基于嗅觉效应的土壤二甲基二硫醚修复目标值制定

我国现行风险评估导则多采用基于土壤中污染物质量分数的Johnson-Ettinger(J&E)模型评估VOCs呼吸暴露健康风险，但对于土壤中异味污染物的特殊性考虑不足。以某农药污染地块土壤中异味污染物二甲基二硫醚为研究对象，分析了二甲基二硫醚在土壤与土壤气中的赋存状态，采用土壤气挥发通量与J&E模型分别计算室内呼吸暴露途径的健康与环境风险，探索基于异味污染物对人体嗅觉效应的土壤修复目标值制定方法。结果表明，土壤中二甲基二硫醚最高检出质量分数与土壤气挥发通量最大值检出点位一致，其余点位土壤气中二甲基二硫醚均有不同程度检出而土壤只有2个点位有检出；二甲基二硫醚作为挥发性比较强的有机物更容易赋存于土壤气相中，采用土壤气挥发通量测试结果来表征二甲基二硫醚的环境风险会更加客观可信。研究区域内二甲基二硫醚人体健康风险可接受，但室内暴露质量浓度最高值为5.28 mg·m⁻³，超过了污染物嗅阈值，存在异味引起的环境风险。基于嗅觉效应采用土壤气挥发通量制定的修复目标值为0.193 mg·kg⁻¹，相比J&E模型提高了一个数量级，修复方量减少约29.75%。基于土壤气挥发通量综合考虑健康风险和嗅觉阈值进行风险评估与土壤修复目标值的制定，既能确保异味污染地块安全利用，又在一定程度上避免了过度修复的问题。本研究结果可为异味污染地块的环境管理提供参考。

Method of establishing soil remediation target value of dimethyl disulfide based on olfactory effect

The Johnson Ettinger (J&E) model based on soil pollutant mass fraction is mostly used to assess the health risk of inhalationexposure to VOCs of the current risk assessment guidelines in China. However, the specificity of odor pollutants in soil is narrowly considered. Herein, the health and environmental risks were calculated by the indoor inhalation exposure pathway via soil gas volatilization flux and J&E model. As an odor pollutant in soil of one pesticide contaminated site, dimethyl disulfide(DMDS) was chosen to explore and analyze occurrence conditions in soil and soil gas and the method of establishing the target of soil remediation due to the odour olfactory effect on humans. These results showed that the highest mass fraction of DMDS in soil were consistent with the highest detected level of soil gas volatilization flux at the same sampling point, and the remaining sampling points showed different degrees of detection of DMDS in soil gas without two points detected DMDS in soil. DMDS was more likely to be deposited in the soil gas phase and it would be more objective and reliable to the utilization of soil gas volatilization flux test results to characterize the environmental risk of DMDS. The human health risk of DMDS was acceptable in the investigation region, but the maximum indoor exposure concentration was 5.28 mg·m−3, which exceeded the odour threshold of pollutants, and there were environmental risks caused by odour. The remediation target value based on olfactory effect was 0.193 mg·kg−1, and the volatilization flux of soil gas exceeds the order of magnitude of J&E model, and the remediation cost could be reduced for around 29.75%. The risk assessment and soil remediation target value could improve the safe use of odour contaminated sites and block excessive remediation due to the soil gas volatilization flux integrated with the health risk and olfactory threshold. This research can provide advanced theoretical reference for the environmental management of odor contaminated sites.