Sulfate, nitrate and ammonium （SNA） are the dominant species in secondary inorganic aerosol, and are considered an important factor in regional haze formation. Size-fractionated aerosol particles for a whole year we...Sulfate, nitrate and ammonium （SNA） are the dominant species in secondary inorganic aerosol, and are considered an important factor in regional haze formation. Size-fractionated aerosol particles for a whole year were collected to study the size distribution of SNA as well as their chemical species in Shanghai. SNA mainly accumulated in fine particles and the highest average ratio of SNA to particulate matter （PM） was observed to be 47% in the fine size fraction （0.49-0.95 ~tm）. Higher sulfur oxidation ratio and nitrogen oxidation ratio values were observed in PM of fine size less than 0.95 ~tm. Ion balance calculations indicated that more secondary sulfate and nitrate would be generated in PM of fine size （0.49-0.95 p.m）. Sulfur K-edge X-ray absorption near-edge structure （XANES） spectra of typical samples were analyzed. Results revealed that sulfur mainly existed as sulfate with a proportion （atomic basis） more than 73% in all size of PM and even higher at 90% in fine particles. Sulfate mainly existed as （NH4）2SO4 and gypsum in PM of Shanghai. Compared to non-haze days, a dramatic increase of （NH4）2SO4 content was found in fine particles on haze days only, which suggested the promoting impact of （NH4）2SO4 on haze formation. According to the result of air mass backward trajectory analysis, more （NH4）2SO4 would be generated during the periods of air mass stagnation. Based on XANES, analysis of sulfate species in size-fractionated aerosol particles can be an effective way to evaluate the impact of sulfate aerosols on regional haze formation.展开更多
The primary productivity of terrestrial ecosystems is influenced by soil phosphorus bioavailability, which depends largely on chemical fractions of phosphorus. The sequential fractionation technique developed by Hedle...The primary productivity of terrestrial ecosystems is influenced by soil phosphorus bioavailability, which depends largely on chemical fractions of phosphorus. The sequential fractionation technique developed by Hedley et al. or its subsequent modification is a well-known method to determine soil phosphorus forms. Hedley sequential fractionation technique separates the phosphorus into fractions based on their different chemical solubilities in extractants with certain chemical properties. Recently, synchrotron-based X-ray absorption near edge structure(XANES) spectroscopy has been employed to measure soil phosphorus species directly and non-invasively. The XANES method provides information concerning local structure and chemical information of target elements at a molecular level. Thus, it can distinguish phosphorus fractions bound by metal oxides or hydroxides(such as Fe, Al, and Ca). In this present work, the phosphorus speciation of topsoil along a glacial foreland chronosequence in Gongga Mountain is determined using these two methods. The changes in soil phosphorus bioavailability along the 120-year-old chronosequence are assessed based on comparisons of the results obtained by these two methods. The results indicate that Hedley sequential fractionation technique shows a greater ability to determine soil bioavailable phosphorus(Resin-P and NaCHO3-P), while XANES is effective in distinguishing phosphorus bound by metal compounds. In the chronosequence, Ca- and Al-bound phosphorus were derived mainly from primary minerals, whose phosphorus contents decreased within 120 years of moraine weathering and soil development. The content of soil bioavailable phosphorus increased rapidly after 30 years since deglaciation. The increasing phosphorus bioavailability promoted the colonizing and primary succession vegetation.展开更多
Bioleaching of chalcopyrite with different crystal structures (α-phase,β-phase and γ-phase) by Acidianus manzaensis was comparatively studied by synchrotron radiation based X-ray diffraction (SR-XRD) and S K-edge X...Bioleaching of chalcopyrite with different crystal structures (α-phase,β-phase and γ-phase) by Acidianus manzaensis was comparatively studied by synchrotron radiation based X-ray diffraction (SR-XRD) and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. The α-phase,β-phase and γ-phase chalcopyrite was prepared by heating original chalcopyrite at 583, 773 and 848 K, respectively. Bioleaching results showed that [Cu^2+] in the leaching solution of α-phase,β-phase,γ-phase and original chalcopyrite after 10 days of bioleaching was 1.27, 1.86, 1.43 and 1.13 g/L, respectively, suggesting that β-phase had a better leaching kinetics than others. SR-XRD and XANES results indicated that jarosite and chalcopyrite were the main components in the leaching residues in all cases, and elemental sulfur formed in the early stage of bioleaching. While for β-phase and γ-phase chalcopyrite during bioleaching, bornite was produced in the initial stage of leaching, and turned into chalcocite on day 6.展开更多
The oxidation state of sulfur is detected in Na20-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure （XANES） spectra at the sulfur K edge. The measured spectra show the only presence ...The oxidation state of sulfur is detected in Na20-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure （XANES） spectra at the sulfur K edge. The measured spectra show the only presence of S^6＋ in the Na20-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S^6＋ is the dominant species, but S^2- is also present on both surfaces. It is not certain whether cation bonds to S^2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.展开更多
X-ray absorption fine structure(XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials sciences, environmental sciences, etc. This re...X-ray absorption fine structure(XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials sciences, environmental sciences, etc. This review article is devoted to the applications of XAFS in nanomaterials. The basic principles of XAFS are briefly described from the view point of practical application, including its theory, data analysis and experiments. Using selected examples from recent literatures, the power of XAFS in determination of local atomic/electronic structures is illustrated for various nanomaterials, covering metal and semiconductor nanoparticles, catalysts, core/shell structures, ultrathin nanosheets, and so on. The utilization of time-resolved XAFS technique is also briefly introduced, for in-situ probing the nucleation/growth processes of nanomaterials and identifying reaction intermediates of nanostructured catalysts under operando conditions.展开更多
基金supported by the National Natural Science Foundation of China(No.11079049)the National Natural Science Foundation for Young Scholars(No.11005141,11005144,11105171,11305242)+1 种基金the Key Program of Basic Research of Shanghai Science and Technology Commission Foundation(No.10JC1417200)the Major Project of Knowledge Innovation Programof Chinese Academy of Sciences(No.KJCX3.SYW.N3)
文摘Sulfate, nitrate and ammonium （SNA） are the dominant species in secondary inorganic aerosol, and are considered an important factor in regional haze formation. Size-fractionated aerosol particles for a whole year were collected to study the size distribution of SNA as well as their chemical species in Shanghai. SNA mainly accumulated in fine particles and the highest average ratio of SNA to particulate matter （PM） was observed to be 47% in the fine size fraction （0.49-0.95 ~tm）. Higher sulfur oxidation ratio and nitrogen oxidation ratio values were observed in PM of fine size less than 0.95 ~tm. Ion balance calculations indicated that more secondary sulfate and nitrate would be generated in PM of fine size （0.49-0.95 p.m）. Sulfur K-edge X-ray absorption near-edge structure （XANES） spectra of typical samples were analyzed. Results revealed that sulfur mainly existed as sulfate with a proportion （atomic basis） more than 73% in all size of PM and even higher at 90% in fine particles. Sulfate mainly existed as （NH4）2SO4 and gypsum in PM of Shanghai. Compared to non-haze days, a dramatic increase of （NH4）2SO4 content was found in fine particles on haze days only, which suggested the promoting impact of （NH4）2SO4 on haze formation. According to the result of air mass backward trajectory analysis, more （NH4）2SO4 would be generated during the periods of air mass stagnation. Based on XANES, analysis of sulfate species in size-fractionated aerosol particles can be an effective way to evaluate the impact of sulfate aerosols on regional haze formation.
基金supported by the National Natural Science Foundation of China(Grant No.41272220)the Chinese Academy of Sciences(Grant Nos.KZCX2-YW-BR-21 and KZZD-EW-TZ-06)
文摘The primary productivity of terrestrial ecosystems is influenced by soil phosphorus bioavailability, which depends largely on chemical fractions of phosphorus. The sequential fractionation technique developed by Hedley et al. or its subsequent modification is a well-known method to determine soil phosphorus forms. Hedley sequential fractionation technique separates the phosphorus into fractions based on their different chemical solubilities in extractants with certain chemical properties. Recently, synchrotron-based X-ray absorption near edge structure(XANES) spectroscopy has been employed to measure soil phosphorus species directly and non-invasively. The XANES method provides information concerning local structure and chemical information of target elements at a molecular level. Thus, it can distinguish phosphorus fractions bound by metal oxides or hydroxides(such as Fe, Al, and Ca). In this present work, the phosphorus speciation of topsoil along a glacial foreland chronosequence in Gongga Mountain is determined using these two methods. The changes in soil phosphorus bioavailability along the 120-year-old chronosequence are assessed based on comparisons of the results obtained by these two methods. The results indicate that Hedley sequential fractionation technique shows a greater ability to determine soil bioavailable phosphorus(Resin-P and NaCHO3-P), while XANES is effective in distinguishing phosphorus bound by metal compounds. In the chronosequence, Ca- and Al-bound phosphorus were derived mainly from primary minerals, whose phosphorus contents decreased within 120 years of moraine weathering and soil development. The content of soil bioavailable phosphorus increased rapidly after 30 years since deglaciation. The increasing phosphorus bioavailability promoted the colonizing and primary succession vegetation.
基金Projects(51774342,51404104) supported by the National Natural Science Foundation of ChinaProject(2017A030313219) supported by the Natural Science Foundation of Guangdong Province,China+2 种基金Project(2015JJ3062) supported by Science Foundation for Youths of Hunan Province,ChinaProjects(2017-BEPC-PT-001052,2016-BEPC-PT-000887) supported by Beijing Synchrotron Radiation Facility Public User Program,ChinaProject(2016-SSRF-PT-004969) supported by the Open Funds of Shanghai Synchrotron Radiation Facility,China
文摘Bioleaching of chalcopyrite with different crystal structures (α-phase,β-phase and γ-phase) by Acidianus manzaensis was comparatively studied by synchrotron radiation based X-ray diffraction (SR-XRD) and S K-edge X-ray absorption near edge structure (XANES) spectroscopy. The α-phase,β-phase and γ-phase chalcopyrite was prepared by heating original chalcopyrite at 583, 773 and 848 K, respectively. Bioleaching results showed that [Cu^2+] in the leaching solution of α-phase,β-phase,γ-phase and original chalcopyrite after 10 days of bioleaching was 1.27, 1.86, 1.43 and 1.13 g/L, respectively, suggesting that β-phase had a better leaching kinetics than others. SR-XRD and XANES results indicated that jarosite and chalcopyrite were the main components in the leaching residues in all cases, and elemental sulfur formed in the early stage of bioleaching. While for β-phase and γ-phase chalcopyrite during bioleaching, bornite was produced in the initial stage of leaching, and turned into chalcocite on day 6.
基金Funded by the National Natural Science Foundation of China(No.50972136)
文摘The oxidation state of sulfur is detected in Na20-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure （XANES） spectra at the sulfur K edge. The measured spectra show the only presence of S^6＋ in the Na20-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S^6＋ is the dominant species, but S^2- is also present on both surfaces. It is not certain whether cation bonds to S^2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated.
基金supported by the National Natural Science Foundation of China (11135008, 11175184 and 11475176)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (11321503)
文摘X-ray absorption fine structure(XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials sciences, environmental sciences, etc. This review article is devoted to the applications of XAFS in nanomaterials. The basic principles of XAFS are briefly described from the view point of practical application, including its theory, data analysis and experiments. Using selected examples from recent literatures, the power of XAFS in determination of local atomic/electronic structures is illustrated for various nanomaterials, covering metal and semiconductor nanoparticles, catalysts, core/shell structures, ultrathin nanosheets, and so on. The utilization of time-resolved XAFS technique is also briefly introduced, for in-situ probing the nucleation/growth processes of nanomaterials and identifying reaction intermediates of nanostructured catalysts under operando conditions.
