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The chemical composition of individual particles can be revealed by single particle mass spectrometers (SPMS). With higher accuracy in the ratio of mass to charge (m/z), more detailed chemical information could be obtained. In the SPMS, the conventional standard-based calibration methods (internal/external) are constrained by the inhomogeneity of ionization lasers and the finite focusing ability of the inlet system, etc., therefore, the mass accuracy is restricted. In this study, we obtained the detailed and trustable chemical composition of single particles utilizing a standard-free mass calibration algorithm. In the algorithm, the characteristic distributions of hundreds of ions were concluded and collected in a database denoted as prototype. Each single-particle mass spectrum was tentatively calibrated by a mass calibration function with specific coefficients. The range of coefficients is constrained by the magnitude of mass deviation to a finite vector space. To find the optimal coefficient vector, the conformity of each tentatively calibrated spectrum to the prototype dataset was assessed. With maximum conformity, the optimal calibrated spectrum was obtained. For more than 98% ambient particles, a twentyfold improvement in mass accuracy, from ~10,000 ppm (integer) to ~500 ppm (2 decimal places) was achieved. The improved mass accuracy validated the determination of adjacent ions with m/z difference ~0.05 Th. Furthermore, atmospheric trace ions that were poorly studied before are successfully specified. The obtained detailed single-particle-level chemical information could help understand the source apportionment, reaction mechanism, and mixing state of atmospheric particles. [ABSTRACT FROM AUTHOR]

Ozone (O3) has become a significant air pollutant in China in recent years. O3 abatement is challenging due to the nonlinear response of O3 to precursors nitrogen oxides (NOx) and volatile organic compounds (VOCs). Photochemical indicators are widely used to estimate the O3-NOx-VOC sensitivity, and this has important policy implications. However, the effectiveness of the indicators has seldom been evaluated. This study examines the applications of four indicators that include the ratio of the production rates of H2O2 and HNO3 (PH2O2/PHNO3), HCHO/NO2, HCHO/NOy, and reactive nitrogen (NOy) in the Yangtze River Delta (YRD) with localized thresholds. The overall accuracy was high (> 92%) for all indicators and not significantly reduced with different simulation periods or in different locations of the region. By comparing with the O3 isopleths, it was found that HCHO/NO2 and HCHO/NOy showed the most consistency, whereas PH2O2/PHNO3 (NOy) tended to underestimate (overestimate) the positive response of O3 to NOx. Additionally, PH2O2/PHNO3 was less likely to attribute the O3 formation to mixed sensitivity than the other indicators, and this demonstrated a preference for a single-pollutant control strategy. This study also revealed that the details in the methodology used to derive the threshold values impacted the results, and this may produce uncertainties in the application of photochemical indicators. [ABSTRACT FROM AUTHOR]

Increased human water use combined with climate change have aggravated water scarcity from the regional to global scales. However, the lack of spatially detailed datasets limits our understanding of the historical water use trend and its key drivers. Here, we present a survey-based reconstruction of China’s sectoral water use in 341 prefectures during 1965 to 2013. The data indicate that water use has doubled during the entire study period, yet with a widespread slowdown of the growth rates from 10.66 km³·y−² before 1975 to 6.23 km³·y−² in 1975 to 1992, and further down to 3.59 km³·y−² afterward. These decelerations were attributed to reduced water use intensities of irrigation and industry, which partly offset the increase driven by pronounced socioeconomic development (i.e., economic growth, population growth, and structural transitions) by 55% in 1975 to 1992 and 83% after 1992. Adoptions for highly efficient irrigation and industrial water recycling technologies explained most of the observed reduction of water use intensities across China. These findings challenge conventional views about an acceleration in water use in China and highlight the opposing roles of different drivers for water use projections. [ABSTRACT FROM AUTHOR]

We present the development of a multiphase adjoint for the Community Multiscale Air Quality (CMAQ) model, a widely used chemical transport model. The adjoint provides location- and time-specific gradients that can be used in various applications such as backward sensitivity analysis, source attribution, optimal pollution control, data assimilation and inverse modeling. The science processes of the CMAQ model include gas-phase chemistry, aerosols, cloud chemistry and dynamics, diffusion and advection. Discrete adjoints are implemented for all the science processes, with an additional continuous adjoint for advection. The development of discrete adjoints is assisted with Algorithmic Differentiation (AD) tools. Particularly, the Kinetic PreProcessor (KPP) is implemented for gas-phase and aqueous chemistry, and two different automatic differentiation tools are used for other processes such as clouds, aerosols, diffusion, and advection. The continuous adjoint of advection is developed manually. For adjoint validation, the brute-force or Finite Difference Method (FDM) is implemented process by process with box- or column-model simulations. Due to the inherent limitations of the FDM caused by numerical round-off errors, the Complex Variable Method (CVM) is adopted where necessary. The adjoint model often shows better agreement with the CVM than with the FDM. The adjoints of all science processes compare favorably with the FDM/CVM. In an example application of the full, multiphase adjoint model, we provide the first estimates of how emissions of PM2.5 affect public health across the US. [ABSTRACT FROM AUTHOR]

In addition to many recent actions taken to reduce emissions from energy production, industry, and transportation, a new campaign substituting residential solid fuels with electricity or natural gas has been launched in Beijing, Tianjin, and 26 other municipalities in northern China, aiming at solving severe ambient air pollution in the region. Quantitative analysis shows that the campaign can accelerate residential energy transition significantly, and if the planned target can be achieved, more than 60% of households are projected to remove solid fuels by 2021, compared with fewer than 20% without the campaign. Emissions of major air pollutants will be reduced substantially. With 60% substitution realized, emission of primary PM2.5 and contribution to ambient PM2.5 concentration in 2021 are projected to be 30% and 41% of those without the campaign. With 60% substitution, average indoor PM2.5 concentrations in living rooms in winter are projected to be reduced from 209 (190 to 230) μg/m³ to 125 (99 to 150) μg/m³. The population-weighted PM2.5 concentrations can be reduced from 140 μg/m³ in 2014 to 78 μg/m³ or 61 μg/m³ in 2021 given that 60% or 100% substitution can be accomplished. Although the original focus of the campaign was to address ambient air quality, exposure reduction comes more from improved indoor air quality because ∼90% of daily exposure of the rural population is attributable to indoor air pollution. Women benefit more than men. [ABSTRACT FROM AUTHOR]

Environmental legislation and proper implementation are critical in environmental protection. In the past, beehive coke ovens (BCOs) were popular in China, resulting in enormous emissions of benzo[a]pyrene (BaP), a common indicator of carcinogenic polycyclic aromatic hydrocarbons. BCOs were banned by the Coal Law in 1996. Although BCO numbers have declined since the ban, they were not eliminated until 2011 due to poor implementation. Here, we present the results of a quantitative evaluation of the health effects of historical BCO operation, the health benefits of the ban, and the adverse impacts of the poor implementation of the ban. With only limited official statistics available, historical and geospatial data about BCOs were reconstructed based on satellite images. Emission inventories of BaP from BCOs were compiled and used to model atmospheric transport, nonoccupational population exposure, and induced lung cancer risk. We demonstrated that more than 20% of the BaP in ambient air was from BCOs in the peak year. The cumulative non-occupational excess lung cancer cases associated with BaP from BCOs was 3,500 (±1,500) from 1982 to 2015. If there was no ban, the cases would be as high as 9,290 (±4,300), indicating the significant health benefits of the Coal Law. On the other hand, if the ban had been fully implemented immediately after the law was enforced in 1996, the cumulative cases would be 1,500 (±620), showing the importance of implementing the law. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) have toxic impacts on humans and ecosystems. One of the most carcinogenic PAHs, benzo(a)pyrene (BaP), is efficiently bound to and transported with atmospheric particles. Laboratory measurements show that particle-bound BaP degrades in a few hours by heterogeneous reaction with ozone, yet field observations indicate BaP persists much longer in the atmosphere, and some previous chemical transport modeling studies have ignored heterogeneous oxidation of BaP to bring model predictions into better agreement with field observations. We attribute this unexplained discrepancy to the shielding of BaP from oxidation by coatings of viscous organic aerosol (OA). Accounting for this OA viscosity-dependent shielding, which varies with temperature and humidity, in a global climate/chemistrymodel brings model predictions into much better agreement with BaP measurements, and demonstrates stronger long-range transport, greater deposition fluxes, and substantially elevated lung cancer risk from PAHs. Model results indicate that the OA coating is more effective in shielding BaP in the middle/high latitudes compared with the tropics because of differences in OA properties (semisolid when cool/dry vs. liquid-like when warm/humid). Faster chemical degradation of BaP in the tropics leads to higher concentrations of BaP oxidation products over the tropics compared with higher latitudes. This study has profound implications demonstrating that OA strongly modulates the atmospheric persistence of PAHs and their cancer risks. [ABSTRACT FROM AUTHOR]

Second language (L2) students'learning of genre for communication in English-medium discourse communities has become an increasingly researched area in the field of English for specific purposes (ESP). This paper outlines current directions of ESP research into the learning of written genres and reviews key empirical studies in three categories: (a) genre learning in different contexts, including writing classrooms, disciplinary communities, and the context that bridges writing classrooms and disciplinary communities, (b) genre knowledge development, in terms of formal, rhetorical, process, and subject-matter knowledge domains, and (c) genre learner characteristics that influence learning processes and knowledge development. This review indicates that the sociorhetorical, textual, and systematic dimensions of genre, as well as the multiple knowledge domains involved, account for the intricacies of genre learning activity. The review also indicates that genre learning could be further explored from the perspectives of sociocultural and critical studies. [ABSTRACT FROM AUTHOR]

The health impacts of polycyclic aromatic hydrocarbons (PAHs), the most concerning organic pollutants, depend not only on the locations and strengths of emission sources, but also on individual susceptibility. Moreover, trans-boundary transport makes them a global concern. In this study, a comprehensive analysis of the global health impacts of polycyclic aromatic hydrocarbons (PAHs) in ambient air is presented. Model resolution is critical in exposure modelling. Globally, incremental lifetime lung cancer risk (ILCR) induced by ambient PAH exposure is 3.1 × 10-5. If the individual susceptibility was not taken into consideration, the overall risk would be underestimated by 55% and the proportion of highly vulnerable population would be underestimated by more than 90%. Emphasizing on individual susceptibility, our study provides an instrumental revision of current risk assessment methodology. In terms of lung cancer risk, the most important sources are combustion of biomass fuels (40%) and fossil fuels (14%) in the residential/ commercial sector, coke (13%) and aluminium (12%) production, and motor vehicles (9%). PAHs can travel long distance globally especially within the Eurasian continent. Still, the risk is dominantly contributed by local. [ABSTRACT FROM AUTHOR]

Black carbon (BC) is increasingly recognized as a significant air pollutant with harmful effects on human health, either in its own right or as a carrier of other chemicals. The adverse impact is of particular concern in those developing regions with high emissions and a growing population density. The results of recent studies indicate that BC emissions could be underestimated by a factor of 2-3 and this is particularly true for the hot-spot Asian region. Here we present a unique inventory at 10-km resolution based on a recently published global fuel consumption data product and updated emission factor measurements. The unique inventory is coupled to an Asia-nested (∼50 km) atmospheric model and used to calculate the global population exposure to BC with fully quantified uncertainty. Evaluating the modeled surface BC concentrations against observations reveals great improvement. The bias is reduced from -88% to -35% in Asia when the unique inventory and higher-resolution model replace a previous inventory combined with a coarse-resolution model. The bias can be further reduced to -12% by downscaling to 10 km using emission as a proxy. Our estimated global population-weighted BC exposure concentration constrained by observations is 2.14 μg.m-3; 130% higher than that obtained using less detailed inventories and low-resolution models. [ABSTRACT FROM AUTHOR]

As increasing numbers of Chinese language learners choose to learn English online, there is a need to investigate popular websites and their language learning designs. This paper reports on the first stage of a study that analyzed the pedagogical, linguistic, and content features of 25 Chinese English Language Learning (ELL) websites ranked according to their value and importance to users. The website ranking was undertaken using a system known as PageRank. The aim of the study was to identify the features characterizing popular sites as opposed to those of less popular sites for the purpose of producing a framework for ELL website design in the Chinese context. The study found that a pedagogical focus with developmental instructional materials accommodating diverse proficiency levels was a major contributor to website popularity. Chinese [ABSTRACT FROM AUTHOR]

An Euler atmospheric transport model (Canadian Model for Environmental Transport of Organochiorine Pesticides, CanMETOP) was applied and validated to estimate polycyclic aromatic hydrocarbon (PAH) ambient air concentrations at ground level in China based on a high-resolution emission inventory. The results were used to evaluate lung cancer risk for the Chinese population caused by inhalation exposure to PAHs. The uncertainties of the transport model, exposure, and risk analysis were assessed by using Monte Carlo simulation, taking into consideration the variation in PAH emission, aerosol and OH radical concentrations, dry deposition, respiration rate, and genetic susceptibility. The average benzo[alpyrene equivalent concentration (B[a]Peq) was 2.43 [≈1.29-4.50 as interquartile range (IR)] ng/m³. The population-weighted B(a]Peq was 7.64 (IR, ≈4.05-14.1) ng/m³ because of the spatial overlap of the emissions and population density. It was estimated that 5.8% (IR, ≈2.0-11%) of China's land area, where 30% (IR, ≈17-43%) of the population lives, exceeded the national ambient B[a]Peq standard of 10 ng/m³. Taking into consideration the variation in exposure concentration, respiration rate, and susceptibility, the overall population attributable fraction (PAF) for lung cancer caused by inhalation exposure to PAHs was 1.6% (IR, ≈0.91-2.6%), corresponding to an excess annual lung cancer incidence rate of 0.65 × 10-5. Although the spatial variability was high, the lung cancer risk in eastern China was higher than in western China, and populations in major cities had a higher risk of lung cancer than rural areas. An extremely high PAF of >44% was estimated in isolated locations near small-scale coke oven operations. [ABSTRACT FROM AUTHOR]