Quantitative passive soil vapor sampling for VOCs--part 3: field experiments.

Area of Science:

• Environmental Science
• Geochemistry
• Analytical Chemistry

Background:

• Volatile organic compounds (VOCs) in contaminated land pose human health risks via vapor intrusion.
• Soil vapor sampling is crucial for assessing VOC contamination but faces challenges due to varied site conditions and sampling complexities.
• Passive sampling offers an alternative to active sampling, yet quantitative relationships and comparative performance data are lacking.

Purpose of the Study:

• To quantitatively establish relationships between sorbed mass, time, and soil vapor concentration for passive samplers.
• To evaluate the relative merits of different passive samplers for measuring soil vapor concentrations.
• To assess the accuracy and precision of passive soil vapor sampling under diverse field conditions.

Main Methods:

• Conducted field experiments using multiple passive soil vapor samplers.
• Varied sampling conditions including geologic material permeability and moisture content.
• Analyzed adsorbed mass over time and compared results to conventional active sampling methods.

Main Results:

• Quantitative relationships between sorbed mass, time, and soil vapor concentration were established.
• Passive samplers demonstrated accuracy and precision comparable to active sampling (within a factor of 2).
• Performance is dependent on low uptake rates to avoid starvation and appropriate exposure durations for compound retention.

Conclusions:

• Quantitative passive soil vapor samplers are a viable tool for accurate VOC assessment.
• Proper design and deployment are critical for reliable performance.
• Passive sampling offers a comparable alternative to active methods for soil vapor monitoring.