Fractional Distributions of Trace Metals in Surface Water of Lake Biwa as Studied by Ultrafiltration and ICP-MS

Department of Applied Chemistry, Graduate School of Engineering, Nagoya University,Furo-cho, Chikusa-ku, Nagoya 464-8603Received April 12, 2005; E-mail: haraguch@apchem.nagoya-u.ac.jpThe distributions of 33 trace metals in the total dissolved fraction (TDF), small molecular weight fraction (SMWF; 10000 Da) of surface water from two sampling stations(No. 1 and No. 2) in Lake Biwa (Japan) were investigated. In the experiment, the concentrations of trace metals inTDF and SMWF were determined by inductively coupled plasma mass spectrometry (ICP-MS) using a laboratory-madechelating resin-packed minicolumn for the preconcentration of trace metals. The concentrations of trace metals inLMWF were calculated by subtracting those in SMWF from those in TDF. The comparison between the distributionsof trace metals in each fraction collected from the sampling stations No. 1 and No. 2 was made, and the enrichmentfactors of trace metals in LMWF were estimated. As a result, it was found that soluble biogenic large molecule–metalcomplexes and hydrogenic particulates were predominantly distributed in LMWF of surface water from Lake Biwa.Furthermore, positive anomalies of Ce and Gd were observed in the shale-normalized rare earth element (REE) distri-bution patterns.The toxicities and bioavailabilities of trace metals in naturalwater depend not only on their total concentrations, but also ontheir distributions of various species as well as on their chemi-cal forms.