Metals in sediments and the edible cockle Cerastoderma edule from two Moroccan Atlantic lagoons: Moulay Bou Selham and Sidi Moussa

Metals (Cd, Cu, Pb and Zn) were determined over a 3-year period in sediment s and bivalves Cerastoderma edule from two lagoon ecosystems on the Morocca n Atlantic coastline, Moulay Bou Selham and Sidi Moussa. Sediment metal con centrations were seasonally influenced, and were highest, generally, in win ter - possibly signifying an increased contribution from run-off from adjac ent arable land and roads. Neither site can be considered highly contaminat ed; however, Cd was enriched at Sidi Moussa, probably as a result of waste discharge from phosphate industries 20 km along the coast to the northeast. This ability to act as a sink for metals at distance from sources demonstr ates the need for surveillance in these sensitive environments. Copper and Zn concentrations in edible cockles C. edule appear to be regulated over th e concentration ranges currently found in lagoon sediments. In contrast, bo dy burdens of Pb and, to a lesser extent Cd, reflect sediment levels and mi ght be useful in future risk assessments. Metal concentrations Cerastoderma edule are seasonally related to the reproductive cycle, however, and sampl e timing will need to be standardised in future monitoring exercises. (C) 2 001 Elsevier Science Ltd. All rights reserved.