2015~2019年日照市PM2.5长期变化特征及其潜在源区分析

利用2015~2019年山东省日照市PM_2.5质量浓度和气象要素的小时数据，对日照市PM_2.5季节污染特征和日照市海陆风特征进行了分析，并基于HYSPLIT模式计算了5年逐日02：00、08：00、14：00和20：00（BTC）的48h后向轨迹，不仅通过轨迹聚类分析和潜在源区分析探讨了日照市不同季节PM_2.5主要传输路径和其轨迹污染特征及其潜在源区分布和贡献，也分析了海陆风对日照市污染物的影响.结果表明：日照市PM_2.5呈现冬季最高、夏季最低的分布特征，监测站点颗粒物浓度在偏西北风影响下较高.日照市不同季节主要输送路径存在差异：春季主要受到偏东和偏北方向气流影响；夏季在副热带高压影响下主要受到来自海上的较为清洁的偏东气流影响；秋季主要受到西北和偏东气流影响；冬季主要受西北和偏北气流影响.整体而言，不同季节受偏西至偏南气流影响时，日照市对应的PM_2.5浓度较高.日照市海陆风春秋季多，夏冬季少；在海陆风影响下，日照市PM_2.5污染和臭氧污染呈现不同的分布特征，且在不同PM_2.5污染等级下，PM_2.5浓度日变化特征也与其在非海陆风日的日变化有所差异.污染潜在源区分析结果表明，日照市最主要的潜在源区位于山东省临沂市、潍坊市、青岛市和江苏省连云港市.

Long term characteristics and potential sources of PM2.5 in Rizhao City from 2015 to 2019

Based on the hourly data of PM_2.5 concentrations and meteorological elements in Rizhao City during 2015 to 2019, the seasonal characteristics of PM_2.5 and its relationship with wind speed and wind direction were analyzed. Also, the characteristics of sea-land in Rizhao City were summarized. Combined with HYSPLIT model and GDAS data, the 48h backward trajectories of PM_2.5 concentrations at 02:00, 08:00, 14:00 and 20:00 (BTC) every day in five years were calculated. The main transport pathways and potential source contribution of PM_2.5 concentrations in different seasons were discussed by cluster analysis and potential source contribution analysis. The influence of sea-land wind on pollutants in Rizhao City was also analyzed. The results showed that the seasonal characteristics of PM_2.5 concentrations in Rizhao City was the highest in winter and the lowest in summer. The particles concentrations of the monitoring station is higher under the influence of northwest wind. There are differences in the main transport routes in different seasons in Rizhao:in spring, it is mainly affected by the easterly and northerly airflow; in summer, it is mainly affected by the cleaner easterly airflow from the sea under the influence of subtropical high system; in autumn, it is mainly affected by the northwest and easterly airflow; in winter, it is mainly affected by the northwest and northerly airflow. On the whole, the PM_2.5 concentrations of Rizhao City is higher in different seasons affected by the westerly to southerly airflow. The sea-land wind days are more in spring and autumn,less in summer and winter. Under the influence of sea-land wind, the PM_2.5 and ozone pollution in Rizhao City present different distribution characteristics, and under different PM_2.5 pollution levels, the daily variation characteristics of PM_2.5 concentrations are also different from those in normal days.The results show that the main potential source areas of Rizhao are Linyi City, Weifang City, Qingdao city and Lianyungang City of Jiangsu Province.