Compositional characterization of suspended particulate matter in HellenicVolcanic Arc hydrothermal centres

Suspended particulate matter (SPM) separated from waters discharging from a number of submarine hydrothermal vents at Palaeochori bay, Milos island wa s analysed for major and trace elements (i.e. Fe, Mn, Cu, Pb, Cd, Ca, Sr, S i, Al, Ba). It was found that SPM in the hydrothermal waters investigated was strongly enriched in Fe, Mn, Si and Ba compared with normal Aegean Sea waters. Four major hydrothermal centres were distinguished on the basis of the SPM chemical characteristics. On average Fe decreases in the four hydrothermal centres in the following order : A > D > C > B while Si decreases as follow s : D > A > C > B. Calcium, Sr, Si and Ba show a strong biogenic affiliation. The marked enric hment of these elements in hydrothermal centre D relative to the other hydr othermal centres indicates strong biological activity there. The diurnal variability of Ca, Sr, Si and Ba shows increase in the afternoo n. On average the concentrations of Fe, Si and Ca were higher in September 1996 than in June 1996. By contrast Mn, Cu, Pb and Sr were more enriched in June than in September 96. (C) 2000 Elsevier Science Ltd. All rights reser ved.