A new approach of air pollution regionalization based on geographically weighted variations for multi-pollutants in China.

Air pollution regionalization is a key and necessary action to identify pollution regions for implementing control measures. Here we present a new approach called Geographically Weighted Rotation Empirical Orthogonal Function (GWREOF) for air pollution regionalization in China. Compared with previous methods, such as EOF, REOF, and K-mean, GWREOF better accounts for the variability of air pollution conditions driven by emission patterns and meteorology with centralized spatial locations. We apply GWREOF to multiple air pollutants (such as PM2.5, O3, and other monitored air pollutants) and air quality metrics using their measured spatial and temporal variations in 337 Chinese cities over 2015-2020. We find that the regionalization results for different air pollutants are highly similar, primarily determined by topography and meteorological conditions in China. Therefore, we propose an integrated regionalization result, which identifies 18 air pollution control regions in China and can be applied to multiple pollutants and different years. We further analyze PM2.5, O3, and OX (O3 + NO2) pollution levels and their correlations in these regions. PM2.5 and O3 correlations are generally strongly positive in southern China while negative in northern China. However, PM2.5 and OX correlations are broadly positive in China, reflecting the crucial role of atmospheric oxidizing capacity. Regional-specific and coordinated control measures are in need as China's air pollution strategy transits from PM2.5-focused to PM2.5-O3 synergic control.

Analysis of VOC emissions and O3 control strategies in the Fenhe Plain cities, China.

Long-term continuous hourly measurements of ambient volatile organic compounds (VOCs) are scarce at the regional scale. In this study, a one-year hourly measurement campaign of VOCs was performed in Lvliang, Linfen, and Yuncheng in the heavily polluted Fenhe Plain region in China. The VOC average (±standard deviation, std) concentrations in Lvliang, Linfen, and Yuncheng were 44.4 ± 24.9, 45.7 ± 24.9, and 37.5 ± 25.0 ppbv, respectively. Compared to published data from the past two decades in China, the observed VOCs were at high concentration levels. VOCs in the Fenhe Plain cities were significantly impacted by industrial sources according to calculated emission ratios but were less affected by liquefied petroleum gas and natural gas (LPG/NG) and traffic emissions than those in megacities abroad. The emission inventories and observation data were combined for verification and identification of the key VOC species and sources controlling ozone (O3). Industrial emissions were the largest source of VOCs, accounting for 65%-79% of the total VOC emissions, while the coking industry accounted for 45.2%-66.0%. The emission inventories significantly underestimated oxygenated VOC (OVOC) emissions through the verification of VOC emission ratios. O3 control scenarios were analyzed by changing VOC/NOX reduction ratios through a photochemical box model. O3 control strategies were formulated considering local pollution control plans, emission inventories, and O3 formation regimes. The O3 reduction of reactivity-control measures was comparable with emission-control measures, ranging from 16% to 41%, which was contrary to the general perception that ozone formation potential (OFP)-based measures were more efficient for O3 reduction. Sources with high VOC emissions are accompanied by high OFP on the Fenhe Plain, indicating that the control of high-emission sources can effectively mitigate O3 pollution on this region.

One-pot facile synthesis of enzyme-encapsulated Zn/Co-infinite coordination polymer nanospheres as a biocatalytic cascade platform for colorimetric monitoring of bacteria viability.

A rapid method for colorimetric monitoring of bacterial viability is described. The colorimetric method was carried out based on glucose oxidase-encapsulated Zn/Co-infinite coordination polymer (Zn/Co-ICP@GOx), which was prepared in aqueous solution free of toxic organic solvents at room temperature. The Zn/Co-ICP@GOx was confirmed to be a robust sphere structure with an average diameter of 147.53 ± 20.40 nm. It integrated the catalytic activity of natural enzyme (GOx) and mimetic peroxidase (Co (П)) all in one, efficiently acting as a biocatalytic cascade platform for glucose catalytic reaction. Exhibiting good multi-enzyme catalytic activity, stability, and selectivity, Zn/Co-ICP@GOx can be used for colorimetric glucose detection. The linear range was 0.01-1.0 mmol/L, and the limit of detection (LOD) was 0.005 mmol/L. As the glucose metabolism is a common expression of bacteria, the remaining glucose can indirectly represent the bacterial viability. Hence, a Zn/Co-ICP@GOx-based colorimetric method was developed for monitoring of bacterial viability. The color was intuitively observed with the naked eye, and the bacterial viability was accurately quantified by measurement of the absorbance at 510 nm. The method was applied to determination of bacterial viability in water and milk samples with recoveries of 99.0-103% and RSD of 0.43-7.5%. The method was rapid (less than 40 min) and applicable to different bacterial species irrespective of Gram-positive and Gram-negative bacteria, providing a universal and promising strategy for real-time monitoring of bacterial viability.

Observations and modeling of OH and HO2 radicals in Chengdu, China in summer 2019.

This study reports on the first continuous measurements of ambient OH and HO2 radicals at a suburban site in Chengdu, Southwest China, which were collected during 2019 as part of a comprehensive field campaign 'CompreHensive field experiment to explOre the photochemical Ozone formation mechaniSm in summEr - 2019 (CHOOSE-2019)'. The mean concentrations (11:00-15:00) of the observed OH and HO2 radicals were 9.5 × 106 and 9.0 × 108 cm-3, respectively. To investigate the state-of-the-art chemical mechanism of radical, closure experiments were conducted with a box model, in which the RACM2 mechanism updated with the latest isoprene chemistry (RACM2-LIM1) was used. In the base run, OH radicals were underestimated by the model for the low-NO regime, which was likely due to the missing OH recycling. However, good agreement between the observed and modeled OH concentrations was achieved when an additional species X (equivalent to 0.25 ppb of NO mixing ratio) from one new OH regeneration cycle (RO2 + X â†’ HO2, HO2 + X â†’ OH) was added into the model. Additionally, in the base run, the model could reproduce the observed HO2 concentrations. Discrepancies in the observed and modeled HO2 concentrations were found in the sensitivity runs with HO2 heterogeneous uptake, indicating that the impact of the uptake may be less significant in Chengdu because of the relatively low aerosol concentrations. The ROx (= OH + HO2 + RO2) primary source was dominated by photolysis reactions, in which HONO, O3, and HCHO photolysis accounted for 34%, 19%, and 23% during the daytime, respectively. The efficiency of radical cycling was quantified by the radical chain length, which was determined by the NO to NO2 ratio successfully. The parameterization of the radical chain length may be very useful for the further determinations of radical recycling.

A resonance Rayleigh scattering and fluorescence quenching dual-channel sensor for sensitive detection of chitosan based on Eosin Y.

The sensitive chitosan (CTS) detection methods based on the resonance Rayleigh scattering (RRS) quenching method and fluorescence quenching of Eosin Y were put forward. In the HAC-NaAC buffer solution, Eosin Y interacted with Triton X-100 to generate the binary complex which served as the RRS spectral probe. When CTS was interacted with the binary complex, the RRS intensity decreased with the increase of CTS. At the same time, the fluorescence intensity of Eosin Y decreased in the presence of Triton X-100, and the fluorescence intensity of "Eosin Y+Triton X-100" system further decreased when CTS was added. So it was further proved that there was a forming complex in "Eosin Y+Triton X100+CTS" system. The interaction was characterized by zeta potential, RRS, fluorescence spectrum, and UV-Vis spectroscopy. Under optimal conditions, there was a good linear relationship between the RRS decreased intensity (ΔI) and the concentration of CTS in the range of 0.05-1.30 µg/mL, with a regression equation of ΔI = 1325c + 73.66 and correlation coefficient (R2) of 0.9907. The detection limit was 0.0777 µg/mL. Likewise, the linear range of the fluorescence quenching was 0.03-1.30 µg/mL; the regression equation was ΔF = 1926c + 294.0 with R2 = 0.9800 under fluorescence quenching. The detection limit was 0.0601 µg/mL. Therefore, the dual-channel sensor for the determination of CTS was applied to the health products, and the results were satisfactory. The t test result showed that there was no statistical difference between the two methods.

A resonance Rayleigh scattering and colorimetric dual-channel sensor for sensitive detection of perfluorooctane sulfonate based on toluidine blue.

This work described the use of a basic phenothiazine dye (toluidine blue, TB) as a resonance Rayleigh scattering (RRS) and colorimetric probe for the detection of perfluorooctane sulfonate (PFOS). Owing to the electrostatic interactions between TB and PFOS, TB in the presence of PFOS caused great enhancement of RRS signal at dual-wavelength (I345 nm and I506 nm) and the ratio changes of absorbance (A502 nm/A630 nm). The RRS enhancement was attributed to the absorption-rescattering resonance effect, the increase of the molecular size, and the enhancement of hydrophobicity. The analytical procedure was implemented by physically mixing TB, Britton-Robinson buffer solution, and PFOS solution (or sample solution) all-in-one, avoiding the tedious pre-derivatization or the preparation of nanoparticles. The whole approach was less than 8 min. Under the optimal conditions, the analytical performance was acquired. The linear ranges for RRS and colorimetry were 0.04-8.0 and 1.0-20 µmol/L, with detection limits of 4.2 nmol/L and 112 nmol/L, respectively. The RRS method was applied to the determination of PFOS in environmental water with recoveries of 93.2-106%. The dual-channel sensor is convenient, rapidly responsive, sensitive, and cost-effective, integrating the advantages of RRS and colorimetry. Graphical abstract.

Spatial-temporal variation characteristics of air pollution in Henan of China: Localized emission inventory, WRF/Chem simulations and potential source contribution analysis.

Henan is the most populous province and one of the most seriously polluted areas in China at present. In this study, we establish an integrated atmospheric emission inventory of primary air pollutants in Henan province for the target year of 2012. The inventory developed here accounts for detailed activity levels of 11 categories of primary anthropogenic emission sources, and determines the best available representation of emission factors. Further, we allocate the annual emissions into a high spatial resolution of 3km×3km with ArcGIS methodology and surrogate indices, such as regional population distribution and gross domestic product (GDP). Our results show that the emissions of VOCs, SO2, PM10, PM2.5, NOX, NH3, CO, BC and OC are about 1.15, 1.24, 1.29, 0.70, 1.93, 1.05, 7.92, 0.27 and 0.25milliontons, respectively. The majority of these pollutant emissions comes from the Central Plain Urban Agglomeration (CPUA) region, particularly Zhengzhou and Pingdingshan. By combining with the emission inventory with the WRF/Chem modeling and backward trajectory analysis, we investigate the temporal and spatial variability of air pollution in the province and explore the causes of higher pollutants concentrations in the region of CPUA during the heavily polluted period of January. The results demonstrate that intensive pollutants emissions and unfavorable meteorological conditions are the main causes of the heavy pollution. Besides, Weighted Potential Source Contribution Function (WPSCF) analysis indicates that local emissions remain the major contributor of PM2.5 in Henan province, although emissions from the neighboring provinces (e.g. Shanxi, Shaanxi, Anhui, and Shandong) are also important contributors.

Atmospheric emission inventory of hazardous trace elements from China's coal-fired power plants--temporal trends and spatial variation characteristics.

Coal-fired power plants are the important sources of anthropogenic atmospheric releases of various hazardous trace elements (HTE) because a large quantity of emissions can cause wide dispersion and possible long-distance transportation. To obtain the temporal trends and spatial variation characteristics of various HTE discharged from coal-fired power plants of China, a multiple-year comprehensive emission inventory of HTE including Hg, As, Se, Pb, Cd, Cr, Ni, and Sb has been established for the period 2000-2010. Thanks to the cobenefit removal effects of conventional particulate matter/sulfur dioxide/nitrogen oxides (PM/SO2/NOx) control devices, emissions of these 8 toxic elements have shown a gradual decline since the peak in 2006. The total emissions of Hg, As, Se, Pb, Cd, Cr, Ni, and Sb are substantial and are estimated at about 118.54, 335.45, 459.4, 705.45, 13.34, 505.03, 446.42, and 82.33 tons (t), respectively, in 2010. Shandong, Jiangsu, Shanxi, and Hebei always rank among the top ten provinces with the highest emissions. Further, future emissions for 2015 and 2020 are projected with scenario analysis. Advanced technologies and integrated management strategies to control HTE are in great need.

Nitrogen oxides emissions from thermal power plants in china: current status and future predictions.

Increasing emissions of nitrogen oxides (NOx) over the Chinese mainland have been of great concern due to their adverse impacts on regional air quality and public health. To explore and obtain the temporal and spatial characteristics of NOx emissions from thermal power plants in China, a unit-based method is developed. The method assesses NOx emissions based on detailed information on unit capacity, boiler and burner patterns, feed fuel types, emission control technologies, and geographical locations. The national total NOx emissions in 2010 are estimated at 7801.6 kt, of which 5495.8 kt is released from coal-fired power plant units of considerable size between 300 and 1000 MW. The top provincial emitter is Shandong where plants are densely concentrated. The average NOx-intensity is estimated at 2.28 g/kWh, markedly higher than that of developed countries, mainly owing to the inadequate application of high-efficiency denitrification devices such as selective catalytic reduction (SCR). Future NOx emissions are predicted by applying scenario analysis, indicating that a reduction of about 40% by the year 2020 can be achieved compared with emissions in 2010. These results suggest that NOx emissions from Chinese thermal power plants could be substantially mitigated within 10 years if reasonable control measures were implemented effectively.

Atmospheric pollution problems and control proposals associated with solid waste management in China: a review.

Along with population growth, rapid urbanization and industrialization process, the volume of municipal solid waste (MSW) generation in China has been increasing sharply in the past 30 years and the total amount of MSW yields will continue to increase. Nowadays, due to global warming warrants particular attention throughout the world, a series of air pollutants (including greenhouse gases, odorous gases, PCDD/Fs, heavy metals, PM, etc.) discharged from waste disposal and treatment processes have become one of the new significant emerging air pollution sources, which arousing great concerns about their adverse effects on surrounding ambient air quality and public health. At present, the overall safely disposed ratio of the collected MSW in China is reported at approximately 78% in 2010, and there are mainly three types of MSW disposal methods practiced in China, including landfill, composting and incineration. The characteristics of air pollutants and greenhouse gases discharge vary substantially among different MSW disposal methods. By presenting a thorough review of MSW generation in China and providing a summarization of the current status of MSW disposal methods practices, this review article makes an integrated overview analysis of existing air pollution problems associated with MSW collection, separation, and disposal processes. Furthermore, some comprehensive control proposals to prevent air pollution for improving MSW management of China in the future are put forward.

Temporal trends and spatial variation characteristics of hazardous air pollutant emission inventory from municipal solid waste incineration in China.

A multiple-year emission inventory of hazardous air pollutants (HAPs), including particulate matter (PM), SO(2), NO(x), CO, HCl, As, Cd, Cr, Hg, Ni, Pb, Sb, and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), discharged from municipal solid waste (MSW) incineration in China has been established for the period 2003-2010 by using the best available emission factors and annual activity data. Our results show that the total emissions have rapidly amounted to 28,471.1 t of NO(x), 12,062.1 t of SO(2), 6500.5 t of CO, 4654.6 t of PM, 3609.1 t of HCl, 69.5 t of Sb, 36.7 t of Hg, 9.4 t of Pb, 4.4 t of Cr, 2.8 t of Ni, 926.7 kg of Cd, 231.7 kg of As, and 23.6 g of PCDD/Fs as TEQ (toxic equivalent quantity) by the year 2010. The majority of HAP emissions are concentrated in the eastern central and southeastern areas of China where most MSW incineration plants are built and put into operation. Between 2003 and 2010, provinces always ranking in the top three with largest HAPs emissions are Zhejiang, Guangdong, and Jiangsu. To better understand the emissions of these HAPs and to adopt effective measures to prevent poisoning risks, more specific field-test data collection is necessary.