Experimental Study On Migration Law Of Volatile Organic Pollutants In The Soil

In recent years, along with the intensification of various production activities,soil environment for human survival has suffered a serious threat by a growingnumber of toxic and hazardous substances, especially the organic pollution. Manyorganic compounds are carcinogenic, teratogenic and mutagenic, which affect humanhealth seriously. Organic pollutants in the soil which will enter the atmosphere,groundwater bodies and other media, through volatilization, leaching and otherprocesses, which leads to secondary pollution. Therefore, it has a very importantsignificance to strengthen the related research, master the migration andtransformation of volatile organic pollutants in the soil for the prevention andtreatment of soil and groundwater contamination caused by organic compounds.Migration law of volatile organic pollutants in soil has been studied by physicalsimulation experiment in the field. The experiments soil column is irrigated bypollution solution and the following conclusions can be drawn:①The movement of toluene and PCE in soil and water movement are notsynchronized. Gas migration rate is faster than solid-phase migration rate, which leadsto the solid-phase distribution of contaminants less than the gas distribution.34dayslater after irrigation(half an hour), only a small amount of toluene is detected in theupper40cm of solid-phase, and none is detected in the lower part, while toluene in thegas occupies the whole profile.141days later, PCE exists in the upper210cm ofsolid-phase with no detection in the deeper soil and gaseous PCE covers the entireprofile. It shows that the migration of volatile organic pollutants in the soil is not onlyinfluenced by the water movement, but also related to their volatility and diffusion inporous media. In porous media, volatilization and dispersion effect is an importantdriving force of migration and distribution of toluene and PCE in the case of soilmoisture driving force is not obvious.②Evaporation and dispersion effects are important driving force of migrationand distribution of toluene and PCE in the soil when the soil water driving force is notobvious in the porous media.For toluene and PCE in the soil, volatilization is themain migration patterns, solid-phase adsorption is an important mode of existence,and degradation and transformation is an important environmental fate.③As the volatile organic compounds, migration law of toluene is similar to PCE,but the migration speed and distribution are different. PCE more easily remain in the soil. PCE still exists in the solid-phase and gas after irrigation141days. Toluene is notdetected in the depth of50cm below of solid–phase after irrigation34days. Gaseoustoluene exist throughout the whole profile, but only be detected in the depth of120cmbelow.141days later, toluene has tended to trace existence.