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The complex air pollution driven by both Ozone (O3) and fine particulate matter (PM2.5) significantly influences the air quality in the Sichuan Basin (SCB). Understanding the O3 formation during autumn and winter is necessary to understand the atmospheric oxidative capacity. Therefore, continuous in-site field observations were carried out during the late summer, early autumn and winter of 2020 in a rural area of Chongqing. The total volatile organic compounds (VOCs) concentration reported by a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) were 13.66 ± 9.75 ppb, 5.50 ± 2.64 ppb, and 9.41 ± 5.11 ppb in late summer, early autumn and winter, respectively. The anthropogenic VOCs (AVOCs) and biogenic VOCs (BVOCs) were 8.48 ± 7.92 ppb and 5.18 ± 2.99 ppb in late summer, 3.31 ± 1.89 ppb and 2.19 ± 0.93 ppb in autumn, and 6.22 ± 3.99 ppb and 3.20 ± 1.27 ppb in winter. A zero-dimensional atmospheric box model was employed to investigate the sensitivity of O3-precursors by relative incremental reactivity (RIR). The RIR values of AVOCs, BVOCs, carbon monoxide (CO), and nitrogen oxides (NOx) were 0.31, 0.71, 0.09, and -0.36 for late summer, 0.24, 0.59, 0.22, and -0.38 for early autumn, and 0.30, 0.64, 0.33 and -0.70 for winter, and the results showed that the O3 formation of sampling area was in the VOC-limited region, and O3 was most sensitive to BVOCs (with highest RIR values, > 0.6). This study can be helpful in understanding O3 formation and interpreting the secondary formation of aerosols in the winter.
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Contaminantes Atmosféricos , Contaminación del Aire , Ozono , Compuestos Orgánicos Volátiles , Ozono/química , Compuestos Orgánicos Volátiles/análisis , Contaminantes Atmosféricos/análisis , China , Contaminación del Aire/análisis , Monitoreo del Ambiente/métodosRESUMEN
Oxygenated volatile organic compounds (OVOCs) are key intermediates in the atmospheric photooxidation process. To further study the primary and secondary sources of OVOCs, their ambient levels were monitored using a proton-transfer reaction mass spectrometer (PTR-MS) at an urban site in the Pearl River Delta of China. Continuous monitoring campaigns were conducted in the spring, summer, fall, and winter of 2016. Among the six types of OVOC species, the mean concentrations of methanol were the highest in each season (up to 13-20ppbv), followed by those of acetone, acetaldehyde and acetic acid (approximately 2-4ppbv), while those of formic acid and methyl ethyl ketone (MEK) were the lowest (approximately 1-2ppbv). As observed from a diurnal variation chart, the OVOCs observed in Shenzhen may have been affected by numerous factors such as their primary and secondary sources and photochemical consumption. The photochemical age-based parameterization method was used to apportion the sources of ambient OVOCs. Methanol had significant anthropogenic primary sources but negligible anthropogenic secondary sources during all of the seasons. Acetone, MEK and acetic acid were mostly attributed to anthropogenic primary sources during each season with smaller contributions from anthropogenic secondary sources. Acetaldehyde had similar contributions from both anthropogenic secondary and anthropogenic primary sources throughout the year. Meanwhile, anthropogenic primary sources contributed the most to formic acid.
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Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Compuestos Orgánicos Volátiles/análisis , China , Procesos FotoquímicosRESUMEN
Framing effect studies indicate that individuals are risk averse for decisions framed as gains but risk-seeking for decisions framed as losses. Findings of age-related differences in susceptibility to framing are mixed. In the current study, we examined emotional arousal in two decision tasks (life saving vs. money gambling) to evaluate the effects of emotion on age differences in the framing effect. When cognitive abilities and styles were controlled, there was a framing effect in the younger group in the life-saving task, a high-emotional arousal task, while older adults did not display this classic framing effect pattern. They showed risk aversion in both positive and negative framing. Age differences existed in the framing effect. Conversely, younger and older adults in the money-gambling task both displayed the framing effect; there was no age difference. When the cognitive abilities were not controlled, the pattern of results in the high-emotional arousal task remained unchanged, while greater framing effects were found, from the perspective of effect size, for older than younger adults in the low-emotional arousal task. Limited cognitive resources would not hamper older adults' performances when their emotional arousal was high. However, older adults with low-level emotional arousal were more susceptible than younger adults to framing because of declining cognitive capacities. This implied the importance of emotion in older adults' decision making and supported the selective engagement hypothesis.
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Envejecimiento/fisiología , Toma de Decisiones/fisiología , Emociones/fisiología , Memoria a Corto Plazo/fisiología , Desempeño Psicomotor/fisiología , Adolescente , Adulto , Factores de Edad , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Large missing sources of daytime atmospheric nitrous acid (HONO), a vital source of hydroxyl radicals (OH) through its photolysis, frequently exist in global coastal regions. In this study, ambient HONO and relevant species were measured at a coastal site in the Pearl River Delta (PRD), China, during October 2019. Relatively high concentrations (0.32 ± 0.19 ppbv) and daytime peaks at approximately 13:00 of HONO were observed, and HONO photolysis was found to be the dominant (55.5 %) source of the primary OH production. A budget analysis of HONO based on traditional sources suggested large unknown sources during the daytime (66.4 %), which had a significant correlation with the mass of coarse particles (PM2.5-10) and photolysis frequency (J(NO2)). When incorporating photolysis of the abundant nitrate measured in coarse particles with a reasonable enhancement factor relative to fine particles due to favorable aerosol conditions, the missing daytime sources of HONO could be fully compensated by coarse particles serving as the largest source at this coastal site. Our study revealed great potential of coarse particles as a strong daytime HONO source, which has been ignored before but can efficiently promote NOx recycling and thus significantly enhance atmospheric oxidation capacity.
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Wastewater treatment plants (WWTPs) are usually considered gateways for microplastics (MPs) to enter the environment because large amounts of sewage are produced and MPs are incompletely removed during treatment processes. However, the contribution of effluent MPs to aquatic environmental pollution and that of sludge application to MPs in agricultural soil are still unknown. This study examines the presence of MPs in sewage and sludge in Shenzhen WWTPs and estimates the annual mass loading of MPs from WWTPs to surface water and farmland soil in China. According to our results, for Shenzhen, the annual contribution of MPs from WWTPs (which was obtained by multiplying the annual treated sewage volume by the estimated MP density in the treated sewage) to surface water could be 70.6-302 tons. With a normalized extrapolation model of population density, the contribution of national urban WWTPs to MPs in surface water was estimated to be 734 -3.10 × 103 tons/year, of which 220-950 tons/year entered the marine environment. Furthermore, the riverine flux of MPs from WWTPs to the ocean amounts to at least 7.0%-30% based on the maximum value of WWTP contribution to MPs in surface water. For sludge, the potential contribution of MPs to agricultural soil from Shenzhen WWTPs is (1.00-2.80) × 103 tons/year. With the above calculation procedure, it was estimated that the contribution of MPs to farmland from sludge application in China is (1.30-3.90) × 104 tons/year. The source appointment results for MPs in China's agricultural soil suggested that the contributions of the main four sources, namely, atmospheric deposition, agricultural mulch film, sludge application, and organic fertilizers, are 52%, 30%, 11%, and 7.0%, respectively.
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Owing to its biotoxicity and inductive effect on photochemical pollution, atmospheric peroxyacetyl nitrate (PAN), which is a typical product of atmospheric photochemical reactions, has attracted much research attention. However, to the best of our knowledge, few comprehensive studies have been conducted on the seasonal variation and key influencing factors of PAN concentrations in southern China. In this study, PAN, ozone (O3), precursor volatile organic compound (VOC), and other pollutant concentrations were measured online for 1 year (from October 2021 to September 2022) in Shenzhen, a megacity in the Greater Bay Area of China. The average concentrations of PAN and peroxypropionyl nitrate (PPN) were 0.54 and 0.08 parts per billion (ppb), and the maximum hourly concentrations reached 10.32 and 1.01 ppb, respectively. The results of the generalized additive model (GAM) showed that the atmospheric oxidation capacity and precursor concentration were the most important factors affecting the PAN concentration. According to the steady-state model, the average cumulative contribution to the peroxyacetyl (PA) radical formation rate by six major carbonyl compounds was calculated at 4.2 × 106 molecules cm-3 s-1, and acetaldehyde (63.0 %) and acetone (13.9 %) contributed the most. Furthermore, the photochemical-age-based parameterization method was used to analyze the source contributions of carbonyl compounds and PA radicals. The results showed that although the primary anthropogenic (40.2 %), biogenic (27.8 %), and secondary anthropogenic (16.4 %) sources were the most important contributors of PA radicals, the biogenic and secondary anthropogenic source contributions both increased considerably in summer, and the cumulative proportion of both sources reached ~70 % in July. In addition, a comparison of PAN pollution processes in different seasons revealed that in summer and winter, the PAN concentration was predominantly limited by precursors and meteorological parameters, such as light intensity, respectively.
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Contaminantes Atmosféricos , Ozono , Compuestos Orgánicos Volátiles , Estaciones del Año , Contaminantes Atmosféricos/análisis , China , Ozono/análisis , Compuestos Orgánicos Volátiles/análisis , Monitoreo del AmbienteRESUMEN
Ambient ozone air pollution is one of the most important environmental challenges in China today, and it is particularly significant to identify pollution sources and formulate control strategies. In present study, we proposed a novel method of positive matrix factorization-SHapley Additive explanation (PMF-SHAP) for evaluating the impact of emission sources on ozone formation, which can quantify the main emission sources of ozone pollution. In this method, we first used the PMF model to identify the source of volatile organic compounds (VOCs), and then quantified various emission sources using a combination of machine learning (ML) models and the SHAP algorithm. The R2 of the optimal ML model in this method was as high as 0.96, indicating that the prediction performance was excellent. Furthermore, we explored the impact of different emission sources on ozone formation, and found that ozone formation in Shenzhen was more affected by VOCs, of which vehicle emission sources may have the greatest impact. Our results suggest that the appropriate combination of traditional models with ML models can well address environmental pollution problems. Moreover, the conclusions obtained based on the PMF-SHAP method were different from the traditional ozone formation potential (OFP) results, providing valuable clues for related mechanism studies.
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Contaminación del Aire , Ozono , Compuestos Orgánicos Volátiles , Ozono/toxicidad , Aprendizaje Automático , Contaminación AmbientalRESUMEN
The volatile organic compounds emitted by plants significantly impact the atmospheric environment. The impacts of drought stress on the biogenic volatile organic compound (BVOC) emissions of plants are still under debate. In this study, the effects of two drought-rehydration cycle groups with different durations on isoprene emissions from Populus nigra (black poplar) seedlings were studied. The P. nigra seedlings were placed in a chamber that controlled the soil water content, radiation, and temperature. The daily emissions of isoprene and physiological parameters were measured. The emission rates of isoprene (Fiso) reached the maximum on the third day (D3), increasing by 58.0% and 64.2% compared with the controlled groups, respectively, and then Fiso significantly decreased. Photosynthesis decreased by 34.2% and 21.6% in D3 in the first and second groups, respectively. After rehydration, Fiso and photosynthesis recovered fully in two groups. However, Fiso showed distinct inconsistencies in two groups, and the recovery rates of Fiso in the second drought group were slower than the recovery rates of Fiso in the first groups. The response of BVOC emissions during the drought-rehydration cycle was classified into three phases, including stimulated, inhibited, and restored after rehydration. The emission pattern of isoprene indicated that isoprene played an important role in the response of plants to drought stress. A drought-rehydration model was constructed, which indicated the regularity of BVOC emissions in the drought-rehydration cycle. BVOC emissions were extremely sensitive to drought, especially during droughts of short duration. Parameters in computational models related to BVOC emissions of plants under drought stress should be continuously improved.
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Populus , Compuestos Orgánicos Volátiles , Populus/fisiología , Sequías , Plantones , Fotosíntesis , Plantas , Fluidoterapia , Hojas de la PlantaRESUMEN
OBJECTIVE: This study aimed to probe into the diagnostic level and clinical value of ultrasound combined with enhanced MRI by Gd-BOPTA in hepatocellular carcinoma (HCC). METHODS: A total of 58 suspected HCC patients in our hospital from January 2016 to November 2020 were collected as the research subjects, including 37 HCC and 21 non-HCC patients. The diagnostic results of ultrasound and enhanced MRI by Gd-BOPTA were compared, and the microvascular invasion in patients was assessed. The independent risk factors of microvascular invasion were analyzed by logistics regression, and the diagnostic value of these factors was tested by ROC. RESULTS: The specificity, sensitivity and accuracy of enhanced MRI by Gd-BOPTA were 89.19%, 90.48% and 94.59%, respectively. The specificity, sensitivity and accuracy of ultrasound were 85.71%, 72.97% and 91.89%, and those of combined diagnosis were 76.19%, 97.30%, and 89.66%, respectively. The confirmation rate of microvascular invasion of enhanced MRI by Gd-BOPTA was dramatically higher than with ultrasound. Tumor diameter, comorbid cirrhosis and differentiation degree were independent risk factors of microvascular invasion, and ROC curve revealed that the area under the curve (AUC) of these risk factors was > 0.6. CONCLUSION: Enhanced MRI by Gd-BOPTA combined with ultrasound has good diagnostic value in HCC patients, and it can be widely used in early HCC diagnosis and clinical examination.
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Oxygenated volatile organic compounds (OVOCs) are important precursors and intermediate products of atmospheric photochemical reactions, which can promote the formation of secondary pollutants such as ozone (O3) and secondary organic aerosol (SOA). However, there have been few studies on the sources of and long-term variation in ambient OVOCs. This study combined sensitive, near real-time measurements of VOCs by proton transfer reaction-mass spectrometry (PTR-MS) with an improved photochemical age parameterization method to quantify daytime sources of OVOCs in an urban atmosphere in China from 2014 to 2019, permitting the observation of the impacts of emission control strategies that were implemented during this period. Temporal variation in six key OVOCs (methanol, acetaldehyde, acetone, methyl ethyl ketone (MEK), formic acid, and acetic acid) were observed. The sum of concentrations of OVOCs was averagely 13% higher during the dry season (November to April), when winds transported polluted air masses to Shenzhen from the continent, than during the wet season, and peak diurnal levels occurred during the daytime year-round due to photochemical production and higher daytime anthropogenic emissions. The average dry season concentration of OVOCs declined from a peak of 30.3 ppb in 2015 to 18.7 ppb in 2019. The results of source apportionment showed that primary anthropogenic sources contributed the most to methanol, MEK, and acetic acid (32-51%); the dominant sources of acetaldehyde and formic acid were both primary and secondary anthropogenic sources; and biomass burning contributed a small fraction (5-11%) to the six OVOCs. From 2014 to 2019, contributions from primary anthropogenic sources of OVOCs decreased significantly by 50-60% due to intensive pollution control measures in Shenzhen, whereas pollution control measures had no observable impact on secondary OVOCs, indicating their formation was not limited by availability of their primary VOC precursors.
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Contaminantes Atmosféricos , Compuestos Orgánicos Volátiles , Contaminantes Atmosféricos/análisis , Atmósfera , China , Monitoreo del Ambiente , Compuestos Orgánicos Volátiles/análisisRESUMEN
Volatile organic compounds (VOCs) are important precursors of photochemical pollution. However, a substantial fraction of VOCs, namely, oxygenated VOCs (OVOCs), have not been sufficiently characterized to evaluate their sources in air pollution in China. In this study, a total of 119 VOCs, including 60 OVOCs in particular, were monitored to provide a more comprehensive picture based on different online measurement techniques, proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and online gas chromatography/mass spectrometry (GC/MS), at a receptor site in southeastern China during a photochemically active period. Positive matrix factorization (PMF) and photochemical age-based parameterization were combined to identify and quantify different sources of major VOCs during daytime hours, with the advantage of including VOC decay processes. The results revealed the unexpected role of biomass burning (21%) in terms of ozone (O3) formation potential (OFP) when including the contributions of OVOCs and large contributions (30-32%) of biomass burning to aldehydes, as more OVOCs were measured in this study. We argue that biomass burning could significantly enhance the continental atmospheric oxidizing capacity, in addition to the well-recognized contributions of primary pollutants, which should be seriously considered in photochemical models and air pollution control strategies.
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Contaminantes Atmosféricos , Contaminación del Aire , Ozono , Compuestos Orgánicos Volátiles , Contaminantes Atmosféricos/análisis , Biomasa , China , Monitoreo del Ambiente , Oxidación-Reducción , Ozono/análisis , Compuestos Orgánicos Volátiles/análisisRESUMEN
Oxygenated volatile organic compounds (OVOCs) are critical precursors of atmospheric ozone (O3) and secondary organic aerosols (SOA). Although China is experiencing increasing O3 pollution from north to south, understanding the major sources of OVOCs in this region is still limited due to their active photochemical behaviors. In this study, five critical OVOCs at a northern urban site (Beijing) and a southern urban site (Shenzhen) were monitored in summer using proton transfer reaction-mass spectrometry (PTR-MS). The mean total concentration of VOCs measured in Beijing (39.4 ppb) was much higher than that measured in Shenzhen (16.7 ppb), with methanol and formaldehyde being the most abundant in concentration at both sites. The source apportionment of daytime OVOCs was conducted effectively using a photochemical age-based parameterization method. Biogenic and anthropogenic secondary sources were the main sources of formaldehyde, acetaldehyde, and acetone at both sites, with a total contribution of 46-82%; acetone also had a large regional-scale background contribution (36-38%); methanol and methyl ethyl ketone (MEK) were mainly derived from anthropogenic primary sources (35-55%) at both sites. In addition, the regional background levels of OVOCs measured in North China were shown to be much higher than those measured in South China. The calculation of the total O3 formation potential (OFP) of OVOCs highlights the comparable contributions from anthropogenic and biogenic sources in both Beijing and Shenzhen, indicating the important role of biogenic OVOC sources even in polluted environments. Since biogenic sources are already important but uncontrollable, anthropogenic emissions in China need to be restricted even more critically in the future.
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Contaminantes Atmosféricos/análisis , Ozono/análisis , Compuestos Orgánicos Volátiles/análisis , Atmósfera , Beijing , China , Monitoreo del AmbienteRESUMEN
Option framing effect is the phenomena that participants often accept more options when they are asked to delete undesired options from a full model (subtractive framing) than they do when they are instructed to add desired options to a base model (additive framing). Whether the same effect exists in different age groups is less well known. To explore the roles of age and purchase motivations on the option framing effect for automobiles purchases, this study adopted a 3 (age group: younger, middle-aged, vs. older) × 2 (option framing: additive vs. subtractive) × 2 (focus condition: information vs. emotion) mixed design. To manipulate purchase motivations, participants in the three age groups were instructed to focus on the ratio of utility and price of options (information-focus) or the extent of pleasure induced by the options (emotion-focus) when they made purchase decisions in two framing conditions. The results revealed similar option framing effect across all age groups in the information-focus condition regarding the total price paid for accepted options. In contrast, the framing effect was not found in the emotion-focus condition. In addition, older adults accepted more options and an overall higher price than younger and middle-aged adults in both focus conditions. This difference was more obvious in the emotion-focus condition than in the information-focus condition. Moreover, both the number of accepted options and the total accepted price of the younger group in the information-focus condition were higher than those in the emotion-focus condition, whereas the older and middle-aged groups accepted same number of options and price between two focus conditions. These results imply that purchase motivation is a moderator of the option framing effect and age characteristics linked with motivations must be considered in sales.