AGU Journal Highlights -- March 19, 2008

Title: A kinematic model for the East African Rift

Authors: D. Sarah Stamps and Eric Calais: Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana, U.S.A.;

Elifuraha Saria: University College for Lands and Architectural Studies, University of Dar Es Salaam, Dar Es Salaam, Tanzania;

Chris Hartnady: Umvoto Africa Ltd., Cape Town, South Africa;

Jean-Mathieu Mocquet: CNRS Géosciences Azur, Valbonne, France;

Cynthia J. Ebinger: Department of Geology and Geophysics, University of Rochester, Rochester, New York, U.S.A.;

Rui M. Fernandes: CGUL, IDL, UBI, Covilha, Portugal

Source: Geophysical Research Letters (GRL) paper 10.1029/2007GL032781, 2008; http://dx.doi.org/10.1029/2007GL032781

11. Corals’ skeletons record nutrient changes

Physical and biogeochemical processes linked to climate variations control the concentration of nutrients within the low-latitude ocean. However, methods for reconstructing past nutrient concentrations in the surface ocean are few and indirect. LaVigne et al. hypothesize that massive coral skeletons, which grow in continuous annual bands, preserve a record of seawater nutrient concentrations present when the organism laid down each band. Noting that phosphorus is often a limiting nutrient in the ocean, the authors analyze a four-year record from a coral sample collected from the Gulf of Panamá where deep waters upwell. Using a laser ablation technique, they found that the ratio of phosphorus to calcium within the coral skeleton tracks the ratio of strontium to calcium. Because high strontium-to-calcium ratios indicate cooler ocean temperatures, the authors are able to link the coral skeleton phosphorus content to documented seasonal upwelling of cold nutrient-rich water. The authors expect that further development of this new method will allow scientists to reconstruct changes in past nutrient availability in the tropics and subtropics with high precision over long timescales.

Title: Skeletal P/Ca tracks upwelling in Gulf of Panamá coral: Evidence for a new seawater phosphate proxy

Authors: Michèle LaVigne, M. Paul Field, and Eleni Anagnostou: Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, U.S.A.;

Andréa G. Grottoli: School of Earth and Planetary Sciences, Ohio State University, Columbus, Ohio, U.S.A.;

Gerard M. Wellington: Department of Biology and Biochemistry, University of Houston, Houston, Texas, U.S.A.;

Robert M. Sherrell: Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, U.S.A.; also at Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey, U.S.A.

Source: Geophysical Research Letters (GRL) paper 10.1029/2007GL031926, 2008; http://dx.doi.org/10.1029/2007GL031926

12. Lead levels rose in North Pacific region atmosphere as declined around North Atlantic