1. State
Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P R China
2. National
Water Quality Laboratory, U.S. Geological Survey, Denver, Colorado 80225, United States
3. Aquatic
Toxicology Laboratory, St. Cloud State University, St. Cloud, Minnesota 56301, United States
4. U.S. Geological Survey, Iowa City, Iowa 52240, United States