Erosion-driven soil carbon cycles: from "source-sink controversy" to "process quantification"

Objective As a critical driver of global biogeochemical cycles, soil erosion profoundly perturbs the terrestrial carbon reservoir. However, the intricate coupling mechanisms between macroscopic physical transport and microscopic biogeochemical turnover remain a severe challenge in contemporary earth sciences. This review aims to systematically synthesize the research progress of erosion-driven soil carbon dynamics, tracking its evolutionary trajectory from historical, qualitative "source-sink" controversies toward modern, full-chain process quantification. By exploring future development directions, this study seeks to deepen modern terrestrial carbon cycle theories, thereby providing process-based scientific support for regional carbon budget accounting frameworks and successfully serving national dual-carbon strategic goals. Methods Adopting a spatiotemporal integrated and landscape-continuum perspective, this study conducts a comprehensive and systematic literature review of core publications from both domestic and international domains. The screening process focused on historical milestones, conceptual frameworks, and cutting-edge advances regarding erosion-carbon interactions. The retrieved literature was systematically evaluated, categorized, and synthesized across three highly interconnected thematic dimensions: charting the historical paradigm shifts of carbon dynamics, integrating the processes of macroscopic physical co-transport, and decoding microscopic biogeochemical response mechanisms. Furthermore, existing mathematical assessment frameworks and numerical simulation models were critically reviewed to diagnose their cross-scale prediction and evaluation capabilities. Results The analysis yields three critical insights regarding erosion-driven carbon cycling. First, the "source-sink" attributes of soil erosion exhibit pronounced spatiotemporal heterogeneity and scale-dependency. At localized, small-scale domains, rapid mechanical disruption dominates, while at catchment scales, dynamic topsoil replacement and sedimentary burial counterbalance carbon losses. This intricate dependency has successfully driven the entire research paradigm to shift from historical qualitative attribute controversies toward the rigorous quantification of full-chain spatiotemporal processes across complex landscape continuums. Second, the deep integration and seamless coupling of macroscopic physical transport processes and micro-scale biogeochemical turnover constitute the absolute and indispensable prerequisite for achieving accurate full-process quantitative assessments. Quantifying how physical forces regulate carbon dynamics requires a holistic integration of macro-scale dynamics—specifically soil aggregate detachment, horizontal runoff transport, and depositional burial—with micro-scale biochemical processes, including microbial heterotrophic respiration, organic matter homeostasis, and enzymatic mineralization pathways. Third, despite its fundamental importance, the interactive quantitative mechanisms governing the interface between physical transport and biochemical responses have not yet been fully elucidated or mathematically formalized. Current scientific frameworks severely lack explicit process-based functions capable of directly linking physical energy inputs, such as rainfall kinetic energy and runoff shear stress, with alterations in biogeochemical reaction rates. Consequently, this deep dislocation between macroscopic physical transport and microscopic biogeochemical mechanisms has emerged as the core bottleneck that strictly restricts existing numerical prediction models—including empirical equations, distributed hydrological frameworks, and large-scale earth system models—from precisely predicting and simulating the dynamic and non-linear spatiotemporal behaviors of erosion-driven soil organic carbon dynamics. Conclusions To structurally resolve current research bottlenecks regarding spatiotemporal scale fragmentation, unknown deep-soil carbon dynamics, and the microbial functional "black box", this review successfully outlines a full-spatiotemporal research framework. It strongly urges developing next-generation coupled numerical models that seamlessly integrate hydrology, sediment transport, and biochemical reactions to answer the objective. Keywords: soil erosion; lateral transport; microbial mechanisms; physical-biochemical coupling; coupled models.