Journal of Environmental Sciences-china最新文献

Multi-axial differential optical absorption spectroscopy (MAX-DOAS) measurements were conducted in Xishuangbanna, Yunnan, China, between November 1, 2021 and June 30, 2022 to obtain vertical distributions of formaldehyde (HCHO) and glyoxal (CHOCHO). The observations show an increase in vertical column densities (VCDs) and volume mixing ratios (VMRs) for both HCHO and CHOCHO concentrations during periods of biomass combustion. The VCDs of HCHO and CHOCHO from TROPOMI are in good agreement with the MAX-DOAS observations. (R²_HCHO = 0.71; R²_CHOCHO = 0.70). Regarding seasonal variations, HCHO predominantly occupies the upper layer (400-800 m) during the biomass burning, possibly attributed to the formation of secondary HCHO as the plume ascends during combustion. CHOCHO is primarily found in the lower layer (0-200 m), suggesting a longer lifespan for HCHO compared to CHOCHO, preventing the latter from diffusing to higher altitudes. Concerning the daily variation patterns, both HCHO and CHOCHO VMRs exhibited peaks at 9:00 and 13:00, which were attributed to the nighttime accumulation and midday oxidation. Furthermore, we also investigated the sources of volatile organic compounds (VOCs) using the CHOCHO to HCHO ratio (R_GF). During the period of biomass burning, there are minimal differences in the daily R_GF across layers, indicating that biomass burning is the predominant source. During the non-biomass burning period, the daily R_GF shows significant differences among layers, indicating that emissions from biological and anthropogenic sources primarily contribute during the period.

P-arsanilic acid (AA) has received widespread attention because of its conversion to more toxic inorganic arsenic compounds (arsenate and arsenite) in the natural ecosystems. Its removal process and mechanisms with co-existence of microplastics remain unkown. In this study, biochar loaded with nano zero-valent iron (nZVI) particles (ISBC) was prepared by using iron scrap obtained from a steel works and wood chips collected from a wood processing plant. The advanced oxidation system of sodium persulfate (PDS) activated by ISBC was applied for AA degradation and inorganic arsenic control in aqueous media. More than 99% of the AA was completely degraded by the ISBC/PDS system, and the As(III) on AA was almost completely oxidized to As(V) and finally removed by ISBC. HCO₃⁻ inhibited the removal of AA by the ISBC/PDS system, while Cl⁻ had a dual effect that showing inhibition at low concentrations yet promotion at high concentrations. The effect of microplastics on the degradation of AA by the ISBC/PDS system was further investigated due to the potential for combined microplastic and organic arsenic contamination in rural/remote areas. Microplastics were found to have little effect on AA degradation in the ISBC/PDS system, while affect the transport of inorganic arsenic generated from AA degradation. Overall, this study provides new insights and methods for efficient removal of p-arsanilic acid from water with coexisting microplastics.

It is still a challenge to develop hierarchically nanostructured catalysts with simple approaches to enhance the low-temperature catalytic activity. Herein, a set of mesoporous Co-Cu binary metal oxides with different morphologies were successfully prepared via a facile ammonium bicarbonate precipitation method without any templates or surfactants, which were further applied for catalytic removal of carcinogenic toluene. Among the catalysts with different ratios, the CoCu_0.2 composite oxide presented the best performance, where the temperature required for 90% conversion of toluene was only 237°C at the high weight hour space velocity (WHSV) of 240,000 mL/(g_cat·hr). Meanwhile, compared to the related Co-Cu composite oxides prepared by using different precipitants (NaOH and H₂C₂O₄), the NH₄HCO₃-derived CoCu_0.2 sample exhibited better catalytic efficiency in toluene oxidation, while the T₉₀ were 22 and 28°C lower than those samples prepared by NaOH and H₂C₂O₄ routes, respectively. Based on various characterizations, it could be deduced that the excellent performance was related to the small crystal size (6.7 nm), large specific surface area (77.0 m²/g), hollow hierarchical nanostructure with abundant high valence Co ions and adsorbed oxygen species. In situ DRIFTS further revealed that the possible reaction pathway for the toluene oxidation over CoCu_0.2 catalyst followed the route of absorbed toluene → benzyl alcohol → benzaldehyde → benzoic acid → carbonate → CO₂ and H₂O. In addition, CoCu_0.2 sample could keep stable with long-time operation and occur little inactivation under humid condition (5 vol.% water), which revealed that the NH₄HCO₃-derived CoCu_0.2 nanocatalyst possessed great potential in industrial applications for VOCs abatement.

To explore the multicenter characteristics of endocrine-like phthalate esters (PAEs) in household dust and propose effective control strategies for global indoor public health. An on-site observational investigation was conducted in nine Chinese cities from 2018 to 2019. A total of 246 household dust samples were collected and analyzed for ten PAE congeners using Gas Chromatography-Mass Spectrometry (GC-MS). Questionnaires were used to gather information on building conditions, indoor behaviors, and ventilation habits. In residential dust from the nine cities, the total concentrations of the ten PAE congeners (∑PAEs) ranged from 0.921 to 29097.297 µg/g. Dicyclohexyl phthalate (DCHP) and di (2-ethylhexyl) phthalate (DEHP) were the dominant congeners in ∑PAEs. Childhood exposure to PAEs through dust ingestion was four orders of magnitude higher than through inhalation, with a carcinogenic risk of 5.47 × 10⁻⁶ for DEHP exposure in household dust. Higher ∑PAEs concentrations were associated with higher temperature, double glazing, wall paint usage, television and computer use, and indoor plant growth. This multicenter on-site investigation confirmed PAE pollution characteristics and uncovered the inacceptable risk of daily DEHP exposure in household dust under real living conditions. Effective mitigation measures based on household-related information, residential characteristics, decoration materials, and lifestyle should be taken to build a healthy household environment.

The ambient air quality has improved significantly under strict emission controls in Beijing, China over the last decade. Black carbon (BC), as a short-lived climate forcer in ambient aerosols, profoundly impacts the air quality and climate. Previous studies have demonstrated a decline in the mass concentration of BC. In this study, we characterized the chemical compositions and size distributions of BC-containing particles during the cold season of 2022 in Beijing using state-of-the-art instruments capable of exclusively measuring BC-containing particles. The optical properties of BC-containing particles were further calculated based on the Mie theory. Moreover, we compared the properties of BC-containing particles in 2022 with the results of previous studies. The results showed that the diameters of BC cores became larger while the coating thickness of BC-containing particles became thinner in 2022. For the coating materials, the mass fraction of nitrate increased obviously, and even replaced organic matter as the dominant component during the peak of the pollution period. Variations in chemical compositions and size distributions resulted in lower mass absorption cross-sections (MAC) of BC-containing particles from 10.5 ± 1.1 m²/g in 2016 to 7.3 ± 0.8 m²/g in 2022, reduced by 30.5%. Our results demonstrate the synergistic benefits of air pollution control in improving air quality and mitigating climate change. Therefore, the MAC of BC adopted in climate models should vary with the changing air pollution levels. This study emphasizes that it is imperative to conduct long-term observations of BC-containing particles to better estimate BC's climate effects.

The accumulation of Cd by rice poses significant health risks. Foliar fertilization with Zn can reduce grain Cd contents in rice grown in Cd-contaminated soils. However, atmospheric deposition on leaves is another vector of Cd contamination, and it remains unclear how Zn application affects the allocation of such Cd. We conducted an experiment where the flag leaves of rice plants were treated with solutions with various Zn concentrations and a constant Cd concentration. The ¹¹¹Cd stable isotope was used to trace the flux of foliar-applied Cd. Higher levels of foliar-applied Zn enhanced Cd efflux and grain allocation. This is attributed to limited sequestration of foliar-applied Cd in the leaf cell symplasm and increased Cd desorption from leaf cell walls when a high Zn²⁺ concentration occurs in the apoplast. Nonionic Zn oxide nanoparticles mitigated these effects. Additionally, the expressions of OsLCT1 and OsZIP7 in flag leaves and OsHMA2 and OsZIP7 in the uppermost nodes were upregulated under high-Zn²⁺ treatment, which may facilitate Cd phloem loading and grain allocation. Caution is advised in using foliar Zn in areas with high atmospheric Cd due to potential grain-contamination risks.

Substantial effects of photochemical reaction losses of volatile organic compounds (VOCs) on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data resolved profiles. Hourly speciated VOC data measured in Shijiazhuang, China from May to September 2021 were used to conduct study. The mean VOC concentration in the daytime and at nighttime were 32.8 and 36.0 ppbv, respectively. Alkanes and aromatics concentrations in the daytime (12.9 and 3.08 ppbv) were lower than nighttime (15.5 and 3.63 ppbv), whereas that of alkenes showed the opposite tendency. The concentration differences between daytime and nighttime for alkynes and halogenated hydrocarbons were uniformly small. The reactivities of the dominant species in factor profiles for gasoline emissions, natural gas and diesel vehicles, and liquefied petroleum gas were relatively low and their profiles were less affected by photochemical losses. Photochemical losses produced a substantial impact on the profiles of solvent use, petrochemical industry emissions, combustion sources, and biogenic emissions where the dominant species in these factor profiles had high reactivities. Although the profile of biogenic emissions was substantially affected by photochemical loss of isoprene, the low emissions at nighttime also had an important impact on its profile. Chemical losses of highly active VOC species substantially reduced their concentrations in apportioned factor profiles. This study results were consistent with the analytical results obtained through initial concentration estimation, suggesting that the initial concentration estimation could be the most effective currently available method for the source analyses of active VOCs although with uncertainty.

Studying the spatiotemporal distribution and transboundary transport of aerosols, NO₂, SO₂, and HCHO in typical regions is crucial for understanding regional pollution causes. In a 2-year study using multi-axis differential optical absorption spectroscopy in Qingdao, Shanghai, Xi'an, and Kunming, we investigated pollutant distribution and transport across Eastern China-Ocean, Tibetan Plateau-Central and Eastern China, and China-Southeast Asia interfaces. First, pollutant distribution was analyzed. Kunming, frequently clouded and misty, exhibited consistently high aerosol optical depth throughout the year. In Qingdao and Shanghai, NO₂ and SO₂, as well as SO₂ in Xi'an, increased in winter. Elevated HCHO in summer in Shanghai and Xi'an, especially Xi'an, suggests potential ozone pollution issues. Subsequently, pollutant transportation across interfaces was studied. At the Eastern China-Ocean interface, the gas transport flux was the largest among other interfaces, with the outflux exceeding the influx, especially in winter and spring. The input of pollutants from the Tibetan Plateau to central-eastern China was larger than the output in winter and spring, with SO₂ having the highest transport flux in winter. The pollution input from Southeast Asia to China significantly exceeded the output, with spring and winter inputs being 3.22 and 3.03 times the output, respectively. Lastly, the transportation characteristics of a pollution event at Kunming were studied. During this period, pollutants were transported from west to east, with the maximum SO₂ transport flux at an altitude of 2.87 km equaling 27.74 µg/(m²·s). It is speculated that this pollution was caused by the transport from Southeast Asian countries to Kunming.

Volatile Organic Compounds (VOCs) are highly harmful to human beings and other organisms, and thus the elimination of VOCs is extremely urgent. Here, La-Si co-doped TiO₂ microsphere photocatalysts, which were prepared by a hydrothermal method, exhibited high photocatalytic activity in the decomposition of formaldehyde compared with TiO₂. The improved activity can be attributed to the promoted separation efficiency and density of the charge carriers, as verified by the electrochemical results in combination with density functional theory calculations. In addition, the Si dopant changed the microstructure and surface acidity, while the addition of La promoted the separation efficiency of charge carriers. More interestingly, it was found that singlet oxygen was the key species in the activation of molecular dioxygen, and it played a pivotal role in the photocatalytic decomposition of formaldehyde. This work provides a novel strategy for the selective activation of dioxygen for use in the decomposition of formaldehyde.

Inhalation of atmospheric PM_2.5 can induce the generation of excessive reactive oxygen species (ROS) in human alveoli, triggering local and systemic inflammation, which can directly or indirectly result in respiratory and cardiovascular diseases. In this study, we assessed the oxidative potential (OP) of fresh and O₃-aged PM_2.5 particles from various urban and rural emission sources using the dithiothreitol (DTT) method. Our results revealed variations in the OP of fresh PM_2.5 among different emission sources, with biomass burning sources exhibiting the highest OP, followed by industrial areas, vehicular emissions, cooking emissions, and suburban areas, respectively. Water-soluble organics and transition metals might potentially exert significant influence on particle OP. O₃ aging notably decreased the OP of PM_2.5 particles, possibly due to the oxidation of highly DTT-active components into low redox-active small molecules. Moreover, the evolution of OP in different PM_2.5 components, including methanol-soluble and insoluble fractions, exhibited distinct responses to O₃ aging for source-oriented PM_2.5. Additionally, differences in chemical composition between fresh and aged PM_2.5 were further elucidated through measurements of component-dependent hygroscopic behaviors and phase transitions. This study systematically delineates variances in the toxic potential of fresh and O₃-aged PM_2.5 from various anthropogenic sources. The findings highlight the intrinsic compositional dependence of particle OP and provide essential insights for assessing the health effects of source-oriented PM_2.5, as well as for formulating human health protection policies.