Zum Kreislauf der Spurenmetalle Aluminium, Eisen und Mangan im subtropischen Ostatlantik (Kanarische Inseln):Vertikaltransport und Wechselwirkungen zwischen Partikeln und Lösung

Abstract

Three stations near the Canary Islands were investigated in 1997 to 1999 for dissolved and particulate trace metals (Al, Fe, Mn).Atmospheric dust input dominates the input of Al, Fe and Mn to the ocean near the Canary Islands. Dissolved Al, Fe, Mn are removed from surface waters by scavenging and vertical particle sedimentation. The importance of adsorption on (Al, Fe) and/or incorporation in (Fe) biogenic material as main scavenging process is shown. Scavenging of dissolved Mn is linked to the absence of light. Residence times in surface waters are calculated (Fe: 47d-1,4yrs; Al: 0,4-2,6 yrs; Mn: 0,6-7 yrs).The vertical distribution of suspended particulate Al, Fe and Mn concentrations is dominated by aggregation/disaggregation processes with organic material. The vertical distribution of suspended particulate Mn at 200m (maxima), however, reflects the intense oxidative scavenging of dissolved Mn. The fast and combined export of the particulate suspended trace metals Al, Fe and Mn out of the surface water via aggregation by particulate organic carbon could be confirmed by short and comparable residence times (Al: 1,8-20d; Fe: 2,2-25d; Mn: 2,5-28d).