Synchrotron X-Ray Imaging and Spectroscopy in Soil Improvement and Remediation: A Review and Perspective

Soil contamination by heavy metals and organic pollutants presents significant challenges to the global environment and public health. However, a lack of micro-scale understanding of the pollution process hinders efforts to remediate and enhance soil quality. Synchrotron-based X-ray imaging and spectroscopy techniques are powerful tools in revealing complex interactions within heterogeneous soil systems. This review systematically explores recent advances in soil research that deepen our knowledge on the chemical states, spatial distribution, and dynamic interactions of heavy metals and organic contaminants via synchrotron-based techniques (e.g., micro-XRF imaging, FTIR, SR-μCT). It highlights the potential of these methods to characterize composition, aggregate structure, and microbial activity within soil matrices with high spatial and temporal resolution, in situ, and with element-specific analysis. Additionally, a forward-looking perspective outlines key research directions to leverage these advantages and develop more effective and sustainable soil restoration strategies. We hope this work emphasizes the role of synchrotron science in field-scale soil applications and inspires future, mechanism-driven, evidence-based soil remediation efforts.