Regulatory Effects Of Agronomic Measures On The Dissipation Of Typical Phthalic Acid Esters In Soil

Phthalic acid esters are esterified derivatives of phthalic acid,which are widely used as plasticizers in various plastic products,such as mulch film.Soil pollution from the leaching of phthalic acid esters in China is common,endangering the safety of farmland ecosystems and human health.Therefore,it has become an urgent issue about how to accelerate the dissipation of phthalate pollution in farmland soil for the national environmental protection department and agricultural department.In this study,bis（2-ethylhexyl）phthalate（DEHP）,which is frequently detected in soil environment,was used as the target pollutant.The effects of agricultural measeures such as adjusting soil moisture and adding micro-nano carbon materials on the dissipation of DEHP were explored,and the microbial mechanism was further elucidated,so as to provide theoretical basis and technical support for the bioremediation of phthalate-contaminated soil.The main results of this study are as follows:（1）The microcosmic culture experiment was performed to study the effect of the drying-wetting（DW）cycle on the dissipation of DEHP in LS（Lou soil）and RS（Red soil）（p<0.05）.The results showed that the dissipation of DEHP in LS was significantly inhibited but promoted in RS by DW cycle.The DW cycle inhibited the diversity of bacterila communities in LS,whereas have little effect on bacterial community in RS.Furthermore the RDA analysis and structural equation modeling showed that the dominating driving factors for the dissipation of DEHP were different in the two types of soils under the DW cycle.The inhibition of the DW cycles on DEHP dissipation in LS was mainly derived from a decline of the diversity of bacterial community,but the interplay between microbial functions and soil attributes TN、Fe²⁺contributed to the promotion of DEHP dissipation in RS under the DW cycles.（2）The impact of soil moisture on the dissipation of DEHP was assessed in LS and RS through microcosm culture experiment as well.The results showed that the increase of water content significantly inhibited the dissipation of DEHP in LS while promoted that in RS.The increase of water content inhibited the diversity and richness of bacterial communities in LS,changed the composition of bacterial communities,and reduced the relative abundance of significantly different bacterial genera in the soil.Contrary to LS,the increase of water content significantly increased the diversity in RS,but also inhibited the abundance of most bacterial genera in the soil,including potentially degrading microorganisms（p<0.05）.The RDA analysis further suggested that the dominating driving factors for the dissipation of DEHP were different in the two types of soils under the moisture gradient.（3）The impact of micro-nano carbon materials on the dissipation of DEHP was assessed in Fluvo-aquic soil（CS）and RS through pot experiments.The results showed that the increase in the particle size of the micro-nano carbon materials had no effect on the dissipation of DEHP but inhibited the growth of Chinese cabbage in CS under a dosage of 50 mg kg^-1.When the addition amount increased to 500 mg kg^-1,the inhibitory effect of micro-nano carbon materials on DEHP dissipation was enhanced with the increase of particle size but the micro-nano carbon materials promoted the growth of Chinese cabbage.Alpha analysis revealed that micro-nano carbon materials had no significant effect on the diversity of microbial communities,but the enrichment capacity and relative abundance of bacteria decreasd with the increase of the particle size under the high-dosage treatment of micro-nano carbon materials in CS.For RS,the inhibitory effect of micro-nano carbon materials on the dissipation of DEHP enhanced with the increase of particle size and the addition of micro-nano carbon materials was not conducive to vegetable growth.