污染场地土壤气中VOCs定量被动采样技术研究及应用

污染场地中土壤气样品的采集是蒸气入侵风险评估的关键，目前最常用的主动土壤气采集技术包括真空苏玛罐和泵吸附管，其操作繁琐、成本高、易受多种因素影响、只能采集短时间的浓度.土壤气定量被动采样技术是一种新兴的采样技术，很好地克服了主动式采样存在的不足，是目前污染场地中土壤气调查的研究热点.通过总结现有研究，就定量被动采样技术的理论、被动采样器吸附剂和外壳材料的选择、被动采样器吸附速率的研究及定量被动采样在污染场地中的应用进行论述.综合研究发现，只要严格控制吸附速率，被动采样能够提供准确的定量土壤气浓度测量；采样器结构的设计、外壳材料的选择能够有效控制吸附速率；吸附速率受环境因素和土壤性质的影响，场地校正是获得准确结果的有效途径.我国在土壤气采样领域的研究刚刚起步，建议:加大高效、广谱型或混合型吸附材料及相应测试方法和设备的研发；加强吸附速率的影响因子及场地校准方法的研究；加强土壤钻孔内土壤气的补给速率的模型和场地实测研究；增加不同种采样器的现场应用比较研究；进行适合我国国情的技术标准的研究与制订. 

Passive Sampling Technology Research and Application for Volatile Organic Compounds from Soil Gas in Contaminated Sites

Soil gas sampling is key to vapor intrusion risk assessment at contaminated sites. Currently, the most common method for soil gas sample collection is the active soil gas sampling technique, where soil gas is drawn into evacuated Summa canisters or sorbent tubes. Active soil gas sampling is complicated and expensive, and only transient samples can be collected. Quantitative passive soil vapor sampling is a promising technique for soil vapor collection, and can overcome the shortcomings of the active sampling technique. Therefore, it has become a cutting-edge research hotspot for soil gas investigation. This paper summarizes the existing research into the theory of quantitative passive sampling, the selection of adsorbent and the shell material of passive sampler, uptake rate as well as the application of passive sampling technique in investigation of practical contaminated sites. The study finds that as long as the uptake rate is strictly controlled, passive sampling could accurately provide quantitative soil gas concentration measurement. The design of the sampler structure and the selection of shell material could effectively control the uptake rate. The uptake rate is affected by environmental factors and soil properties, while field calibration is an effective way to obtain accurate results. Because the research of soil gas sampling has just started in China, more efforts should be made to study the following:efficient, broad-spectrum or hybrid adsorption materials and corresponding testing methods and equipments;factors controlling the uptake rate of passive samplers as well as field calibration method;models and field measurements of soil gas delivery rate within soil boreholes;comparative field application of different kind of samplers;and drafting technical guidelines which are suitable for China.