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Effects of dissolved organic matter and nonionic surfactants on the ecotoxicity of pyrene in the soil

The present paper is concerned about our study findings of the effects of dissolved organic matter(DOM) and nonionic surfactants on ecotoxicity of pyrene in the soil.The results of our experiments show that DOM is a kind of surfactant.With the increase of its concentration,the surface tension of DOM solution would decrease more tardily by 14.9 mN/m in the range of test concentration.However,the surface tension of surfactant Tween-80 and Triton X-100 tends to decrease at the test concentration range on a big margin by 24.7 mN/m and 22.6 mN/m,respectively.The sensitive range of pyrene inhibiting root elongation of Oryza sativa stands from 0 to 200 mg/kg,while its maximal inhibition concentration is 100 mg/kg.At the presence of DOM,it would be possible for the eco-toxicity of pyrene to get alleviated with the inhabited degree related to surface activity.Such effects could be strengthened with increase of the concentration of DOM.In our experiment,we managed to alleviate the eco-toxicity of pyrene of Oryza sativa by adding DOM to the pyrene-contaminated soil,for example,by adding Tween-80 and Triton R X-100 to it.Joining DOM,and the surfactant Triton and Tween,the inhibition rate of pyrene root elongation is likely to get significantly reduced with increase of concentration of DOM and the surfactants,on the contrary,the seed germination index could be found increased with the rising concentration The results also indicated that,when DOM added to soil together with Tween-80 or TritonR X-100,the eco-toxicity of pyrene of Oryza sativa was weaker than that effected by adding DOM to soil singly,and strengthener than that effected by adding Tween-80 or TritonR X-100 singly.Comparing the DOM treatment individually,it would be possible to reduce the inhibitory effect of pyrene significantly on the root elongation of Oryza sativa,but the trend still turns to be declining with the increase of DOM mass fraction.To be sure,its inhibition rate is likely to drop by 8.26% to 15.47%(Tween-80) and 4.93% to 11.20%(Triton X-100) in the test concentration.