PIXE APPLICATION FOR MEASUREMENT OF BIOACCUMULATION OF LEAD BY MARINE MICRO-ALGAE

Abstract

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 Pb 2+ 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 Pb 2+ 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.