllss et al. 1977). The chemical composition of the film-forming substances is complex and can be subject to rapid alterations (Brockmann et al. 1976). Therefore, artificial films with known chemical and physicochemical characteristics have been used for simulating defined and reproducible modifications of the sea surf;;lce in order to gain insight into the influence of these slicks on air-sea interaction processes (Barger (This research has been sponsored by the I_>eutschc Forschllngsgemeinschaft (German Sci~IICC Foundation) tljrollgh the SonderforschungsI)ereicll 94-Meercsforschung-H~~ll7l,urg. and Garrett 1974; Hiihnerfuss and Garrett 1981). In recent years several phenomena have been investigated with the help of artificial surface films: evaporation (La Mer 1972; Mansfield 1972), windwaveand wave-wave-coupling (Barger et al. 1970; Mallinger and Mickelson 1973; Hiihnerfuss et al. 1975, 1981u, 1982), the modification of brightness temperature of the sea surface by slicks (Alpers et al. 1982), and the influence of slicks on KU-band (IIiihnerfuss et al. 1978) and Xand L-band radar signals (IIiihnerftlss et al. 1981u). During these experiments the chemical and physicochemical constancy of the surface films has always been assumed but never proved. We here present an investigation of the variation in time and space of artificial surface films and thei] possible interference with gas exchange. During the experiment KOFF 74 (Kombiniertes Oberfl;cichen-Film-Projckt = joint surface film project) on 20 and 21 August 1974 in the North Sea west of Sylt, the interaction of oleyl alcohol (9-octa-