HR: 15:25h
AN: B13E-08    [Abstracts]
TI: Trace element proxies (Sr/Ca, Ba/Ca and Pb/Ca) in Bivalve shells: environmental signals or not?
AU: * Gillikin, D P
EM: David.Gillikin@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Dehairs, F
EM: fdehairs@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Steenmans, D
EM: calmar@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Meng, L
EM: calmar@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Haifeng, T
EM: calmar@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Navez, J
EM: jnavez@africamuseum.be
AF: Department of Geology Royal Museum for Central Africa, Leuvensesteenweg 13, Tervuren, 3080 Belgium
AU: Andre, L
EM: lucandre@africamuseum.be
AF: Department of Geology Royal Museum for Central Africa, Leuvensesteenweg 13, Tervuren, 3080 Belgium
AU: Baeyens, W
EM: wbaeyens@vub.ac.be
AF: Department of Analytical and Environmental Chemistry (ANCH) Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: Keppens, E
EM: ekeppens@vub.ac.be
AF: Department of Geology Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium
AU: CALMARS group, .
EM: calmar@vub.ac.be
AF: A BELSPO funded project, http://www.vub.ac.be/calmar, Brussels, 1050 Belgium
AB: Coral and sclerosponge skeletons have both been used as recorders of their environment. Sr/Ca, Ba/Ca and Pb/Ca have all shown to be useful in these substrates, giving insight into the past environment in which the skeleton grew (e.g., Lea et al., 1989, Nature 340, 373-376; Beck et al., 1992, Science 257, 644-647; Lazareth et al., 2000, Geology 28, 515-518; Rosenheim et al., 2004, Geology 32, 145-148). Although bivalves have not been studied as extensively as corals, these proxies are apparently not as reliable in bivalves (e.g., Vander Putten et al., 2000, GCA 64, 997-1011). We therefore investigate Sr/Ca and Pb/Ca in two species of aragonitic clams (Mercenaria mercenaria and Saxidomus giganteus) and Ba/Ca in the calcite layer of the mussel Mytilus edulis. Results indicate that Sr/Ca is primarily controlled by growth rate in S. giganteus whereas there was no relationship between these parameters in M. mercenaria. Pb/Ca is somewhat reproducible between specimens of S. giganteus, however long-term Pb/Ca records (1949-2003) in the shell of M. mercenaria did not show the expected curve of anthropogenically introduced lead, indicating that they are not recording environmental Pb concentrations. Therefore, Sr/Ca and Pb/Ca incorporation seem to be regulated by biological processes and not directly by environmental parameters. Ba/Ca in M. edulis shells on the other hand, does seem to be directly linked to the environment. Shells grown under laboratory and natural conditions both show the same linear relationship between dissolved Ba/Ca and shell Ba/Ca. Experiments involving manipulations of dissolved and particulate (i.e. food) Ba/Ca, suggest that the dominant pathway of barium into the shell is from the dissolved phase via the hemolymph. We were unable to explain the large peaks noted in the Ba/Ca profiles, however, they did not seem linked to phytoplankton blooms as has been previously suggested (Stecher et al., 1996, GCA 60, 3445-3456; Vander Putten et al., 2000; Lazareth et al., 2003, Est. Coast. Shelf Sci. 17, 1461-1470).
DE: 4875 Trace elements
DE: 4267 Paleoceanography
DE: 1040 Isotopic composition/chemistry
DE: 1045 Low-temperature geochemistry
DE: 1050 Marine geochemistry (4835, 4850)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting