徐州市大气PM2.5与O3作用关系的季节变化

通过2013~2017年徐州市环境监测资料分析季风影响下主要大气复合污染物PM_2.5和O₃的相关性，并基于气象观测资料进一步探究PM_2.5和O₃相互作用机制的季节变化特征.结果表明：夏季风季节，PM_2.5和O₃呈正相关，相关系数高达0.56；冬季风季节，PM_2.5和O₃呈负相关，相关系数为-0.34，均通过了99%的置信检验，表明徐州市PM_2.5和O₃相互作用呈现相反的季节变化.夏季风季节，太阳辐射强，气温较高，大气氧化性较强，O₃主导大气氧化性，大气氧化性通过促进二次颗粒物生成使得PM_2.5浓度升高，夏季风季节以O₃对PM_2.5的促进作用主导城市大气复合污染变化；冬季风季节，太阳辐射弱，气温较低，大气氧化性较弱，高浓度的PM_2.5削弱太阳辐射抑制大气光化学，导致O₃生成率降低，冬季风季节以PM_2.5对O₃的抑制作用主导城市大气复合污染变化.

Seasonal variation of the relationship between surface PM2.5 and O3 concentrations in Xuzhou

The correlation between major atmospheric pollutants PM_2.5 and O₃ under the effect of East Asian monsoons was analyzed by using the environmental monitoring observations from 2013 to 2017 in Xuzhou. Based on meteorological observations, this paper further investigated the seasonal variation of interaction mechanism between PM_2.5 and O₃. The results showed that:PM_2.5 and O₃ were positively related with the correlation coefficient of 0.56 in summer monsoon (SM), while PM_2.5 and O₃ were negatively related with the correlation coefficient of -0.30 in winter monsoon (WM), both passing the confidence test of 99%. This indicated that the interaction of air compound pollutants PM_2.5 and O₃ in Xuzhou presented opposite the seasonal changes. In SM featured by strong solar radiation, high air temperature and strong oxidation, O₃ dominated the atmospheric oxidation, and oxidation effectively promoted secondary particle formation. The promotion of O₃ on PM_2.5 dominated the changes of air compound pollution in SM. In WM, the air temperature was low and the atmospheric oxidation was weak, then the enhanced PM_2.5 levels could suppress atmospheric photochemistry by reducing solar radiation, with the ozone change rate decreasing and peaking time postponing. The inhibitory effect of PM_2.5 on O₃ dominated the changes of air compound pollution in WM in Xuzhou.