Abstract
Abstract. The paper analyzed the variation characteristics of AQI and its correlation with PM2.5 and PM10 of in Beijing-Tianjin-Hebei region from July 2015 to July 2018 based on hours of pollutants in Beijing-Tianjin-Hebei region, using AQI calculation method and statistical correlation evaluation method. Results showed that:(1) The air quality compliance rate in Beijing-Tianjin-Hebei region was 67%, the average AQI was 97.6577, and the air quality was good. The distribution frequency of primary pollutants was PM2.5, followed by PM10, which accounts for 78.9% of the distribution frequency of the six major pollutants, indicated that PM2.5 and PM10 had a greater impact on the air quality of Beijing-Tianjin-Hebei. (2) The correlation between AQI and PM2.5 and PM10 was significantly positively correlated. R2 was 0.8225 and 0.7749, respectively, P < 0.01, indicated that both showed a greater impact on air quality. (3) AQI and PM2.5 and PM10 showed a gradual decrease trend at 9h–16h, ie 9h highest and 16h lowest. The AQI fluctuated between 94.2816 and 103.3562, indicated that the air quality at 9h–16h was good or slightly polluted. (4) The spatial distribution of AQI, PM2.5 and PM10 was characterized by low northwest and high southeast, and the southeastern part was gradually decreasing from 9h–16h. AQI was negatively correlated with elevation. The higher the elevation, the better the air quality, and the worse the air quality.
Highlights
With the rapid development of the economy in the Beijing-Tianjin-Hebei region, the problem of air pollution became increasingly serious(Iii et al.,2002)
The Air Quality Index (AQI) classification calculation refers to the new ambient air quality standard (GB3095-2012), mainly using sulfur dioxide (SO2) and nitrogen dioxide ( NO2), carbon monoxide (CO), ozone (O3), and PM10, PM2.5 and other six pollutant concentration values to convert into corresponding indexes, which can be used for environmental status assessment, trend evaluation and retrospective evaluation, providing timely and accurate Air quality
The 9h-16h data was Averaged as the daily average daily value, and the ratio of the number of days of AQI in the Beijing-Tianjin-Hebei region to the total number of days was calculated, so as to obtain the distribution frequency of different air quality levels in the Beijing-Tianjin-Hebei region.It could be seen from Figure 2 that the AQI was the second/good distribution frequency (40%), which was 2/5 of the total research scale days.The air quality was the first/optimal distribution frequency, which was 24% and the air quality was the sixth/severe pollution had the lowest frequency and its value was 2%
Summary
With the rapid development of the economy in the Beijing-Tianjin-Hebei region, the problem of air pollution became increasingly serious(Iii et al.,2002). Pei et al (2018) used air quality monitoring data combined with spatial autocorrelation analysis to analyze the temporal and spatial distribution characteristics of AQI in Shenzhen.The results showed that AQI was positive spatial autocorrelation, and the primary pollutants were different every year. AQI was the best in summer and the worst in winter.Previous studies have mainly analyzed the temporal and spatial distribution of AQI from the daily, seasonal and annual scales, and rarely involved hourly scales.this paper selected the Beijing-Tianjin-Hebei region with developed economy and high industrial population as the research area, and used AQI calculation method and statistical correlation evaluation method to study the characteristics of AQI and analyze the correlation between AQI and PM particle concentration and hourly temporal and spatial distribution. The DEM (Digital Elevation Model) data was selected from the SRTM (Shuttle Radar Topography Mission) Space Shuttle Radar Topography Mission 90m resolution digital elevation data from the Geospatial Data Cloud website (http://www.gscloud.cn/search)
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