Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an ad...Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.展开更多
Strong and rapid responses of soil microbial respiration to pulses,such as those from available soil organic matter(SOM)or water input from precipitation(especially in arid areas),are common.However,how soil microbes ...Strong and rapid responses of soil microbial respiration to pulses,such as those from available soil organic matter(SOM)or water input from precipitation(especially in arid areas),are common.However,how soil microbes utilize new SOM inputs and the effects that temperature may have on their activities are unclear owing to the limitation in the application of traditional isotopic techniques at minute scales.In the present study,we developed a system of measuring 12CO2 and δ^13C minutely and synchronously under controlled incubation temperatures,i.e.,for 48 h at 7,10,15,20,and 25℃,to explore the carbon utilization strategies of soil microbes.We measured the respiration rates of soil microbes in response to different carbon sources,i.e.,added glucose(Rg)and initial SOM(Rs),as well as the total respiration rate(Rt).All responses were rapid and characterized by unimodal curves.Furthermore,the characteristic values of these curves,such as the maximum of rate(R-max),the time required to achieve R-max,and the ratio of the duration of R-max to that of 1/2 R-max,were all dependent on incubation temperature.Interestingly,temperature greatly influenced the strategy that microorganisms employed to utilize different carbon sources.The effects of temperature on the intensity of the microbial respiratory response and the ratio of Rg/Rs are important for evaluating the effect of land-use changes or variations in seasonal temperature on SOM turnover and should be considered in ecological models in future studies.展开更多
基金supported by the National Natural Science Foundation of China(91126006,11305102)the Research Fund for the Doctoral Program of Higher Education of China(20130073110046)
文摘Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.
基金National Key Research and Development Program of China(2016YFA0600104,2016YFC0500102)Natural Science Foundation of China(31770655,41671045)Program of Youth Innovation Research Team Project(LENOM2016Q0005)
文摘Strong and rapid responses of soil microbial respiration to pulses,such as those from available soil organic matter(SOM)or water input from precipitation(especially in arid areas),are common.However,how soil microbes utilize new SOM inputs and the effects that temperature may have on their activities are unclear owing to the limitation in the application of traditional isotopic techniques at minute scales.In the present study,we developed a system of measuring 12CO2 and δ^13C minutely and synchronously under controlled incubation temperatures,i.e.,for 48 h at 7,10,15,20,and 25℃,to explore the carbon utilization strategies of soil microbes.We measured the respiration rates of soil microbes in response to different carbon sources,i.e.,added glucose(Rg)and initial SOM(Rs),as well as the total respiration rate(Rt).All responses were rapid and characterized by unimodal curves.Furthermore,the characteristic values of these curves,such as the maximum of rate(R-max),the time required to achieve R-max,and the ratio of the duration of R-max to that of 1/2 R-max,were all dependent on incubation temperature.Interestingly,temperature greatly influenced the strategy that microorganisms employed to utilize different carbon sources.The effects of temperature on the intensity of the microbial respiratory response and the ratio of Rg/Rs are important for evaluating the effect of land-use changes or variations in seasonal temperature on SOM turnover and should be considered in ecological models in future studies.
