The concentrations of heavy metals, Mn, Zn, Fe and Hg were determined
in sediments and in the whole soft tissue of the clam Galatea paradoxa
from two clam fishing locations, Ada and Aveglo at the Volta estuary
in Ghana from March to September 2008. Thirty clams were obtained from
each sampling location monthly and grouped into three size classes of
10 individuals each based on shell lengths as follows: small (25-40mm),
medium (41-55mm), and large (above 55mm). Metal concentrations in the
tissues of the different clam size-classes from the two stations were
similar and did not vary significantly.A comparative evaluation of the
metal concentrations in the clams and sediments however, revealed
significant variations in concentrations for Zn, Fe and, Hg.
Concentration of Fe in the sediment from Ada for June was 18 times
higher than the concentration in the clams similarly, Hg concentrations
were approximately 5 times higher in the clam tissues than in the
sediments. On the basis of calculated BSAFs the metal enrichment in the
tissues of the clams rank in the following order Hg>Mn>Fe. The
BSAFs indicated a significant accumulation of Hg in the clam tissues
relative to the concentrations of other metals in the sediments. The
concentrations of the studied metal in the clam and sediment samples
are similar to those observed in areas under low pollution impact and
the current the levels of contamination of these metals in the estuary
do not exceed the clams′ capacity of regulation