Effect of atmospheric HNO2 and O3 on OH radical formation during daytime in the Pearl River Delta Region

基于珠三角地区大气超级监测站2013年10月大气中 HNO2和 O3质量浓度及其光解速率常数等相关参数的在线监测结果，测算了这2种气态污染物通过光解产生 OH 自由基的速率，揭示了日间 HNO2和 O3对 OH 自由基生成的影响。观测期间，O3日间平均质量浓度为158．0μg／m3，HNO2日间平均质量浓度为2．4μg／m3；O3和 HNO2光解产生 OH 自由基的平均速率分别为7．0×106和2．9×107个／（cm3·s）。HNO2和 O3光解生成 OH 自由基的相关光解速率常数和 OH 自由基生成速率随长波紫外线辐射强度增强而增大；但 HNO2光解相关参数与长波紫外线辐射强度的一次线性相关性优于 O3光解相关参数与长波紫外线辐射强度的相关性；相对湿度对 O3光解生成 OH 自由基具有重要的正影响。Photolysis of HNO2 and O3 in the atmosphere is an important source of OH radical,and plays a crucial role in the for-mation of photochemical pollution.Based on the online observation of gaseous HNO2 ,O3 ,and their photolysis rate constants during October of 2013 at the atmospheric supersite in the Pearl River Delta region,the OH radical production rates from HNO2 and O3 photolysis were evaluated respectively and compared to reveal their effects on the OH radical formation.During daytime of the measurement period,the average concentrations of HNO2 and O3 were 2.4 and 158.0 μg/m3 ,respectively,and corresponding OH radical production rates were 2.9×107 and 7.0×106 molecule/(cm3 ·s),respectively.The photolysis rate constants and OH radical production rates of both HNO2 and O3 increased with ultra violet A enhancement,while the linear correlation of these pa-rameters of HNO2 versus ultra violet A were better than those of O3 .The OH production from O3 photolysis was significantly positively influenced by the atmospheric relative humidity.国家自然科学基金资助项目(41303075，U1301234)；国家重大科学仪器设备开发专项资助项目121387-139