Inhibition Toxicity Of Some Pesticides, Heavy Metals, And Their Mixtures To Vibrio Qinghaiensis Sp.-Q67

Some herbicides, insecticides, and heavy metals were selected as the target compounds. Using the inhibition of luminous intensity of Vibrio qinghaiensis sp.—Q67 as toxicity indicators, the rules of toxicities change for the target compounds as well as their mixtures were studied through the microplate toxicity test procedure. The results can provide theoretical basis and statistic supports for the ecological risk assessment of pesticides and heavy metals.Using the microplate toxicity test procedure, the toxicities of twelve pesticides (desmetryn, metribuzin, metamitron, simetryn, prometon, velpar, glyphosate, asulam, dicamba, diquat, bromacil, and dichlorvos) and eight heavy metal compounds (CdCl₂·2.5H₂O, Ni(NO₃)₂·6H₂O, CoSO₄·7H₂O, ZnSO₄·7H₂O, HgCl₂, Fe(NO₃)₃·9H₂O, MnCl₂·4H₂O, and CuSO₄·5H₂O) to Vibrio qinghaiensis sp.—Q67 were examined. The result showed that all the tested substances have the typical S-shaped dose-response curve (DRC), and all the DRCs can be effectively described by the Weibull or Logit function.The combined toxicities among three equivalent-effect concentration ratio mixtures (EE6-01, EE6-10, and EE6-50) and six uniform design concentration ratio mixtures (UD6-1～UD6-6) including six pesticides, dichlorvos, bromacil, diquat, velpar, prometon, and simetryn, to Vibrio qinghaiensis sp.—Q67 were examined. The total-response of mixtures with the diverse concentration compositions of six pesticides were predicted by the dose addition (DA) and independent action (IA) principles. It was found that the total-dose-response curves (t-DRCs) of three mixtures, EE6-50, UD6-2, and UD6-4, which have a high concentration of diquat were deviated from the DRCs predicted by DA principle, showed independent action or synergism feature, whereas the combined toxicities of the other six mixtures could be evaluated by the DA model. To examine the special effect of diquat on the mixture toxicity, three five- pesticide mixtures excluding the diquat were constructed. The results showed that the DRCs of the new three mixtures had no significant differences from the DRCs predicted by the DA model.Finally, 5 herbicides, Dicamba, Asulam, Simetryn, Bromacil, and Velpar, and 4 heavy metal compounds, CdCl₂·2.5H₂O, Ni(NO₃)₂·6H₂O, CoSO₄·7H₂O, and ZnSO₄·7H₂O were selected as the target compounds. The combined toxicities among three equivalent-effect concentration ratio mixtures (EE9-05, EE9-10, and EE9-50) and ten uniform design concentration ratio mixtures (UD9-01^UD9-10) to Vibrio qinghaiensis sp.—Q67 were examined. Through comparing the observed toxicities and the ones predicted by DA and IA models, we can see that the toxicities of mixtures with the diverse concentration compositions of five different herbicides and four heavy metals could be evaluated by the DA model.