Trace metals with seasonal considerations in coastal algae and molluscs from Beirut,Lebanon

Twelve species of intertidal algae and molluscs from Ras Beirut, Lebanon have been investigated for their heavy metal content. Atomic absorption spectrophotometric analysis showed that the algae and molluscs concentrated similar levels of most metals. However, of the twelve organisms, Brachydontes variabilis had the highest copper, Patella coerulea and Colpomenia sinuosa had the highest iron, and Pinctada radiata had the highest zinc values with rather elevated cadmium. Cystoseira spinosa concentrated the lowest levels of zinc, and nickel was variable in all organisms.Seasonal comparisons of metal levels were also considered in three algae and three molluscs studied previously. The only signs of seasonal variation in the algae were with nickel and iron in Halimeda tuna and lead in Pterocladia pinnata. Both cadmium and lead were generally lowest in the spring samples of the algae. Lead and nickel concentrations in the molluscs were generally highest in the summer and lowest in the spring. Slight seasonal trends were seen with lead and iron in Brachydontes variabilis and lead in Monodonta turbinata.The lack of comparison data from the Mediterranean, particularly the eastern basin, makes it essential that studies of this nature be continued.