Abstract
To study the role of submicron particulate matter on visibility degradation in Shanghai, mass concentrations of PM1, secondary inorganic aerosol (SIA) in PM1, and SIA precursor gasses were on-line monitored during a 4-week intensive campaign in December 2012. During the campaign, 8 haze periods were identified when on average PM1mass increased to 62.1 ± 25.6 μg/m3compared to 30.7 ± 17.1 μg/m3during clear weather periods. The sum of SIA in PM1increased in mass concentration during the haze from 14.9 ± 7.4 μg/m3during clear periods to 29.7 ± 10.7 μg/m3during the haze periods. Correlation coefficients (R2) of the visibility as function of mass concentrations of SIA species in PM1show negative exponential relations implying the importance of the SIA species in visibility reduction. The important role of ammonia in SIA formation is recognized and demonstrated. Generally, ammonium neutralizes sulfate and nitrate and the molar equivalent ratio of ammonium versus the sum of sulfate and nitrate increases during the haze episodes. Air mass backward trajectories introducing the haze periods show the impact of nonlocal ammonia on visibility degradation in Shanghai.
Highlights
The elevated concentrations of haze responsible air pollutants have an adverse impact on human health and the environment [1, 2] and concerns about the adverse effects have led to studies focusing on trends and chemistry of haze episodes in urban China
In previous visibility degradation studies, haze episodes are defined as a continuous period of longer than 4 hours when the visibility is below 10 km while the RH value does not exceed 90% [7, 58, 59]
During the measurement period the average hourly mass concentrations of SIA species in PM1 were as follows: [NH4+] averaged 4.1 ± 2.6 μg/m3, [SO42−] averaged 6.0 ± 2.8 μg/m3, and [NO3−] averaged 5.4 ± 4.9 μg/m3. The sum of these SIA species averaged 15.5 ± 9.8 μg/m3 which accounted for 51.1 ± 12.9% of the PM1 mass
Summary
The elevated concentrations of haze responsible air pollutants have an adverse impact on human health and the environment [1, 2] and concerns about the adverse effects have led to studies focusing on trends and chemistry of haze episodes in urban China. The submicron aerosol size range (described as PM1 where the aerosol aerodynamic diameter is equal or less than 1.0 μm) is highly efficient in scattering of light [2]. This size fraction comprises a large mass of secondary inorganic aerosol sulfate (SIA)
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.
