June 2008 Geology and GSA Today media highlights

Steven T. Goldsmith et al., The Ohio State University, Dept. of Earth Sciences, 267 Mendenhall Laboratory, Columbus, Ohio 43210, USA. Pages 483-486.

Goldsmith et al. completed one of the first known semicontinuous monitoring studies of large-scale particulate organic carbon (POC) delivery coupled with hyperpycnal suspended sediment concentrations during a typhoon event. This linkage provides evidence for the removal and potential rapid burial of significant quantities of organic carbon from terrestrial systems. These POC fluxes, when combined with storm-derived carbon dioxide consumption from silicate weathering, elucidate the important role these short-term aperiodic storm events on small mountainous rivers have on modifying Earth's climate over geologic time. As recent studies suggest, cyclone intensity and monsoonal frequency may be increasing owing to global warming; even larger POC fluxes, greater silicate weathering-driven carbon dioxide consumption, and more rapid organic carbon burial may occur in Taiwan and similar locales in the future. Goldsmith et al.'s study contributes to the understanding of delivery fluxes from small mountainous rivers and how these fluxes may change with future climate change. This work was completed under funding from the U.S. National Science Foundations' East Asia and Pacific Summer Institute and GEO-EAR Hydrologic Sciences programs.

Modern iron isotope perspective on the benthic iron shuttle and the redox evolution of ancient oceans

Silke Severmann et al., Dept. of Earth Sciences, 2258 Geology Building, University of California, Riverside, California 92521, USA. Pages 487-490.

Iron shuttling from shallow shelf sediments to deep basin sediments is a process that is characteristic of marine environments where oxygen is absent in the water column, such as the modern Black Sea. Severmann et al. show that this iron shuttle has a distinct iron isotope signature, which is preserved in the sediments, and which can be used to identify similar environments in the rock record. Although such environments are rather rare in the modern oxic ocean, they were much more widespread in the earlier parts of Earth's history. Severmann et al.'s isotope data from the Black Sea can therefore guide our interpretation of the geological record and help us to reconstruct the chemical composition of ancient oceans. Because the cycling of iron is very sensitive to the presence of oxygen, the iron isotope record may tell us when oxygen first appeared in the surface ocean and in the atmosphere.

Regulation of the monsoon climate by two different orbital rhythms and forcing mechanisms

Takeshi Nakagawa et al., Dept. of Geography, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK; . Pages 491-494.