Abstract:

A series of experiments were conducted to study absorption, biodegradation and volatilization in natural attenuation of diesel pollution in sand layer of vadose zone quantitatively. According to the results of adsorption experiments, adsorption equilibrium time of diesel sewage by fine sand was 24 h, and theoretic absorption quantity to TPH was calculated to 234 mg/kg. At the same time, 1000 mg/L of HgCl₂ was confirmed to be the most effective inhibitor of biological effect. By exploring the three columns as contrasts,the first-order attenuation kinetics equations of biodegradation and volatilization in the diesel polluted sand layer of vadose zone were established respectively as   ρ（TPH）＝25.48e^{-0.002 7x}  and   ρ（TPH）= 25.48e^{-0.022 1x}, and the half-life times were 256.67 d and 31.36 d. According to the experiments,  the natural attenuation period  from un-polluted condtion to polluted condition by diesel palyed a key role in natural attenuation, in which absorption, biodegradation and volatilization all occupied  important proportions.

Key words: diesel, vadose zone, natural attenuation, pollution