风蚀沙尘对新疆绿洲城市大气环境的影响研究

Study on the influence of aeolian dust on the atmospheric environment of oasis cities in Xinjiang,northwest China

通过分析2020年新疆16个绿洲城市的环境监测记录和气象观测数据,研究沙尘天气频率、大气降尘强度和PM_(10)(空气动力直径≤10μm的颗粒物)浓度的变化特征以及风蚀沙尘对绿洲城市大气环境的影响.统计分析结果显示:2020年南疆沙尘天气日数为180 d,是北疆和东疆沙尘天气总日数的4倍以上;新疆地区春夏两季浮尘天气日数占全年沙尘天气总日数的50%以上;北疆、东疆和南疆城市沙尘天气PM_(10)浓度较非沙尘天气分别增加14%~253%、20%~422%和24%~804%.风蚀沙尘造成75%的绿洲城市年均PM_(10)浓度高于国家环境空气质量标准的二级浓度限制,且呈现出由北向南递增的变化趋势;南疆城市风蚀沙尘中PM_(10)贡献率高达67%,其次是东疆和北疆城市,分别为22%和11%.新疆绿洲城市降尘强度和PM_(10)浓度呈显著正相关,南疆最大月均降尘强度为143 t·km^(-2),是北疆和东疆的14倍和8倍;风蚀沙尘造成南疆城市空气质量污染比重均在80%以上,大气能见度显著低于北疆和东疆.总之,风蚀沙尘对新疆绿洲城市大气环境的影响显著,其影响程度与沙尘天气发生频率和地处沙源区密切相关.

By analyzing environmental monitoring records and meteorological observation data from 16 oasis cities in Xinjiang,China in 2020,we studied the variation characteristics of dust frequency,atmospheric dustfall intensity,and PM_(10)(particulate matter with aerodynamic diameter≤10μm)concentration,and their influences on the atmospheric environment.Statistical analysis shows that the annual dust occurrence in southern Xinjiang is 180 days,which is more than four times the total number of dust days in northern and eastern Xinjiang.Aeolian dust events that occur in the spring and summer in Xinjiang account for more than 50%of the annual dust days.Compared with non-dust weather,PM_(10) concentrations in northern,eastern,and southern Xinjiang increased by 14%~253%,20%~422%,and 24%~804%,respectively,during aeolian dust events.Due to the influences of windblown dust,the annual average PM_(10) concentration in 75%of oasis cities in Xinjiang exceeds the second-level concentration limit of the national ambient air quality standards,and gradually increases from north to south.Aeolian dust contributes more than 67%of PM_(10) in southern Xinjiang,followed by eastern Xinjiang and northern Xinjiang with 22%and 11%,respectively.There is a significant positive correlation between urban dustfall intensity and PM_(10) concentration.The maximum monthly average dustfall intensity in southern Xinjiang is 143 t·km−2,which is 14 times and 8 times higher than that in northern and eastern Xinjiang.The proportion of air pollution caused by aeolian dust is above 80%in all cities of southern Xinjiang,which leads to notably lower atmospheric visibility than that in northern and eastern Xinjiang.In general,aeolian dust has a significant impact on the atmospheric environment of oasis cities in Xinjiang,northwestern China,and its effects are closely related to the frequency of dust outbreaks and dust sources.