Characteristics of secondary inorganic aerosol and sulfate species in size-fractionated aerosol particles in Shanghai

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.

Sulfur speciation and bioaccumulation in camphor tree leaves as atmospheric sulfur indicator analyzed by synchrotron radiation XRF and XANES

Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.

Characterization of extracellular polymeric substances in the biofilms of typical bacteria by the sulfur K-edge XANES spectroscopy

A combined approach of physicochemical extraction and sulfur K-edge X-ray absorption near-edge structure（XANES） spectroscopy was applied to characterize the extracellular polymeric substances（EPS） of typical bacterial biofilms in this study. Physicochemical analysis showed variation of the contents of DNA,polysaccharide and protein in different fractions of EPS in different mediums. The sulfur K-edge XANES analysis yielded a variety of spectra.Spectral fitting of the XANES spectra utilizing a large set of model compounds showed that there was more reduced sulfur in both LB-EPS（loosely bound EPS） and TB-EPS（tightly bound EPS） of all the biofilms in LB medium than in R2 A medium. More oxidized sulfur was identified in LB-EPS than that in TB-EPS,suggesting different niches and physiological heterogeneity in the biofilms. Our results suggested that the sulfur K-edge XANES can be a useful tool to analyze the sulfur speciation in EPS of biofilms.

Optical design and optimization study of metrology sector at high energy photon source

Introduction X-ray metrology,including the metrological calibration of X-ray detectors,optical elements and sources,is important for many frontier science,such as X-ray astronomy,EUV-lithography,plasma physics.Among many types of X-ray sources,synchrotron-radiation is considered perfect for X-ray metrology,mainly due to that arbitrarily X-rays specifications can be tailored to meet the demands of metrological calibration of X-ray detectors and optical elements.As a consequence,many metrology beamlines around the world are built,upgrading or to be constructed,including the metrology sector to be constructed at High Energy Photon Source(HEPS).Method One reasonable way to access good metrological data is using a stable X-ray beam,which means that beam position as well as flux should be as constant as possible and the beamline configuration should be simple and robust to reduce the uncertainty from beamline itself.In addition,the spectral purity of monochromatic X-rays is another crucial factor for X-ray metrology,which means stray X-rays and harmonic X-rays must be as low as possible.Many measures are taken to satisfy these requirements.Conclusion An optical design of the metrology sector optimized for synchrotron-radiation-based-metrology is described here.The metrology sector,ranging from 50 eV to 20 keV,will be set up to meet the growing needs of X-ray metrology in China.All beamlines’configurations are simple and easy to use,with an acceptable ratio of high-order harmonics and stray X-rays,which can be under 1%in the entire energy range.

A soft X-ray cryogenic radiometer built on BSRF

Introduction In the field of the high injection rate X-ray meterage,currently there are no national standards in China,which are urgently needed in areas such as inertial confinement fusion diagnosis and aerospace observation.Globally,many metrology laboratories have developed their own meterage standards based on Cryogenic radiometers.And one soft X-ray cryogenic radiometer has been installed at 4B7B experiment station on Beijing Synchrotron Radiation Facility to measure the X-ray power from 50 nW to 1μW.Purpose The purpose is to verify the accuracy of the X-ray power measurement and the performance of the cryogenic radiometer.Experimental The spectral responsivity of a Si photodiode detector calibrated in the Physikalisch-Technische Bundesanstalt of Germany is calibrated at 750eV again with the cryogenic radiometer based on synchrotron light source.Results Some important performance parameters(e.g.,time constant,responsivity,and nonequivalence error)of the cryogenic radiometer were measured and were in agreement with the design indexes.Calibration results show that total relative uncertainties of X-ray power measurement were below 1%(k=1),and that good consistency was received compared with the calibrations done by the PTB.Conclusion The cryogenic radiometer built at 4B7B is reliable and accurate for soft X-ray power measurement.And the performance of the cryogenic radiometer is also very good.