Groundwater pollution of petroleum hydrocarbons is one of serious environment issues

which has potential great impact on human health and environment ecosystem.Although some efforts have been made to remove the petroleum contaminants

the results seem to be unsatisfied.There are a number of compounds in petroleum pollutants with different functional groups(chainalkanes: Chs

cycloalkanes:Cys

aromatics: Ars

and asphaltenes: Aps)

and their existence phases and migration pathways are various in vadose zone.However

these diversities are often ignored in prediction of environmental impacts and in design of remedial measures.So

in the present paper based on a survey for real contaminated sites the experimental study was conducted in a soil column to simulate

during leaching by contaminated water

the residue and migration of petroleum fraction #em/em#.e.Chs

Cys

Ars and Aps

in vadose zone when they penetrate into the soil and water.While the distinctions caused by both compounds characteristics and media properties was discussed.The results demonstrated that differences in solubility

fugacity and viscosity of the compounds and relative permeability of media were mainly factors leading to their migration diversity.Leaching factors of Chs

Cys

Ars and Aps in fined soil were 38.2

11.7

83.6 and 7.4×10-3 mg·L-1

respectively.Hence

the migration of Chs and Ars (volatilizing factor 43.9 mg·L-1) were significant and so they could be leached out of soil column.Especially

Ars (volatilizing factor up to 43.9 mg·L-1) was easier to leach out.Conversely

Aps was inclined to remain or be entrapped in soil due to its powerful viscosity.Because the permeability was the lowest for fine soil column

the components and amount of hydrocarbons pollutants accumulated were more and great

mainly on its upper layers

and decreased rapidly with depth of column.In contrast

for medium and coarse soil column

the residues were main Aps

and distributed in the whole column.At the end of leaching

soil samples of three columns were collected to determine the types and concentrations of compounds remained in soil.The analysis results showed that Chs and Aps could be remained in vadose zone for a long period

which is useful and helpful for risk assessment and remedial implements.