北京市核心区秋冬季大气日降尘污染特征OA

Drawing on foreign standards,a daily dustfall measurement method was developed by incorporating a filtration step into the Chinese standard procedure.Using a single typical monitoring site in Beijing’s Xicheng District,the pollution characteristics of daily dustfall during autumn and winter were investigated.A sand core filtration device with quartz or mixed cellulose ester filters was used to determine daily dustfall,and the results met the required criteria for recovery rate,parallelism,and time closure.During the autumn and winter seasons,the daily dustfall ranged from 0.06 to 2.33 t·(km2·d)−1.Although only 4%of the days experienced daily dustfall exceeding 0.7 t·(km2·d)−1,they contributed to 25%of the total dustfall,with the highest values predominantly observed in January,March,and December.Moreover,the proportion of insoluble dustfall during autumn and winter was 83%±12%.A logarithmic model was established to estimate the proportion(y)based on the insoluble dustfall(x),represented by the equation y=9.36ln(x)+99.98.A strong positive correlation was found with average wind speed,and the equation for predicting daily dustfall(y)based on average wind speed(x)was y=0.06e0.61x.Strong winds reach level 3 or above had a significant impact on total dustfall.To effectively reduce dustfall pollution,it is recommended to formulate specific control measures,suspend earthwork operations,cover bare ground,and increase the frequency of watering at construction sites when wind speeds reach level 3 or higher.