甘肃省区域颗粒物时空分布特征及传输路径

Spatial and temporal distribution characteristics and transport path analysis of regional particulate matter over Gansu Province

基于甘肃省2018~2019年颗粒物质量浓度监测数据,分析了全省大气颗粒物浓度的时空变化及排放特征,并利用HYSPLIT后向轨迹模式研究了颗粒物传输路径.结果表明:颗粒物(PM_(10)和PM_(2.5))空间分布呈现区域特征:PM_(10)浓度高值位于河西走廊地区,由北向南呈阶梯式递减;PM_(2.5)以陇中地区为高值中心,向南北两侧递减,陇南地区为全省颗粒物清洁区.不同地区PM_(10)与PM_(2.5)地面浓度季节变化特征存在差异,陇中、陇东和陇南地区PM_(10)和PM_(2.5)浓度变化特征一致,陇中和陇东地区颗粒物(PM_(10)与PM_(2.5))浓度冬高夏低,陇南地区则为冬高秋低;河西走廊PM_(10)和PM_(2.5)浓度季节变化不同,PM_(2.5)冬高夏低,PM_(10)春高夏低.后向轨迹聚类结果表明全省春季、冬季均受到来自中亚及新疆的偏西气流影响,该路径输送下可吸入颗粒物(PM_(10))浓度明显高于其他路径,是典型的沙尘输送路径,4大分区受沙尘传输影响程度依次为河西>陇中>陇东>陇南,来自陕西、川渝的偏东路径是陇南地区颗粒物的主要输送路径,该路径下PM_(2.5)/PM_(10)比值大于0.5,明显高于偏西路径,说明偏东路径人为源污染贡献显著.研究结果有助于全面认识全省颗粒物污染特点、为分区制定颗粒物污染防治政策、以及区域污染协同治理提供科学的参考依据.

Based on the monitoring data of particulate matter mass concentration,the spatial-temporal variation and emission characteristics of atmospheric particulate matter concentration were analyzed across the Gansu Province for the time period of 2018~2019,with a focus of the transport path of particulate matter using the HYSPLIT backward trajectory model.The results suggested that:Different spatial distribution of PM_(10) and PM_(2.5) were shown across the Gansu Province with a significant regional dependency.The peak value of PM_(10) concentration was located at the Hexi Corridor area,with a strong step-decreasing from north to south.While,the high value center of PM_(2.5) concentration was observed over Longzhong region,which experienced a extending decreasing to the north and south.Furthermore,Longnan region was identified as the noticeable clean area of particulate matter across the Gansu Province.Significant discrepancies were found in the seasonal variation of PM_(10)/PM_(2.5) concentrations among different regions.The similar seasonal patterns of PM_(10)/PM_(2.5) concentration were found over central Gansu,eastern Gansu and southern Gansu,with the concentration of PM_(10) and PM_(2.5) both peaking in winter(winter)but plunging in summer(autumn)at Longzhong and Longdong(Longnan).However,different seasonal variations of PM_(10) and PM_(2.5) concentrations were found over Hexi Corridor,where PM_(2.5) was found to be experiencing high concentration in winter and low in summer,but high concentration of PM_(10) was shown in spring and low in summer.The backward trajectory clustering results showed that the Gansu province was strongly governed by the west air current which come from central Asia and Xinjiang,especially in spring and winter time.This path is considered to be a typical dust transport pathway across the Gansu Province when considering the higher concentration of PM_(10) than others,with which affecting.the four regions in the order of Hexi>Longzhong>Longdong>Longnan.The eastern path from Shanxi,Sichuan&Chongqing with PM_(2.5)/PM_(10) ratio over 0.5which is significantly higher than the western one was deemed to be the dominant transmission path in Longnan area,which indicated that the contribution of man-made source pollution along the eastern path is significant.The results of this study can serve as a scientific reference for comprehensively understanding the characteristics of particulate pollution in the Gansu Province,formulating regional particulate pollution prevention and regional cooperative governance policies.