School of Geography, Beijing Normal University, Beijing, China

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hong Kong, China

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

now at: Nicholas School, Duke University, Durham, North Carolina, USA

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

Department of Chemistry, University of California, Irvine, California, USA

Argonne National Laboratory, Argonne, Illinois, USA