Practical Gas Sampling Method Enables Rapid Evaluation of all Major Dissolved Gases in Groundwater
Researchers at the Oak Ridge National Laboratory recently developed a practical method to sample all major dissolved gases present in groundwater without the need for pumping groundwater to the surface or the need for multiple analytical methods to measure gas concentrations. Traditional dissolved gas sampling techniques in the field are labor intensive, time-consuming efforts. This new passive sampling technique requires little sampling effort, allowing researchers to quickly deploy, retrieve, and analyze gas samples from multiple locations. Concentrations of dissolved gases such as oxygen, hydrogen, nitrogen, carbon dioxide, methane, nitrous oxide, and carbon monoxide yield important information on microbial and chemical processes occurring in the subsurface. Microorganisms profoundly affect the transport of contaminants in the subsurface, and these methods can help identify which microbial processes are active in the subsurface. The sampling device is suspended in a well until it equilibrates with ambient conditions, and then it is removed for analysis in the laboratory. The technique is highly sensitive to trace levels of gases and can provide researchers and modelers with information on active microbial processes in the subsurface. Understanding which microbial processes are active at a specific field site will help in refining simulations of contaminant transport, understanding bioremediation, monitoring natural attenuation processes and devising new techniques to intercept and immobilize contaminants.
Environmental Science & Technology 42(10) 3766-3772, 2008.