Abstract
Tish investigation was conducted in order to examine whether the content of heavy metals, i. e., mercury, cadmium, leed, copper, zine, manganese, nickel, cobalt, chromium, and arsenic in short-neck clams Tapes japonica, was correlated with that in the nearby mud.
Pair samples, clam and mud, were simultaneously collected from fifteen stations of the waters of the Inland Sea in Yamaguchi Prefecture where industrial pollution was not expected. After wet digestion, the heavy metals in the edible portion of the clam samples were determined by colorimetric and atomic absorption spectrometric methods. The mud samples were treated with acid extraction (0.1 NHCI and 0.001 NHCI) in addition to wet digestion, and the metals were determnined by the same methods as used for the clam samples.
The results obtained are as follows:
1. In the mud samples, the extraction rate of heavy meatls by acid solutions varied widely with the kind of metals and the location of sampling. The variation was highest for cadmium and lowest for mercury.
2. The levels of heavy metals in the short-neck clams and the mud were within the standards of food hygiene and environmental sanitatio, respectively.
3. There was no relationship between the heavy metal contents in short-neck clams and those in the mud where the clam inhabited.
