Development and Validation of a Testing Protocol for Carbon Sequestration Using a Controlled Environment (SWUTC/12/476660-00028-1)

Carbon footprints, carbon credits and associated carbon sequestration techniques are rapidly becoming part of how environmental mitigation business is conducted, not only in Texas but globally. Terrestrial carbon sequestration is the general term used for the capture and long-term storage of carbon dioxide. For a transportation facility, this occurs through the natural processes of the roadside vegetation and soil. Texas has a state-maintained highway system of approximately 80,000 linear miles of roadway with more than 1.1 million acres of right-of-way, not including the street systems of cities, towns and local communities. The majority of these roadways have supporting vegetation within their rights-of-way that usually consists of various combinations of grasses, shrubs and trees. Roadside carbon sequestration measurement practices typically rely on modeling and in-situ measurements. This project conducted initial testing to develop a method for quantifying plant and soil carbon sequestration capabilities under the controlled conditions of the Texas Transportation Institute's Environmental and Emissions Research Facility (EERF). Plants and soil were subjected to heavy-duty truck emissions over a six week period. Samples were analyzed for changes in carbon and nitrogen content over time. Due to the plant injury that occurred during testing, the sequestration capabilities of these plant materials and soils were inconclusive. A comparison of samples taken over the course of the study indicated that the desired results may have been accomplished had the initial exposure in the EERF been reduced to a more moderate level. Modifications to this technique for future research on specific soils and plant materials may help identify plant and soil combinations to maximize roadside carbon sequestration.