[Natural attenuation of BTEX in the underground environment].

It was found that the naturally attenuation of BTEX occurred. In this process, volatilization and biodegradation are the important mechanisms. Taking benzene for example, at the concentration of 11.40 mg/L, the relative proportions of volatilization and biodegradation accounting for natural degradation were 16.36% and 4.91%. Comparatively, at the concentration of 3.30 mg/L for toluene, the relative proportions of volatilization and biodegradation accounting for natural degradation were 11.04% and 41.50%. It demonstrated that different components of BTEX had different attenuation trends. Furthermore, the higher the concentration of BTEX was, the faster the BTEX volatilized, and more important volatilization was. The effect of biodegradation on toluene was more efficiency, whose proportion accounting for natural degradation was 41.50%, and xylene only occupied 8.49%, while, benzene and ethylbenzene were hardly degraded.