<正>Methyl tert-butyl ether(MTBE),a gasoline additive,possesses serious problems to the environmental health.In the present study,a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil.The isolate was identified as Chryseobacterium sp.,a new species capable of degrading MTBE.In order to enhance its degradation ability,selected environment factors were investigated.The results showed that the optimal temperature was in the range of 25-30℃,the pH was 7.0, the inoculum size was 2×10~8 CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L.The maximum MTBE utilization rate(v_(max))was 102 nmol MTBE/(mg cell protein-h).Furthermore,it was found that the isolate could also degrade tert-butyl alcohol(TBA).The degradation rates of TBA were much faster than those of MTBE.The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration.Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture.
As an additive of gasoline,methyl tert-butyl ether(MTBE)has a higher solubility in water,which is about 20 times as high as that of benzene.This characteristic results in MTBE dissolving out of the gasoline into the soil and groundwater.Due to relative unique physicochemical behavior of MTBE it would be an ideal candidate for use in environmental forensic investigations.In order to study the transport and distribution of MTBE in saturated zone of ground water,a two-dimensional experimental cell was setup to simulate the real environment of the groundwater flow.The effects of soil and groundwater flow velocity on the MTBE transport were investigated.The results show that the mobile distance of MTBE in vertical direction was smaller than that in horizontal direction paralleling with the groundwater flow.Because the main dynamics of groundwater flow direction was convection and dispersion,the movement of MTBE is also diffusion in the vertical direction.In addition,the transport of MTBE was more quick in high permeability porous media,and the increase of groundwater flow velocity can accelerate the MTBE plume de-velopment,but the irregularity and randomness of the plume are enhanced synchronously.These research results can give some helps for the investigation of MTBE movement in the groundwater,also can make some references for other petroleum contamination behavior.
Li Hong Li Xingang Gao Chuanbo Huang Guoqiang Jiang Bin
