基于嗅觉效应的土壤苯系物关键因子识别及安全阈值研究

Key factors identification and safety thresholds investigation of soil contaminated by BTEX based on the olfactory effect

以某化工退役地块为例,从化学浓度及异味贡献两个角度对比了典型土壤气样品中苯系物的污染特征;并从嗅觉效应的角度,研究推导了基于嗅觉效应的主要致嗅组分土壤安全阈值,为污染地块异味风险控制提供理论依据.该地块土壤气组分中以苯浓度最高,其次为氯苯,分别占苯系物总质量浓度的67.3%和10.1%.从异味贡献来看,核心致嗅成分为乙苯,占土壤气总异味活度值的53.2%;其次为甲苯,异味贡献平均占比为14.1%.基于地块未来公园绿地规划,构建了长期及短期两种异味暴露场景下的概念模型和计算公式.经分析计算,短期(涉及建设开挖)的异味暴露风险较长期异味暴露风险更需引起关注.土壤中关键致嗅因子乙苯、甲苯、苯、间/对-二甲苯的土壤异味安全阈值分别为12.9、35、559.3和60.7 mg·kg^(-1).将计算所得的安全阈值与现行土壤标准相较,以甲苯和间/对-二甲苯的反差最为显著.研究结果表明:存在异味的污染地块,应同时兼顾考虑毒理学健康效应和基于嗅觉效应的安全阈值,确保污染地块的安全利用.

The current study conducted a field investigation of vacant chemical plant and analyzed the BTEX contaminations regarding chemical concentrations and odor contribution. Meantime,safety threshold of the olfactory constituent in the studied soil was inferred,which provided a theoretical basis for odor control in the contaminated site. The concentration of Benzene in soil samples was the highest,followed by that of Chlorobenzene,accounting for 67.3% and 10.1% of the total mass concentration of BTEX,respectively. Notably,the main olfactory constituent was Ethylbenzene representing 53.2% of the total odor activity value of soil gas. The second highest olfactory component of which was Methylbenzene whose average odor contribution was 14.1%. Considering this site to be reclaimed as a park,conceptual models and calculation formulas were constructed under long-term and short-term odor exposure scenarios,which showed that more attention should be paid to short-term(the period of excavation and construction)than the long-term issues. The safety threshold of key olfactory constituents of Ethylbenzene,Methylbenzene,Benzene,and m&p-Xylene was 12.9,35,559.3,and 60.7 mg·kg^(-1),respectively. Among them,the thresholds of Methylbenzene and m&p-Xylene in the sampled squares mostly uncomplied to the current soil safety standards,and thereby a safe soil utilization entails the considerations of the toxicological health and olfactory effect related issues the remediation.