Screening and Distribution Characteristics of Odorous Substances in Soil of Typical Pesticide-Contaminated Site
MA Yan;ZHENG Hongguang;SHI Yi;ZHANG Fan;YAO Juejun;ZHAO Weiguang;DU Xiaoming;School of Chemical and Environmental Engineering, China University of Mining & Technology-Beijing;Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment;Chinese Research Academy of Environmental Sciences;
The prominent environmental problems caused by odors in the remediation of pesticide-contaminated sites in China have become important for screening the odorous substances in the soil and clarifying the distribution of odor substances in the soil. In this study, a typical pesticide-contaminated site was selected as the study area, the main odorous substances in the soil were screened by scan analysis of soil gas samples, compared with the odor list, and the odor activity values and cumulative odor contribution were calculated.Based on the screening results, soil samples were collected and analyzed by GC-MS to determine the extent of pollution and spatial distribution of the main odor substances in the soil. The results showed that:(1) The main odorous substances found at the site were dimethyl sulfide, dimethyl disulfide, toluene, trichloroethylene, carbon disulfide, chloroform, o-xylene, m/p-xylene, benzene, thiophene,methylcyclohexane, n-hexane, tetrachloroethylene, ethylbenzene, and carbon tetrachloride(15 kinds of odor substances). Their Odor Activity values were 7,287.5, 2,755.6, 714.8, 676.7, 438.5, 294.5, 229.4, 74.7, 55.4, 50.0, 49.6, 18.9, 3.1, 1.7 and 0.6, respectively.(2) The main odor substances with cumulative odor contribution of more than 90% were dimethyl sulfide, dimethyl disulfide, and toluene,trichloroethylene. The highest contents of these main odor substances were 10.9, 48.5, 797.7 and 33,000.0 mg/kg, respectively. The main distribution areas of these odorous substances on site included storage tank and dichlorvos production areas and herbicide, pyrethroid,oxidation chlorine production, paraquat, and omethoate workshops.(3) The vertical distribution generally showed a trend of increasing first and then decreasing. These odorous substances were mainly concentrated in the 1.8-6.8 m silty clay layer and the 6.8-10.6 m silt soil layer. The research shows that there are many kinds of odor substances in the soil of pesticide-contaminated sites, and the cumulative odor contribution analysis method can be used to screen the odor substances. The spatial distribution of odor substances in the soil of the study area is mainly related to the production process, soil depth, and soil properties.