Abstract: The contamination of crude oil in the sea is a major threat to marine organism and the environment

safely. The detection of crude oil in the sand near the sea is of significance to petroleum exploration and environmental

protection. Reflected terahertz time-domain spectroscopy is used for the quantitative detection of the crude

oil in the sand. A detailed analysis is performed about the delay time and wave velocity across the sample. The research

indicates that the relationship between the crude oil concentration and the delay time shows linear decrement

character，the reflected terahertz time-domain spectroscopy is a potential method for quantitative detection in the

environmental protection.

Key words: crude oil, terahertz wave, pollution, quantitative analysis