Gastropod shells as pollution indicators, Red Sea coast, Egypt

Thirty samples of gastropod shells belonging to Nerita albicilla and Canarium (Gibberulus) gibbosus from 15 stations along the Egyptian Red Sea coast were selected for chemical analysis. The analysis indicated that Nerita is a geochemical marker for a sizeable group of trace elements including; Cu, Pb, Zn, Ag, Th, Ba, Tl, S, Sc and Se, while Canarium is a good accumulator of the elements, Mo, U, Au and K. Both species have the same selectivity for Ni, Mn, Fe, As, Sr and P. The differences in sensitivity between the two species are attributed to the mode of life and incorporation of the elements within the crystal lattice of calcium carbonates composing the shells. On basis of the obtained data, the study area can be subdivided into three zones namely; almost pristine, moderately polluted zone and markedly polluted. Pollution is mostly attributed to anthropogenic sources.