Consecutive haze and dust pollution drives episodic atmospheric phosphorus enrichment and dry deposition over China's...

Atmospheric pollution events can trigger pulsed phosphorus deposition into the ocean, rapidly altering nutrient dynamics. Haze and dust event differ markedly in sources, particle sizes, and ecological impacts. This study investigates atmospheric P concentrations and dry deposition during a consecutive haze-dust episode in November 2018 over China's marginal sea. It aims to characterize the variations of atmospheric P and quantify its dry deposition fluxes. Furthermore, the study evaluates the contribution of these atmospheric inputs to marine primary productivity in the region. A high-resolution anthropogenic P emission inventory was developed, and coarse-mode P was incorporated into the WRF-CMAQ dust module. The model reproduced observed P concentrations well, capturing both magnitude and temporal variation, with normalized mean bias within ±5 %. Anthropogenic P emissions showed clear spatial heterogeneity, with eastern China exhibiting higher rates. Industrial (39.1 %) and residential (38.0 %) categories were dominant. During the haze period, atmospheric P concentration increased from 5.5 in clean days to 16.9 ng m^-3 and dry deposition from 0.36 to 1.60 μg m^-2·d^-1 over the Bohai and Yellow Seas, where haze occurred. Both were dominated by fine particles. In contrast, the dust period saw P concentrations surge to 69.1 ng m^-3 and deposition flux reach 31.7 μg m^-2·d^-1, dominated by coarse particles and affecting a larger area than haze. Using the Redfield ratio and solubility estimates, atmospheric P deposition was estimated to support 10.5 mgC·m^-2·month^-1 of marine primary productivity in November 2018, with 73 % from coarse-mode input. These findings highlight the significant role of short-term, high-intensity pollution events in shaping coastal nutrient dynamics.