<p>Heavy metals in lake sediments pose significant threats to both the environment and human health, necessitating urgent investigation into their source distribution and quantitative risk assessment. To systematically examine the seasonal variations, ecological impacts, and health risks of heavy metals (As, Cd, Cr, Cu, Pb, Zn) in these sediments, we conducted multi-period sampling covering both non-ice-sealing period and ice-sealing period. Our analytical framework integrates a improved geo-accumulation index method, potential ecological risk assessment, and a health risk model based on Monte Carlo simulation. The results indicate that heavy metal concentrations consistently exceeded local background levels, with Cd, Cr, Cu, and Zn exhibiting significantly higher enrichment during the ice-sealing period. By incorporating the coefficient of variation, improved geo-accumulation index method effectively mitigated the common limitation of overestimation caused by sporadic high-pollution sites in traditional approaches, demonstrating superior assessment performance. Among the elements analyzed, As and Cr pose higher non-carcinogenic risks to children, primarily through hand-to-mouth exposure. To mitigate health hazards caused by toxic heavy metals in sediments, stringent regulations should be established to control waste discharges from both traffic and industrial activities.</p>