Geology. (Abstracts-2003 Annual Meetings)

Article excerpt

George McCready Price and the Founders of the Law of Faunal Succession. Ralph Stearley, Calvin College, Department of Geology, Geography & Environmental Studies, Grand Rapids, MI 49546

George McCready Price is credited with launching the twentieth-century movement known as "flood geology' (Numbers 1992). His long publishing career spanned over 50 years. Price accomplished most of his geological research by reading reports and textbooks authored by others; he lacked formal geological training and had little field experience. Price reasoned from his armchair that formations could not be universal in geographic scope and hence their combined faunas were being illegitimately extrapolated to global significance. In particular, Price (The New Geology, 1923) accused William Smith and Georges Cuvier of extrapolating a "crude rule of thumb" that may or may not have been of local use, to the scope of a "cosmogony.' Price further belittled Smith as "ignorant." Price, however, exhibited a profound ignorance of the history of field-oriented empirical research, which led to the generalization of the law of faunal succession. This ignorance and associated armchair cynicism were bequeathed to the flood geo logy movement which blossomed in the last half of the twentieth century.

Seasonal Variation in Trace Metal Association with Iron and Manganese (Hydr) Oxides in the Kalamazoo River Watershed, Kalamazoo, Michigan. Noah Ndenga, Carla M. Koretsky, Doug Miller, and Johnson Haas, Western Michigan University, Department of Geosciences, Kalamazoo, MI 49008

Seasonal variability of trace metal speciation associated with seasonal changes in vertical redox stratification was studied in freshwater lake and marsh sediments from the Kalamazoo River watershed. Pore waters and sediments were sampled anaerobically at 1-2 cm intervals from the SWI to -50 cm depth during fall 2001 and winter, spring, and summer 2002. The fresh pore waters were analyzed for pH, alkalinity, dissolved Fe(II)/Fe(III), Mn(II), sulfide, sulfate, ammonium, and phosphate. A two-step sequential extraction procedure was used to assess the concentration of trace metals (Cr, Co, Cu, Zn, Cd, Pb, and U) associated with "readily microbially reducible" amorphous and crystalline Fe and Mn (hydr) oxide minerals (Kostka and Luther, 1994, GCA 58, 1701). Porosities and organic carbon of the sediment were also determined. Consistently higher concentrations of Fe, Mn, Cr, and U were present in the ascorbic acid fraction, while Pb, Zn, and Cu were always enriched in the HCl fraction. There was also a consistent d ecrease in concentrations of ascorbate extractable Fe and Mn between winter and summer.

Competitive Effects of Uranyl-Organic Complexes on U(VI) Reduction by Shewanella putrefaciens. Abraham Northup and Johnson Haas, Western Michigan University, Department of Geosciences, Kalamazoo, MI 49008

Previous work by Haas and DiChristina (ES&T 2002,36) demonstrates that Fe(III) reduction by the facultative Fe(III)-reducing bacterium S. putrefaciens is mediated by competitive speciation among dissolved organic ligands and functional groups on the cell surface. Haas and DiChristina (2002) showed that rates of Fe(III) reduction by S. putrefaciens correlate with the thermodynamic stability constants of the Fe(III)-organic ligand complexes. The aforementioned work served as a comparative study for U(VI) reduction by S. putrefaciens. S. putrefaciens can also use U(VI) as a terminal electron acceptor, coupling U(VI) reduction to growth. In this study, S. purrefaciens was incubated in experimental media containing U(VI) in the form of aqueous complexes with a variety of organic ligands that differ significantly in structure and stability with respect to U(VI) chelation. Rates of U(VI) reduction by S. putrefaciens vary strongly as a function of U(VI) aqueous speciarion. In contrast with Fe(III) reduction by this bacterium, inhibition of U(VI) reduction does not appear to vary as a simple function of thermodynamic stability constants of the appropriate 1:1 metal organic complex. …