Environmental history told by mussel shells

Abstract

Each year a mussel produces an incremental layer of its shell composed mainly of calcium carbonate and a small fraction of organic substance. Many other elements are simultaneously deposited in these annual layers and are assumed to be essentially immobile. Although use of shells of bivalves has been suggested for monitoring metals in natural waters, little is known of the relationship of environmental conditions and age of molluscs with the concentration and distribution of elements in the shell. The nuclear microprobe was used to determine the temporal history of concentrations of elements in a shell of the freshwater mussel Anodonta. The high spatial (3 μm) resolution allowed analyses within parts of single years.