1. College of Environmental Science and Engineering Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University) Ministry of Education Changsha 410082 P. R. China
2. Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hung Hom, Kowloon Hong Kong 999077 P. R. China
3. State Key Laboratory of Utilization of Woody Oil Resource Hunan Academy of Forestry Changsha 410004 P. R. China