Phosphorus (P), iron (Fe), and sulfur (S) are essential nutrients for living organisms and have significant environmental impacts on aquatic ecosystems. However, the biogeochemistry of P, Fe, and S across the sediment-water interface (SWI) in cold-arid regions remains poorly understood. Herein, we first applied a combination of high-resolution in situ techniques, namely diffusive gradients in thin films (DGT) and a home-made two-dimensional miniature-DGT (2D-MDGT), to simultaneously analyze the dynamic distributions of P, Fe, and S across the SWI in Ugii Lake, Mongolia. The concentrations of labile P, Fe, and S in the sediment profiles range from 0.01 to 0.15 mg L-1, 0.12 to 1.10 mg L-1, and 0.15 to 0.4 mg L-1, respectively, with a considerable number of hotspots. Spatially, labile P and Fe were higher in the near-shore region more vulnerable to exogenous pollution than the central region, while labile S showed the opposite trend. In vertical profiles, the distributions of labile P and Fe showed a significant positive correlation (P < 0.01), indicating that Fe redox cycling dominated P mobility. In contrast, a weak relationship between labile P and S as well as labile Fe and S indicated limited contributions of S to P mobilization. The in situ measurements of diffusion fluxes of P, Fe, and S across the SWI showed values of 0.015-0.031 mg m(-2) d(-1), 0.067-0.288 mg m(-2) d(-1), and 1.087-1.801 mg m(-2) d(-1), respectively, indicating strong upward mobility of these elements from the sediment to the overlying water. Overall, the study first captured 2D fine-scale co-distributions of P, Fe and S across the SWI in Ugii Lake and filled the gap on P-Fe-S redox cycling processes and mechanisms at the fine scale, which provided a reference and theoretical basis for water quality control in cold-arid lakes.