1. School of Environmental Sciences, University of East Anglia, Norwich NR47TJ, UK.
2. State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, AS, 10 Fenghui South Road, Post Office Box 17, China.
3. Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark.
4. Laboratoire Inter-universitaire des Systèmes Atmospherique, Universités Paris 7 and Paris 12, UMR CNRS 7583, Paris, France.
5. National Institute of Water and Atmospheric Research Centre for Chemical and Physical Oceanography, Department of Chemistry; Post Office Box 56; University of Otago, Dunedin, New Zealand.