[Source and Cause Analysis of High Concentration of Inorganic Aerosol During Two Typical Pollution Processes in Winter over Tianjin].

Inorganic aerosol is the main component of haze days in winter over Tianjin. In this study, two typical high concentrations of secondary inorganic aerosol (SIA) processes, defined as CASE1 and CASE2, were selected during polluted days in January 2020 over Tianjin, and the effects of meteorological factors, regional transport, and chemical processes were comprehensively investigated combined with observations and numerical models (WRF-NAQPMS). The average SIA concentrations in CASE1 and CASE2 were 76.

[Spatial Distribution Characteristics of PM and O in Beijing-Tianjin-Hebei Region Based on Time Series Decomposition].

Notably, clear spatial differences occur in the distribution of air pollution among cities in the Beijing-Tianjin-Hebei (BTH) Region. Clarifying the concentration distribution of PM and O at different time scales is helpful to formulate scientific and effective pollution prevention and control measures. Here, the concentrations of PM and O were decomposed using a seasonal-trend decomposition procedure based on the loess (STL) method; their long-term, seasonal, and short-term components were obtained; and their temporal and spatial distribution characteristics were studied.

[Spatio-temporal Distribution Characteristics of Secondary Aerosol in Beijing-Tianjin-Hebei Urban Agglomeration in Winter].

The secondary component is an important factor causing PM pollution in the Beijing-Tianjin-Hebei urban agglomeration in winter. In this study, the CO tracer method was used to estimate the secondary PM concentration of the Beijing-Tianjin-Hebei urban agglomeration in the winter of 2017-2021. The temporal and spatial distribution characteristics were analyzed, and the influencing factors of regional secondary PM were discussed.

[Exploring Formation of Ozone in Typical Cities in Beijing-Tianjin-Hebei Region Using Process Analysis].

As the problem of O pollution in the Beijing-Tianjin-Hebei region becomes increasingly prominent, it is of great significance to explore and analyze the ozone variation characteristics and causes of the pollution process in the Beijing-Tianjin-Hebei region for regional air pollution prevention and control. The observations in this study showed that high O concentration in spring and summer of the Beijing-Tianjin-Hebei region was higher in the south and lower in the north. The high O concentration in Beijing, Tianjin, and Shijiazhuang was often accompanied by the influence of southern wind.

[Analysis of Change and Driving Factors of PM Mass Concentration in Tianjin from 2000 to 2020].

Based on real-time tracking data, PM mass concentration, and meteorological observations of the Tianjin Meteorological Bureau and the Ecological Environment Bureau, combined with the fine particle meteorological condition diffusion index constructed using the environmental model, the change and driving factors of the PM mass concentration in Tianjin from 2000 to 2020 were studied to analyze the impact of meteorology on the atmospheric environment. The study showed that change in PM mass concentration in Tianjin took place in three stages from 2000 to 2020; the first stage showed a continuous increase from 2000 to 2007. The rapid increase in emissions in this stage was the dominant factor, and its effect was four times that of the annual fluctuation in meteorological conditions.

[Impact of Air Humidity on PM Mass Concentration and Visibility During Winter in Tianjin].

Air humidity is a key meteorological factor in regulating visibility changes and haze episodes. Based on multi-year historical data of PM mass concentration, visibility, relative humidity(RH), and specific humidity() during winter in Tianjin, the impact of air humidity on PM mass concentration and visibility was investigated. Between 2015 and 2020, the PM mass concentration showed an overall decline of 28.

[Heavy Pollution Episode in Tianjin Based on UAV Meteorological Sounding and Numerical Model].

Pollution occurs in the boundary layer, and the thermal and dynamic vertical structure of the boundary layer has a significant influence on the formation of heavy pollution episodes. Based on unmanned aerial vehicle (UAV) sounding, ground-based remote sensing and numerical modeling, this paper analyzes the vertical structure of the boundary layer and the causes of pollution during the heavy pollution episode in Tianjin from January 10 to 15, 2019, with a view to strengthening the understanding of the influence law of boundary layer processes on heavy pollution in northern coastal cities and improving the accuracy of weather forecasts and heavy pollution warnings. The results show that atmospheric temperature stratification had a significant influence on the formation, persistence, and dissipation of heavy pollution episodes.

[Transport Characteristics of Air Pollution in Tianjin Based on Weather Background].

Regional transport is an important factor when considering the prevention and control of air pollution. The aim of this study was to provide support for the joint prevention and control of air pollution in the Beijing-Tianjin-Hebei region. With a focus on an analysis of the relationship between regional transport and meteorological conditions based on the weather background, an atmospheric chemical model was developed to quantitatively estimate the impact of regional transport on Tianjin from October 2016 to September 2017.

[Effects of VOCs on Ozone Formation in the Tianjin Suburbs in Summer].

Volatile organic compounds (VOCs) play an important role in the formation of ozone. The concentrations of VOCs in the Jinnan District of Tianjin were monitored by the Syntech Spectras GC955 online monitoring system, and the ozone generation potential of VOCs was calculated by the maximum incremental activity factor. The results showed that the total concentration of VOCs in the Jinnan District was (32.

[Transport Characteristics of PAN and O in the Lower Atmosphere of the Boundary Layer in Tianjin in Summer].

The volume concentration of peroxyacetyl nitrate (PAN) and O in the atmosphere were measured at the Tianjin Meteorological Tower in summer 2017 by using the online instrument with meteorological parameters and back trajectory analysis to analyze the delivery characteristics of PAN and O. The average volume concentrations of PAN and O during the observational period are (0.73±0.

[Construction and Application of Vertical Diffusion Index for Analyzing Weather During Pollution Events in Tianjin].

Based on temperature and wind speed data from the 255 meter tall meteorological tower, the characteristics of atmospheric stability were analyzed in Tianjin, with the vertical diffusion index and constructed by atmospheric chemical models. This provided information to use the vertical dispersion analysis method to forecast pollution from weather data. The results show that the comprehensive use of atmospheric stability and the vertical diffusion index can provide a better pollution forecast.

[Characteristics of the Size Distribution of Water-soluble Ions During a Heavy Pollution Episode in the Winter in Tianjin].

To characterize the size distribution of water-soluble inorganic ions (WSⅡ) during a heavy pollution episode, particle samples were collected by an Andersen cascade sampler in Tianjin in January 2014, and the concentrations of eight WSⅡ (Na, NH, K, Mg, Ca, Cl, NO, and SO) during a typical haze episode were analyzed by ion chromatography. The sources and formation mechanisms of WSⅡ were analyzed based on their size distributions. The results showed that the daily average concentrations of PM and PM were (138±100) μg·m and (227±142) μg·m, respectively, and the average concentration of total WSⅡ concentrations (TWSⅡ) in the coarse and fine particles were (34.

Vertical observation and analysis on rapid formation and evolutionary mechanisms of a prolonged haze episode over central-eastern China.

To clarify the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze and fog (HF) episode that occurred in central-eastern China from Dec 20 to 25, 2015, a novel campaign was conducted and vertical profiles of wind, temperature, light extinction coefficient (LEC) and PM concentration were used to analyze the rapid formation and evolutionary mechanisms of this HF episode. The substantial downward transportation of regional pollution from high layers and stagnant weather conditions favorable for the local pollution accumulation were the two main causes of the rapid increase in pollutant concentration. Southwest wind speeds of 4m/s between 300 and 600m and obvious downward flows were observed, whereas the southwest wind speeds were low below 300m, and strong temperature inversion with intensity of 4.

Characterization and source apportionment of size-segregated atmospheric particulate matter collected at ground level and from the urban canopy in Tianjin.

To investigate the size distributions of chemical compositions and sources of particulate matter (PM) at ground level and from the urban canopy, a study was conducted on a 255 m meteorological tower in Tianjin from December 2013 to January 2014. Thirteen sets of 8 size-segregated particles were collected with cascade impactor at 10 m and 220 m. Twelve components of particles, including water-soluble inorganic ions and carbonaceous species, were analyzed and used to apportion the sources of PM with positive matrix factorization.

Vertical characteristics of PM2.5 during the heating season in Tianjin, China.

In this study, PM2.5 samples were collected at four heights (10m, 40m, 120m and 220m) at a meteorological tower in the daytime and nighttime during the heating season in Tianjin, China. The vertical variation and diurnal variability of the concentrations of PM2.

Vertical characteristics of levels and potential sources of water-soluble ions in PM₁₀ in a Chinese megacity.

To investigate the vertical characteristics of ions in PM10 as well as the contributions and possible locations of their sources, eight water-soluble ions were measured at four heights simultaneously along a meteorological tower in Tianjin, China. The total ion concentrations showed a general decreasing trend with increasing height, ranging from 64.94μgm(-3) at 10m to 44.

[Study on photo-degradation kinetics of hemin in the presence of anion surfactant].

A novel photodecomposition behavior of hemin was described. With RhB-H2O2 system a flow injection chemiluminescence method has been applied to the study of the photolytic kinetics of hemin under ultraviolet light. And the sodium dodecyl sulfonate (SDS) was added as a photostability-stabilizer.

[Determination of Levofloxacin by chemiluminescence method].

A novel chemiluminescence method for the determination of Levofloxacin is based on its enhancement effect on thereaction of luminol with H2O2. The calibration graph is linear over the range of 5.53 x 10(-11)-2.