Abstract:

The stable isotope technique tracing the mechanism of petroleum hydrocarbon biodegradation is a newly developed and effective method in recent years. The variations of TPH, DIC and the dominant terminal electron accepters (SO^2-₄ and so on), δ¹³C and δ³⁴S of DIC and SO^2-₄ have been analyzed on the basis of the geological and hydrogeological conditions of a petroleum hydrocarbon contaminated site. The results indicate that the groundwater was contaminated by petroleum hydrocarbons at various degrees and the values of electron accepters and pH increased along the groundwater flow in the central line of the plume while TPH and DIC reduced. The value of δ¹³C was lower than that of the uncontaminated groundwater and it decreased with DIC along the flow direction. The result of stable carbon isotope balance shows that the increase of DIC of gorundwater is mainly originated from biodegradation of petroleum hydrocarbon. Meanwhile, the values of δ³⁴S decreased along the plume while SO^2-₄ increased and it can be inferred that the biodegradation of petroleum hydrocarbon with the bacterial sulfate reduction be undergone if the Rayleigh model is assumed.

Key words: groundwater pollution, petroleum, biodegradation, isotope