Assessment of Toxicity Interactions of Azole Fungicides Mixtures on Raphidocelis subcapitata
The widespread presence of azole fungicides in aquatic environments has raised concerns about their po-tential harmful effects on the growth of aquatic organisms.However,the toxic interactions that may occur when these fungicides are combined remain largely unexplored.To investigate these interactions on non-target organisms,specifically green algae,we selected nine azole fungicides,namely difenoconazole,penconazole metconazole,tetra-conazole,flutriafol,fuberidazole,triflumizole,terrazole,and hymexazol,to create binary mixtures.A total of 173 binary mixtures were created using a direct equipartition ray design.The microplate toxicity analysis method was used to systematically measure the growth inhibition toxicity of these mixtures on Raphidocelis subcapitata.Toxici-ty was assessed using the negative logarithm of the median effective concentration(pEC50)as an indicator.The pEC50 values of 173 binary triazole fungicide mixtures ranged from 3.053 to 6.415.Mixtures containing metcona-zole and fuberidazole showed the highest toxicity,with maximum pEC50 values of 6.415 and 6.140,respectively.Toxicity interactions were qualitatively analyzed using concentration addition,independent action,and isobologram approaches.Quantitative assessments were performed using model deviation ratio,toxic unit,additivity index,mixture toxicity index,and combination index methods.The results showed that the binary mixtures designed with difenoconazole,penconazole,and triflumizole exhibited a higher frequency of synergistic effects,with occurrences of 46.9％,46.1％,and 61.1％,respectively.In contrast,mixtures designed with flutriafol,fuberidazole,and metcona-zole generally exhibited reduced toxicity,showing additive and antagonistic effects.The toxic unit,mixture toxicity index,and combination index methods produced more consistent evaluations of these interactions.The mixtures predominantly showed synergistic and additive effects at low concentrations,while additive and antagonistic effects were more prevalent at high concentrations.The interactions of the mixtures were mainly additive at environmental-ly relevant concentrations.
azole fungicidesRaphidocelis subcapitatacombined toxicitypredictive model
万方数据
维普
