The WRF model with chemistry （WRF-Chem） was employed to simulate the impacts of anthropogenic aerosols on summer precipitation over the Beijing-Tianjin-Hebei urban agglomeration in China. With the aid of a high-reso...The WRF model with chemistry （WRF-Chem） was employed to simulate the impacts of anthropogenic aerosols on summer precipitation over the Beijing-Tianjin-Hebei urban agglomeration in China. With the aid of a high-resolution gridded inventory of anthropogenic emissions of trace gases and aerosols, we conducted relatively long-term regional simulations, considering direct, semi-direct and indirect effects of the aerosols. Comparing the results of sensitivity experiments with and without emissions, it was found that anthropogenic aerosols tended to enhance summer precipitation over the metropolitan areas. Domain-averaged rainfall was increased throughout the day, except for the time around noon. Aerosols shifted the precipitation probability distribution from light or moderate to extreme rain. Further analysis showed that the anthropogenic aerosol radiative forcing had a cooling effect at the land surface, but a warming effect in the atmosphere. However, enhanced convective strength and updrafts accompanied by water vapor increases and cyclone-like wind shear anomalies were found in the urban areas. These responses may originate from cloud microphysical effects of aerosols on convection, which were identified as the primary cause for the summer rainfall enhancement.展开更多
During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris...During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.展开更多
Organic aerosol is formed in coal mines due to heat release and evaporation of organics from coal during the longwall operation.This frictional heating occurs when a metallic cutting bit strikes a rock.Thus formed org...Organic aerosol is formed in coal mines due to heat release and evaporation of organics from coal during the longwall operation.This frictional heating occurs when a metallic cutting bit strikes a rock.Thus formed organic aerosol can contribute significantly to the explosivity of methane/air atmosphere in coal mines.In this paper,the flammable limits for the methane-air mixtures with organic aerosol are determined.For this purpose,organic aerosol is synthesizes from the coal-tar pitch in a laboratory evaporation-nucleation flow chamber.Aerosol particles synthesized under laboratory conditions are aggregates consisting of small primary particles with the fractal-like dimension Df=2.0±0.1,which is close to Df=2.1±0.1 of coal mine aerosol.It is shown that the flammability of organic aerosol/methane mixture in air is in good agreement with the Le Chatelier additive principle.The lower ignition limit for the pure organic aerosol in air is 44 g/m^3.展开更多
The quality of the MODIS C6 3-km and 10-km aerosol optical depth（AOD） products retrieved by the Dark Target（DT）method is discussed using ground-based observations in the Beijing–Tianjin–Hebei region from 1 Augus...The quality of the MODIS C6 3-km and 10-km aerosol optical depth（AOD） products retrieved by the Dark Target（DT）method is discussed using ground-based observations in the Beijing–Tianjin–Hebei region from 1 August 2007 to 31 July2008. Good consistency exists between the 3-km and 10-km products and ground-based observations. The retrieval accuracy of the two products both show distinctive seasonality. The percentage falling within the expected error（EE） is largest in the winter, moderate in the spring and autumn, and smallest in the summer. A worse overestimation appears in the spring and summer（27%–66%）. However, the 3-km and 10-km products over different surfaces still exhibit obvious deviations. The 10-km product performs better in the large cities, while the 3-km product has advantages in the suburbs. In urban areas, the percentage falling within EE of the 3-km AOD product（18%–59%） is lower than that for the 10-km AOD product（31%–69%）. However, in suburban areas, the percentage falling within EE of the 3-km AOD product（61%–84%） is higher than for the 10 km AOD product（54%–83%）.The percentages falling within EE differ considerably when the AOD is greater than1.5（73% and 63% for the 3-km and 10-km products, respectively）. On the whole, the 3-km（10-km） AOD product performs better in suburban（urban） areas.展开更多
Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aeros...Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.展开更多
基金supported by the Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issuesof the Chinese Academy of Sciences(Grant No.XDA05090207)the National Natural Science Foundation of China(Grant Nos.41275108 and 41105051)
文摘The WRF model with chemistry （WRF-Chem） was employed to simulate the impacts of anthropogenic aerosols on summer precipitation over the Beijing-Tianjin-Hebei urban agglomeration in China. With the aid of a high-resolution gridded inventory of anthropogenic emissions of trace gases and aerosols, we conducted relatively long-term regional simulations, considering direct, semi-direct and indirect effects of the aerosols. Comparing the results of sensitivity experiments with and without emissions, it was found that anthropogenic aerosols tended to enhance summer precipitation over the metropolitan areas. Domain-averaged rainfall was increased throughout the day, except for the time around noon. Aerosols shifted the precipitation probability distribution from light or moderate to extreme rain. Further analysis showed that the anthropogenic aerosol radiative forcing had a cooling effect at the land surface, but a warming effect in the atmosphere. However, enhanced convective strength and updrafts accompanied by water vapor increases and cyclone-like wind shear anomalies were found in the urban areas. These responses may originate from cloud microphysical effects of aerosols on convection, which were identified as the primary cause for the summer rainfall enhancement.
基金financially supported by the Nuclear Energy Science and Technology and Human Resource Development Project of the Japan Atomic Energy Agency/Collaborative Laboratories for Advanced Decommissioning Science(No.R04I034)Ruicong Xu appreciates the scholarship(financial support)from the Chinese Scholarship Council(CSC No.202106380073).
文摘During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.
基金RFBR and Novosibirsk region(Grant No.19-43-540009).
文摘Organic aerosol is formed in coal mines due to heat release and evaporation of organics from coal during the longwall operation.This frictional heating occurs when a metallic cutting bit strikes a rock.Thus formed organic aerosol can contribute significantly to the explosivity of methane/air atmosphere in coal mines.In this paper,the flammable limits for the methane-air mixtures with organic aerosol are determined.For this purpose,organic aerosol is synthesizes from the coal-tar pitch in a laboratory evaporation-nucleation flow chamber.Aerosol particles synthesized under laboratory conditions are aggregates consisting of small primary particles with the fractal-like dimension Df=2.0±0.1,which is close to Df=2.1±0.1 of coal mine aerosol.It is shown that the flammability of organic aerosol/methane mixture in air is in good agreement with the Le Chatelier additive principle.The lower ignition limit for the pure organic aerosol in air is 44 g/m^3.
基金supported by the National Natural Science Foundation of China(Grant Nos.41375036,41222033,41305076)the Key Project of National Natural Science Foundation of China(Grant Nos.91644226)+1 种基金the CAS(Chinese Academy of Sciences)Strategic Priority Research Program(Grant No.XDA05100102,XDB05020103)the National Basic Research Program of China(Grant Nos.2016YFC0202001 and 2014CB441200)
文摘The quality of the MODIS C6 3-km and 10-km aerosol optical depth（AOD） products retrieved by the Dark Target（DT）method is discussed using ground-based observations in the Beijing–Tianjin–Hebei region from 1 August 2007 to 31 July2008. Good consistency exists between the 3-km and 10-km products and ground-based observations. The retrieval accuracy of the two products both show distinctive seasonality. The percentage falling within the expected error（EE） is largest in the winter, moderate in the spring and autumn, and smallest in the summer. A worse overestimation appears in the spring and summer（27%–66%）. However, the 3-km and 10-km products over different surfaces still exhibit obvious deviations. The 10-km product performs better in the large cities, while the 3-km product has advantages in the suburbs. In urban areas, the percentage falling within EE of the 3-km AOD product（18%–59%） is lower than that for the 10-km AOD product（31%–69%）. However, in suburban areas, the percentage falling within EE of the 3-km AOD product（61%–84%） is higher than for the 10 km AOD product（54%–83%）.The percentages falling within EE differ considerably when the AOD is greater than1.5（73% and 63% for the 3-km and 10-km products, respectively）. On the whole, the 3-km（10-km） AOD product performs better in suburban（urban） areas.
文摘Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.
