Concentrations and influences of negatively charged oxygen ions in a typical agro-pastoral ecotone: A case study of Duolun County in Inner Mongolia, China

To explore the presence and concentrations of negatively charged oxygen ions in the atmosphere in a typical farming-pastoral ecotone, and reveal the effects of negatively charged oxygen ions on meteorological and air pollution parameters, including air pressure, air temperature, wind speed, precipitation, O₃, and SO₂, differences in negatively charged oxygen ion concentrations in different atmospheres and different underlying surfaces were compared to provide a decision-making basis for ecological protection and economic construction. Kruskal-Wallis test and Spearman analysis were used to statistically assess relationships. The results showed that: 1) air concentrations of negatively charged oxygen ions were highest at 06:00, and lowest at 14:00 – 15:00, with significant differences in negatively charged oxygen ion concentrations (P < 0.05) under different surface and environmental conditions, and seasonal variations, and 2) negatively charged oxygen ion concentrations display obvious inter-monthly variation, representing a normal distribution, with August as the center of the time span from June to October. Concentrations of negatively charged oxygen ions from July to August were the highest in the year, with little fluctuation from December to April. 3) a negative correlation was observed between diurnal variation in air temperature and negatively charged oxygen ion concentrations and a positive correlation was observed between monthly variations in air temperature and negatively charged ion concentrations. Negatively charged oxygen ion concentrations correlated positively with relative humidity, and negatively with wind speed. Concentrations did not change with time scale. Monthly variation in negatively charged oxygen ion concentrations correlated positively with precipitation, but not with air pressure or sunshine hours. 4) the daily mean concentration of negative oxygen ions correlates negatively with PM 10, CO, SO₂, NO₂, and O₃, and seasonal differences were observed. No correlation with PM 2.5 was noted.