我国城市地区PM_(2.5)和O_(3)污染相关性:2017~2022年时空演变特征与协同防控启示

The correlation between PM_(2.5) and O_(3) pollution in urban areas of China:spatiotemporal variation from 2017 to 2022 and implication for synergistic prevention and control

基于2017~2022年全国地级及以上城市空气质量监测数据及各省(自治区、直辖市)污染排放数据,计算PM_(2.5)日均浓度(DA PM_(2.5))和O_(3)日最大8h滑动平均值(MDA8_O_(3))间的皮尔逊相关系数(R_(p)),分区域分时段研究了二者相关性的时空变化特征,从污染排放等方面分析其原因.结果表明:从时空变化上看,全国范围内DA PM_(2.5)和MDA8_O_(3)第一、四季度在统计上无显著相关性(R_(p)=-0.11~0.03),仅西南、华南地区为正相关(R_(p)=0.11~0.32).全国范围内DA PM_(2.5)和MDA8O_(3)在第二季度(R_(p)=0.26~0.36)、第三季度(R_(p)=0.46~0.55)呈正相关,汾渭平原及西北地区在部分年份不相关.污染排放是影响PM_(2.5)和O_(3)污染相关性的主要因素.从时间变化上看,全国和各区域一次PM_(2.5)、二氧化硫排放特征值(ECV_(PM_(2.5))、ECV_(SO_(2)))下降而氮氧化物、挥发性有机物排放特征值(ECVNOx和ECVVOCs)上升,这与大部分省(自治区、直辖市)R_(p)平均值上升的趋势一致.从空间分布上看,在ECVPM_(2.5)和ECVSO2低而ECV_(NOx)和ECV_(VOCs)高的地区,PM_(2.5)与O_(3)污染正相关性较强.提出全国不同区域差异化的污染防控启示.京津冀及周边、长三角、东北和西南地区(第二、三季度)以及华南地区(全年),需关注NO_(x)和VOCs排放控制.京津冀及周边、长三角、东北和西南地区(第一、四季度)以及汾渭平原和西北地区(全年),需加强一次PM_(2.5)污染减排.

Based on air quality monitoring data in all cities nationwide from 2017 to 2022,the Pearson correlation coefficient(R_(p))between PM_(2.5)daily average concentration(DA PM_(2.5))and the maximum daily 8-hour moving average of O_(3)(MDA8_O_(3))was calculated,and the spatiotemporal variation characteristics of R_(p)was investigated.The results show that:There was no statistically significant correlation between DA PM_(2.5)and MDA8_O_(3)in the first and fourth quarters nationwide(R_(p)=-0.11~0.03),and positive correlation was only found in Southwest and South China(R_(p)=0.11~0.32).A nationwide positive correlation existed between DA PM_(2.5)and MDA8_O_(3)in the second(R_(p)=0.26~0.36)and the third quarters(R_(p)=0.46~0.55),but no correlation in Fen-Wei Plain and Northwest China for some years.Pollutant emission is the main factor affecting the correlation between PM_(2.5)and O_(3)pollution.Temporally,the emission characteristic values of primary PM_(2.5)and sulfur dioxide(ECV_(PM_(2.5))and ECV_(SO_(2)))decreased while those of nitrogen oxides and volatile organic compounds(ECV_(NO_(x))and ECV_(VOCs))increased,which is consistent with the increasing trend of the average R_(p)values in most provinces(autonomous regions and municipalities directly under the Central Government).Spatially,for regions with relatively lower ECV_(PM_(2.5))and ECV_(SO_(2))but higher ECV_(VOCs)and ECV_(NO_(x)),the positive correlation between PM_(2.5)and O_(3)pollution is stronger.Based on the findings above,it is proposed that Beijing-Tianjin-Hebei and its surrounding area(BTH),Yangtze River Delta(YRD),Northeast and Southwest China(in the second and third quarters),and Southern China(year-round)shall pay attention to NOx and VOCs emission control,while BTH,YRD,Northeast and Southwest China(in the first and fourth quarters),and Fen-Wei Plain and the Northwest China(year-round),need to mitigate primary PM_(2.5)emission.