The Arctic tundra contains a large amount of soil organic matter (SOM), and approximately half of Earth's SOM is associated with permafrost in high-latitude ecosystems. Arctic SOM has been undergoing thawing and accelerated microbial degradation as temperatures increase, producing large amounts of active organic carbon and greenhouse gases (e.g., carbon dioxide and methane). It is vital to measure current levels of these gas emissions from the tundra accurately, as a baseline for future measurements and for more accurate modeling of likely effects from the increased warming of Arctic SOM. However, the Arctic tundra is a complicated multi-phase system, and soil temperatures may stay below freezing for eight months or more every year, making the detection of soil gas emissions extremely difficult under field conditions. Current sensor technologies are inadequate for making accurate measurements of greenhouse gases in Arctic soils. This project will develop a low-cost, low-power multimodal sensor that can provide spatially and temporally expansive, continuous in situ measurements of dynamic changes of soil carbon dioxide and methane across the Arctic over time. The envisioned sensor will be small, inexpensive, and will need little power for operation. It can be deployed across wide areas to obtain soil gas data in natural conditions and will enable near-real-time reporting of field measurement data year-round. Data from these sensors will help advance knowledge in several disciplines, such as understanding the influence of permafrost warming on Arctic soil carbon release, and the fundamental biogeochemical or carbon cycling processes in the Arctic ecosystem. That new knowledge will help facilitate the development of new ways of managing soils and natural resources in cold environments.
This project will be carried out by an established interdisciplinary team with complementary expertise to develop the new sensor technology to address challenges in Arctic soil gas analysis. The key innovation is the use of ionic liquids (ILs) as a selective solvent and electrolyte for the development of miniaturized multimodal electrochemical and piezoelectric quartz crystal microbalance (E-QCM) sensors to measure soil gases in situ. ILs possess unique solvent and electrolyte properties that make them suitable for use under Arctic conditions where conventional sensing materials would be subject to both physical and chemical changes. The project will (1) Develop a multimodal E-QCM sensor and sensor array for methane and carbon dioxide detection under Arctic conditions; (2) Characterize and validate these sensor arrays using synthetic Arctic soils with known composition; and (3) Develop a rugged sensor package for in situ field tests in natural Arctic soils. The new sensors are expected to operate under Arctic conditions, simultaneously monitoring both electrochemical and piezoelectric signals of soil methane and carbon dioxide with the redundancy, sensitivity, and selectivity required for in situ measurement of soil gases in Arctic tundra.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
