Bioaccumulation kinetics and organ distribution of nickel in the marine clam (Protothaca staminea)

Man's activities, primarily fossil fuel combustion, currently introduce about 47 x 10/sup 6/ kg of Ni per year into the world's atmosphere; this rate is expected to increase greatly during the next 20 years. Much of this Ni is associated with sub-micron atmospheric particles. When these particles deposit at the sea surface, about 47% of the associated Ni is released in a soluble form that could enter marine food webs. Ni is normally present in seawater at 0.1 to 2.4 ..mu..g/L and Ni concentrations in marine pelycepods range from 0.05 to 3.2 ..mu..g/g dry wt, depending upon the location of collection. Higher concentrations of Ni in seawater may be toxic to marine life. The 48-h LC/sub 50/ for Ni is 1180 and 310 ..mu..g/L for oyster embryos and hard-shell clam embryos, respectively. Little information exists regarding the ability of marine shellfish to concentrate Ni from seawater. Our studies were undertaken to determine the degree of bioconcentration, kinetics of accumulation, and tissue distribution of Ni in marine clams exposed to seawater enriched with subtoxic levels of Ni.