See more from this Division: Topical Sessions
See more from this Session: Sclerochronological Archives from Rivers to the Sea: Documentation, Interpretation, and Utility
Abstract:
In unionid freshwater bivalves, δ18O has previously been applied as a proxy for water source or discharge. As shell aragonite is precipitated in isotopic equilibrium with the ambient water, analyzing growth increments can reveal seasonal patterns in δ18O.
The project (BSIK) aims at the reconstruction of late Holocene discharge patterns of the Rhine and Meuse rivers through geochemical analyses on growth increments of freshwater mussels.
We studied freshwater bivalves of the genus Unio. These are found naturally in the rivers Rhine and Meuse. The results of a monitoring experiment in which we examine the relationship between water and shell chemistry at high resolution are presented. The Unionids were kept in cages while temperature and pH were measured and water samples were taken every 14 days. After 18 months the shells were taken out and sampled at high resolution. We demonstrate that these species precipitate their shell in equilibrium with the ambient water. As such, unionid shell δ18O can serve as a proxy for past river composition and wet and dry periods.
Subsequently an extrapolation is made to the past. We show records of shells from archaeological finds and we present reconstructions of river water composition, floods and droughts for time slices in the Neolithic, Roman times, Middle Ages and Little Ice Age.
See more from this Division: Topical Sessions
See more from this Session: Sclerochronological Archives from Rivers to the Sea: Documentation, Interpretation, and Utility