Near surface ozone is a typical secondary pollutant, and is mostly generated by a series of complex photochemical reactions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the air ...under sunlight. At present, a large number of studies have applied FNR (a ratio of formaldehyde (HCHO) to nitrogen dioxide (NO2) retrieved by satellite) indicator to study the ozone formation sensitivity (OFS). OFS analysis is critical for taking targeted ozone pollution prevention and control measures. Regional OFS can be more accurately diagnosed by utilizing localized FNR threshold. In this study, localized FNR thresholds were established for four severe ozone polluted urban agglomerations in China (Beijing-Tianjin-Hebei (BTH) region, Yangtze River Delta (YRD) region, Pearl River Delta (PRD) region, and Chengdu-Chongqing (CY) region), based on the statistical analysis between FNR (obtained from OMI observation, with daily transit time of approximately 13:45 local standard time) and ΔO3/ΔNO2 (the ratio of ozone change to nitrogen dioxide change between two consecutive months, obtained from ground measurements) from 2014 to 2016. And these thresholds were verified by the statistical analysis between FNR and ΔO3/O3 (ozone change rate between two consecutive months), and between FNR and O3 concentration during the OFS significant shift months. Furthermore, the results were also compared and verified with the method proposed by previous studies. The results indicate that there are significant regional dependences in the FNR threshold, and the lower–upper limits for the four urban agglomerations are as follows: 0.65–1.21 for BTH, 0.64–1.48 for the YRD, 1.25–2.39 for the PRD, and 1.44–3.69 for CY (FNR < lower limit indicates VOCs-limited regime; lower limit < FNR < upper limit indicates transitional regime; FNR > upper limit indicates NOx-limited regime). This method eliminates the problems associated with the undifferentiated use of FNR thresholds in different regions and significantly reduces the deviations for OFS.
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•Monthly variation differences of OFS were found in four urban agglomerations.•FNR threshold was determined by its statistical relationship with ΔO3/ΔNO2.•Localized FNR thresholds of four urban agglomerations were established.•Localized FNR thresholds significantly reduced the deviations with other studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to the influences of precursors emissions, meteorology, geography and other factors, ozone formation sensitivity (OFS) is generally spatially and temporally heterogeneous. This study ...characterized detailed spatial and temporal variations of OFS in Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2012 to 2016 based on OMI satellite data, and analyzed the relationships of OFS with precursors emissions, meteorology and land use types (LUTs). From 2012 to 2016, the OFS tended to be NOx-limited in GBA, with the value of FNR (HCHO/NO2) increasing from 2.04 to 2.22. According to the total annual emission statistics of precursors, NOx emissions decreased by 33.1% and VOCs emissions increased by 35.2% from 2012 to 2016, directly resulting in OFS tending to be NOx-limited. The Grey Relation Analysis results show that total column water (TCW), surface net solar radiation (SSR), air temperature at 2 m (T2) and surface pressure (SP) are the top four meteorological factors with the greatest influences on OFS. There are significant positive correlations between FNR and T2, SSR, TCW, and significant negative correlations between FNR and SP. In GBA, the OFS tends to be NOx-limited regime in wet season (higher T2, SSR, TCW and lower SP) and VOCs-limited regime in dry season (lower T2, SSR, TCW and higher SP). The FNR displays obvious gradient variations on different LUTs, with the highest in “Rural areas”, second in “Suburban areas” and lowest in “Urban areas”.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Volatile organic compounds (VOCs) are essential pollutants affecting ambient air quality. In the Pearl River Delta of China, furniture manufacturing contributes significantly to VOCs emissions, ...mainly from coatings. Therefore, the source substitution of coatings is the most effective way to reduce VOCs emissions. In this study, eight typical furniture enterprises with five different coatings types (traditional solvent coatings (solvent and solvent ultraviolet (UV) coatings) and low VOCs content coatings (waterborne, waterborne UV, and powder coatings)) were selected for field monitoring to reveal differences in VOCs emission characteristics, environmental impacts and health risks between traditional solvent coatings and low-VOCs coatings. The results showed that solvent coating VOCs have the highest concentration (143.32 mg/m3) and are much higher than that of solvent UV coating (45.96 mg/m3) and other coatings (≤11.81 mg/m3). The highest proportion of VOCs of solvent (UV) coating is aromatic hydrocarbons (50.73% (44.05%)). While oxygenated VOCs rank first in low-VOCs coatings (47.81%–59.20%). Compared with other coatings, the solvent coating has the greatest contribution to the formation potential of ozone and secondary organic aerosols. Meanwhile, the solvent coating has the highest carcinogenic risk of ethylbenzene in the spraying workshop (8.53 × 10−6), and only solvent coating in the spraying workshop has the non-carcinogenic risk of xylene (1.07). Finally, through scenario analysis, the environmental benefits of low-VOCs coatings substituting solvent coating were quantified. The study will help accelerate the process of source substitution of coatings and promote cleaner production in the furniture industry.
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•VOCs spectra of five different coating types in furniture industry were obtained.•Solvent coating has a much higher contribution to secondary pollutants than others.•Solvent (ultraviolet) coatings exist a carcinogenic risk of ethylbenzene.•Only solvent coating in spraying workshop has a non-carcinogenic risk of xylene.•The environmental benefits of low-VOCs coatings substitution were quantified.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The development of low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR) catalysts is desirable but still challenging. Herein, a low-cost Mn–Fe/SAPO-34 catalyst was successfully ...synthesized using natural ferromanganese ore (FO) and industrial waste lithium-silicon-powder (LSP) by solid-state ion exchange (SSIE) method, and showed high NH3-SCR activity at low temperature range (150–200 °C) with high N2 selectivity. After loading FO, Mn–O and Fe–O bonds on Mn–Fe/SAPO-34 were weakened, which were beneficial to electron transfer and the oxidation-reduction cycle of SCR. The coexisting of Mn and Fe promoted the dispersion of Fe, resulted in high amounts of Oa, Mn4+ and Fe3+ which facilitated the adsorption and activization of NH3 over Mn–Fe/SAPO-34 catalyst. The Brønsted and Lewis acid sites participate in NH3-SCR, and the adsorbed nitrate species could quickly react with the adsorbed NH3 species via the Langmuir–Hinshelwood (L-H) mechanism. The Mn–Fe/SAPO-34 integrated the advantages of low-cost, resource saving and environment friendly, giving a low-carbon and sustainable choice for the industrial application of NOx abatement.
Low-cost Mn–Fe/SAPO-34 catalyst was synthesized using natural ferromanganese ore and industrial waste lithium-silicon-powder for NOx abatement. Display omitted
•Low-cost Mn–Fe/SAPO-34 catalyst is prepared from ferromanganese ore and LSP waste.•1.2Mn–Fe/SAPO-34 exhibits superior NOx conversion at low temperature (<200 °C).•Coexisting of Mn and Fe in natural FO facilitate NH3 adsorption and activization.•The symbiosis of Mn and Fe promote formation of Oa, Mn4+ and Fe3+ on Mn–Fe/SAPO-34.•Mn–Fe/SAPO-34 gives a low-carbon and sustainable choice for NOx abatement.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Marine-derived
Aspergillus terreus
produces a variety of structurally novel secondary metabolites, most of which show unique biological activities. However, the lack of efficient genetic tools limits ...the discovery of new compounds, the elucidation of involved biosynthesis mechanism, as well as the strain engineering efforts. Therefore, in this study, we first established both an effective PEG-mediated chemical transformation system of protoplasts and an electroporation system of conidia in a marine-derived fungus
A
.
terreus
RA2905. To overcome the insensitivity of RA2905 to fungicides, the uracil auxotrophy strain (
pyrG
gene deletion mutant, Δ
pyrG
) was constructed using PEG-mediated transformation system, and using Δ
pyrG
as the genetic background, the methyltransferase gene
laeA
-overexpression transformants were further constructed through both PEG- and electroporation-mediated transformations, which showed enhanced terrein production. Besides, in this study, an efficient CRISPR/Cas9 genome-editing system was established for the first time in
A
.
terreus
, and a higher gene deletion efficiency of 71% for APSES transcription factor gene
stuA
could be achieved when using short homologous arms compared with conventional long homologous ones. In addition, using a non-integrative Cas9 plasmid, another efficient and marker-free genome-editing system was established, which allowing repeatable and unlimited genetic manipulation in
A
.
terreus
. Using the marker-free genome-editing system, we successfully developed the Δ
pyrG
Δ
ku70
double-deletion mutant in RA2905, which could further improve gene deletion efficiency. In conclusion, efficient genetic manipulation systems along with a variety of functional mutants were developed in this study, which would significantly expedite both theoretical and applied researches in not only
A
.
terreus
but also other marine-derived filamentous fungi.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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The selective catalytic reduction (SCR) of NOx by NH3 is one of the most mature technologies for NOx treatment. Catalysts are the main factors affecting denitrification efficiency. ...Zeolites as low-temperature NH3-SCR catalysts have been extensively studied in the past few years. In this work, the mechanism of zeolites for NH3-SCR reaction was reviewed and the denitrification performances of zeolite catalysts prepared by different methods were compared. The effects of sulfur and water poisoning on zeolite catalysts in NH3-SCR reaction were also analyzed. Several ways to address the problems in low-temperature NH3-SCR reaction were discussed. Hopefully, this review could provide a fundamental understanding of SCR reaction on zeolite catalysts and pave the way toward similar studies to realize its commercial applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Waxy maize (a standard starch of normal granule size) and five small granule starches from different botanical sources (rice, wheat B type, oat, quinoa and amaranth) were subjected to ...2-octenyl-1-succinic anhydride (OSA) modification. Changes of pasting, gel texture, thermal and rheological properties were investigated. Different small granule starches showed quite different property changes after OSA modification. Pasting viscosity was generally increased in OSA starches, among which OSA oat starch had notably high peak and breakdown viscosity but low setback viscosity. Gel hardness of rice, wheat B type, oat and quinoa starches was reduced by OSA treatment, whereas that of waxy maize and amaranth starches was increased. Amylose content was considered to be the major factor influencing pasting, gel and thermal property of OSA starches. Esterification increased pseudoplastic flow behavior of all starches, while OSA oat starch uniquely had reduced flow consistency coefficient. The dynamic rheological properties were also changed differentially among OSA starches. Viscoelastic properties of rice, wheat B type, oat and quinoa starches were increased after OSA treatment, whereas those of waxy maize and amaranth starches were decreased. This study showed that diverse functionalities from OSA small granule starches may fulfil different demands in product development.
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•Effects of octenylsuccinylate (OSA) modification on each kind of starch differ.•Pasting temperature and gel hardness are positively correlated to amylose content.•Highest pasting, gel and flow behavior parameter values occur in OSA oat starch.•Varied OSA small granule sources could potentially meet demands in food production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The introduction of AC promoted the formation of mesopores, surface adsorbed oxygen, and Mn4+ species on the Mn-Fe/Z, which facilitated electron transfer and improved the oxidation–reduction cycle of ...SCR, and therefore resulted in high NO conversion at 125 °C (95.1%).
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•AC added Mn-Fe/Z catalyst was made of ferromanganese ore and industrial waste.•Mn-Fe/Z exhibited high NH3-SCR activity with 95% NO conversion at 125 °C.•The introduction of AC facilitated the formation of mesopores.•AC addition promoted the surface adsorbed oxygen, acid sites and Mn4+ formation.•The introduction of AC weakened the chemical bond of Mn-O and Fe-O on Mn-Fe/Z.
A Mn-Fe/Z catalyst was prepared by industrial waste lithium silicon powder (LSP) and natural ferromanganese ore for high efficiency removal of NOx in flue gas. In the support synthesis stage, activated carbon (AC) was added to regulate the pore structure and surface physicochemical properties of the catalyst. The NO conversion at 125 °C increased from 71.8% (Mn-Fe/Z0, without AC added) to 95.1% (Mn-Fe/Z1, 1.0 wt% AC added). The introduction of AC promoted the formation of mesopores, surface adsorbed oxygen, and Mn4+, which were beneficial to the electron transfer and the oxidation–reduction cycle of SCR. Besides, the AC addition weakened the chemical bond of Mn-O and Fe-O on Mn-Fe/Z, and promoted the formation of surface acid sites, which facilitated the NH3-SCR. Lewis acid sites participated in NH3-SCR, and the adsorbed NH3 reacted with gaseous NO species followed the Eley-Rideal (E-R) reaction mechanism. The above findings provide useful information for new catalyst design for NH3-SCR at low temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Low−temperature selective catalytic reduction of NOx by NH3 (NH3−SCR) for diminishing SO2 poisoning remains an issue in flue gas denitrification (DeNOx). Herein, A novel CNTs functionalized low ...temperature NH3−SCR catalyst CeO2/CNTs−GAC was prepared, which showed high NO conversion activity (100% at 150 °C) and SO2 resistance. The addition of CNTs restrained SO2 adsorption but improved the selective adsorption of NO, which restricted the deposition of (NH4)2SO4 and/or Ce2(SO4)3, and resulted in high SO2 resistance. The addition of CNTs facilitated the diffusion and transportation of NH3 and NO, and the electron transfer on CeO2/CNTs−GAC, leading to higher content of Ce3+ and adsorbed O species on the CeO2/CNTs−GAC surface and promoted formation of surface-adsorbed oxygen OA. Therefore, CeO2/CNTs−GAC provided abundant NO adsorption and activation sites, facilitating “fast SCR” reaction and enhancing the NH3−SCR reaction. The proposed CeO2/CNTs−GAC catalyst exhibited higher NH3−SCR activity, N2 selectivity, catalytic durability and SO2 resistance than CeO2/GAC.
A novel CNTs functionalized low temperature NH3−SCR catalyst CeO2/CNTs−GAC was prepared, which showed high NO conversion activity and SO2 resistance. Display omitted
•A novel CNTs functionalized low temperature NH3−SCR catalyst CeO2/CNTs−GAC was obtained.•CNTs promoted the formation of mesopores and electron transfer on CeO2/CNTs−GAC.•CeO2/CNTs−GAC provided abundant NO adsorption sites and NO activation sites.•CNTs restrained SO2 adsorption but improved the selective adsorption of NO.•CeO2/CNTs−GAC exhibited high low−temperature NH3−SCR activity with SO2 resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
