The ozone layer depletion and its recovery, as well as the climate influence of ozone-depleting substances (ODSs) and their substitutes that influence climate, are of interest to both the scientific community and the public. Here we report on the emissions of ODSs and their substitute from China, which is currently the largest consumer (and emitter) of these substances. We provide, for the first time, a comprehensive information on ODSs and replacement Hydrofluorocarbon (HFC) emissions in China starting from 1980 based on reported production and usage. We also assess the impacts (and costs) of controls on ODS consumption and emissions on the ozone layer (in terms of CFC-11-equivalent) and climate (in CO2-equivalent). In addition, we show that while China’s future ODS emissions are likely to be defined as long as there is full compliance with the Montreal Protocol, its HFC emissions through 2050 are very uncertain. Our findings imply that HFC controls over the next decades that are more stringent than those under the Kigali Amendment to the Montreal Protocol would be beneficial in mitigating global climate change.
Recent studies on biochars confirmed their potential benefits in improving soil fertility and sequestrating contaminants. However, little information on the changes in structural characteristics and metal speciation of biochars after exposure to soils is currently available. The aim of this study was to use double experimental bags to study the transformation of ozonized biochars derived from poultry manure and drying sludge (denoted PB and SB, respectively) in typic udic ferrisols. The carbon and sulfur functional groups and chemical characteristics of the biochars were determined using spectroscopic techniques, such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy spectroscopy, combined with chemical extractions. Metal species were characterized using Cu K-edge X-ray absorption near-edge structure and chemical sequential fractionation schemes. The results showed that the potential changes in structural characteristics and metal species of biochars in soil were highly dependent on the composition of the biochars. PB comprised highly aromatic and chemically stable C, whereas SB contained a substantial amount of easily degradable C. Oxygen-containing groups slightly increased after incubation in the soil with either 60% water holding capacity (WHC) or flooding for 3 months. Sulfur in the biochars was predominantly inorganic S. Minerals such as K, Na, Mg, and S were mobilized from the biochars, accounting for 5-55% depending on the properties and sources of the element. Both PB and SB contained high concentrations of Cu and Zn. CuO in PB dissolved within 3 months, whereas CuS in both PB and SB was partly oxidized in the soil with 60% WHC for 9 months and adsorbed to the organic phase. Zn had relatively high mobility in both biochars, resulting in its vertical migration into soils.
Trace elements in atmospheric particular matter play a significant role in controlling aerosolbehavior, and can thereby endanger air quality. Here, the comprehensive investigation on the elemental characteristics and sources in fine and coarse particles at Chifeng was presented. The daily samples of particular matter (PM2.5 and PM10) were collected at six sites for a one-year period, and concentrations of 19 elements were analyzed. Results showed that Al, K, Ca, Fe were the most concentrated elements, in both PM2.5 and PM10. The crustal elements mainly in coarse particles (PM2.5–10) presented higher levels during March to May, due to the increased dust suspension in springtime. The highly enriched elements as Pb, Cd mainly in fine particles (PM2.5) presented elevated levels in cold seasons, related to the increased emissions of coal combustion for heating. Site Songshan had significantly higher Pb, As, Cd levels, ascribing to the influence of coal mining. The influences of metallurgy industries on Fe, Cu, Zn levels in both size fractions were also observed. Positive matrix factorization (PMF) identified four common sources for trace elements in both fine and coarse fractions, namely fugitive dust, coal mining, a mixed industrial factor with iron and zinc, and copper smelting. The factors of coal combustion, biomass burning, oil combustion, vehicle emission and fireworks were merely obtained for fine particles. The crustal elements were mainly related to the impact of fugitive dust, while the notable impacts of coal combustion and iron/steel production were also confirmed. Cu was attributed to copper smelting in both sizes, while the major sources of Zn varied from vehicle emission (44.3%), coal combustion (32.1%) in PM2.5 to mixed industrial factor (89.3%) in PM2.5–10. Although coal combustion, coal mining and copper smelting contributed <20% of the total elemental concentrations, they were responsible for >80% of the toxic elements Pb, As, Cd.
Chengdu is a megacity in the southwest of China with high ozone (O3) mixing ratio. Observation of volatile organic compounds (VOCs), NO2 and O3 with high temporal resolution was conducted in Chengdu to investigate the chemical processes and causes of high O3 levels. The hourly mixing ratios of VOCs, NO2, and O3 were monitored by an online system from 28 August to 7 October, 2016. According to meteorological conditions, Chengdu, with relative warm weather and low wind speed, is favorable to O3 formation. Part of the O3 in Chengdu may be transported from the downtown area. In O3 episodes, the average mixing ratios of NO2 and O3 were 20.20 ppbv and 47.95 ppbv, respectively. In non-O3 episodes, the average mixing ratios of NO2 and O3 were 16.38 ppbv and 35.15 ppbv, respectively. The average mixing ratio of total VOCs (TVOCs) was 40.29 ppbv in non-O3episodes, which was lower than that in O3 episodes (53.19 ppbv). Alkenes comprised 51.7% of the total O3 formation potential (OFP) in Chengdu, followed by aromatics which accounted for 24.2%. Ethylene, trans-pentene, propene, and BTEX (benzene, ethylbenzene, toluene, m/p-xylene, o-xylene) were also major contributors to the OFP in Chengdu. In O3 episodes, intensive secondary formations were observed during the campaign. Oxygenated VOCs (OVOCs), such as acetone, Methylethylketone (MEK), and Methylvinylketone (MVK) were abundant. Isoprene rapidly converted to MVK and Methacrolein (MACR) during O3 episodes. Acetone was mainly the oxidant of C3-C5 hydrocarbons.
In this paper, we report the device performance of a high-voltage enhancement-mode (E-mode) GaN MOSHEMT on silicon substrate. Normally off operation is realized by a self-terminated precision gate recess process on an optimized high-electronmobility transistor structure. The GaN MOSHEMT is fully pinched off at zero gate bias, suggesting a ``true'' normally off operation. The threshold voltage is 0.4 V with a drain current density of 1 mu A/mm as the criteria. The device with 15-mu m gate-drain distance and 100-mu m gate width exhibits a maximum drain current of 356 mA/mm at 8-V gate bias. The on/off current ratio of the device is larger than 1010 with a subthreshold slope of 80 mV/dec. The gate leakage current is below 10-7 mA/mm up to 9-V gate bias. The off-state breakdown voltage (BV) is as high as 1528 V (880 V) measured with floating (grounded) silicon substrate at a drain leakage current criterion of 5 mu A/mm. The specific on-resistance (R-ON,R-SP) of the device is 2.79 m Omega.cm(2), and the power figure of merit (BV2/R-ON,R-SP) is 277 MW/cm(2). High-voltage pulsed I-V measurement indicates that the dynamic on-resistance is only 1.6 times the static one with a pulsewidth of 10 mu s at 400-V off-state quiescent drain bias. The high performance of the normally off GaN MOSHEMT is supposed to benefit from the high quality low pressure chemical vapor deposition Si3N4 passivation layer and the advanced E-mode device fabrication process.
Research on unconventional shale reservoirs has increased dramatically due to the decline of production from conventional reserves. Geochemical properties and pore microstructures are known to be important factors that affect the storage capacity and nano-mechanical properties of self-sourced organic- rich shales. In this study, eleven shale samples were collected from the Upper and Lower Members of the Bakken Formation for the analysis of mineralogy, geochemical properties, and pore structure. Bulk pyrolysis analysis was conducted using the default method and two modified methods, namely the reservoir and the shale reservoir methods. Although all three methods showed the Bakken samples to be organic-rich and to have considerable remaining hydrocarbon generating potential, it was the shale reservoir method that gave the highest hydrocarbons yield because it captured most of the lighter thermo-vaporizable hydrocarbons. Thus, the shale method is considered to be more appropriate for the geochemical analysis of the Bakken samples. This method also showed that most of the remaining potential is due to the cracking of heavy hydrocarbons, NSO compounds (Resins+Asphaltenes) and kerogen. The organic matter in the samples is mixed II/III type (oil and gas-prone), is thermally mature, and plots at the peak of the oil window. The VRo-eq values, based on solid bitumen Ro measurements and conversion, ranged from 0.85% to 0.98%. The pore structures obtained from the image analysis method showed that total surface porosity of the samples ranged from 3.89% to 11.56% and that organic porosity is not the main contributor of total porosity for the samples analyzed. The pore structures of the samples are heterogeneous due to differences in lacunarity values. Results of the impact of mineralogical composition on pore structures demonstrate that clay minerals and feldspar have a positive influence on porosity while quartz, pyrite, and that TOC has a negative impact.
The co-processing of wastes in cement production has become an irreversible trend worldwide. However, secondary pollution particularly the air pollution has rarely been investigated despite it may compromise the environmental benefits of waste utilization. In this study, we collected the atmospheric particulate matter (PM10) around a cement plant in Changping district in Beijing, China, which co-processes hazardous wastes and municipal sewage sludge, and investigated the characteristics of trace elements, inorganic and organic species in the samples. The results show that volatile elements (Zn, As, Se, Sc, Cd, Sb and Pb) that are abundant in the wastes can be highly enriched in PM10 compared with local soil, reflecting the influences from cement production. The water-soluble species were generally dominated by organics, which were moderately oxidized with an average oxygen-to-carbon atomic ratio (O/C) of 0.25 and an organic mass-to-organic carbon (OM/OC) ratio of 1.49. In addition, single particle imaging analyses revealed eight types of aerosol particles: S-rich, K-rich, Na-rich, fly ash, mineral, organic, metal and soot. Furthermore, the single particle analysis suggests that the metals released from the cement production may act as catalysts to promote the heterogeneous formations of sulfate and other secondary organic species. Overall, as a preliminary yet pioneering study, our findings highlight the possibly important but understudied influences of solid waste treatment processes on local air quality and haze formation. (C) 2018 Elsevier Ltd. All rights reserved.
We evaluate four high-resolution model simulations of pollutant emissions, chemical transformation, and downwind transport for the Athabasca oil sands using the Global Environmental Multiscale -Modelling Air-quality and Chemistry (GEM-MACH) model, and compare model results with surface monitoring network and aircraft observations of multiple pollutants, for simulations spanning a time period corresponding to an aircraft measurement campaign in the summer of 2013. We have focussed here on the impact of different representations of the model's aerosol size distribution and plume-rise parameterization on model results. The use of a more finely resolved representation of the aerosol size distribution was found to have a significant impact on model performance, reducing the magnitude of the original surface PM2.5 negative biases 32 %, from -2.62 to -1.72 mu gm(-3). We compared model predictions of SO2, NO2, and speciated particulate matter concentrations from simulations employing the commonly used Briggs (1984) plume-rise algorithms to redistribute emissions from large stacks, with stack plume observations. As in our companion paper (Gordon et al., 2017), we found that Briggs algorithms based on estimates of atmospheric stability at the stack height resulted in under-predictions of plume rise, with 116 out of 176 test cases falling below the model : observation 1 : 2 line, 59 cases falling within a factor of 2 of the observed plume heights, and an average model plume height of 289m compared to an average observed plume height of 822 m. We used a high-resolution meteorological model to confirm the presence of significant horizontal heterogeneity in the local meteorological conditions driving plume rise. Using these simulated meteorological conditions at the stack locations, we found that a layered buoyancy approach for estimating plume rise in stable to neutral atmospheres, coupled with the assumption of free rise in convectively unstable atmospheres, resulted in much better model performance relative to observations (124 out of 176 cases falling within a factor of 2 of the observed plume height, with 69 of these cases above and 55 of these cases below the 1 : 1 line and within a factor of 2 of observed values). This is in contrast to our companion paper, wherein this layered approach (driven by meteorological observations not co-located with the stacks) showed a relatively modest impact on predicted plume heights. Persistent issues with over-fumigation of plumes in the model were linked to a more rapid decrease in simulated temperature with increasing height than was observed. This in turn may have led to overestimates of near-surface diffusivity, resulting in excessive fumigation.
OBJECTIVE: To test the causal effect of childhood BMI on adult cardiometabolic diseases using a Mendelian randomization analysis. RESEARCH DESIGN AND METHODS: We used 15 single nucleotide polymorphisms as instrumental variables for childhood BMI to test the causal effect of childhood BMI on cardiometabolic diseases using summary-level data from consortia. RESULTS: We found that a 1-SD increase in childhood BMI (kg/m(2)) was associated with an 83% increase in risk of type 2 diabetes (odds ratio [OR] 1.83 [95% CI 1.46, 2.30]; P = 2.5 x 10(-7)) and a 28% increase in risk of coronary artery disease (CAD) (OR 1.28 [95% CI 1.17, 1.39]; P = 2.1 x 10(-8)) at the Bonferroni-adjusted level of significance (P < 0.017) in adults. In addition, a 1-SD increase in childhood BMI was associated with a 0.587-SD increase in adulthood BMI (kg/m(2)), a 0.062-SD increase in hip circumference (cm), a 0.602-SD increase in waist circumference (cm), a 0.111 pmol/L increase in log fasting insulin, a 0.068 increase in log-transformed HOMA of ss-cell function (%), a 0.126 increase in log-transformed HOMA of insulin resistance (%), and a 0.109-SD increase in triglyceride (mg/dL) but a 0.138-SD decrease in HDL (mg/dL) in adults at the Bonferroni-adjusted level of significance (P < 0.0026). CONCLUSIONS: A genetic predisposition to higher childhood BMI was associated with increased risk of type 2 diabetes and CAD in adult life. These results provide evidence supportive of a causal association between childhood BMI and these outcomes.
Nitryl chloride (ClNO2) accumulation at night acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5 and a suite of inorganic halogens including ClNO2 and reactions of chloride with volatile organic compounds (Cl-VOCs) in the gas and particle phases utilising the Filter Inlet for Gas and AEROsols time-of-flight chemical ionisation mass spectrometer (FIGAERO-ToF-CIMS) during an intensive measurement campaign 40 km northwest of Beijing in May and June 2016. A maximum mixing ratio of 2900 ppt of ClNO2 was observed with a mean campaign nighttime mixing ratio of 487 ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high mixing ratios persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3 x 10(5) molecules cm(-3) from ClNO2 alone, peaking at 09:30 LT and up to 8.4 x 10(5) molecules cm(-3) when including the supporting inorganic halogen measurements.Cl-VOCs were observed in the particle and gas phases for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady-state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to secondary organic aerosol (SOA) formation.
BACKGROUND: Because of the rapid change in economic development and lifestyle in China, and the ageing population, concerns have grown that chronic obstructive pulmonary disease (COPD) could become epidemic. An up-to-date nationwide estimation of COPD prevalence in China is needed. METHODS: We did a cross-sectional survey of a nationally representative sample of individuals from mainland China aged 40 years or older. The primary outcome was COPD, defined according to the 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) lung function criteria. FINDINGS: Between Dec 29, 2014, and Dec 31, 2015, 66 752 adults were recruited to the study population. The estimated standardised prevalence of COPD was 13·6% (95% CI 12·0-15·2). The prevalence of COPD differed significantly between men and women (19·0%, 95% CI 16·9-21·2 vs 8·1%, 6·8-9·3; p<0·0001), mainly because of a significant difference in smoking status between men and women (current smokers 58·2% vs 4·0%). The prevalence of COPD differed by geographic region, with the highest prevalence in southwest China (20·2%, 95% CI 14·7-25·8) and the lowest in central China (10·2%, 8·2-12·2). Among adults with COPD, 56·4% (95% CI 53·7-59·2) had mild disease (GOLD stage I), 36·3% (34·3-38·3) had moderate disease (GOLD stage II), 6·5% (5·5-7·4) had severe disease (GOLD stage III), and 0·9% (0·6-1·1) had very severe disease (GOLD stage IV). INTERPRETATION: In a large, nationally representative sample of adults aged 40 years or older, the estimated overall prevalence of COPD in China in 2014-15 was 13·6%, indicating that this disease has become a major public-health problem. Strategies aimed at prevention and treatment of COPD are needed urgently. FUNDING: Chinese Central Government, the Ministry of Science and Technology of The People's Republic of China, and the National Natural Science Foundation of China.
BACKGROUND: Because of the rapid change in economic development and lifestyle in China, and the ageing population, concerns have grown that chronic obstructive pulmonary disease (COPD) could become epidemic. An up-to-date nationwide estimation of COPD prevalence in China is needed. METHODS: We did a cross-sectional survey of a nationally representative sample of individuals from mainland China aged 40 years or older. The primary outcome was COPD, defined according to the 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) lung function criteria. FINDINGS: Between Dec 29, 2014, and Dec 31, 2015, 66 752 adults were recruited to the study population. The estimated standardised prevalence of COPD was 13·6% (95% CI 12·0-15·2). The prevalence of COPD differed significantly between men and women (19·0%, 95% CI 16·9-21·2 vs 8·1%, 6·8-9·3; p<0·0001), mainly because of a significant difference in smoking status between men and women (current smokers 58·2% vs 4·0%). The prevalence of COPD differed by geographic region, with the highest prevalence in southwest China (20·2%, 95% CI 14·7-25·8) and the lowest in central China (10·2%, 8·2-12·2). Among adults with COPD, 56·4% (95% CI 53·7-59·2) had mild disease (GOLD stage I), 36·3% (34·3-38·3) had moderate disease (GOLD stage II), 6·5% (5·5-7·4) had severe disease (GOLD stage III), and 0·9% (0·6-1·1) had very severe disease (GOLD stage IV). INTERPRETATION: In a large, nationally representative sample of adults aged 40 years or older, the estimated overall prevalence of COPD in China in 2014-15 was 13·6%, indicating that this disease has become a major public-health problem. Strategies aimed at prevention and treatment of COPD are needed urgently. FUNDING: Chinese Central Government, the Ministry of Science and Technology of The People's Republic of China, and the National Natural Science Foundation of China.
Background Because of the rapid change in economic development and lifestyle in China, and the ageing population, concerns have grown that chronic obstructive pulmonary disease (COPD) could become epidemic. An up-to-date nationwide estimation of COPD prevalence in China is needed. Methods We did a cross-sectional survey of a nationally representative sample of individuals from mainland China aged 40 years or older. The primary outcome was COPD, defined according to the 2017 Global Initiative for Chronic Obstructive Lung Disease (GOLD) lung function criteria. Findings Between Dec 29, 2014, and Dec 31, 2015, 66 752 adults were recruited to the study population. The estimated standardised prevalence of COPD was 13.6% (95% CI 12.0-15.2). The prevalence of COPD differed significantly between men and women (19.0%, 95% CI 16.9-21.2 vs 8.1%, 6.8-9.3; p< 0.0001), mainly because of a significant difference in smoking status between men and women (current smokers 58.2% vs 4.0%). The prevalence of COPD differed by geographic region, with the highest prevalence in southwest China (20.2%, 95% CI 14.7-25.8) and the lowest in central China (10.2%, 8.2-12.2). Among adults with COPD, 56.4% (95% CI 53.7-59.2) had mild disease (GOLD stage I), 36.3% (34.3-38.3) had moderate disease (GOLD stage II), 6.5% (5.5-7.4) had severe disease (GOLD stage III), and 0.9% (0.6-1.1) had very severe disease (GOLD stage IV). Interpretation In a large, nationally representative sample of adults aged 40 years or older, the estimated overall prevalence of COPD in China in 2014-15 was 13.6%, indicating that this disease has become a major public-health problem. Strategies aimed at prevention and treatment of COPD are needed urgently.
PURPOSE: A common variant of the melatonin receptor 1B (MTNR1B) gene has been related to increased signaling of melatonin, a hormone previously associated with body fatness mainly through effects on energy metabolism. We examined whether the MTNR1B variant affects changes of body fatness and composition in response to a dietary weight loss intervention. METHODS: The MTNR1B rs10830963 variant was genotyped for 722 overweight and obese individuals, who were randomly assigned to one of four diets varying in macronutrient composition. Anthropometric and body composition measurements (DXA scan) were collected at baseline and at 6 and 24 months of follow-up. RESULTS: Statistically significant interactions were observed between the MTNR1B genotype and low-/high-fat diet on changes in weight, body mass index (BMI), waist circumference (WC) and total body fat (p interaction = 0.01, 0.02, 0.002 and 0.04, respectively), at 6 months of dietary intervention. In the low-fat diet group, increasing number of the sleep disruption-related G allele was significantly associated with a decrease in weight (p = 0.004), BMI (p = 0.005) and WC (p = 0.001). In the high-fat diet group, carrying the G allele was positively associated with changes in body fat (p = 0.03). At 2 years, the associations remained statistically significant for changes in body weight (p = 0.02), BMI (p = 0.02) and WC (p = 0.048) in the low-fat diet group, although the gene-diet interaction became less significant. CONCLUSIONS: The results suggest that carriers of the G allele of the MTNR1B rs10830963 may have a greater improvement in body adiposity and fat distribution when eating a low-fat diet.
