1. Lecturer, School of Mathematics and Physics, China Univ. of Geosciences, Wuhan, Hubei 430074, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Hubei Key Laboratory of Yangtze River Basin Environmental Aquatic Science, China Univ. of Geosciences, Wuhan, Hubei 430078, China.
2. Professor, Dept. of Geology and Geophysics, Texas A&M Univ., College Station, TX 77843-3115 (corresponding author).
3. Ph.D. Candidate, School of Environmental Studies, China Univ. of Geosciences, Wuhan 430074, China.