Mercury (Hg) cycling is essential to explore in marine ecosystems because of the adverse effects of Hg on the health of humans and marine organisms via bioaccumulation. The California Current Ecosystem (CCE), which experiences seasonal coastal upwelling, is home to commercially and ecologically important fisheries and therefore important to study for Hg bioaccumulation. Coastal upwelling is thought to provide a pathway for Hg to be supplied into the mixed layer of the ocean, but it is poorly studied concerning its effect on Hg removal via particle scavenging. Upwelling stimulates primary production (PP), leading to more particles that adsorb Hg and sink out of the mixed layer. These processes may contribute to a possible negative feedback mechanism for Hg cycling in the upwelling regions. We collected particle samples following two upwelling water parcels and one non-upwelling water parcel during the 2021 CCE Long Term Ecological Research Process Cruise. Here, we present the profiles of total and mono-methylmercury (MMHg) in both small size-fraction (SSF) and large size-fraction (LSF) suspended particles. There was relatively high total mercury in the upwelling region (SSF: 90-400 fM; LSF: 3-25 fM) compared to the open ocean (SSF: 90-300 fM; LSF: 2-8 fM). The fraction of MMHg to THg varied greatly (3-50%) depending on depth and region. Interestingly, high sinking flux in the upwelling region strengthens our belief in the negative feedback in Hg cycling moderated by upwelling. To test our hypothesis, we explicitly accounted for the opposing Hg fluxes related to upwelling in a mass balance model to estimate Hg-related fluxes in the mixed layer. We found that upwelling plays a minor role in supplying Hg, while sinking flux partly driven by upwelling becomes more dominant. We tested the robustness of our estimates by comparing the model results with observations. In parallel, we observed a negative correlation between PP and dissolved Hg in the mixed layer, which indirectly supports our hypothesis of the non-negligible contribution of upwelling to Hg removal.