The eosFD has traditionally been used by ecology and climate change researchers trying to understand environmental gases. In recent years carbon dioxide (CO2) efflux- the movement of CO2 into and out of the soil – has emerged as a powerful tool for understanding and monitoring subsurface contamination by light non-aqueous phase liquids or LNAPL – think petroleum products (or hydrocarbons) like gasoline, benzene, toluene, xylene, etc.
Generally, we associate biodegradation with the breakdown of common organic materials we encounter everyday in our compost bins, like paper towel or food scraps. LNAPL impacted soils can be cleaned naturally through these same processes by microorganisms present in the soil. Diverse types of microbes can be actively degrading contaminants at a site through a variety of processes at different depths in the soil. For example, bacteria, archaea and fungi can break down hydrocarbons at shallow depths where oxygen is present in the soil. However, only bacteria and archaea are capable of breaking down hydrocarbons at greater depths where there is limited or no oxygen.
These microorganisms break down LNAPL in the soil through a complex process known as methanogenesis. In the simplest terms, methanogenesis occurs when the by-products of one group of organisms are degraded by another group of organisms. In the case of LNAPL, contaminants are progressively degraded into methane (CH4) at depth (in the absence of oxygen). The CH4 is then converted to CO2 as it migrates upward through shallower, oxygen-rich soil. Eventually, this CO2 reaches the soil surface and gets emitted to the atmosphere. By measuring these CO2 emissions – or effluxes – at the soil surface, researchers and environmental consultants can determine the rate of biodegradation occurring at an LNAPL impacted site.
The eosFD is ideal for monitoring the biodegradation that occurs at LNAPL impacted sites. Unlike other chamber or trap-based methods, the eosFD measures CO2 efflux directly and is designed for long-term deployment. Low power consumption means the eosFD can operate optimally in the field for long periods of time, allowing for the collection of continuous data. This means that temporal variations and trends in microbial activity and hydrocarbon degradation can be closely monitored with ease. Spatial delineation of LNAPL plume boundaries can also be determined by measuring CO2 emissions at multiple locations. Finally, because it measures CO2 efflux directly via an internal gas sensor, the eosFD eliminates the need for calculating effluxes and the need for laboratory analysis of gas samples.
Eosense is striving to help researchers and environmental consultants to better understand processes like biodegradation occurring at LNAPL impacted sites. By providing high quality continuous measurements, our goal is to facilitate a higher standard of risk-based management of contaminated sites, so we can contribute the the clean up and restoration of our land. With this in mind, we are currently looking for partners for pilot projects related to monitoring LNAPL degradation at contaminated sites. This is an exciting application for the eosFD, and we are eager to roll up our sleeves and help you quantify and monitor LNAPL degradation at your site.