Bull. Environ. Contam. Toxicol. (1995)54:191-197 91995Springer-Verlag New York Inc. i Snvironrrmntal Co~l~. rnir~t, ion ano ~ico~:gy Geochemical Partitioning of Trace Metals in the Potential Culture-Bed of the Marine Bivalve, Anadara granosa M. J. Maah, I. Mat, A. Johari Centre for Foundation Studies in Science, University of Malaya, 59100 Kuala Lumpur, Malaysia Received: 31 December 1993/Accepted:25 August 1994 The relative distribution of trace metals in coastal sediment geochemical phases has received considerable attention as a mean of assessing the degree of trace metal pollution (Rosental et al. 1986; Abaychi and Douabul 1986; Rule and Alden 1992; Abu-Hilal 1993). Metals in the non-residual fraction (exchangeable, carbonate, easily reducible, moderately reducible and organic phases) have been demonstrated to be strongly correlated with tissue-metal concentrations in various benthic organisms (Luoma and Bryan 1978; Langston 1982; Bourgoin et al. 1991). Among these phases, the oxides of manganese (easily reducible phase) and iron (moderately reducible phase) and organic matter have been emphasized as important scavengers of available trace metals (Arakel and Hongjun 1991; Young and Harvey 1992; Abu-Hilal 1993). Therefore, these phases are undoubtedly among the criteria that should be considered explicitly when assessing the potential bioavailability of metals. The marine bivalve Anadara granosa is commercially cultured in the tidal mudflats along the western coast of the Peninsular Malaysia. The purpose of this study was to provide an assessment of the geochemical partitioning of trace metals in sediments collected from a culture-bed ofA. granosa. The selected area is thought to receive minimal or restricted impacts of trace metal pollution. The present investigation is of significance as a baseline of information for comparative studies with other aquaculture areas in the region. MATERIALS AND METHODS Tidal mud flats along the Straits of Tuba separating the Island of Dayang Bunting and the Island of Tuba of Langkawi Archipelago, Peninsular Malaysia were selected as study sites (Fig. 1). These areas have been designated by the Fisheries Department of Malaysia as the potential culture-bed for A. granosa. Surficial sediments (upper 5 cm) were manually sampled with acid-washed plastic tubes from four stations between the mean high water and low water neap tide levels. Three pooled samples approximately 300 m apart were designated for each station. The sediments are texturally homogeneous and at least partially anaerobic due to the presence of a black-sulphide rich layer about 3-5 cm below the sediment-water interface. However, attempts were not made to purge the atmospheric air with nitrogen during the sampling period. Correspondence to: M. J. Maah 191