PM2.5 and its major chemical compositions were sampled and analyzed in January, April, July and October of 2014 at Beijing (BJ), Tianjin (TJ), Langfang (LF) and Baoding (BD) in order to probe the ...temporal and spatial characteristics as well as source apportionment of PM2.5 in the Beijing-Tianjin-Hebei (BTH) region. The results showed that PM2.5 pollution was severe in the BTH region. The average annual concentrations of PM2.5 at four sampling sites were in the range of 126–180 μg/m3, with more than 95% of sampling days exceeding 35 μg/m3, the limit ceiling of average annual concentration of PM2.5 regulated in the Chinese National Ambient Air Quality Standards (GB3095-2012). Additionally, concentrations of PM2.5 and its major chemical species were seasonally dependent and demonstrated spatially similar variation characteristics in the BTH region. Concentration of toxic heavy metals, such as As, Cd, Cr, Cu, Mn, Ni, Pb, Sb, Se, and Zn, were higher in winter and autumn. Secondary inorganic ions (SO42−, NO3−, and NH4+) were the three-major water-soluble inorganic ions (WSIIs) of PM2.5 and their mass ratios to PM2.5 were higher in summer and autumn. The organic carbon (OC) and elemental carbon (EC) concentrations were lower in spring and summer than in autumn and winter. Five factors were selected in Positive Matrix Factorization (PMF) model analysis, and the results showed that PM2.5 pollution was dominated by vehicle emissions in Beijing, combustion emissions including coal burning and biomass combustion in Langfang and Baoding, and soil and construction dust emissions in Tianjin, respectively. The air mass that were derived from the south and southeast local areas around BTH regions reflected the features of short-distant and small-scale air transport. Shandong, Henan, and Hebei were identified the major potential sources-areas of secondary aerosol emissions to PM2.5.
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•We present the temp-spatial PM2.5 variations at four cities in BTH region of China.•PM2.5 concentrations and its species show spatially similar variation in BTH region.•PMF results indicate PM2.5 pollution is dominated by vehicle emissions in Beijing.•Coal combustion plays a significant contribution on PM2.5 in LangFang and Baoding.•Soil and construction dust constitute most important components of PM2.5 in TianJin.
PM2.5 mass and its major chemical composition in the BTH region were seasonally dependent and demonstrated spatially similar variation characteristics. PMF results indicated that PM2.5 was dominated by vehicle emissions in Beijing, coal and biomass combustion emissions in Langfang and Baoding, and soil and construction dust emissions in Tianjin, respectively.
The two-dimensional quantum dots (2D-QDs) have been developed significantly in the past decades. The 2D-QDs could be used in bioimaging, biosensing, drug/gene delivery, and photodynamic/photothermal ...therapy. The potential applications in biology receive increasing attention, which makes them the novel and emerging candidates in biomaterial research fields. In this context, we discuss a variety of 2D-QDs with different physical and chemical properties. We focuse on the latest synthesis progress and recent applications in biotechnological, and biomedical applications of the 2D-QDs and we also evaluate the challenges and prospects in this field.
China has become the largest producer of iron and steel throughout the world since 1996. However, as an energy-and-pollution intensive manufacturing sector, a detailed comprehensive emission ...inventory of air pollutants for iron and steel industry of China is still not available. To obtain and better understand the temporal trends and spatial variation characteristics of typical hazardous air pollutants (HAPs) emissions from iron and steel production in China, a comprehensive emission inventory of multiple air pollutants, including size segregated particulate matter (TSP/PM10/PM2.5), gaseous pollutants (SO2, NOx, CO), heavy metals (Pb, Cd, Hg, As, Cr, Ni etc.), as well as the more dangerous PCDD/Fs, is established with the unit-based annual activity, specific dynamic emission factors for the historical period of 1978–2011, and the future potential trends till to 2050 are forecasted by using scenario analysis. Our results show that emissions of gaseous pollutants and particulate matter have experienced a gradual increase tendency since 2000, while emissions of priority-controlled heavy metals (Hg, Pb, As, Cd, Cr, and Ni) have exhibited a short-term fluctuation during the period of 1990 to 2005. With regard to the spatial distribution of HAPs emissions in base year 2011, Bohai economic circle is identified as the top emission intensity region where iron and steel smelting plants are densely built; within iron and steel industry, blast furnaces contribute the majority of PM emissions, sinter plants account for most of gaseous pollutants and the majority of PCDD/Fs, whereas steel making processes are responsible for the majority of heavy metal emissions. Moreover, comparisons of future emission trends under three scenarios indicate that advanced technologies and integrated whole process management strategies are in great need to further diminish various hazardous air pollutants from iron and steel industry in the future.
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•A comprehensive emission inventory for iron and steel industry of China•Unit-based emissions are specially calculated for iron and steel industry.•The emission inventory includes 18 pollutants.•Emission trends for 1978–2050 studied by dynamic emission factor.•Monte Carlo Simulation is provided to quantify the uncertainties of emissions.
Severe hazes occurred during 2016–2017 winter manifested winter haze was still a tough challenge in Beijing since the unprecedented haze in January 2013. Three haze episodes were identified from ...December 15, 2016 to January 15, 2017 in Beijing: the Red-Alert episode, the mixed haze-dust episode and the longest and heaviest Cross 2017 New Year's Haze episode. We analyzed the chemical components (water-soluble inorganic ions, carbonaceous components and trace elements) of multi-size airborne particles (PM1, PM2.5, PM10) samples, as well as the associated gaseous pollutants and meteorological parameters. Compared with the well-documented severe haze in January 2013, 2016–2017 winter haze was characterized by more stagnant synoptic conditions, sustained accumulation growth of PM enhanced by secondary reactions and regional contribution, as well as prominent fine particles mainly constituted by high concentrations of carbonaceous aerosol, secondary inorganic ions and anthropogenic elements. With strict pollution control measures since the enacting of Clean Air Action Plan in 2013, ambient concentrations of SO2, as well as SO42− and most anthropogenic elements in PM2.5 have decreased, whereas NO3− and NH4+ concentration in PM2.5 increased by as high as 77.9% and 47.3% respectively compared with January 2013. The ratios of NO3− /SO42− in PM1, PM2.5, PM10 were higher than 1.0 no matter during normal period or haze period, totally different with the results in January 2013, which suggested the increased relative contribution from mobile sources and decreased contribution from coal combustion in Beijing. Nitrate and its precursors had become major concerns during winter haze in Beijing, although the rapid growth of sulfate still played an important role in the formation and evolution of extremely heavy haze events. Under ammonium-rich and high relative humidity conditions, NO3− was thought to mainly be produced by enhanced heterogeneous reactions. To prevent Beijing winter haze effectively, it's quite crucial to cut NOx, NH3, SO2 and VOCs emissions simultaneously and strengthen regional cooperation on air pollution control.
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•Characteristics, precursors and sources of PM2.5 have changed obviously since the enacting of Clean Air Action Plan in 2013.•Compared with January 2013, SO2, SO42− and trace elements in PM2.5 decreased, whereas NO3− and NH4+ increased significantly.•2016–2017 winter haze is featured with more stagnant meteorology and sustained accumulation of PM2.5 enhanced by regional transport and secondary reactions.•Carbonaceous aerosol (OC, EC) and secondary inorganic aerosol (SO42−, NO3− and NH4+) were two major parts in PM with fine-mode size distributions.
A bottom-up inventory of atmospheric emissions of five precedent-controlled toxic heavy metals (HMs), including mercury (Hg), arsenic (As), lead (Pb), cadmium (Cd), and chromium (Cr), from primary ...anthropogenic sources in China is established for the period 2000–2010. Total emissions of HMs demonstrate a gradually ascending trend along with the increase of coal consumption and industrial production, which are estimated at approximately 842.22 t for Hg, 4196.31 t for As, 29272.14 t for Pb, 795.29 t for Cd, and 13715.33 t for Cr for 2010. Coal combustion is found to be the primary source of HMs emissions. Owing to the dramatic differences of coal use by industrial and power sectors among provinces, spatial allocation performs remarkably uneven characteristics, and spatial distribution features are demonstrated by allocating the emissions into 0.5° × 0.5° grid cells with GDP and population as surrogate indexes. Further, HMs emissions from specified anthropogenic sources under three different control scenarios for the target year 2015 are projected, and collaborative and specialized control strategies are proposed to meet the demand of emission reduction goals of different regions. In the future, a whole processes control management system will be the most effective way for control of HMs.
Sensor drift fault calibration is essential to maintain the operation of heating, ventilation and air conditioning systems (HVAC) in buildings. Bayesian inference (BI) is becoming more and more ...popular as a commonly used sensor fault calibration method. However, this method focused mainly on sensor bias fault, and it could be difficult to calibrate drift fault that changes with time. Therefore, a dynamic calibration method for sensor drift fault of HVAC systems based on BI is developed. Taking the drift fault calibration of the chilled water supply temperature sensor of the chiller as an example, the performance of the proposed dynamic calibration method is evaluated. Results show that the combination of the Exponentially Weighted Moving-Average (EWMA) method with high detection accuracy and the proposed BI dynamic calibration method can effectively improve the calibration accuracy of drift fault, and the Mean Absolute Percentage Error (MAPE) value between the calibrated and normal data is less than 5%.
► Air pollution problems generated in MSW management processes in China are presented. ► Both quantity and composition of MSW generation in China are identified. ► The status of different methods for ...MSW treatment and disposal are reviewed. ► Some comprehensive control proposals for improving MSW management are proposed.
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.
Airborne particles in urban Beijing during haze days and normal days were collected and analyzed in the autumn and winter seasons to reveal the chemical characteristics variations of air pollution. ...The air quality in haze days was substantially worse than that in normal days. Both the relatively low wind speed and high relative humidity were in favor of the accumulation of pollution species and new formation of secondary PM2.5 in the atmosphere. Elevated concentrations of elements and water-soluble inorganic ions were found on haze days for both PM10 and PM2.5. Particularly, the crustal element, such as Fe, in both PM10 and PM2.5 were substantially higher in autumn normal days and winter haze days than those in autumn haze days and winter normal days, indicating that the abundance of Fe in autumn haze days mainly be originated from crustal dust while in winter haze days it might be primarily emitted from anthropogenic sources (iron and steel smelting) instead of road dust. Secondary ion species (SO42−, NO3−, NH4+) in particles were generated much more during haze episodes, and contributed a higher proportion in PM2.5 than in PM10 during the two sampling periods. Moreover, HYSPLIT model was used to explain the possible transport of airborne particles from distant sources. By comparing with south-type trajectory, west-type trajectory entrained larger amounts of primary crustal pollutants, while, south-type trajectory was comprised of a higher mass of anthropogenic pollution species. The results of back trajectory analysis indicated that the elevated concentration of aerosol and its chemical components during haze days might be caused by the integrated effects of accumulation under stagnant meteorological condition and the transport emissions of pollutants from anthropogenic sources surrounding Beijing city.
•Stagnant weather factors and accumulated pollution species favor for haze formation.•Elevated concentrations of elements and WSIIs are detected on haze days for both PM.•Anthropogenic species are more inclined to accumulate and generate in fine particle.•Aerosol is apt to more acidic on haze days due to more secondary species formation.•Regional transport contributes the elevated content of anthropogenic elements in PM.
A multiple-year comprehensive emission inventory of typical hazardous air pollutants (HAPs) from China's cement industry for the period 1980–2012, has been established by using technology-based ...dynamic emission factors and detailed annual plant-specific cement production from different types of kilns. Our results show that the total emissions of various HAPs (SO2, NOX, CO, PM, Hg, Cd, Cr, Pb, Zn, As, Ni and Cu) have rapidly increased by about 1–21 times at an annual average growth rate of 1–10% over the past three decades. Remarkably uneven spatial allocation features of these pollutants among provinces are observed. HAPs emissions are primarily concentrated in the eastern and coastal provinces due to the concentration of cement plants and their huge volume of coal consumption. We predict the future emission trends of HAPs through 2050 based on industry construction and policy guidance, and our scenario analysis indicates that HAPs emissions will drop substantially because of the combined effects of cement production yields reduction and the increasing application rate of various air pollution control devices. The study suggests that highlighted attention should be paid to this energy-intensive industry to ensure stricter emission standards are implemented for these HAPs emissions in the future.
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•We develop a comprehensive emission inventory of HAPs from China's cement industry.•Dynamic EFs of shaft, new suspension pre-heater and other rotary kilns are proposed.•We use transformed normal distribution function to reflect historical EFs variation.•Future trends of HAPs emission till 2050 are predicted with three scenario analysis.•HAPs emissions from 2961 plants in 2012 are allocated into 15 km × 15 km gridded cells.
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.
