CADMIUM BIOACCUMULATION BY CLAMS DWELLING IN DIFFERENT SALINITY REGIMES ALONG THE SAUDI COAST OF THE ARABIAN GULF

The objective of this study was to investigate Cd bioaccumulation in clams living in different salinities. Several hundred clams (Maritrix maritrix) and sediment samples were collected during 1985-1986 from 12 locations on the Saudi coastal areas of the Arabian Gulf. Soft tissue from each clam was removed and digested in HNO3. Sediments were also digested in HNO3. Cadmium in the recently collected seawater samples was extracted using pyrrolidine carbodithioic acid-chloroform system. Cadmium in all the collected samples was determined using an inductively coupled argon plasma analyzer. Concentrations of Cd in the sediments varied insignificantly between 0.1 and 0.22 mg kg-1. Significant geographical variations in the mean Cd concentrations in clams (P < 0.05) were found. Intrastation differences in Cd bioaccumulation were also significant. Correlation between biometric observations and Cd concentrations in clams was not significant (P < 0.05). Seawater salinity was significantly (P < 0.05) correlated to the mean Cd concentrations in clams and seawater. Cadmium accumulation in the clams was supported by the chemical behavior of Cd in seawater.