Biographical note of the first author: Xiu-Ling JI, female, born in 1975, assistant Professor, majoring in ecotoxicology and environmental chemistry. Correspondence should be addressed to Prof. Wen-Hua WANG. 800 Dongchuan Road, Shanghai 200740, China. Tel: 86-21-54745262; Fax 86-21-54740825. E-mail: whwang@sjtu.edu.cn