Paleoclimate, Paleoceanography, and Global Biogeochemistry

Biogeochemical studies at Rutgers University draw on the expertise of several research groups to examine a diverse array of topics.  Geological and biological processes act together to modify atmospheric and seawater chemistry through time: tectonic outgassing and erosional processes are the primary suppliers of most major elements in geochemical cycles; biologically-mediated redox processes alter mobile elemental reservoirs before geological processes sequester (remove) elements from these mobile reservoirs.  This biological overprint of geological processes forms complex feedback loops in biogeochemical cycles that are recorded in proxy records; these proxies, studied in conjunction with numerical models, provide a window on paleobiogeochemical interactions through geologic time.

Recently, Rutgers researchers have published a series of important papers that document long-term changes in the global carbon cycle, and related these changes to changing atmospheric gas concentrations and mammal evolution.  We use high-resolution d13Ccarb records of carbonates (d13Ccarb, Katz et al., 2005a) and organic matter (d13Corg, Falkowski et al., 2005), in conjunction with published sulfur isotopes of sulfates (Kampschulte and Strauss, 2004), in model simulations to reconstruct carbon sequestration and atmospheric CO2 (Katz et al., in press) and O2 levels (Falkowski et al., 2005) (Figure 1).  These model results indicate that organic carbon burial and pO2 have increased since the Early Jurassic, while pCO2 has decreased since the Early Cretaceous.  The overall increase in O2 was a critical factor in the evolution, radiation, and subsequent increase in average size of placental mammals (Falkowski et al., 2005).

References:

Falkowski, P.G., Katz, M.E., Milligan, A., Fennel, K., Cramer, B.S., Aubry, M.P., Berner, R.A., Novacek, M., and Zapole, W.M., 2005. The rise of oxygen over the past 205 million years and the evolution of large placental mammals. Science 309:2202-2204.

Kampschulte, A., Strauss, H. , 2004. The sulfur isotopic evolution of Phanerozoic seawater based on the analysis of structurally substituted sulfate in carbonates

Chemical Geology 204:255-286.

Katz, M.E., Wright, J.D., Miller, K.G., Cramer, B.S., Fennel, K., and Falkowski, P.G., 2005a. Biological overprint of the geological carbon cycle. Marine Geology. 217:323-338.

Katz, M.E., Fennel, K., Berner, R.A., and Falkowski, P.G., 2005b. Long-Term Trends in the Global Carbon Cycle: Biogeochemical Records of the Past ~200 myrs. AGU Ann. Mtg. San Franciso CA.

Katz, M.E., Fennel, K., and Falkowski, P.G., in press. Geochemical and biological consequences of phytoplankton evolution. In: Evolution of Aquatic Photoautotrophs, Falkowski, P.G. and Knoll, A., Editors.