4 May 2026

Freshwater Wetland Carbon Flux Analysis Pertinent to the Net Emissions Analysis Tool Improvement: Method Development and Testing

Palustrine wetlands are ecosystems of interest due to their capacity to sequester large amounts of greenhouse gases. This field study in Washington and Idaho was conducted as proof of concept of methods for measuring carbon emissions in palustrine wetlands. The regions of Washington and Idaho were chosen as they span three different Environmental Protection Agency (EPA) Level 1 ecoregions in a relatively close geological area. Data were collected across all three ecoregions in an effort to detail the potential differences between palustrine wetlands within them. Carbon dioxide flux measurements were compared across two instruments: LICOR 8,100A and CIRAS-4. Supporting data related to vegetation and site characteristics were incorporated into the overall analyses. Results suggest that carbon dioxide flux varies in relation to several factors. Additional research will be required to inform the application of site-specific data which can improve the application of tools designed to quantify project scale estimates for net greenhouse gas emissions.

22 Jan 2026

Carbon Partitioning Effects on Martensitic Phase Transformation of Type 301 Steel Under Various Thermal Processing Conditions

Abstract: Simultaneous improvement of strength and ductility in steels has been a daunting challenge for materials scientists, as these properties are by nature mutually exclusive. One design approach that has the merit to use traditional steel processing technologies is the thermo-mechanical stabilization of the austenitic phase. Owing to its highly symmetric FCC crystal structure, if austenite can be maintained during processing, and then further preserved under mechanical deformation, the final microstructure can solve the Pareto design problem where the high strength does not compromise the ability of the material to resist strain localization/incompatibility. The thermomechanical stability of austenite is achieved through compositional modification of the phase, thereby making the control of the elemental partitioning mechanism between existing phases during manufacturing as the main design metric. In this work, we have developed a phase field framework to model the partitioning mechanism of one of the cheapest austenite stabilizers, carbon, in a 301 stainless steel grade. The model uses a coupled framework between thermomechanical and latent heat effects to capture carbon partitioning during martensite nucleation, propagation, and growth kinetics as well as austenite stability and distribution during and after various heat treatment routines. Various microstructures were simulated for the quench state only as well as quench-and-temper heat treatment routines. The resulting microstructure and carbon distribution shed light on various evolutionary effects such as carbon segregation, grain boundary effects, stable martensite morphology, austenite distribution, and phase fraction. In particular, the model was able to reproduce the evolution of carbon-depleted martensite zones and carbon-enriched austenite regions as well as carbon distribution similar to experimental observation at austenite–martensite interfaces.