Abstract:  In this study, the daily data of air quality and the conventional meteorological data from the Hotan Oasis were used to analyze the air quality over the study area from January 1, 2015 to December 31, 2017. The relationships among the air quality and the meteorological factors were discussed. The results showed that the three-year average AQI in the Hotan Oasis was 199, the air pollution was moderate, and the days with air pollution accounted for 78.1% of the total. Seasonally, the air quality in spring was the worst, then that in summer, and the air pollution was the slightest in autumn and winter. The annual average concentrations of PM₁₀ and PM_2.5 were 333 μg·m^-3 and 100 μg·m^-3, and the days when the values of PM₁₀ and PM_2.5 exceeded the standards accounted for 75.7% and 49.5% of the total, respectively. The days when the values of other pollutants exceeded the standards were lower than 3%. The concentration of PM₁₀ was the highest in spring, then in summer and autumn, and it was the lowest in winter. The concentration of PM_2.5 was the highest in spring, then in summer and winter, and it was the lowest in autumn. The concentrations of SO₂, NO₂ and CO were the highest in winter, then in spring and autumn, and it was the lowest in summer. O₃ concentration was the highest in summer, then in spring and autumn, and it was the lowest in winter. Except precipitation, AQI was significantly correlated with other meteorological factors. Except the absence of correlations between the average temperature and PM_2.5, relative humidity and CO, and precipitation and SO₂, PM₁₀, O₃ and PM_2.5, other meteorological factors affected significantly the IAQI. Visibility was significantly correlated with AQI and IAQI. AQI decreased with the increase of visibility. Under the similar visibility, the pollutant concentration was higher in summer half year when the occurring frequency of dust weather was high than that in winter half year when the occurring frequency of dust weather was low. With the improvement of visibility, the concentrations of SO_2, PM₁₀, CO and PM_2.5 tended to a decrease, the concentration of O₃ increased, and the concentration of NO₂ changed irregularly. Moreover, the concentrations of PM₁₀, O₃ and PM_2.5 were higher in summer half year than in winter half year, and the concentrations of SO₂, CO and NO₂ were higher in winter half year than in summer half year. When the visibility was lower than 1 km, the pollutant concentration under dense floating dust weather was similar to that in sandstorm; when the visibility varied in a range of 1-3.5 km, the pollutant concentration under floating dust weather was similar to that under blowing sand weather; when the visibility was higher than 3.5 km, the pollutant concentration under floating dust weather was higher than that under blowing sand weather. The concentrations of PM₁₀ and PM_2.5 decreased with the increase of the lowest visibility, and the change of concentrations of other pollutants with the change of the lowest visibility was different.

Key words: air quality')">

air quality, meteorological factor, Oasis, Hotan, Xinjiang