上海春季大气PM1分布特征

Distribution characteristics of atmospheric PM_1 in spring at Shanghai

利用2015年春季(3月—5月)上海地区9个大气成分站在线观测获得的地面PM_1质量浓度数据,研究该地区PM_1浓度时空分布特征。结果表明,上海地区各站PM_1污染浓度水平总体较高,整个上海地区的PM_1小时平均浓度为26.3μg?m^(-3),最大值为126.4μg?m^(-3),最小值为2.4μg?m^(-3);各站PM_1浓度的日变化分布表现为峰值类型和峰值时间不一;各站PM_1三个主要粒径段的质量浓度比值均有一定的差异,其中东滩PM_1比例最大,宝山最小;上海春季PM_1的浓度逆周末效应,可能是由于春季气象条件周期性影响。

Background, aim, and scope Atmospheric particulate matter seriously affect China＇s air quality. As a large city of Shanghai, with the rapid development since the reform and opening, the increase of various human activities lead to the huge consumption of energy and fossil fuels, also makes the urban environment quality, especially the air quality will worsen which appeared a series of atmospheric pollution problems. Previous studies have focused on the TSP, PM10 and PM2.5, etc., for the pollution level of PM1 research is less. Therefore, analysis of the characteristics of sub-micron particles PM1 concentration in Shanghai is of great significance for research and control of atmospheric pollution. Materials and methods The spatial and temporal distribution characteristics of PM1 concentration in the area were studied by using the ground PM1 mass concentration data obtained from 9 atmospheric composition stations in Shanghai area during spring（March, 2015）. We analyzed the concentration distribution and daily variation and weekend effect of PM1 in spring at Shanghai. Results The result shows that the average hourly concentration of PM1 in Shanghai area is 26.3 μg·m^-3, the maximum value is 126.4 μg·m^-3, the minimum value is 2.4 μg·m^-3. The maximum average hourly concentration of PM1 is occurred in Baoshan Station, about 164.8 μg·m^-3, and minimum value is occurred in Dongtan Station, about 0.9 μg·m^-3. The PM1 average concentration of each site from high to low is Xujiahui, Baoshan, Shenshan, Pudong, Chongming, Jinshan, Xiaoyangshan, Lingang and Dongtan. The largest fluctuation of PM1 concentration is occurred in Baoshan, and the least is occurred in Xiaoyangshan. The daily variation of PM1 concentration in each station showed diurnal variation law peak type and peak time. The daily average of PM1 in Xuhui and Pudong presents obvious bimodal curve. The first peak is occurred in 7：00 am to 10：00 am, and the second peak is occurred in 18：00 pm. The second peak is lower than the first peak. The daily average of PM1 in Baoshan present not obvious bimodal curve. The peak is occurred in 6：00 am and 18：00 pm. The PM1 daily average of Shenshan, Jinshan and Lingang stations present weak bimodal curve. There are two peaks during 8：00 am to 14：00 pm. The daily average of Dongtan and Chongming is present unimodal distribution, the peak respectively occurred in 9：00 am and 7：00 am. There were some differences in the mass concentration ratios of the three main grain sizes of PM1 in each station, the Dongtan Station PM1 ratio was the largest, Baoshan minimum. Shanghai spring PM1 concentrations reverse weekend benefits. Discussion The diurnal variation of PM1 in spring at Shanghai urban is mainly due to vehicle emissions in the rush hour, while in suburbs is due to pollutant transport. Shanghai spring PM1 concentrations reverse weekend benefits, may be due to cyclical impact of spring weather conditions. Conclusions The results show that the overall level of PM1 pollution in Shanghai area is higher, the average concentration of PM1 in Shanghai area is 26.3μg·m^-3, the maximum value is 126.4 μg·m^-3, the minimum value is 2.4 μg·m^-3; the daily variation of PM1 concentration in each station showed diurnal variation law peak type and peak time. There were some differences in the mass concentration ratios of the three main grain sizes of PM1 in each station, the Dongtan Station PM1 ratio was the largest, Baoshan minimum. Shanghai spring PM1 concentrations reverse weekend benefits, may be due to cyclical impact of spring weather conditions. Recommendations and perspectives The search provide a significant scientific basis in to understand the spatial and temporal distribution characteristics of PM1 concentration in spring at Shanghai.