新疆和田绿洲空气质量状况与气象条件的关系

利用和田绿洲空气质量日报数据和同期的常规气象资料,分析了2015年1月1日至2017年12月31日该区的空气质量特征,探讨了气象条件和空气质量之间的相互关系。结果表明：和田绿洲近3 a平均环境空气质量指数（AQI）为199,达到空气质量中度污染标准,污染天数占总日数的78.1%。其中,春季空气质量最差,以严重污染为主;其次是夏季,以轻度和严重污染为主;再次是秋季和冬季,以轻度污染为主。PM₁₀、PM_2.5浓度年平均分别为332 μg·m^-3和100μg·m^-3,超标率为75.7%和49.5%,其余污染物超标率在3%以下,其中PM₁₀浓度春季最大,夏、秋季其次,冬季最小;PM_2.5浓度春季最大,夏、冬季其次,秋季最小;SO₂、NO₂、CO浓度冬季最大,春、秋季次之,夏季最小;O₃浓度夏季最大,春、秋季次之,冬季最小。除降水量外,AQI与其余气象因子均呈极显著相关;除平均气温与PM_2.5、相对湿度与CO、降水与SO₂、PM₁₀、O₃、PM_2.5无相关外,其余气象因子对污染物浓度 均有显著影响;能见度与AQI和各类污染物浓度均为极显著相关。随着能见度的上升,AQI下降,在同样能见度条件下,AQI在沙尘多发期的夏半年高于沙尘少发期的冬半年;不管在沙尘多发期还是少发期,随着能见度的转好,SO₂、PM₁₀、CO、PM_2.5污染物浓度呈减少趋势,O₃浓度呈增多趋势,NO₂浓度无明显的规律,而且PM₁₀、O₃、PM_2.5浓度夏半年高于冬半年,SO₂、CO、NO₂浓度冬半年高于夏半年。在沙尘天气期间,最低能见度小于1 km的浓浮尘和沙尘暴天气AQI相互接近,最低能见度在1～3.5 km的浮尘和扬沙天气AQI相互接近,当最低能见度大于3.5 km时,浮尘天气的AQI高于扬沙天气的AQI;PM₁₀、PM_2.5浓度随着最低能见度升高而变小,其他污染物浓度虽然随着最低能见度的变化有一定的差别,但规律不明显。

Relationship between Air Quality and Meteorological Conditions in the Hotan Oasis,Xinjiang

In this study, the daily dataof air quality and the conventional meteorological data from the Hotan Oasiswere used to analyze the air quality over the study area from January 1, 2015to December 31, 2017. The relationships among the air quality and the meteorologicalfactors were discussed. The results showed that the three-year average AQI inthe Hotan Oasis was 199, the air pollution was moderate, and the days with airpollution accounted for 78.1% of the total. Seasonally, the air quality inspring was the worst, then that in summer, and the air pollution was theslightest in autumn and winter. The annual average concentrations of PM₁₀ and PM_2.5 were 333 μg·m^-3 and 100 μg·m^-3, andthe days when the values of PM₁₀ and PM_2.5 exceeded thestandards accounted for 75.7% and 49.5% of the total, respectively. The days whenthe values of other pollutants exceeded the standards were lower than 3%. Theconcentration of PM₁₀ was the highest in spring, then in summer andautumn, 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 inautumn. The concentrations of SO₂, NO₂ and CO were thehighest in winter, then in spring and autumn, and it was the lowest in summer.O₃ concentration was the highest in summer, then in spring andautumn, and it was the lowest in winter. Except precipitation, AQI wassignificantly correlated with other meteorological factors. Except the absenceof correlations between the average temperature and PM_2.5, relativehumidity and CO, and precipitation and SO₂, PM₁₀, O₃ and PM_2.5, other meteorological factors affected significantly theIAQI. Visibility was significantly correlated with AQI and IAQI. AQI decreasedwith the increase of visibility. Under the similar visibility, the pollutantconcentration was higher in summer half year when the occurring frequency ofdust weather was high than that in winter half year when the occurringfrequency of dust weather was low. With the improvement of visibility, theconcentrations of SO_2, PM₁₀, CO and PM_2.5 tendedto a decrease, the concentration of O₃ increased, and the concentrationof NO₂ changed irregularly. Moreover, the concentrations of PM₁₀,O₃ and PM_2.5 were higher in summer half year than inwinter half year, and the concentrations of SO₂, CO and NO₂ were higher in winter half year than in summer half year. When the visibilitywas lower than 1 km, the pollutant concentration under dense floating dust weatherwas similar to that in sandstorm; when the visibility varied in a range of 1-3.5km, the pollutant concentration under floating dust weather was similar to thatunder blowing sand weather; when the visibility was higher than 3.5 km, thepollutant concentration under floating dust weather was higher than that under blowingsand weather. The concentrations of PM₁₀ and PM_2.5 decreased with the increase of the lowest visibility, and the change of concentrationsof other pollutants with the change of the lowest visibility was different.