2018—2019年保定市PM_(2.5)质量浓度分布及其与气象因素相关性分析

Atmospheric PM mass concentration distribution and its correlation with meteorological factors in Baoding City from 2018-2019

目的分析保定市大气细颗粒物(PM_(2.5))质量浓度分布及其与气象因素的关系。方法 2018—2019年每年1—12月,在保定市采集PM_(2.5)滤膜样品208张,同时记录环境温度、相对湿度以及大气压等实时气象数据,用重量分析法对PM_(2.5)的质量浓度进行分析,用离子色谱法对PM_(2.5)中Cl^(-)、NO3^(-)、SO4^(2-)、NH4^(+)4种水溶性无机离子进行分析,用Spearman秩相关性分析对大气PM_(2.5)与气象要素间的关系进行分析。结果 2019年保定市PM_(2.5)年平均质量浓度(73.1μg/m^(3))低于2018年(85.4μg/m^(3)),且出现周期性规律即两年中月均PM_(2.5)质量浓度最高均出现在1月份最低均出现在8月份;2018年PM_(2.5)质量浓度与平均气压呈显著正相关(r=0.310,P<0.01),与平均温度呈显著负相关(r=-0.454,P<0.01);2019年PM_(2.5)质量浓度与平均温度呈显著负相关(r=-0.493,P<0.01),与平均气压呈显著正相关(r=0.394,P<0.01)。结论 2018—2019保定市PM_(2.5)年平均质量浓度低于GB 3095—2012《环境空气质量标准》所规定的PM_(2.5)二级浓度限值,且出现周期性规律即两年月均PM_(2.5)质量浓度最高均出现在1月份,最低均出现在8月份,两年平均PM_(2.5)质量浓度均与平均温度呈显著负相关关系,与平均气压呈显著正相关关系。

Objective To study the atmospheric PM_(2.5) mass concentration distribution in Baoding City and its relationship with meteorological factors. Methods Totally 208 membrane samples of PM_(2.5) were collected in Baoding City from January to December in 2018-2019. At the same time, the real time meteorological data such as ambient temperature, relative humidity and atmospheric pressure were recorded.The mass concentration of PM_(2.5) was analyzed by gravimetric method. Four water-soluble inorganic ions(Cl^(-),NO3^(-),SO4^(2-),NH4^(+)) in PM_(2.5) were analyzed by ion chromatography. Spearman correlation analysis was used to investigate the relationship between atmospheric PM_(2.5) and meteorological factors. Results In Baoding City, the annual average mass concentration of PM_(2.5) in 2019(73.1 g/m^(3)) was lower than that in 2018(85.4 μg/m^(3)). There was a periodic characteristic,namely the highest monthly average PM_(2.5) concentration occurred in January and the lowest in August in two years. In 2018, the mass concentration of PM_(2.5) was significantly positively correlated with atmospheric pressure(r=0.310,P<0.01), and significantly negatively correlated with temperature(r=-0.454,P<0.01). In 2019, the mass concentration of PM_(2.5) was significantly negatively correlated with temperature(r=-0.493,P<0.01), and significantly positively correlated with atmospheric pressure(r=0.394, P<0.01).Conclusion From 2018-2019, the annual average mass concentration of PM_(2.5) in Baoding City is less than the secondary concentration limit of PM_(2.5) stipulated by GB 3095-2012 Ambient air quality standard, and there is a periodic characteristic,namely the highest monthly average PM_(2.5) concentration occurs in January and the lowest in August in two years. In two years, the average mass concentration of PM_(2.5) is significantly negatively correlated with temperature, and significantly positively correlated with atmospheric pressure.