MicroRNAs (miRNAs) control the proliferation of thymic epithelial cells (TECs) for thymic involution. Previous studies have shown that expression levels of miR-152-3p were significantly increased in ...the thymus and TECs during the involution of the mouse thymus. However, the possible function and potential molecular mechanism of miR-152-3p remains unclear. This study identified that the overexpression of miR-152-3p can inhibit, while the inhibition of miR-152-3p can promote, the proliferation of murine medullary thymic epithelial cell line 1 (MTEC1) cells. Moreover, miR-152-3p expression was quantitatively analyzed to negatively regulate
, and the
gene was found to be a direct target of miR-152-3p, using the luciferase reporter assay. Importantly, silencing
was found to block the G1 phase of cells and inhibit the cell cycle, which was consistent with the overexpression of miR-152-3p. Furthermore, co-transfection studies of siRNA-
(si
) and the miR-152-3p mimic further established that miR-152-3p inhibited the proliferation of MTEC1 cells by targeting
and reducing the expression of
. Taken together, this study proved miR-152-3p to be an important molecule that regulates the proliferation of TECs and therefore provides a new reference for delaying thymus involution and thymus regeneration.
Mercury (Hg) is a ubiquitous environmental toxicant that has caused global concern due to its persistence and bioaccumulation in the environment. Wet deposition is a crucial Hg input for both ...terrestrial and aquatic environments and is a significant indicator for evaluating the effectiveness of anthropogenic Hg control. Rainwater samples were collected from May 2014 to October 2018 in Chongming Island to understand the multi-year Hg wet deposition characteristics. The annual Hg wet deposition flux ranged from 2.6 to 9.8 μg m−2 yr−1 (mean: 4.9 μg m−2 yr−1). Hg wet deposition flux in Chongming was comparable to the observations at temperate and subtropical background sites (2.0–10.2 μg m−2 yr−1) in the northern hemisphere. Hg wet deposition flux decreased from 8.6 μg m−2 yr−1 in 2014–2015 to 3.8 μg m−2 yr−1 in 2016 and was attributed to a decrease in the volume-weighted mean (VWM) Hg concentration (−4.1 ng L−1 yr−1). The reduced VWM Hg was explained by the decreasing atmospheric Hg and anthropogenic emissions reductions. The annual Hg wet deposition flux further decreased from 3.8 μg m−2 in 2016 to 2.6 μg m−2 in 2018. The reduction of warm season (April–September) rainfall amounts (356–845 mm) mainly contributed to the Hg wet deposition flux reduction during 2016–2018. The multi-year monitoring results suggest that long-term measurements are necessary when using wet deposition as an indicator to reflect the impact of anthropogenic efforts on mercury pollution control and meteorological condition variations.
In this study, the poisoning effects of SO2 on the V2O5–WO3/TiO2 (1%VWTi) and CeO2–WO3/TiO2 (5%CeWTi) selective catalytic reduction (SCR) catalysts were investigated in the presence of steam, and ...also the regeneration of deactivated catalysts was studied. After pretreating the catalysts in a flow of NH3 + SO2 + H2O + O2 at 200 °C for 24 h, it was observed that the low-temperature SCR (LT-SCR) activity decreased significantly over the 1%VWTi and 5%CeWTi catalysts. For 1%VWTi, NH4HSO4 (ABS) was the main product detected after the poisoning process. Both of NH4HSO4 and cerium sulfate species were formed on the poisoned 5%CeWTi catalyst, indicating that SO2 reacted with Ce3+/Ce4+, even in the presence of high concentration of NH3. The decrease of BET specific surface area, NO x adsorption capacity, the ratio of chemisorbed oxygen, and reducibility were responsible for the irreversible deactivation of the poisoned 5%CeWTi catalyst. Meanwhile, the LT-SCR activity could be recovered over the poisoned 1%VWTi after regeneration at 400 °C, but not for the 5%CeWTi catalyst. For industrial application, it is suggested that the regeneration process can be utilized for 1%VWTi catalysts after a period of time after NH4HSO4 accumulated on the catalysts.
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Emission limit is a significant index of pollution control in most countries. However, the determination of a reasonable limit value and corresponding supported technical paths is always a challenge ...during the implementation procedure. In this study, we developed an emission-limit-oriented strategy which links the emission limit with reduction amount via technical paths, so as to control the Hg emissions in the coal-fired power plants in China. Results indicate that tightening the emission limit does not always guarantee the reduction of Hg amounts, especially when coal consumptions keep increasing during the economic growth period. By comprehensively considering the feasibility of different technical paths, the emission limit of 5 μg/m3 is recommended to be executed in 2025. Under the guidance of this limit, the reduction amount of emitted Hg will reach as large as 63 t during 2015–2025 by primarily using multipollutant control measures. During 2025–2030, both alternative energy measures and specific Hg removal measures will be applied to achieve the emission limit of 1 μg/m3 in 2030. The assessment method developed in this study can be used to establish the emission-limit-oriented control strategies in other countries or industries, which will assist the success of the Minamata Convention on Mercury.
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Mercury （Hg） is a global threat to hu- man and environmental health 1. To address this global issue, the Minamata Convention on Mercury （MC） was agreed upon by 128 countries on 19 January 2013. China ...officially ratified the MC in August 2016. As the largest emit- ter of atmospheric Hg, China accounts for 30-40% of global Hg emissions 2. Additionally, projection of the atmospheric emission of rig in 2050 also indicates China＇s significant contribution 3. Whether there are major knowledge or policy gaps are key questions for not only the development of a Chinese Convention Implementation Plan, but also the overall success of the MC.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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•The C-X (Cl, Br and I) groups sever as chemisorption sites for elemental mercury.•The different ratio of C-X groups explains the result that halide modified effect follows the order: ...I>Br>Cl.•The formation of C-X groups depended on the reducibility and size of halide ions.
The mechanism of three halides (chloride, bromide and iodide) modification and reason for their modified effect difference was investigated in this study. Bio-chars derived from cotton straw were further activated and modified with microwave/steam and halides impregnation. Modified bio-chars serving as mercury sorbent was measured via BET, SEM and XPS analyses. The chemisorption site was identified as crucial factor for mercury adsorption performance via pore structure, SEM analysis and adsorption testing study. Based on XPS analysis of bio-char prior to and after adsorption testing, carbon–halide functional groups (C-X) were dominant chemisorption sites oxidizing Hg0 into mercury halide (HgCl2, HgBr2 and HgI2). The amount of C-X groups possibly decided halide modification effect order: I−>Br−>Cl−. The formation of C-X groups depended on the reducibility and size of halide ions. In order to verify the adsorption mechanism, the molecular sieve (MCM-22) as non-carbon carrier was used to compare with bio-char. Results suggested that the lack of C-X groups decreased mercury removal performance in experimental condition. This paper firstly explained the reason for modified difference of three halides in term of chemisorption site formation mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
As the largest emission source in the Pan-Third Pole region, residential solid fuel combustion gains increasing public concern regarding air pollution–associated health impacts. This study firstly ...developed emission inventories by combining energy statistics, fuel-mix survey, and detailed emission factors considering different fuel types, stove types, and altitudes, and we achieved full regional coverage and increased spatial resolution from 9 × 9 km to 1 km × 1 km. Total CO2, CO, PM2.5, SO2, and NO x emissions (coefficient of variation) were estimated to be 823 Mt (24%), 53 Mt (28%), 4525 kt (48%), 1388 kt (55%), and 1275 kt (46%) in 2020. India, Pakistan, and Bangladesh combined contributed 73, 57, 65, 67, and 69% of total CO2, CO, PM2.5, SO2, and NO x emissions, respectively, due to the large population. The Qinghai–Tibet Plateau had the second-highest emission intensity, mainly due to the high fuel consumption per capita. Unlike the emissions of the Pan-Third Pole in existing Asian inventories, dung cake combustion dominated total PM2.5, SO2, and NO x emissions rather than firewood combustion with proportions of 54, 70, and 67%, respectively. The effect of altitude on combustion efficiencies increased PM2.5 emissions by about 21% from the region. The method and results can provide technical guidance for emission inventory refinement in the Pan-Third Pole and other regions.
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Accurately tracking carbon flows is crucial for preventing carbon leakage and allocating responsibility for reducing CO2eq emissions. In this study, we developed an ensemble model to effectively ...track carbon flows within China’s power system. Our approach integrates coal quality tests, individual power plant datasets, a dynamic material-energy flow analysis model, and an extended version of an interconnected power grid model that incorporates transmission and distribution (T&D) losses. Our results not only provide accurate quantification of unit-based CO2eq emissions based on coal quality data but also enable the assessment of emissions attributed to T&D losses and emission shifts resulting from interprovincial coal and electricity trade. Remarkably, for CO2eq emissions from coal-fired units, the disparity between the guideline and our study can be as high as −95%, 287%. We identify Guangdong, Hebei, Jiangsu, and Zhejiang provinces as the major importers of both coal and electricity, responsible for transferring nearly half of their user-based emissions to coal and power bases. Significantly, T&D losses, often overlooked, contribute to 15–20% of provincial emissions at the user side. Our findings emphasize the necessity of up-to-date life cycle emissions and spatial carbon shifts in effectively allocating emission reduction responsibilities from the national level to provinces.
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•Ultra-low emission (ULE) retrofit significantly improves the overall Hg removal efficiency of devices.•The improvement of overall Hg removal after ULE retrofit mainly comes from the ...effect of dust removal devices.•Hg contents of both fly ash and gypsum are significantly lower than 25 mg/kg.•Large amount of Hg embodied in fly ash and gypsum calls for policies to guide the disposal of these wastes.
China has applied the ultra-low emission technology in coal-fired power plants to control traditional air pollutants and to reduce Hg emissions synergically. In this study, we applied field experiment, model calculation, and literature review to evaluate the Hg control effect of ultra-low emission technology and the potential cross-media effect comprehensively. The dominant ultra-low emission technology significantly improves the atmospheric Hg removal efficiency from 75% to 87%. Such improvement mainly comes from the effect of dust removal devices. Based on the calculated distribution characteristic of Hg content of wastes, we find out that the improvement of Hg control effect of air pollution control devices significantly increase the Hg content of fly ash, which rises from 0.16 mg/kg to 0.33 mg/kg. However, the Hg content of gypsum decreases from 0.75 mg/kg to 0.51 mg/kg. Whether or not to carry out ultra-low emission retrofits, Hg contents of wastes from coal-fired power plants are overall lower than the limit of 25 mg/kg which is intended to be set as the limit for Hg-containing wastes. However, the embodied more than two hundreds of tons Hg in these wastes still require policies to guide the disposal of these wastes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Heavy metal emissions from non-ferrous smelting plants have been a rising concern. However, their emission characteristics were still unclear. In this study, the concentrations and gas-particle ...partition of five major heavy metals (Cu, Pb, As, Cr and Cd) in the flue gas from a typical copper smelting plant were measured. The bi-modal distribution of both particulate matter and heavy metals indicated that the particles in super-micron mode was caused by the mechanical crushing and escaping of raw materials, whereas the formation of submicron mode was due to the evaporation and subsequent condensation of volatile substances. The excellent performance of existing air pollution control devices in the studied smelter could substantially reduce the particulate matter and heavy metal concentrations in the extraction and smelting stages by 99.2%−99.9%. The emission factors of PM2.5, Cu, Pb, As, Cr, and Cd were only 283, 2.49, 0.97, 5.92, 0.28, and 0.06 g/t, mostly as the fugitive emission (84.2% on average). In addition, the ‘unfilterable’ phase of the heavy metals, including the gaseous species and solutes in the filter-penetrated droplet, accounted for averagely 45.8% of the total emissions at the outlet, which indicates the huge underestimation by particle collection only.
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•Emission factors of Pb, As and Cr were 0.97, 5.92, and 0.28 g/t from copper smelting.•Pb, As and Cr emission might be 30–60% underestimated by ignoring unfilterable PM.•Fugitive emission contributed 70–90% of HMs to the atmosphere from copper smelting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
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