Minor and trace element chemistry of modern shells: a laser ablation inductively coupled plasma mass spectrometry study

Laser ablation inductively coupled plasma mass spectrometry was used in a study of minor and trace metal contents of the hard parts of modern shelly organisms from the west coast of Wales. This technique achieves sub-parts per million sensitivities with a spatial resolution of 25 μm. Seasonal variations in Mg are observed in Patella vulgata, Patella aspera and Mytilus edulis which relate to variations in water temperature. Lead, Zn and Cu are unevenly distributed in the shells. Large, long-lived bivalves such as Arctica islandica have the potential to record single, major pollution events from which chronologies may be erected, as well as reflecting regional geochemical differences. The maximum pollutant metal contents of Patella sp., a grazer and Mytilus edulis, a filter feeder, reflect both the regional seawater chemistry of Cardigan Bay and the feeding mode. Bulk shell compositions will not necessarily reflect these features. The soft tissues concentrate metals over a long period and show lower-magnitude regional variations than the hard parts.