Abstract
ABSTRACTTo better understand the chemical characteristics and the potential source regions of PM2.5 measured from 18 January until 22 January 2016 in Shijiazhuang, China, PM2.5 was measured continuously and integrated daily sampling using mid-volume samplers was conducted at the three sites. The mean concentration of PM2.5 at the three sites reached 113, 131 and 119 µg m–3 during the sampling period, the higher concentrations occurred at early morning and noon, similar variation trends were found in the three sites. The concentrations of OC were higher than EC at three sampling sites and the OC/EC ratios ranged from 9.09 to 12.4 with a daily mean value of 10.8 during a haze pollution episode (HPE), which suggested that carbonaceous compositions might be from same source. The total concentration of water soluble inorganic ions (WSII) at the sites ranged from 72.2 to 100.0 µg m–3 with a mean of 84.3 µg m–3. The dominant species were NO3–, SO42–, NH4+, Cl–, accounting for 88.4% of the mean PM2.5 WSII mass. The most abundant measured element was Na with average mass concentrations of 41.5, 37.0, and 38.1 µg m–3 during the HPE. Relative humidity during HPE was higher than during clean days with average values of 70.1% and 60.2%, suggesting that high relative humidity and low wind speed favored formation of secondary inorganic ions and accelerated hygroscopic growth. The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) and a potential source contribution function (PSCF) analysis were used to assess the data. Back-trajectories for the three sites identified similar transport pathways. PSCF analysis showed a significant regional impact on PM2.5 at Shijiazhuang during the polluted period. The potential source areas for PM2.5 in Shijiazhuang were the Beijing-Tianjin region and Shandong Province. The results of the present study show the need for the development of PM2.5 control measurements on a regional scale.
Highlights
Since January 2013, China has been suffering severe and long-term haze pollution events
The concentrations of organic carbon (OC) were higher than elemental carbon (EC) at three sampling sites and the OC/EC ratios ranged from 9.09 to 12.4 with a daily mean value of 10.8 during a haze pollution episode (HPE), which suggested that carbonaceous compositions might be from same source
It can be seen that the event between January 19 and 21 is one of several occurring during this month
Summary
Since January 2013, China has been suffering severe and long-term haze pollution events. According to the “2014 report on the state of the environment in China” (MEP, 2014), 11.2% of the 161 cities in China met the annual average concentration of PM2.5 Grade II standard of 35 μg m–3 and 24-hour average of 75.0 μg m–3. Shijiazhuang, capital of Hebei Province, is ranked as the 2nd most polluted city in China with a highest hourly average concentration of PM2.5 of more than 750 μg m–3 and extraordinarily persistent haze. According to a related study (Wang et al, 2015a), the regional source contributions to PM2.5 in Shijiazhuang were 27.9%, while the major local contributions were industrial, domestic and agricultural. By the end of 2017, coal-fired boiler with sizes below 10 tons of coal burned per hour would be phased out. The ambient concentrations of PM still significantly exceed the air quality standard and particulate air pollution remains very serious
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
