1. Key Laboratory of the Three Gorges Reservoir Region’s Eco-environments, Ministry of Education, Institute of Environment and Ecology, Chongqing University, 174 Shapingba Road, Chongqing 400045, P. R. China
2. Gastrointestinal Cancer Center, Chongqing University Cancer Hospital, 174 Shapingba Road, Chongqing 400045, P. R. China
3. School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074, P. R. China