2024 Abstracts

AquaMEND: Reconciling Multiple Impacts of Salinization on Soil Carbon Biogeochemistry


Jianqiu Zheng1* ([email protected]), Melanie Mayes2,3, Michael Weintraub4, Timothy Scheibe1, Vanessa Bailey1, COMPASS-FME team


1Pacific Northwest National Laboratory, Richland, WA; 2Oak Ridge National Laboratory, Oak Ridge, TN; 3University of Tennessee, Knoxville, TN; 4University of Toledo, Toledo, OH



Soil salinization exacerbated by climate change poses a global threat to ecosystem function and soil quality. Despite extensive research, consensus on the impact of salinity on belowground carbon cycling remains elusive, hindering accurate predictions. Salinity influences carbon cycling through direct effects on microbial activity and indirect alterations to soil physicochemical properties. Current models inadequately represent the interplay of salinity, cation exchange, pH, and soil organic carbon availability, relying on linear reduction functions that overlook specific physicochemical changes induced by salinity. To address this gap, researchers propose an integrated model framework, AquaMEND that combines microbial-explicit and aqueous-explicit geochemical models. This model’s explicit salinity module captures salinity-induced cation exchange and surface complexation, important processes governing solute chemistry and nutrient availability in soils, which offers a substantial leap towards more realistic and dynamic simulations of soil salinity change and solute behaviors. Coupling with salinity response functions, researchers have derived to capture the salinity impact on both salt-sensitive and salt-resistant microbial processes and are able to simulate how the abiotic and biotic mechanisms work individually and collectively to regulate various organic and inorganic pools and fluxes.

The parallel structure of aqueous and non-aqueous phases, together with an energetic framework to consistently build microbial functions and associated physiological traits, making this model highly flexible and versatile in solving dynamic coupling of organics, minerals, and microbes under various environmental settings.