新疆地区大气环境容量系数的气候特征及其在空气质量变化中的作用

新疆在我国属于冬半年大气环境容量系数(A值)显著偏低的区域.研究了1975—2019年新疆大气环境容量系数的时空变化特征.新疆的低A值区主要分布在塔里木盆地北部和新疆东部;研究期间新疆的大气环境容量系数在随机波动中整体呈下降趋势,这与新疆平均风速的变化较为一致,主要是由气候变化引起.新疆A值的季节差异大,春夏高、秋冬低;A值的冬季均值远小于年均值,说明新疆冬季的大气自净能力很弱.新疆4个地级市的月均A值与PM_2.5浓度具有显著的负相关,A值能够较好地反映当地空气污染的气象条件特征.南疆城市则由于沙尘天气的影响,大气颗粒物浓度很高,但A值与PM_2.5浓度的相关性较差.还基于A值,利用城市大气环境荷载指数对新疆4个地级市的大气污染排放变率进行了评估.

Climate characteristics of atmospheric environmental capacity coefficient and its role in air quality change in Xinjiang, China

Xinjiang belongs to the region where the atmospheric environmental capacity coefficient (A value) is significantly lower in winter half year in China. The temporal and spatial variation characteristics of atmospheric environmental capacity coefficient in Xinjiang from 1975 to 2019 were studied. The low A value areas in Xinjiang are mainly distributed in the northern Tarim Basin and the eastern Xinjiang. In the past 45 years, Xinjiang''s atmospheric environmental capacity coefficient showed a downward trend in random fluctuations, which was consistent with the change of average wind speed in Xinjiang, mainly caused by climate change. The seasonal difference of A value in Xinjiang is large, which is high in spring and summer and low in autumn and winter. The winter mean value of A is much smaller than the annual mean value, which indicates that Xinjiang''s atmospheric self-purification ability in winter in is very weak. The monthly average A value of the four prefecture-level cities in Xinjiang has a significant negative correlation with PM_2.5 concentration, and A value can better reflect the meteorological conditions of local air pollution. However, due to the influence of dust weather, the concentration of atmospheric particulate matter is very high in southern Xinjiang, but the correlation between A value and PM_2.5 concentration is poor. Based on the A value, the variation rates of air pollution emission in the four prefecture-level cities in Xinjiang were also evaluated by using the urban atmospheric environment load index in this paper.