1. Envair/Aerochem, Placitas, New Mexico, USA
2. Tropochem, Palo Alto, California, USA
3. Consultant, Danville, California, USA
4. Desert Research Institute, Reno, Nevada, USA
5. State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, People’s Republic of China