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Enhanced sulfur and nitrogen deposition has been observed in many transect regions worldwide, from urban/agricultural areas to mountains. The Sichuan Basin (SCB), with 18 prefectural cities, is the most economically-developed region in western China, while the rural Qinghai-Tibetan Plateau (QTP) lies west of the SCB. Previous regional and national atmospheric modeling studies have suggested that large areas in the SCB-to-QTP transect region experience excessive deposition of sulfur and nitrogen. In this study, we applied a passive monitoring method at 11 sites (one in urban Chengdu and 10 from fivenature reserves) in this transect region from September 2021 to October 2022 to confirm the high sulfur and nitrogen deposition fluxes and to understand the gaps between the modeling and observation results for this transect region. These observations suggest that the five reserves are under eutrophication risk, and only two reserves are partially under acidification risk. Owing to the complex topography and landscapes, both sulfur and nitrogen deposition and critical loads exhibit large spatial variations within a reserve, such as Mount Emei. Regional atmospheric modeling may not accurately capture the spatial variations in deposition fluxes within a reserve; however, it can capture general spatial patterns over the entire transect. This study demonstrates that a combination of state-of-the-art atmospheric chemical models and low-cost monitoring methods is helpful for ecological risk assessments at a regional scale. [ABSTRACT FROM AUTHOR]

To understand characteristics of air pollutants and their associated health risks in recent heating seasons in China, ambient monitoring data of six air pollutants in ‘2 + 26’ cities in Beijing-Tianjin-Hebei and its surrounding areas (known as the BTH2+26 cities) during 2016–2020 heating seasons was analyzed. Results show that daily average concentrations of PM2.5, PM10, SO2, NO2, and CO dropped significantly in BTH2+26 cities from the 2016-2017 heating season to 2019-2020 heating season, while 8h O3 increased markedly. During 2016-2020 heating seasons, annual average values of total excess risks (ERtotal) were 2.3% mainly contributed by PM2.5 (54.4%) and PM10 (36.1%). With PM2.5 pollution worsening, PM10 and NO2 were the important contribution factors of the enhanced ERtotal. Higher health-risk based air quality index (HAQI) values were mainly concentrated in the western Hebei and northern Henan. HAQI showed spatial agglomeration effect in four heating seasons. Impact factors of HAQI varied in different heating seasons. These findings can provide useful insights for China to further propose effective control strategies to alleviate air pollution in the future. [ABSTRACT FROM AUTHOR]

Reducing anthropogenic volatile organic compounds (VOCs) is the most effective way to mitigate O3 pollution, which has increased over the past decades in China. From 2012 to 2017, special stainless-steel cylinders were used to collect ambient air samples from the urban area of Beibei district, Chongqing. Three-step pre-concentration gas chromatography–mass spectrometry was used to detect the collected air samples. The composition, concentration, photochemical reactivity, and sources of VOCs in Beibei were analyzed. During the observation period, the annual average VOC concentration was 31.3 ppbv, which was at an intermediate range compared to other cities in China. Alkanes (36.8%) and aromatics (35.6%) were the most abundant VOC groups, followed by halo-hydrocarbons (14.4%) and alkenes (12.6%). The overall trend of seasonal distribution of VOC concentration was high in summer and autumn, and low in winter and spring, with a statistically significant difference between summer and winter concentrations. The ozone formation potential (OFP) showed that alkenes were the most active species, followed by aromatics and alkanes, and summer was the season with the highest OFP (131.6 ppbv). Three major emission sources were identified through principal component analysis (PCA), i.e., vehicle exhaust emissions (66.2%), fuel oil evaporation (24.8%), and industrial sources (9.0%). To ameliorate the air quality within the study area, concerted efforts should be directed towards curtailing traffic emissions and mitigating the release of alkenes, particularly emphasizing more stringent interventions during the summer season. [ABSTRACT FROM AUTHOR]

In this work, FeS supported SBA-15 mesoporous silica catalyst (FeS@SBA-15) was synthesized successfully, characterized and first applied to persulfate (PS) activation for the degradation of imidacloprid in wastewater. The as-prepared 3.5-FeS@SBA-15 presented an impressive imidacloprid removal efficiency of 93.1% and reaction stoichiometric efficiency (RSE) of 1.82% after 5 min, ascribed to the synergetic effects of improved FeS dispersion and abundant surface sites by SBA-15. Electron paramagnetic resonance spectra and quenching experiments proved that both SO4·- and ·OH were produced in FeS@SBA-15/PS system, and SO4·- played a dominant role in the degradation process. The S2- can accelerate the cycling of Fe(III)/Fe(II) during activation and increase the steady-state concentration of Fe(II). More importantly, the constructed heterogeneous system exhibited an efficient and stable catalytic activity over a wide range of pH (3.0-9.0), temperature (283K-313K), inorganic ion (NO3-) and humic acid (1-20 mg/L). Moreover, the density functional theory calculations were conducted to predict the potential reaction sites of imidacloprid. Based on eighteen identified intermediates, four main degradation pathways were proposed: hydroxylation, dechlorination, hydrolysis, and the ring cleavage of the imidazolidine. ECOSAR analysis indicated hydroxylation and dechlorination played a key role in the detoxification of the formed compounds. These findings would provide new insights into the application of FeS@SBA-15 catalyst in wastewater treatment and the removal mechanism of imidacloprid from wastewater. [ABSTRACT FROM AUTHOR]

Odor pollution caused by brownfield site has attracted increasing attention. However, to date, fewer suitable materials can be used to control the emission of odor pollutant from brownfield site during remediation. This study prepared a kind of combined hydrogel solution based on sodium alginate and carboxymethyl cellulose sodium (CHS-SC) and tested the possibility of its membrane in controlling the emission of three odor pollutants (trichloroethylene, dimethyl disulfide, and p-xylene) from polluted soil. Our results showed that CHS-SC membrane could effectively control the emission of three odor pollutants from polluted soil. Comparatively, CHS-SC membrane had higher control rates for three odor pollutants at high ambient temperature (32 °C), short storage time of CHS-SC (5 days, 25 °C), and low odor pollutant concentration (2 ml/kg soil) than at low ambient temperature (2 °C), long storage time of CHS-SC (10 d, 25 °C), and high odor pollutant concentration (4 ml/kg soil), respectively. CHS-SC membrane was degraded by 79.23% after 150 days in soil and slightly changed soil bacterial community, indicating that it had good biodegradability and environmental friendliness. In addition, CHS-SC cost was the lowest among the products with similar function. This study shows that CHS-SC is effective in short-timely controlling the emission of odor pollutants from brownfield site. [ABSTRACT FROM AUTHOR]

Solvents, components of pesticide emulsifiable concentrates (ECs), emit quantities of volatile organic compounds (VOCs) into the atmosphere. In the air, their active involvement in oxidative chemical reactions with oxidants exposed to ultraviolet solar radiation can result in the formation of ozone. The quantitative assessment of VOC emissions from agricultural pesticide applications remains hampered by many factors, especially the volatility coefficient of solvents in pesticides. Therefore, this study identified solvents in 20 widely used pesticide products in China. The volatility coefficients of the solvents were investigated based on a spraying test to evaluate VOC emissions from agricultural pesticide applications and their ozone formation potential (OFP). The results suggest that VOC emissions from agricultural pesticide applications amount to 0.60 Mt in 2017, with insecticides, fungicides, and herbicides contributing 0.39 Mt, 0.12 Mt, and 0.09 Mt of VOCs, respectively. Since VOC emission and maximum incremental reactivity (MIR) led to an OFP value (2.1 g ozone/g product) for insecticides, a primary consideration should be to decrease use of solvents with high volatility coefficients and large MIR values in insecticide products. This work could provide valuable insights regarding response options to reduce VOC emissions and ozone formation. [ABSTRACT FROM AUTHOR]

This study aimed to determine the concentration and composition of condensed tannins (CT) in different tissues of purple prairie clover (PPC; Dalea purpurea Vent.) at different maturities and to determine their protein-precipitating capacity. The compositions of CT were elucidated after thiolysis with benzyl mercaptan followed by high-performance liquid-chromatography (HPLC) and 1H–13C heteronuclear single quantum coherence (HSQC) NMR spectroscopy. The results indicated that PPC flowering heads contained the highest CT concentration. Purple prairie clover CT consisted mainly of epicatechin (EC) and epigallocatechin (EGC) subunits. CT in the leaves were composed of more EC and less EGC than CT in stems and flowering heads at both the early flowering (EF) and late flowering (LF) head stages. The mean degree of polymerization was the highest for CT in stems and increased with maturity. CT isolated from PPC leaves at the early flowering head stage exhibited the greatest biological activity in terms of protein precipitation. Overall, the CT in PPC were predominantly procyanidins and the concentration and composition varied among the plant tissues and with maturity. [ABSTRACT FROM AUTHOR]

Ethyl acetate is one of typical volatile organic compounds (VOCs) emitting from solvent use, and removing ethyl acetate from exhaust air is vital to VOCs abatement. The mesoporous manganese oxide (MnOx) samples were sonochemically synthesized by the reduction of KMnO4 using Mn(NO3)2. The characterization shows that γ‐MnO2, β‐MnO2, and bixbyite‐like Mn2O3 were obtained by calcining the MnOx samples from 200°C to 500°C. The results show that γ‐MnO2 and β‐MnO2 possess more Mn4+ than bixbyite‐like Mn2O3. β‐MnO2 has the highest contents of surface oxygen species (Oads) and average oxidation state (AOS) among the MnOx catalysts. Based on a 7‐day test, β‐MnO2 performed the highest activity for the catalytic ozonation of ethyl acetate compared with the other MnOx catalysts. The results show that ethyl acetate is easy to be destroyed but difficult to be completely mineralized by catalytic ozonation. Lower gas hourly space velocity (GHSV) leads to higher CO2 selectivity and more intermediate products form in the catalytic ozonation of ethyl acetate under higher GHSV. A further study indicates that β‐MnO2 has a long‐term stability for catalytic ozonation of ethyl acetate because the accumulation and the decomposition of intermediate products are in a dynamic equilibrium during the catalytic ozonation. [ABSTRACT FROM AUTHOR]

BACKGROUND: The objective of this study was to determine the effects of forage conservation method and condensed tannins (CT) in conserved forage on rumen fermentation. Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g kg−1 dry matter (DM) of CT was harvested at full flower and preserved as freeze‐dried green chop (F), hay (H) or silage (S). Batch culture incubations were conducted using conserved forages as a substrate and treatments were arranged as 3 × 2 factorial design of forage type (F, H and S) with or without polyethylene glycol (PEG). PEG was used to isolate the effects of CT on fermentation. Incubation was repeated twice with quadruplicate vials for each treatment in each incubation. 15N‐labelled ammonium sulfate was used as microbial N marker and headspace gas was sampled to determine methane production. RESULTS: Concentrations of neutral detergent fiber (NDF) and acid detergent fiber were lower (P < 0.01) in F than in H or S. Ensiling decreased (P < 0.001) total phenolics and extractable CT, but had no effect on total CT, whereas none of these phenolic fractions were altered in H. Hay and silage had lower (P < 0.01) true DM disappearance (TDMD) and NDF disappearance (NDFD) than F. Inclusion of PEG did not affect TDMD or NDFD after 8, 24 or 72 h of incubation. Productions of total gas, methane and total volatile fatty acid and the rate of gas production (c) were also similar, but ammonia was higher (P < 0.05) and microbial N was lower (P < 0.05) with than without PEG after 72 h of incubation. After 72 h, a lower (P < 0.001) proportion of acetate but higher (P < 0.05) proportion of propionate was noted with S, resulting in a lower (P < 0.001) acetate:propionate ratio as compared to F or H after 8 h of incubation. CONCLUSION: Condensed tannins in PPC decreased protein degradation in vitro, but had minimal effects on overall rumen fermentation, and conservation of PPC as hay or silage had little effect on the efficacy of CT in modulating rumen fermentation. © 2020 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture © 2020 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Incorporation of legume species into native North American pastures is considered an effective method to increase native pasture productivity and improve the nutritive value of forage. This study evaluated the effects of inclusion of purple prairie clover (PPC, Dalea purpurea Vent.), a native legume forage, with native cool-season grasses on the in vitro fermentation and in situ digestibility of mixed forages. Methods: Whole plant PPC and mixtures of cool-season grasses were harvested when the PPC reached the vegetative (VEG), full flower (FL) and seedpod (SP) stages, and were combined in ratios (DM basis) of 0:100, 25:75, 50:50, 75:25 and 100:0 at each maturity. In vitro ruminal incubations using these mixtures were conducted for 48 h to determine gas production (GP), in vitro DM disappearance (IVDMD), total volatile fatty acids (VFA) and ammonia-N production. Mixtures of forages harvested when the PPC reached the FL stage and 50:50 mixture of forages harvested at VEG, FL and SP stages were incubated in the rumen of three heifers for 0, 2, 6, 12, 24, 48, 72 and 96 h to determine in situ degradabilities of DM, neutral detergent fibre (aNDF) and crude protein (CP). Results: Contents of aNDF and ADF increased (P < 0.01), while CP decreased (P < 0.001) as PPC matured. Concentrations of extractable condensed tannins in PPC ranked as FL > VEG > SP (P < 0.05). Regardless of PPC proportions in the mixture, GP decreased (P < 0.05) with increasing PPC maturity. Increasing PPC proportions linearly increased (P < 0.001) GP, IVDMD and total VFA at VEG, but linearly decreased (P < 0.001) them at SP. Irrespective of PPC maturity, ammonia-N production linearly increased (P < 0.01) with increasing proportions of PPC and the concentration was higher (P < 0.05) at VEG than at FL and SP stages. Increasing proportion of PPC at either maturity linearly increased (P < 0.001) molar percentage of acetate (A) and branched-chain VFA, but linearly decreased (P < 0.001) molar percentage of propionate (P), resulting in a linearly increase (P < 0.001) in the A:P ratio. Increasing FL PPC in the mixture linearly and quadratically (P < 0.01) increased a (soluble fraction), but linearly and quadratically decreased (P < 0.01) b (potentially degradable fraction) for DM and aNDF, resulting in linear (P < 0.05) and quadratic (P < 0.01) increases in DM and aNDF maximum potential degradabilities (a + b). Effective degradabilities of DM and aNDF were also linearly and quadratically increased (P < 0.05), and CP was quadratically increased (P < 0.05) with increasing FL PPC, with the greatest effective degradability being observed with ratios between 50:50 and 75:25. Ruminal maximum potential degradabilities of DM and aNDF decreased (P < 0.001) as the forage matured. Effective degradability of DM ranked as VEG > FL > SP (P < 0.001), whereas the effective degradability of aNDF was similar between VEG and FL and both were greater (P < 0.01) than SP. Conclusions: Inclusion of vegetative PPC in a mixed forage diet resulted in the greatest digestibility and incorporation of PPC before seedpod stage with native grasses had a positive effect on ruminal fermentation. Effects of PPC on ruminal digestion depend on both the stage of maturity and its proportion in mixed legume-grass pastures. Pastures containing 50% of PPC in full flower stage would likely provide the greatest quality diet to grazing ruminants subject to potential animal selectivity. [ABSTRACT FROM AUTHOR]

γ-MnO2, β-MnO2 and Mn2O3 with mesoporous structure were prepared as catalysts by using SBA-15 as hard template at different calcination temperatures. The catalysts were characterized by XRD, HRTEM, N2 adsorption–desorption, XPS, FTIR. The activity of three catalysts for catalytic ozonation of toluene followed the order of β-MnO2 > γ-MnO2 > Mn2O3. The results showed that the mesoporous β-MnO2 exhibited the best catalytic performance because it has the highest average oxidation state of Mn and the most abundant surface adsorbed oxygen. Specifically, the toluene conversion could reach to 100% and the CO2 selectivity could reach up to 83% at 70–90 mg/m3 of toluene concentration over the catalyst. It can be inferred that reaction mechanism consists of two cycles including ozone decomposition and toluene adsorption on active sites of β-MnO2, which obeys L–H mechanism. The active oxygen (O*) produced in the first cycle can oxidize the toluene molecule adsorbed in the second cycle. Simultaneously, the mesoporous β-MnO2 had good stability, which reflected that it showed good performance on the catalytic ozonation of toluene during the 47-day test. In summary, this work makes it possible to remove VOCs for reality. [ABSTRACT FROM AUTHOR]

The present study assessed the effect of purple prairie clover (PPC) and PPC condensed tannins (CT) on the fecal microbiota of lambs using high-throughput 16S rRNA gene pyrosequencing. A total of 18 individual lambs were randomly divided into three groups and fed either green chop alfalfa (Alf), a 40:60 (DM basis; Mix) mixture of Alf and PPC, or Mix supplemented with polyethylene glycol (Mix-P) for 18 days. Fecal samples were collected on days 13 through 18 using digital rectal retrieval. The DNA of fecal samples was extracted and the microbial 16S rRNA gene amplicons were sequenced using 454 pyrosequencing. Regardless of diet, the bacterial community was dominated by Firmicutes and Bacteroidetes with many sequences unclassified at the genus level. Forage type and CT had no effect on the fecal microbial composition at the phylum level or on α-diversity. Compared to the Alf diet, the Mix diet reduced the relative abundance of Akkermansia ( P = 0.03) and Asteroleplasma ( P = 0.05). Fecal microbial populations in Alf and Mix-P clustered separately from each other when assessed using unweighted UniFrac ( P < 0.05). These results indicate that PPC CT up to 36 g/kg DM in the diet had no major effect on fecal microbial flora at the phyla level and exerted only minor effects on the genera composition of fecal microbiota in lambs. [ABSTRACT FROM AUTHOR]

Toluene biofiltration by microorganisms (an unplanted treatment) and by the combination of ryegrass ( Lolium perenne L.) and microorganisms (a planted treatment) was investigated in this study. The results showed that toluene was completely removed by the unplanted and the planted biofilters in less than 0.2 g m inlet toluene concentration. Toluene removal capacity for the planted biofilter was significantly higher than that for the unplanted biofilter in the range of 0.2-0.5 g m inlet toluene concentration. This study revealed a significant ( p < 0.01) increase in the microbial activity in the planted biofilter in comparison with the unplanted biofilter, indicating that ryegrass growing in a biofilter would significantly ( p < 0.05) enhance toluene biodegradation. [ABSTRACT FROM AUTHOR]

The amount and biodegradability of dissolved organic carbon (DOC) in forest floors can contribute to carbon sequestration in soils and the release of CO-C from soil to the atmosphere. There is only limited knowledge about the biodegradation of DOC in soil extracts and leachates due to the limitations inherent in degradation experiments. Differences in the biodegradation of DOC were studied in forest soil extracts using cold and hot water and 4 mmol/L CaCl solution and in soil leachates sampled under different conditions over a wide range of DOC concentrations. From these results, we developed a simple and rapid method for determining the biodegradable organic C in forest floors. The hot water extracts and CaCl extracts after CH3Cl fumigation contained higher concentrations of biodegradable organic C than the cold water extracts and CaCl extracts before fumigation, with rapid DOC degradation occurring 24-48 h after incubation with an inoculum, followed by slow DOC degradation till 120-168 h into the incubation. During a 7-d incubation with an inoculum, the variation in DOC degradation in the different soil extracts was consistent with the change in special UV absorbance at 254 nm. Relatively higher levels of biodegradable organic C were detected in soil leachates from the forest canopy than in forest gaps between April and October 2008 ( P <0.05). Relatively lower concentrations of DOC and biodegradable organic C were observed in soil leachates from N-fertilized plots during the growing season compared with the control, with the exception of the plot treated with KNO at a rate of 45 kg N ha a. Around 77.4% to 96.3% of the variability in the biodegradable organic C concentrations in the forest floors could be accounted for by the initial DOC concentration and UV absorbance at 254 nm. Compared with the conventional inoculum incubation method, the method of analyzing UV absorbance at 254 nm is less time consuming and requires a much smaller sample volume. The results suggest that the regression models obtained using the initial DOC concentration and UV absorbance can provide a rapid, simple and reliable method for determining the biodegradable organic C content, especially in field studies involving relatively large numbers of samples. [ABSTRACT FROM AUTHOR]

Using the free-air CO2 enrichment (FACE) techniques, we carried out a 3-year mono-factorial experiment in temperate paddy rice fields of Japan (1998–2000) and a 3-year multifactorial experiment in subtropical paddy rice fields in the Yangtze River delta in China (2001–2003), to investigate the methane (CH4) emissions in response to an elevated atmospheric CO2 concentration (200±40 mmol mol−1 higher than that in the ambient atmosphere). No significant effect of the elevated CO2 upon seasonal accumulative CH4 emissions was observed in the first rice season, but significant stimulatory effects (CH4 increase ranging from 38% to 188%, with a mean of 88%) were observed in the second and third rice seasons in the fields with or without organic matter addition. The stimulatory effects of the elevated CO2 upon seasonal accumulative CH4 emissions were negatively correlated with the addition rates of decomposable organic carbon ( P<0.05), but positively with the rates of nitrogen fertilizers applied in either the current rice season ( P<0.05) or the whole year ( P<0.01). Six mechanisms were proposed to explain collectively the observations. Soil nitrogen availability was identified as an important regulator. The effect of soil nitrogen availability on the observed relation between elevated CO2 and CH4 emission can be explained by (a) modifying the C/N ratio of the plant residues formed in the previous growing season(s); (b) changing the inhibitory effect of high C/N ratio on plant residue decomposition in the current growing season; and (c) altering the stimulatory effects of CO2 enrichment upon plant growth, as well as nitrogen uptake in the current growing season. This study implies that the concurrent enrichment of reactive nitrogen in the global ecosystems may accelerate the increase of atmospheric methane by initiating a stimulatory effect of the ongoing dramatic atmospheric CO2 enrichment upon methane emissions from nitrogen-poor paddy rice ecosystems and further amplifying the existing stimulatory effect in nitrogen-rich paddy rice ecosystems. [ABSTRACT FROM AUTHOR]

To gain insights into the impacts of emission reduction measures on the characteristics and sources of trace elements during the 2014 Asia-Pacific Economic Cooperation (APEC) summit, PM2.5 samples were simultaneously collected from an urban site and a suburban site in Beijing from September 15th to November 12th, and fifteen metallic elements were analyzed, including five crustal elements (Mg, Al, K, Ca and Fe), nine trace metals (V, Cr, Mn, Co, Cu, Zn, Ag, Cd and Pb) and As. Most of the trace metals (V, Cr, Mn, As, Cd and Pb) decreased more than 40% due to the emission regulations during APEC, while the crustal elements decreased considerably (4–45%). Relative to the daytime, trace metals increased during the nighttime at both sites before the APEC summit, but no significant difference was observed during the APEC summit, suggesting suppressed emissions from anthropogenic activities. Five sources (dust, traffic exhaust, industrial sources, coal and oil combustion and biomass burning) were resolved using positive matrix factorization (PMF), which were collectively decreased by 30.7% at the urban site and 14.4% at the suburban site during the APEC summit. Coal and oil combustion regulations were the most effective for reducing the trace elements concentrations (urban site: 63.1%; suburban site: 52.0%), followed by measures to reduce traffic exhaust (52.8%) at the urban site and measures to reduce biomass burning (37.7%) at the suburban site. Our results signify that future control efforts of metallic elements in megacities like Beijing should prioritize coal and oil combustion, as well as traffic emissions. [ABSTRACT FROM AUTHOR]