LIU Yun-qin1, 2, 3, LIU Yun-guo, HU Xin-jiang
(1.College of Environmental Science and Engineering, Hunan Univ, Changsha,Hunan410082, China;2. Key Laboratory of Environmental Biology and Pollution Control of the Ministry of Education, Hunan Univ, Changsha,Hunan410082, China; 3. Hunan Vocational College of Commerce ,Changsha,Hunan410205 , China)