The Study Of Joint Toxicity Of Acetochlor,Butachlor And Heavy Metals On Photobacterium Phosphoreum And Zebrafish (B.Rerio) Embryos

Photobacterium phosphoreum and zebrafish embryos were selected as the researchorganisms in the experiment. Single toxicities of herbicides acetochlor and butachlor,heavymetals Cu and Zn on the two organisms were tested. The joint toxicities of binary mixturesand ternary mixtures made up of acetochlor,butachlor and heavy metals on photobacteriumphosphoreum and zebrafish(B. Rerio)embryos at different proportions(toxic unit ratios were1:1,1:4,4:1 and 1:1:1) were also studied.The experiment indicated that the differences of single toxicities on photobacteriumphosphoreum among the four chemicals were not too big and their orders of magnitude weresimilar. Among the four chemicals, Zn was the most toxic to photobacterium phosphoreum ,acetochlor the second, and Cu was the least toxic. Great discrepancy of their effects onzebrafish(B. Rerio)embryos was found at different developing stages. But mostly, thesequence of their toxicities on B. Rerio embryos was Cu>butachlor>acetochlor>Zn. Themost sensitive endpoint of butachlor on zebrafish embryos was development of the eye andspontaneous movements within 20 seconds at 24h. The most sensitive endpoints of other threechemicals were the same--rate of hatched at 72h. The most sensitive dead-endpoints of thefour chemicals on zebrafish embryos were 72h-Coagulated eggs(Cu24,48,72h wrere thesame). Butachlor had differential nerve toxicity on B. Rerio embryos, which was alsodiscovered due to the experiment.Toxic unit(TU),additional index(AI) and mixture toxic index(MTI) were adopted toevaluate the joint toxic effects of acetochlor,butachlor and heavy metals on P. phosphoreum. The samemeans were also adopted to evaluate the joint toxic effects of acetochlor,butachlor and heavymetals on B. Rerio embryos.Different evaluating methods might have different evaluations on the same experimentalresults, which was found via the experiment and the evaluating results. But most evaluationswere uniform. However, after the evaluating parameters were analyzed, the conclusiveevaluations were got, which were more accurate and more significative.The combined toxicological experiment showed: same chemicals at different toxic unitratios might not have same joint toxic effects on organisms and sometimes, the differencesmight be very big. The experiment also showed: different creatures might get differentsensitivities on chemicals and mixtures might not represent same joint toxic effects on them.Though acetochlor and butachlor were homologues, if they combined with the same heavymetals at same toxic ratios, their joint effects on the same creatures might differentiate greatly,and some of the effects might be opposite. Thus, whether we could estimate the joint toxicityof mixture by its homologues, needed to be considered.The experimental results confirmed that photobacterium phosphoreum and zebrafish(B.Rerio)embryos were favourable to carry out combined toxicological experiment. With theirnormative,rigorous experimental methods and exact results, the two creatures could beapplied to detect the joint toxicities of chemicals widely.