[Size Distribution Characteristics of Water-Soluble Inorganic Ions During Summer and Autumn in Zhengzhou].

To study the compositional characteristics of atmospheric particulates with different particle sizes in the central city of Zhengzhou, China, a Tisch graded impact sampler was used to sample atmospheric particulates in summer and autumn. The mass concentrations of water-soluble inorganic ions, including anions (Cl, F, NO, and SO) and cations (Na, Ca, NH, K, and Mg) were measured by ion chromatography, and the online ion chromatography-based analyzer MARGA monitored the real-time concentration of particulate nitrate. The results showed that the average concentration of water-soluble ions in Zhengzhou City was (70.9±52.1) μg·m during the sampling period, and the order of water-soluble ion mass concentrations was NO > SO > NH > Ca > Na > Cl > Mg > K > F; NO, SO, and NH accounted for 79.9% of total water-soluble ions. The NO concentration was mainly concentrated in the 0.65-3.3 μm particle size segment, despite the SO concentration being concentrated in the ≤ 1.1 μm particle size segment in autumn or summer. Both NO and SO had a bimodal distribution in summer and autumn and were mainly distributed as fine particles. NH showed seasonal variation with a bimodal distribution in summer and a unimodal distribution in autumn. Zhengzhou City had serious ozone pollution in summer, and O and NO showed the "staggered peak" phenomenon, indicating photochemical reactions in the atmosphere. In autumn, water-soluble inorganic ion concentration in particulate matter was high, and the ratio of[NO]/[SO] was higher than 0.5. The mobile source is an important source of particles. NOR and SOR peaks were on the 1.1-2.1 μm particle size segment in summer, whereas those in the 0.65-1.1 μm particle size segment occurred in autumn. The sulfur gas-to-grain conversion in summer was larger than that of nitrogen, contrary to the result in autumn.