120 Deutsche }Iydrographische Zeitschrift, Jahrgang 28, 1975, Heft 3 Unser Dank gilt allen, die bei Konstruktion und Anfertigung mitgewirkt haben sowie Kapitan und Mannschaft yon VFS ,,Gau[t", deren Einsatz zu einem guten Gelingen bei- getragen hat. Literatur Duce, 1%.A., J. G. Quinn, C. E. Olney et al., 1972 : Enrichment of heavy metals and organic compounds in the surface microlayer of Nar- ragansett Bay, I~hode Island. Science 176~ 161. Harvey, G.R., W.G. Steinhauer and J.M. Teal, 1973: Polyehlorobiphenyls in North Atlantic Ocean water. Science 1807 No 4086, 643. Keizer, P.D., 1974: [Private Mitteilung]. Bedford Institute of Oceanography. Larsson, K., G. Odham and A. STdergren, 1974: On lipid surface films on the sea. 1. A simple method for sampling and studies of composition. Mar. Chem. 2~ 49. Majori, L., F. Petronio, G. Nedoc!an et al., 1973: Marine pollution by hydrocarbons in the Northern Adriatic Sea. l~ev. int. Ocdanogr. mdd. 31-32~ 137. Stadler, D. und U. Ziebarth [in Vorberei- tung]. Stadler, D. [unverSffentlicht] : Interner Quar- talsberieht 1/74. Dieter Stadler, Karl Schomaker Eingegangen im M~rz 1975 Anschrift der Verfasser: Dr. Dieter Stadler, Karl Schomaker, Deutsches Hydrographisches Institut, 2 Hamburg 4, Bernhard-Nocht-Str. 78 The Release of Manganese in Sea Water by Eolian Dust from Africa* UDG 551.464.671.1 : 551.465.7 Introduction The eolian dust particles, especially the clay-type materials, transported from the North African continent have associated with them either adsorbed or loosely bound ionic coatings. In order to ascertain the nature and relative rates of release of free ionic species from this dust upon entering sea water, electron spin resonance (ESR) spectroscopy was performed on two characteristic samples with a Varian E-line EPR Spectrometer. The two samples tested were Ghana eolian dust collected on board the I~.V. "Atlantis II" and material collected from the top of a sand dune close to Dakar, Senegal. Results Two dust samples investigated for free radicals in the dry solid phase by EStr (Sz ekielda and Lepple [unpublished data]) were again tested for the release of free ionic species in sea water solution. For this purpose Sargasso sea water was employed. Its background reference spectrum is included in Fig. 1. No discernible free ions were observed even with a high receiver gain factor. * This research was conducted under NATO l~esearch Grant, No. 807, "Air-Sea Interaction of Eolian Dust," which is acknowledged.