A Sustainable Solution Using Ice Nucleation Active Bacteria to Enhance the Strength of Permafrost Under Climatic Warming

ABSTRACT Climatic warming accelerates permafrost ice thawing, resulting in ground subsidence and subsequent loss of load‐bearing capacity. Compensating the loss of ice content by using ice nucleation active (INA) bacteria in permafrost can be efficient to solve this problem. However, the performance and work mechanism of INA bacteria catalyzing ice formation in permafrost under climatic warming remain unclear. Therefore, the effect of INA bacterium Pseudomonas syringae on the ice formation and shear strength of frozen soil is investigated by conducting nuclear magnet resonance (NMR) and direct shear tests. The unfrozen water content and the shear strength of specimens with P. syringae concentrations of 0–20 g/L under temperatures ranging from −5°C to −0.1°C are measured and compared. The classic nucleation theory is used to illustrate the work mechanism of P. syringae in permafrost. Results indicate that P. syringae can significantly increase the shear strength of frozen soil by 13%–64% during soil thawing. The enhanced shear strength is attributed to the ice‐bonding cohesion at temperatures from −5°C to −1°C, and the internal friction angle from −0.5°C to −0.1°C. Adding P. syringae with a concentration of 1 g/L can slow down the permafrost warming rate and maintain the unfrozen water content at a constant value. P. syringae exhibits higher ice‐triggering ability near 0°C resulting from the decreased nucleation barrier during soil thawing. Using INA bacteria provides a sustainable solution to deal with permafrost warming and thawing, and the resulting landform changes and structural instability.