武夷山市臭氧分布特征及其与气象要素关系分析

Characteristics of Ozone Pollution Distribution and Its Correlation Analysis with Meteorological Factors in Wuyishan

武夷山是著名的旅游胜地,同时地理环境复杂,气候资源丰富,也是东亚季风影响敏感区。为科学认识清洁区域的臭氧分布特征及污染的天气学成因,也为进一步开展臭氧污染预警预报和科学治理提供技术支撑,利用2015—2019年武夷山市逐小时污染物浓度监测数据和地面常规气象观测资料,采用统计分析和SPSS相关性分析等方法,对近年来武夷山市臭氧分布特征及其与气象要素的关系进行研究。结果表明,2015—2019年武夷山市臭氧的年评价值(MDA8-90)由110μg·m^(−3)增长至133μg·m^(−3),ρ(O_(3)–8 h)超过《环境空气质量标准》(GB 3095—2012)二级标准限值的天数从0 d上升到9 d,O_(3)作为首要污染物占比从48.5%上升为85.1%;同时,首要污染物为PM_(2.5)的天数呈逐年递减趋势,PM_(2.5)的首要污染物天数从2015年的36 d下降到2019年的8 d。春末(4—5月)和初秋(9—10月)是臭氧污染最为严重的季节,80.0%的臭氧超标日集中在这4个月。武夷山市ρ(O_(3))小时均值分布均呈现单峰型分布,最高值出现在14:00,而后开始下降,最低值出现在07:00。ρ(O_(3)–8 h)与日最高气温、平均风速、太阳日总辐射和日照时数呈显著正相关,相关系数分别为0.370**,0.402**,0.564**,0.565**;与相对湿度呈显著负相关(相关系数为−0.646**),并呈现先升后降的趋势。一些气象要素如高温度和低相对湿度等有助于该区域臭氧浓度的升高,当环境温度>25℃、相对湿度<70%时,都有利于对流层空气中臭氧的生成,更容易造成O_(3)浓度超标。此外当风速≤2.0 m·s^(−1)时,随着风速的增加,ρ(O_(3)–8 h)增大,而当风速>2.0 m·s^(−1)时,ρ(O_(3)–8 h)随风速的增加呈显著下降趋势。

Wuyi Mountain is a well-known attraction, and at the same time it has a complex geographical environment and rich climate resources. Wuyi Mountain is also a sensitive area affected by the East Asian monsoon. To have a scientific understanding of the characteristics of ozone distribution and its synoptic causes of pollution in clean region, and technological support for carrying out warning, forecast and management of ozone pollution, based on the data of hourly pollutant concentration in two environmental monitoring stations and meteorological factors data from national meteorological stations of Wuyishan City from 2015 to 2019, we used statistical analysis and correlation analysis in SPSS to analyze the characteristics of ozone pollution distribution and its correlation with meteorological factors. The results showed that the annual evaluation of O3(MDA8-90) was increased from 110 μg·m-3 to 133 μg·m-3 in 2015-2019 in Wuyishan City. According to the standard limits of level 2 of Ambient Air Quality Standard(GB 3095-2012), the number of days that daily maximum 8-h average O3 concentration(ρ(O3-8 h)) exceeding the upper limit increased from 0 day to 9 days. The proportion of days that O3 was primary pollutant increased from 48.5% to 85.1%, meanwhile the proportion of days that PM2.5 was primary pollutant was decreasing year by year, the days of primary pollutant of PM2.5 was decreased from 36 days to 8 days. The O3 pollution of Wuyishan City was the most severe in the late spring(April and May) and early autumn(September and October), 80.0% of days exceeding the standard of O3 was on these 4 mouths. Diurnal variation of ρ(O3) showed a single peaked distribution, with the maximum value appearing at 14:00 and the minimum value at 07:00. Daily maximum temperature, wind speed, daily solar radiation and sunshine duration were significantly correlated with ρ(O3–8 h), and correlation coefficient were 0.370**, 0.402**, 0.564**, 0.565** respectively. The relative humidity was negatively correlated with ρ(O3–8 h), and correlation coefficient was-0.646**, and showed a trend of initially increasing and then decreasing. The studies also present that some states of meteorological factors had a significant effect on the increase of ozone concentration, such as high temperature and low relative humidity. When the environmental temperature>25 ℃ and relative humidity<70%, it was conducive to the generation of ozone in the troposphere, and ρ(O3) would exceed the standard. Furthermore, when the average wind speed was less than 2.0 m·s-1, ρ(O3-8 h) increased with the increase of average wind speed. When the average wind speed was more than 2.0 m·s-1, ρ(O3-8 h)decreased with the increase of the average wind speed.