Abstract: The limit of detection (LOD) was increased by preserving with methanol when collecting soil volatile organic compounds (VOCs), which may result in undetecting of higher levels of VOCs. Thus, it exerts the influence on the determination of site pollution risk. Firstly, the improvement range of LOD after soil VOCs sampling preserved with methanol was calculated. Secondly, it is assumed that the contents of 62 VOCs commonly in soil were equal to the screening value (or risk control value) of soil contamination of construction land. Thirdly, the comparisons between the improved LODs and screening values (or risk control values) of these VOCs were made to analyze the risk levels of contaminated site. According to the analysis, the corresponding sampling suggestions were put forward. The results show that 1,2,3-trichloropropane, 1,2-Dibromoethane and chloroethylene were the most affected pollutants in the first type of construction land use, followed by vinyl chloride, bromodichloromethane, trichloromethane, 1,1-dichloropropene, 1,2-dibromo-3-chloropropane, 1,2-dichloroethane, methyl bromide, 1, 1,2-trichloroethane, benzene, trichloroethylene, carbon tetrachloride, 1,2-dichloropropane, while other pollutants had little effect. Nevertheless, trichloromethane, 1,2,3-trichloropropane, 1,2-dibromoethane and vinyl chloride were the moderately affected pollutants in the second type of construction land use, while other pollutants had been little affected.

Key words: risk screening values for soil contamination, risk control values for soil contamination, volatile organic compounds, methanol, determination of site pollution risk