Heavy metals availability in sediments and their accumulation in two edible bivalves at Suez Bay, Egypt

Sediment samples were collected from 23 stations in the inshore and offshore zones of Suez Bay, Egypt, along with two edible bivalve species, Callista sp. and Circenita callipyga. The grain size analyses revealed that the Suez Bay seafloor sediments were mostly made up of sand, with minor constituents of gravel and mud. The bioavailable forms of Fe, Mn, Zn, Cu, Ni, Pb, and Cd were estimated by using a flame atomic absorption spectrophotometer on the bulk sediment and the finest fractions Ø3, Ø4 and Ø5 samples (AAS). At both the inshore and offshore stations, Fe and Mn had the highest concentrations in sediment, while Ni had the lowest. In budding plants, Pb and Cd were insignificant in bulk sediments in spite of their abundance in the finest fractions. For evaluating heavy metals accumulation in their soft tissue, about 30 individuals of Callista sp. and Circenita callipyga (commonly known as the Venus Clam) were chosen. Except for Pb and Cd in Callista sp., all metal concentrations in soft tissues of the two bivalve species were lower than the allowed limits. The bio-sediment accumulation factor (BSAF) was calculated to assess bivalves' ability to bioaccumulate metals in their soft tissues. The data revealed that all of the analysed metals in the collected bivalve species had BSAF values less than unity (<1.0 μg/g wet weight), with the exception of Cd, which had the highest BSAF value in Callista sp (2.13 μg/g wet weight).