PIXE application for measurement of bioaccumulation of lead by marine micro-algae

Marine micro-algae (Nannochloropsis sp., and Phaeodactylum sp.,) were obtained from the Pacific Ocean of Iwate Pref., Japan and purely cultured in nutritive seawater as a culture solution. The culture size for algae was 10-250 ml and every apparatus was small and of low cost. Marine micro-algae were given in different culture solutions including Pb2+ from 0.01 to 1.0 mg/l. The algae in 5 ml of the culture solution were collected on a polycarbonate filter (pore size: 1.0 μm) by suction filtration. The algae on the filter were subjected to PIXE analysis. Concentrations of Na, Mg, Si, P, S, Cl, K, Ca, Cr, Mn, Fe, Cu, Zn, Sr and Pb were simultaneously determined. PIXE can do multi-element analysis for a sample of below 1 mg. The quantity of lead in marine micro-algae increases in proportion to the Pb2+ concentration in the culture solution. The concentration factor (wet weight base) for lead is given as 200±20 ml/g for Nannochloropsis sp. and 1900±400 ml/g for Phaeodactylum sp.. It is shown that PIXE is a powerful tool for the measurement of the bioaccumulation of trace elements. (author)