Major Atmospheric Pollutants Research Articles

The effect of elevated ozone on floral chemistry of Brassicaceae species

Tropospheric ozone is a major atmospheric pollutant; it is phytotoxic and has a strong effect on phytochemicals, which are constitutively present in plant tissues, but also produced de novo in response to stress. It has been shown that ozone exposure can modify volatile phytochemical emissions from leaves, which could disturb interactions between plants and other organisms. However, there is a lack of knowledge on the effects of ozone on floral chemistry. The aim of this study was to determine the effects of two elevated ozone exposure scenarios (80 and 120 ppb during daylight hours for 5 consecutive days) on the floral volatile emissions and floral chemical (molecular size range C6–C20) content of four Brassicaceae species: Sinapis alba, Sinapis arvensis, Brassica napus and Brassica nigra. The results showed that the emissions of individual compounds and their relative contributions to volatile blends are both affected by ozone exposure. In addition, for all four species studied, three diterpenes (neophytadiene, cis-phytol and trans-phytol) were present in significantly lower amounts and a fourth diterpene (hexahydrofarnesyl acetone) in significantly greater amounts in ozone-exposed plants. Consistent effects of ozone exposure on volatile emissions and terpene content were observed for each of the four species studied with no significant effect of exposure level. It appeared that B. napus is the most ozone-sensitive species, whereas B. nigra is the most ozone-tolerant. Since earlier studies have indicated that ratios of phytochemicals can have substantial effects on the efficacy of chemical use by pollinators, these changes may have ecological and biological relevance that should be the focus of further elucidation.

Spatio-Temporal Variations of Multiple Primary Air Pollutants Emissions in Beijing of China, 2006–2015

Air pollution in Beijing, China has attracted continuous worldwide public attention along with the rapid urbanization of the city. By implementing a set of air pollution mitigation measures, the air quality of Beijing has been gradually improved in recent years. In this study, the intrinsic factors leading to air quality improvement in Beijing are studied via a quantitative evaluation of the temporal and spatial changes in emissions of primary air pollutants over the past ten years. Based on detailed activity levels of each economic sector and a localized database containing source and pollutant specific emission factors, an integrated emissions inventory of primary air pollutants discharged from various sources between 2006 and 2015 is established. With the implementation of phased air pollution mitigation measures, and the Clean Air Action Plan, the original coal-dominated energy structure in Beijing has undergone tremendous changes, resulting in the substantial reduction of multiple air pollutants. The total of emissions of six major atmospheric pollutants (PM10, PM2.5, SO2, NOX, VOCs and NH3) in Beijing decreased by 35% in 2015 compared to 2006—this noticeable decrease was well consistent with the declining trend of ambient concentration of criterion air pollutants (SO2, PM10, PM2.5 and NO2) and air quality improvement, thus showing a good correlation between the emission of air pollutants and the outcome of air quality. SO2 emission declined the most, at about 71.7%, which was related to the vigorous promotion of combustion source control, such as the shutdown of coal-fired facilities and domestic stoves and transition to clean energy, like natural gas or electricity. Emissions of PM decreased considerably (by 48%) due to energy structure optimization, industrial structure adjustments, and end-of-pipe PM source control. In general, NOX, NH3, and VOCs decreased relatively slightly, by 25%, 14%, and 2%, respectively, and accordingly, they represented the limiting factors for improving air quality and the key points of air pollution mitigation in Beijing for the future.

Influence of temperature and humidity on the detection of benzene vapor by a piezoelectric crystal sensor

The influence of temperature and humidity on the determination of benzene concentration were characterized using a piezoelectric crystal gas sensor. Sensing layers coated with polymethylphenylsiloxane and polyvinylchloride was used for real-time monitoring of benzene, a major atmospheric pollutant. When the humidity was varied from 35% to 75%, the detection limitations of the sensor were reduced and the response and frequency recovery times increased. However, when the temperature was increased from 5 °C to 60 °C, the response and recovery time were decreased but the sensitivity performance was degraded. Models were developed for the correlation between the benzene concentration and temperature and humidity.

NO2 hotspots: Are we measuring in the right places?

Abstract Nitrogen Dioxide (NO2) is a major atmospheric pollutant which is produced from a variety of anthropogenic sources, notably vehicular emissions. High NO2 concentrations are found in and around the urban environment and as such pose a significant threat to human health. Diffusion tube surveys of NO2 concentrations were carried out at a variety of intersections and road layouts over a 3-month period in 2017. This study identified that ‘hotspots’ in NO2 concentrations frequently occurred in sections of road where vehicles are accelerating or queueing. Under these conditions, concentrations were elevated by 58.6% and 52.6% respectively compared to when vehicles were cruising. Analysis of environmental factors which influence NO2 concentrations show that meteorology, topography, traffic volume and driver behaviour all contribute. The results highlight the complexity of monitoring hotspot locations and show the need for traffic and driver behaviour to be included in vehicle emission models. Additionally, the investigation suggests need for caution when relying on in-situ monitors to determine pollutant exceedances as there is shown to be substantial variation along a street and the location of the monitor is critical.

Correlation analysis of AQI characteristics and meteorological conditions in heating season

According to the China air quality monitoring platform, the monthly average of the Air Quality Index for monitoring the heating season in Xi’an and the monthly concentration of major atmospheric pollutants in the past three years, the relationship between five major atmospheric pollutants and meteorological conditions was analyzed, the main results are as follows: (1) in the past three years, the air quality in Xi’an heating season was mild pollution, and the most serious degree of pollution was in January each year. (2) The main pollutants in Xi’an were PM2.5 and PM10, but in recent years, the content of pollutants NO2 and O3 has risen sharply, so we should strengthen the protection and the treatment of NO2 and O3. (3) The precipitation has a certain impact on air quality index. (4) The air quality in Xi’an is closely related to meteorological elements.

Recent advances in supported molecular sieve catalysts with wide temperature range for selective catalytic reduction of NO X with C3H6.

NOX is a major atmospheric pollutant that is emanated by motor vehicles, thermal power plants, and industrial boilers. Therefore, the removal of NOX is a research hotspot in the exhaust gas treatment field. Numerous methods have been used to eliminate NOX: the selective catalytic reduction of NOX using C3H6 as the reducing agent (C3H6-SCR) is an effective method to remove NOX. The key issue in NOX removal in C3H6-SCR is to obtain catalysts with low-temperature activity and wide operating temperatures. Till date, different supported wide-temperature-active molecular sieve catalysts have been prepared and used in C3H6-SCR reactions. Studies have shown that the catalytic performance of supported catalysts is related not only to the active component but also to the structural and textural parameters of the molecular sieve supports. This review summarizes the structural and textural characteristics, catalytic properties, and catalytic mechanism of molecular sieve catalysts with different pore structures for C3H6-SCR reactions. The design strategies of supported molecular sieve catalysts are suggested. The goal of this review is to highlight (1) the structural and textural characteristics and low-temperature catalytic performance of different supported molecular sieve catalysts; (2) the relationship between wide-temperature window and loaded active components, as well as carriers of the supported molecular sieve catalysts; and (3) design strategies and development prospects of supported molecular sieve catalysts with low-temperature activity and wide-temperature operating range for C3H6-SCR reactions.

Improving urban air quality in China: investigation and control measures of PM2.5, PM10, NO2 and SO2 in air

In recent years, the quality of urban atmospheric environment in China has caused widespread concern in the whole society. Improving air quality has become a major content of air pollution prevention and control in China. To do a good job in atmospheric prevention and control, we must investigate and analyze the sources of major atmospheric pollutants and their pollution characteristics firstly. With the acceleration of urbanization, the air pollution situation in Jinan city has become an environmental problem that people are particularly worried about. Based on the monitoring data of Jinan atmospheric environment, this paper analyzed the monthly average concentration values of PM2.5, PM10, NO2 and SO2 in Jinan City from 2015 to 2017. Meanwhile, the main reasons for the air pollution in Jinan City were clarified in detail. Finally, air pollution control strategies were proposed corresponding the aspects of pollution sources, topography and meteorological conditions, rational planning, environmental supervision capabilities, environmental awareness, and practical treatment technologies in Jinan City. These measures can provide a theoretical basis for relevant leading departments to build a beautiful city.

Time-Based Trend of Carbon Emissions in the Composting Process of Swine Manure in the Context of Agriculture 4.0

The widespread raising of swine in farms becomes a serious problem in terms of the emission of carbon dioxide (CO2) and methane (CH4). This study aims to measure concentrations of carbon dioxide and methane, which account for the largest percentage of carbon emissions, to temporally estimate the carbon emitted during the pig-manure composting process. The research subject was a farmhouse raising 3000 growing pigs and 100 mother pigs. The capacity of the composting facility for pig manure treatment was 330 m2, and the daily treatment was about 6 tons. After the pig manure discharged from the pig farm was delivered to the composting facility, for the 8 days including 6 before mixing and 2 after mixing, the concentrations of CO2 and CH4 were measured. The result shows that the CO2 and CH4 concentrations in the composting facility were 1208 ± 385 ppm and 95 ± 10 ppm, respectively. In the comparison of concentrations before and after mixing at the composting facility, the values of both CO2 and CH4 increased, and the temperature increased as well. The concentration of CO2 and CH4 increased to 499 ± 103 ppm and 3 ± 11 ppm, respectively, and the temperature rose by 3.7 ± 1.0 °C and 1.6 ± 2.4 °C, respectively. In the correlation analysis (r = 0, p < 0.05), the carbon dioxide emission in the composting process was 15.564 ± 3.671 tons C/year, whereas carbon emission was 1.379 ± 0.147 tons C/year. The concentrations of CO2 and methane, which are the current major atmospheric pollution sources, were respectively analyzed during the pig-manure composting process in this study to understand their effects. Thus, this paper attempts to elucidate the carbon cycle by measuring and analyzing the carbon data obtained from livestock excretions to secure a supply chain based on the intelligent use of the data.

Investigation on air pollution control strategy in Hangzhou for post-G20/pre-Asian-games period (2018–2020)

For the purpose of offering a detailed atmospheric pollution control strategy to the Hangzhou government to make the major atmospheric pollutants (SO2, NO2, PM2.5 and PM10) meet the environmental regulation aim required by the 13th Five Year Plan of Hangzhou, the WRF/CMAQ model is used to simulate the pollution level over Hangzhou. Observed data from five local environmental monitoring stations in the downtown Hangzhou are selected to evaluate the performance of simulation. The indicator factors confirm the accuracy of the WRF/CMAQ modeling system. Results show the local emission sources account for 15.8%, 68.6%, 48.3% and 59.2% of the overall SO2, NO2, PM2.5 and PM10 concentration in 2017, respectively. And the research on the separate local sectors indicates traffic donates 71.6% of local NO2 emission while industry contributes 73.8%, 53.2% and 56.7% of the total local emission of SO2, PM2.5 and PM10, respectively. The more severe pollution during the wintertime was mainly due to low wet deposition, low temperature, low wind speed, prevailing wind direction, the condition of local deciduous plants and urban heat island. If the local traffic and industry are cut down by 6% and 10%, respectively, the air pollution control targets on SO2, NO2, PM2.5 and PM10 in 2020 can be hit.

Temporal and spatial variation of particulate matter and its correlation with other criteria of air pollutants in Lanzhou, China, in spring-summer periods

The present study on major atmospheric pollutants is based on data received from 5 ground-based air-quality monitoring stations and satellite sounding which provides for the use of Moderate Resolution Imaging Spectroradiometer (MODIS) to study aerosol optical depth on the territory of the city of Lanzhou, Gansu Province. Data were received in the spring-summer period of 2014–2017. The present paper is intended to analyze the mass concentrations and spatial-temporal variation of PM 2.5 , PM 10 , CO, SO 2 , NO 2 and O 3 in the above city. When comparing and averaging the daily, monthly, and annual pollutants concentrations, it was revealed that the average PM 2.5 and PM 10 concentrations exceeded the Chinese Ambient Air Quality Standards (CAAQS) and were 42.37 and 112.67 μg/m 3 , respectively. Of all studied days, 62.5% showed high PM 2.5 concentration, and 78.2% - high PM 10 concentration. PM 2.5 and PM 10 demonstrated a strong correlation (R 2 = 0.81) with PM 2.5 being about 37% of PM 10 . This indicates that decrease of PM 10 emissions is very critical for reducing pollution with PM and thus for improving the air quality in China. The linear correlation analysis reveals unstable correlation between PM and gaseous pollutants, average correlation between PM and SO 2 (PM 2.5 /SO 2 r = 0.439; PM 10 /SO 2 r = 0.328), negative correlation between PM, SO 2 , NO 2 , CO and O 3 (PM 2.5 /O 3 r = −0.335, PM 10 /O 3 r = −0.213, SO 2 /O 3 r = −0.527, NO 2 /O 3 r = −0.272, CO/O 3 r = −0.558), and strong correlation between other gaseous pollutants (NO 2 /CO r = 0.502, NO 2 /SO 2 r = 0.534, SO 2 /CO r = 0.706). • Algorithm developed to identify active dust emission from HYSPLIT and CALIPSO. • To determine the level of aerosol pollution using satellite data MODIS. • The most powerful sources dust fraction were the territories of China and Mongolia (Taklimakan and Gobi Desert).

Trends and Spatiotemporal Patterns of Tropospheric NO2 over China During 2005–2014

Nitrogen dioxide (NO2) is one of the major atmospheric pollutants, and the concentration of NO2 is regarded as one of the indicators of air quality. In the past decades, China has experienced rapid economic growth and severe NO2 pollution to match. We evaluate the trends and spatiotemporal patterns of tropospheric NO2 over mainland China from 2005 to 2014 using vertical column density (VCD) datasets retrieved from the Ozone Monitoring Instrument (OMI). Results show that from 2005 to 2014, NO2 pollution regions have enlarged at the national scale, and high NO2 VCDs are mainly concentrated over highly populated regions in eastern China. The year 2011 is the turning point. Tropospheric NO2 VCDs first significantly increase by 0.19 × 1015 molec cm−2 year−1 (R 2 = 0.94, P = 0.002) from 2005 to 2011, and then decrease by 0.21 × 1015 molec cm−2 year−1 (R 2 = 0.97, P = 0.016) from 2011 to 2014. Since 2011, tropospheric NO2 VCDs over central-east China decrease remarkably. Tropospheric NO2 VCDs is higher in November (3.630 × 1015 molec/cm2), December (4.758 × 1015 molec/cm2), and January (4.863 × 1015 molec/cm2), while lower in July (1.684 × 1015 molec/cm2), August (1.627 × 1015 molec/cm2), and September (1.703 × 1015 molec/cm2), indicating that winter and spring are the most polluted seasons. Due to the huge gap in population density and industry development between western and eastern China, the spatial pattern of tropospheric NO2 VCDs shows large west-east difference.

Trash to treasure: Use flue gas SO2 to produce H2 via a photoelectrochemical process

Sulfur dioxide (SO2), emitting from power plant and factories, has been one of the major atmospheric pollutants and causes lots of harmful environmental issues. Although some mature desulfurization technologies are available, a more economic or even profitable approach for flue gas desulfurization is greatly desirable. Herein, we report SO2 can be efficiently recycled to produce H2 via a photoelectrochemical (PEC) water splitting process based on Mo-doped BiVO4 inverse opals. Via this process, the SO2 removal rate is higher than 97%, the absorbed SO2 can act as a sacrifice reagent to produce H2 in the PEC water splitting. With the design of the highly ordered porous structure, the generation rate of H2 is improved by tens of times. Via the proposed process, the SO2 released (0.03 kg) from coal power plant for a generation of 1 kW h electricity can be recycled to produce around 10 L H2. By combining with ammonia-based desulfurization technology, the production of H2 can greatly reduce the cost of ammonia-based desulfurization technology and make it profitable.

Nanocrystalline ZnO–SnO2 mixed metal oxide powder: microstructural study, optical properties, and photocatalytic activity

In this study, nanocrystalline ZnO–SnO2 mixed metal oxide powder was prepared by co-precipitation using Zn(CH3COO)2∙2H2O and SnCl4∙5H2O as precursor materials. The powder was characterized by X–ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Williamson–Hall method was used to evaluate the micro structural parameters of ZnO–SnO2 such as crystallite sizes and lattice strain. The photoluminescence property of the sample was studied at different temperatures (10–300 K). Results showed that the emission intensity decreases with temperature increasing. The photocatalytic activity at the gas–solid interface was assessed by monitoring the degradation of nitrogen oxides, a major atmospheric pollutant. The results show that the nanocrystalline ZnO–SnO2 mixed metal oxide powder exhibits higher and more stable photocatalytic activity against photocorrosion than ZnO alone.

Effects of 1,4-naphthoquinone aged carbon black particles on the cell membrane of human bronchial epithelium

Black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs), which are major atmospheric pollutants in China, are hazardous to humans following inhalation. BC can be oxidized by PAHs forming secondary particles of which the health effects are unknown. In this study, carbon black (CB) was used to simulate BC to reveal the adverse effects of 1,4-naphthoquinone aged carbon black (CB/1,4-NQ) particles on the membrane of human bronchial epithelial (16HBE) cells. It was showed that, the cell viability, cell membrane fluidity, membrane potential and mitochondrial membrane potential were significantly decreased after 16HBE cells were treated with CB, 1,4-NQ or CB/1,4-NQ. Meanwhile, the cell membrane permeability and intracellular Ca2+ concentration were increased. CB/1,4-NQ could induce more adverse effects on cell membrane than single CB treated, while less than 1,4-NQ. The results indicated that CB/1,4-NQ particles in the atmosphere may cause more damage to health, and the effects on cell membrane can be used to evaluate the early health effects of the particulate matter exposure.

Inverse Relations of PM2.5 and O3 in Air Compound Pollution between Cold and Hot Seasons over an Urban Area of East China

Abstract: By analyzing the data of urban air pollutant measurements from 2013 to 2015 in Nanjing, East China, we found that the correlation coefficients between major atmospheric compound pollutants PM2.5 and O3 were respectively 0.40 in hot season (June, July and August) and −0.16 in cold season (December, January and February) with both passing the confidence level of 99%. This provides evidence for the inverse relations of ambient PM2.5 and O3 between cold and hot seasons in an urban area of East China. To understand the interaction of PM2.5 and O3 in air compound pollution, the underlying mechanisms on the inversion relations between cold and hot seasons were investigated from the seasonal variations in atmospheric oxidation and radiative forcing of PM2.5 based on three-year environmental and meteorological data. The analyses showed that the augmentation of atmospheric oxidation could strengthen the production of secondary particles with the contribution up to 26.76% to ambient PM2.5 levels. High O3 concentrations in a strong oxidative air condition during hot season promoted the formation of secondary particles, which could result in a positive correlation between PM2.5 and O3 in hot season. In cold season with weak atmospheric oxidation, the enhanced PM2.5 levels suppressed surface solar radiation, which could weaken O3 production for decreasing ambient O3 level with the low diurnal peaks. Under the high PM2.5 level exceeding 115 μg·m−3, the surface O3 concentration dropped to 12.7 μg·m−3 at noon with a significant inhibitory effect, leading to a negative correlation between PM2.5 and O3 in cold season. This observational study revealed the interaction of PM2.5 and O3 in air compound pollution for understanding the seasonal change of atmospheric environment.

Spatial analysis of haze–fog pollution in China

Haze–fog pollution has been one of the major atmospheric pollution problems in China. This study is aimed at understanding spatial distribution and spatial correlation of haze–fog pollution in China from 2001 to 2010 using exploratory spatial data analysis technique. The results show that spatial distribution of haze–fog pollution is not changed obviously in the 10 years, and the most serious polluted region is distributed in Beijing–Tianjin–Hebei region. The values of global Moran’s I vary from 0.4066 to 0.4842, which indicates that haze–fog pollution is not distributed randomly, but has spatial agglomeration effects. The High–High agglomeration type is mainly distributed in central China, which contains 15, 14, 14, and 13 regions for the years of 2001, 2004, 2007, and 2010, respectively, while the Low–Low agglomeration type is concentrated in western and eastern China, which contains 11, 10, 10, and 8 regions for the years of 2001, 2004, 2007, and 2010, respectively. The results should provide policy guidance for public authorities to control haze–fog pollution. Further researches are still needed because of the complexity of haze–fog pollution and variety of influence factors.

Microkinetic Modeling of the Effects of Oxygen on the Catalytic Reduction of NO on Pt and Rh in Automotive Aftertreatment

Nitric oxides and unburned hydrocarbons from automotive engines are major atmospheric pollutants. A strategy based on the simultaneous reduction of NO and oxidation of hydrocarbon can be very effective in aftertreatment. In this study, the various regimes of operation of this selective catalytic reduction process using propene as a representative hydrocarbon, with and without the presence of oxygen, are delineated. Detailed kinetic modeling using quantitative microkinetics for Pt and Rh catalysts is performed. Interesting catalytic features including coking and oxygen poisoning are clearly identified. An optimal operating regime in which the complete conversion of NO and C3H6 occurs in the presence of small amounts of oxygen is highlighted.

Truncated tetragonal bipyramidal anatase nanocrystals formed without use of capping agents from the supercritical drying of a TiO2sol

Titanium dioxide (TiO2) nanoparticles are extremely attractive materials for numerous applications, especially in the anatase form. We have made these shaped, <10 nm anatase nanoparticles (NPs) via the supercritical (SC) drying of a titania sol, made by a “green” aqueous sol–gel nanosynthesis route. The SC drying was carried out in alcohol at 255–260 °C, and no further heating or processing of the NPs was required. The true phase composition (crystalline and amorphous phases) and the microstructure of the NPs was thoroughly characterised by the advanced X-ray methods, such as Rietveld-reference intensity ratio (RIR) and the whole powder pattern modelling (WPPM) technique, and HR-TEM analysis. Furthermore, the NPs were also characterised by Raman, FT-IR and optical spectroscopy. These anatase NPs showed themselves to exhibit a truncated tetragonal bipyramidal shape, exposing the {101} (side) and {001} (top) faces. They had a euhedral crystal habit, with sharply defined and easily recognised faces, and were very homogeneous and monodisperse in both shape and size. The photocatalytic activity (PCA) of the samples was assessed in gas–solid phase by monitoring the degradation of nitrogen oxides (NOx), a major atmospheric pollutant. Results showed that the particular shape of these anatase NPs played a key role in their photocatalytic behaviour. In fact, these truncated tetragonal bipyramidal nanocrystals exhibited an enhanced photocatalytic activity, double that of spherical anatase NPs of a similar size reported previously by the authors. This was attributed to the exposure of mainly the {101} and, to a lesser extent, {001} crystal faces, which are more reactive under photocatalysis for redox reactions.

The Concentrations and Reduction of Airborne Particulate Matter (PM10, PM2.5, PM1) at Shelterbelt Site in Beijing

Particulate matter is a serious source of air pollution in urban areas, where it exerts adverse effects on human health. This article focuses on the study of subduction of shelterbelts for atmospheric particulates. The results suggest that (1) the PM mass concentration is higher in the morning or both morning and noon inside the shelterbelts and lower mass concentrations at other times; (2) the particle mass concentration inside shelterbelt is higher than outside; (3) the particle interception efficiency of the two forest belts over the three months in descending order was PM10 &gt; PM1 &gt; PM2.5; and (4) the two shelterbelts captured air pollutants at rates of 1496.285 and 909.075 kg/month and the major atmospheric pollutant in Beijing city is PM10. Future research directions are to study PM mass concentration variation of shelterbelt with different tree species and different configuration.

High Resolution Emission Inventory of NOx and CO for Mega City Delhi, India

In order to support as critical input to air quality forecasting task during Commonwealth Games (CWG) – 2010 in mega city Delhi, we have developed a high resolution emission inventory of major atmospheric pollutants. For the same, inventories of ozone precursors like NOx and CO are developed over a domain of 70 km × 65 km with a grid of 1.67 km × 1.67 km resolution covering Delhi and surrounding region using Geographical Information System (GIS) technique for base year 2010. All possible source of emission like transport, thermal power plants, industries, residential, slum cooking and commercial cooking are taken into account for the first time. It has been found that total emissions of NOx and CO over the study area are found to be 255 and 703 Gg/yr for 2010 respectively. The spatial distributions of major hot spots are discussed with possible dominant sources at particular regions. The present inventory will help to improve the modeling study over mega city, Delhi and its surrounding regions.