The seasonal dynamics of particulate organic carbon (POC) sources in saline lakes within arid environments are poorly understood due to the complex interactions among climate variability, hydrological pulses, and anthropogenic influences. This study integrates stable carbon isotope ratios (delta C-13(POC)), C/N elemental ratios, and Bayesian MixSIAR modeling to quantify seasonal shifts in POC source across 6 saline lakes in Turpan-Hami Basin, China. The results show that terrestrial C3 plant material predominantly contributes to POC in spring (5.5-30.2 % contribution), while soil organic matter (SOM) and sewage-derived inputs become more prominent in summer (up to 43 % and 22 %, respectively). Allochthonous sources account for 51-65 % of annual POC flux, with autochthonous algal contributions peaking in Huancaihu Lake during summer (27 % contribution). Salinity exhibited no significant correlation with POC characteristics, whereas C/N ratios demonstrate strong covariation with POC sources, serving as more reliable indicators. delta C-13(POC) values were significantly more negative in summer (-23.4 parts per thousand to -19.85 parts per thousand) compared to spring (-27.68 parts per thousand to -22.59 parts per thousand) (p < 0.05), reflecting the decrease in contribution from terrestrial C3 plants. These findings demonstrate that hydrological seasonality and anthropogenic activities outweigh salinity as primary controls on POC composition in arid saline lakes. The study provides critical insights for developing source-specific management strategies in fragile lake ecosystems under global change pressures, particularly for mitigating sewage inputs and anthropogenic soil erosion during peak tourism seasons and protecting watersheds during spring melt periods.