Indoor air particles in research vessel from Shanghai to Antarctic: Characteristics, influencing factors, and potential controlling pathway

Despite millions of seafarers and passengers staying on ships each year, few studies have been conducted on the indoor air quality inside ship hulls. In this study, we investigated the levels and size distribution of indoor particulate matter during two cruises of the research vessel “Xuelong” from Shanghai to Antarctica. The results showed that the particle size less than 2.5 μm(PM_(2.5)), and particle size less than 10 μm(PM_(10)) concentrations in different rooms of the ship widely varied. We observed high particulate matter(PM) levels in some of the rooms. The mass concentration distribution was dominated by 1–4 μm particles, which may have been caused by the hygroscopic growth of fine particles. The dominant factors influencing PM concentrations were indoor temperature, relative humidity, and human activity. We quantified contributions of these factors to the levels of indoor particles using a generalized additive model. In clean rooms, the levels of indoor particles were controlled by temperature and relative humidity, whereas in polluted rooms, the levels of indoor particles were mainly influenced by temperature and human activity, which implied that controlling temperature and human activity would efficiently reduce the levels of indoor particles.

Acidity of Aerosols during Winter Heavy Haze Events in Beijing and Gucheng, China

We investigated the acidity and concentrations of water-soluble ions in PM2.5 aerosol samples collected from an urban site in Beijing and a rural site in Gucheng, Hebei Province from November 2016 to January 2017 to gain an insight into the formation of secondary inorganic species. The average SO4^2–, NO3^–, and NH4^＋ concentrations were 8.3,12.5, and 14.1 μg m^–3, respectively, at the urban site and 14.0, 14.2, and 24.2 μg m^（–3）, respectively, at the rural site.The nitrogen and sulfur oxidation ratios in urban Beijing were correlated with relative humidity（with correlation coefficient r = 0.79 and 0.67, respectively） and the aerosol loadings. Based on a parameterization model, we found that the rate constant of the heterogeneous reactions for SO2 on polluted days was about 10 times higher than that on clear days, suggesting that the heterogeneous reactions in the aerosol water played an essential role in haze events.The ISORROPIA II model was used to predict the aerosol pH, which had a mean（range） of 5.0（4.9–5.2） and 5.3（4.6–6.3） at the urban and rural site, respectively. Under the conditions with this predicted pH value, oxidation by dissolved NO2 and the hydrolysis of N2O5 may be the major heterogeneous reactions forming SO4^2– and NO3^– in haze.We also analyzed the sensitivity of the aerosol p H to changes in the concentrations of SO4^2–, NO3^–, and NH4^＋ under haze conditions. The aerosol p H was more sensitive to the SO4^2– and NH4^＋ concentrations with opposing trends, than to the NO3^– concentrations. The sensitivity of the p H was relatively weak overall, which was attributed to the buffering effect of NH3 partitioning.