Experimental Study On The Distribution And Migration Of Escherichia Coli In Multi-media

Sewage,sludge and livestock manure contain a large number of pathogenic microorganisms,and once they are applied to the soil,they will lead to a large number of pathogenic microorganisms entering the soil environment,which will ignite soil biological pollution at any time and then pose a serious threat to agricultural products and water sources.In this study,the distribution and migration characteristics of E.coli in multi-media were systematically studied by combining sampling analysis,static batch experiments and pot experiments,taking environmental pollution indicator bacteriaE.coli as the research object and lettuce as the test plant,elucidating the adsorption kinetic model of E.coli in soil,revealing the distribution characteristics of E.coli in interrhizosphere soil,non-rhizosphere soil,plant and drench solution and its influence on this basis,we explore the conceptual model of E.coli migration characteristics in water-soil plant systems,and provide data support for the control and abatement of biological pollution in agricultural soils,agricultural products and groundwater.The main conclusions obtained in this paper are as follows:(1)The quasi-secondary kinetic equation can better characterize the adsorption kinetics of soil on E.coli in arable land.The adsorption rate of soil on E.coli is mainly controlled by both surface adsorption and extra-particle diffusion;the adsorption kinetic process of soil on E.coli goes through three stages: fast(0-20 min),slow(20-60 min)and equilibrium(80-120 min);the adsorption of soil on the adsorption of E.coli by soil was significantly influenced by biochar,ionic strength and indigenous microorganisms.(2)Biochar,ionic strength and indigenous microorganisms significantly affected the distribution characteristics of E.coli in multi-media(P<0.05),where the addition of biochar and the presence of indigenous microorganisms significantly reduced the retention of E.coli in non-rhizosphere soil,inter-rhizosphere soil,leachate and lettuce,and the increase of ionic strength significantly reduced the retention of E.coli in nonrhizosphere soil.(3)The distribution of E.coli numbers in the multi-media was in the order of noninter-rhizosphere soil > inter-rhizosphere soil > leachate > lettuce,with a decreasing trend in time.(4)E.coli had significant migration characteristics in the water-soil-plant multimedia.On day 18 of the pot test,the number of E.coli retained by the soil ranged from0.079% to 0.830%,migrated to lettuce from 0.0002‰ to 0.0009‰,and penetrated the soil to the drench solution from 0.010% to 0.053%;on day 60 of the pot test,the percentage of E.coli retained in the soil ranged from 0.0016% to 0.0092%,migrated to lettuce from 0.0003(?) to 0.0057(?),and penetrated the soil to the drench solution from0.0010% to 0.0048.(5)The results of the above studies show that the potential contamination risk of biological contamination of soil to agricultural products and water sources cannot be ignored.