scholarly journals Eight-year variations in atmospheric radiocesium in Fukushima City

2021 ◽  
Author(s):  
Akira Watanabe ◽  
Mizuo Kajino ◽  
Kazuhiko Ninomiya ◽  
Yoshitaka Nagahashi ◽  
Atsushi Shinohara
Keyword(s):  
Particle Size ◽  
Numerical Model ◽  
Causal Relationship ◽  
Seasonal Variations ◽  
Fluorescence Analysis ◽  
Terrestrial Ecosystems ◽  
Nuclear Accident ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
X Ray

Abstract. After the Fukushima nuclear accident, atmospheric 134Cs and 137Cs measurements were taken in Fukushima city for eight years, from March 2011 to March 2019. The surface air concentrations and deposition of radio-Cs were high in winter and low in summer; these trends are the opposite of those observed in a contaminated forest area. The half-lives of 137Cs in the concentrations and deposition before 2015 (275 d and 1.11 y) were significantly shorter than those after 2015 (756 d and 4.69 y). The dissolved fractions of precipitation were larger than the particulate fractions before 2015, but the particulate fractions were larger after 2016. The half-lives of 137Cs in the concentrations and deposition were shorter before 2015, probably because the dissolved radio-Cs was discharged from the local terrestrial ecosystems more rapidly than the particulate radio-Cs. X-ray fluorescence analysis suggested that biotite may have played a key role in the environmental behavior of particulate forms of radio-Cs after 2014. However, the causal relationship between the seasonal variations in particle size distributions and the possible sources of particles is not yet fully understood. The current study also proposes a method of evaluating the consistency of a numerical model for radio-Cs resuspension and suggests that improvements to the model are necessary.

scholarly journals X-Ray Dynamical Diffraction in Powder Samples with Time-Dependent Particle Size Distributions - ADDENDUM

MRS Advances ◽  
2020 ◽  
Vol 5 (29-30) ◽  
pp. 1623-1623
Author(s):  
Adriana Valério ◽  
Sérgio L. Morelhão ◽  
Alex J. Freitas Cabral ◽  
Márcio M. Soares ◽  
Cláudio M. R. Remédios
Keyword(s):  
Particle Size ◽  
Time Dependent ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Powder Samples

scholarly journals Spatial and Seasonal Variations of PM Concentration and Size Distribution in Manure-Belt Poultry Layer Houses

2019 ◽  
Vol 62 (2) ◽  
pp. 415-427 ◽  
Author(s):  
Reyna M. Knight ◽  
Xinjie Tong ◽  
Zhenyu Liu ◽  
Sewoon Hong ◽  
Lingying Zhao
Keyword(s):  
Particle Size ◽  
Particulate Matter ◽  
Size Distribution ◽  
Seasonal Variations ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Potential Health ◽  
Significant Difference ◽  
Autumn And Winter ◽  
Mass Concentrations

Abstract. Poultry layer houses are a significant source of particulate matter (PM) emissions, which potentially affect worker and animal health. Particulate matter characteristics, such as concentration and size distribution inside layer houses, are critical information for assessment of the potential health risks and development of effective PM mitigation technologies. However, this information and its spatial and seasonal variations are lacking for typical layer facilities. In this study, two TSI DustTrak monitors (DRX 8533) and an Aerodynamic Particle Sizer (APS 3321) were used to measure PM mass concentrations and number-weighted particle size distributions in two typical manure-belt poultry layer houses in Ohio in three seasons: summer, autumn, and winter. Bimodal particle size distributions were consistently observed. The average count median diameters (mean ±SD) were 1.68 ±0.25, 2.16 ±0.31, and 1.87 ±0.07 µm in summer, autumn, and winter, respectively. The average geometric standard deviations of particle size were 2.16 ±0.23, 2.16 ±0.18, and 1.74 ±0.17 in the three seasons, respectively. The average mass concentrations were 67.4 ±54.9, 289.9 ±216.2, and 428.1 ±269.9 µg m-3 for PM2.5; 73.6 ±59.5, 314.6 ±228.9, and 480.8 ±306.5 µg m-3 for PM4; and 118.8 ±99.6, 532.5 ±353.0, and 686.2 ±417.7 µg m-3 for PM10 in the three seasons, respectively. Both statistically significant (p < 0.05) and practically significant (difference of means >20% of smaller value) seasonal variations were observed. Spatial variations were only practically significant for autumn mass concentrations, likely due to external dust infiltration from nearby agricultural activities. The OSHA-mandated permissible exposure limit for respirable PM was not exceeded in any season. Keywords: Air quality, Particulate matter, Poultry housing, Seasonal variation, Spatial variation.

Phase and Particle Size Analysis of SnO2 Nanomaterials

2015 ◽  
Vol 1109 ◽  
pp. 314-318
Author(s):  
Nor Diyana Abdul Aziz ◽  
Kelimah Elong ◽  
Norlida Kamarulzaman
Keyword(s):  
Particle Size ◽  
Particle Size Analysis ◽  
Annealed Sample ◽  
Degree Of Crystallinity ◽  
Size Analysis ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Particle Size Distributions ◽  
X Ray ◽  
Particle Sizer

Tin Oxide (SnO2) is a metal oxide which has many applications in industry. In this study, SnO2 powders were synthesized by a self-propagating combustion (SPC) method. The product was annealed at 800 °C for 12 and 24 h before characterizing with X-Ray Diffraction (XRD) for phase studies. X-Ray Diffraction results showed that both samples are pure of tetragonal structure with space group P42/mnm. The sample annealed at a longer period, that is, 24 h, shows a higher degree of crystallinity compared to the 12 h annealed sample. It also shows a smaller full width at half maximum (FWHM), indicating larger crystallite size for the 24 h annealed sample. The particle size analysis reveals that there are two groups of particle size distributions for both samples. SEM results give values that are different from the particle sizer results due to the different nature of the measurement methods.

Application of Proton Induced X-Ray Emission Analysis to the St. Louis Regional Air Pollution Study

1974 ◽  
Vol 18 ◽  
pp. 588-597
Author(s):  
R. Akselsson ◽  
C. Orsini ◽  
D. L. Meinert ◽  
T. B. Johansson ◽  
R. E. Van Grieken ◽  
...  
Keyword(s):  
Air Pollution ◽  
Particle Size ◽  
Sampling Period ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Emission Analysis ◽  
X Ray ◽  
Particle Size Fractions ◽  
Pollution Study ◽  
Time Variations

AbstractThe St. Louis aerosol was sampled during the period 16-22 August 1973 simultaneously at two locations using cascade impactors for sequential 12-hour samples. The six particle size fractions of each sampling were individually analyzed using PIXE for elements from S to Br and beyond and for heavy elements including Pb which permitted time variations of concentrations and particle size distributions to be followed and related to meteorological changes during the sampling period. In addition, the data were compared with average levels of the elements in coastal north Florida and maritime Bermuda as well as at a third St. Louis site. From this it appeared that some of the concentrations in St. Louis were at natural levels whereas others appeared to be higher and linked to air pollution sources. These relationships and others in this study may lead to criteria for distinguishing between pollutants and natural background in urban aerosols.

Study on the Seasonal Variation of Surface Sediment Composition in Estuaries

1988 ◽  
Vol 20 (6-7) ◽  
pp. 123-132
Author(s):  
O. Kawara
Keyword(s):  
Particle Size ◽  
Seasonal Variation ◽  
Surface Sediment ◽  
Seasonal Variations ◽  
River Estuary ◽  
Water Runoff ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Sediment Composition ◽  
Sediment Size

The purpose of this study, as the first step toward clarifying the pollutant transport mechanism of sediments, is to clarify the characteristics of the seasonal changes of surface sediment composition in estuaries based on observation. Remarkable seasonal variations are found in the particle size distributions and the concentrations of the constituents of the surface sediments, though the patterns of the variations are different in each estuary observed. The seasonal variations of the concentrations show good correspondence to those of the particle size distributions. One cause of the seasonal variation is the variation of river discharges. When the sediment size in the Asahi River estuary, Okayama prefecture, became finer, the fresh water inflow to the estuary was about 2.5-3.5 times as much as ordinary water runoff (100-150m3/s) and the change was completed in about 10 days. On the other hand, the change to coarser sediment was completed in a day, by the inflow of over 400m3/s.

Textured Coatings from Colloidal Suspensions of Faceted Oxide Microcrystals

1992 ◽  
Vol 286 ◽  
Author(s):  
Gregg.W. Steadman ◽  
J. R. Brewster ◽  
J. D. Budai ◽  
L. A. Boatner
Keyword(s):  
Particle Size ◽  
Colloidal Suspensions ◽  
Fiber Texture ◽  
Preferred Orientation ◽  
Morphological Properties ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
Particle Size Distributions ◽  
X Ray ◽  
Flat Substrate

ABSTRACTThe morphological properties of cubic, faceted MgO microcrystals have been exploited in the formation of textured coatings. Coatings exhibiting a <100> “fiber” texture were formed by centrifugal sedimentation of colloidal suspensions onto a flat substrate. A decrease in the degree of preferred orientation in the coatings with increasing areal coverage of the particles was quantified for several particle-size distributions by using x-ray diffraction. Novel methods for the deposition of particles exhibiting an in-plane preferred orientation in addition to fiber texture have been investigated.

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