title: The combined and second exposure effect of copper (II) and chlortetracycline on fresh water algae, Chlorella pyrenoidosa and Microcystis aeruginosa.
abstract: In the experiment, Chlorella pyrenoidosa and Microcystis aeruginosa were chosen to test the individual, combined and second exposure effect of Cu(2+) and chlortetracycline (CTC). The 96 h EC50s of each test were calculated, with the ranges of 0.972-15.6 μmol/L (Cu(2+)), 29.5-102.5 μmol/L (CTC), 14.4-78.9 μmol/L (mixture). The combined toxicities were evaluated with toxicity units (TU) method. The toxicity of complex of Cu(2+) and chlortetracycline was analyzed using concentration addition (CA) model. In the initial test, the combined effect of the two substances was partly additive to C. pyrenoidosa and antagonistic to M. aeruginosa, while in the second exposure test, the combined effect was synergistic to both algae. The biochemical indicators measured in the experiment included chlorophyll fluorescence (Fv/Fm), MDA content, SOD activity and content of soluble proteins. When under combined stress, the biochemical features of both algae were significantly different between the initial test and the second exposure test.
authors.affiliation: College of Resource and Environmental Science, Wuhan University, Wuhan, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Lu
authors.affiliation: College of Resource and Environmental Science, Wuhan University, Wuhan, PR China.
authors.forename: Yixiao
authors.initials: Y
authors.lastname: Wu
authors.affiliation: College of Resource and Environmental Science, Wuhan University, Wuhan, PR China.
authors.forename: Huijun
authors.initials: H
authors.lastname: Ding
authors.affiliation: College of Resource and Environmental Science, Wuhan University, Wuhan, PR China. Electronic address: zhangwh@whu.edu.cn.
authors.forename: Weihao
authors.initials: W
authors.lastname: Zhang
mesh_terms: D002708:Chlorella / Q000145:classification / Q000187:drug effects*; D002751:Chlortetracycline / Q000633:toxicity*; D003300:Copper / Q000633:toxicity*; D005618:Fresh Water; D046931:Microcystis / Q000145:classification / Q000187:drug effects*; D013045:Species Specificity
chemical_list: D003300:Copper; D002751:Chlortetracycline
keywords: Chlorella pyrenoidosa; Chlortetracycline; Copper; Microcystis aeruginosa; Second exposure