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Improving the Representation of Cross-Boundary Transport of Anthropogenic Pollution in East Asia Using Radon-222.
Get PDFWe report on 10 years of hourly atmospheric radon, CO, and SO2 observations at Gosan Station, Korea. An improved radon detector was installed during this period and performance of the detectors is compared. A technique is developed whereby the distribution of radon concentrations from a fetch region can be used to select air masses that have consistently been in direct contact with land-based emissions, and have been least diluted en route to the measurement site. Hourly radon concentrations are used to demonstrate and characterise contamination of remote-fetch pollution observations by local emissions at this key WMO GAW site, and a seasonally-varying 5-hour diurnal sampling window is proposed for
days on which diurnal cycles are evident to minimise these effects. The seasonal variability in mixing depth and
“background” pollutant concentrations are characterised. Based on a subset of observations most representative of the
important regional fetch areas for this site, and least affected by local emissions, seasonal estimates of CO and SO2 in air
masses originating from South China, North China, Korea and Japan are compared across the decade of observations. 2016, © Taiwan Association for Aerosol Researc
Ion irradiation as a tool for modifying the surface and optical properties of plasma polymerised thin films
No full textRadio frequency (R.F.) glow discharge polyterpenol thin films were prepared on silicon wafers and irradiated with I10+ ions to fluences of 1 × 1010 and 1 × 1012 ions/cm2. Post-irradiation characterisation of these films indicated the development of well-defined nano-scale ion entry tracks, highlighting prospective applications for ion irradiated polyterpenol thin films in a variety of membrane and nanotube-fabrication functions. Optical characterisation showed the films to be optically transparent within the visible spectrum and revealed an ability to selectively control the thin film refractive index as a function of fluence. This indicates that ion irradiation processing may be employed to produce plasma-polymer waveguides to accommodate a variety of wavelengths. XRR probing of the substrate-thin film interface revealed interfacial roughness values comparable to those obtained for the uncoated substrate’s surface (i.e., both on the order of 5 Å), indicating minimal substrate etching during the plasma deposition process. © 2015, Elsevier B.V
Surface segregation of Niobium and Tantalum in Titanium Dioxide: Overview
No full textSegregation in crystals results in surface layer enrichment of selected lattice elements. The present work considers the phenomenon of segregation in solid solutions of TiO2 doped with donor-type elements, such as niobium and tantalum. The focus is on the effect of oxygen activity on segregation at elevated temperatures. It is shown that the effect of oxygen activity on the segregation-induced enrichment may be used for engineering of oxide materials in general and TiO2-based materials in particular with controlled surface composition that is required to achieve the desired reactivity and photoreactivity for energy conversion in general and solar energy conversion in particular. The development of the related surface engineering procedures requires correct determination of oxygen activity during processing and the segregation-induced concentration gradients within the surface layer.© The American Ceramic Society, 2016.Copyright © 1999-2020 John Wiley & Sons, In
Stable Isotope Analysis of the Contribution of Microalgal Diets to the Growth and Survival of Pacific Oyster Crassostrea gigas (Thunberg, 1979) Larvae
No full textStable carbon and nitrogen isotope analyses were used to evaluate the influence of microalgal diet on growth and survival of hatchery-reared Pacific oysterCrassostrea gigas larvae.D-veliger larvae were fedmonospecific diets of Pavlova lutheri (P), Tahitian Isochrysis aff. galbana (T), and Chaetoceros calcitrans (C), and a standard hatchery trispecific diet of 25P:25T:50C (PTC). The dietary effects on nutrient assimilation, isotopic turnover rates, and discrimination factors were assessed using exponential models. Of the four dietary treatments evaluated over the 15-day feeding trial, larvae fed C. calcitrans and PTC had the best growth and high survival. Larvae in all dietary treatments had relatively high isotopic turnover rates (0.075–0.327/day), although some discrimination factors found in this study were out of the normal range for aquatic invertebrates (Δ13C: 0.4‰–4.1‰ and δ15N: 0.1‰–5.3‰). Overall, the turnover rates and discrimination factors for δ13C and δ15N indicated that C. gigas larvae assimilate C. calcitrans and PTC best under hatchery rearing conditions. The results demonstrated the application potential of stable isotope analysis to evaluate optimal diets and feeding regimes to enhance hatchery performance of bivalve larvae and postlarval stages.© 2016, BioOne
Visualising the relationships between synoptic circulation type and air quality in Sydney, a subtropical coastal-basin environment.
No full textOzone and particle pollution are of concern for the Sydney basin, in particular during warm months (November to March) when pollution levels can exceed national standards. Previous studies on the relationship between synoptic circulation and air quality focused on high pollution days or aggregated air quality conditions over the region as a whole. This study provides both temporal and spatial analyses of the synoptic processes affecting warm-month ozone and particle pollution in Sydney. A warm-month synoptic catalogue was developed by applying the self-organising map method to the NCEP/NCAR geopotential height reanalysis for south-east Australia. The catalogue was linked to mesoscale meteorological features such as drainage flows and sea breezes, and subsequently to the spatial variability in air quality across the Sydney basin. The typical synoptic types commonly associated with high or low ozone and PM10 levels, as well as variations in visibility, were identified. The results suggest that, due to Sydney's subtropical coastal-basin environment, the interaction between meso- and synoptic-scale features determine local air quality conditions in the region, rather than the synoptic conditions alone. Emissions from bushfires appear to have considerable impacts on the synoptic modulation to visibility and PM10 levels, with such impacts tending to be more at a local scale. In contrast, no comparable impacts were found for ozone pollution. For ozone and visibility, the probability for an exceedance day under some synoptic types varied considerably over time, implying that there might have been a shift in the role of synoptic modulation to local air quality associated with changes in air emissions profiles. This study provides a leap in our understanding of the relationship between synoptic circulation and air quality in a coastal-basin environment. The results are useful for improving air quality forecasting in Sydney, with the methodology developed readily applicable to similar regions elsewhere. © 2016, Royal Meteorological Society
The observation of slip phenomena in single crystal Fe samples during in situ micro-mechanical testing through orientation imaging
No full textThis paper reports a study of local orientation change occurring within micro-scale tensile samples as a function of strain. These samples were fabricated from a thin film of single crystal bcc Fe and deformed in tension using an in situ micro-mechanical testing device inside a scanning electron microscope. Samples were loaded along the direction parallel to the specimen axis, strained to different levels, and then subjected to electron backscatter diffraction scans over the entire area of the gauge section. Analysis of the surface orientation data shows that, within a necked zone of the micro-sample gauge section, there are two distinct regions of significant orientation change, in which local crystal rotations occur in opposite directions. These two regions are separated by an intermediate band that shows minimal misorientation from the original state. Crystal rotations within the two regions that develop opposite orientations are found to be consistent with classic single crystal slip, where the slip direction rotates toward the tensile axis. It is shown that increasing tensile strain causes an increasing degree of rotation away from the starting orientation. The tests also illustrate the occurrence of slip on at least two different slip systems, based on the slip traces and orientation change. © 2014 Microscopy Society of America
Studying the effects of Zr-doping in (Bi0.5Na0.5)TiO3 via diffraction and spectroscopy
No full textThe structural properties of (Bi0.5Na0.5)Ti1−xZrxO3 (where 0 ≤ x ≤ 0.7) have been investigated using powder diffraction and X-ray absorption spectroscopy. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Doping small amounts of Zr into the B site of (Bi0.5Na0.5)TiO3 initially stabilizes the rhombohedral phase before the orthorhombic Pnma phase begins to form at x = 0.5. Analysis of the Ti K-edge and Zr L3-edge XANES spectra show that the crystallographic phase change has very little effect on the local structure of Ti4+/Zr4+ cations, suggesting that there is little change in the cation off-center displacement within the BO6 octahedra with each successive phase change. © The Royal Society of Chemistry 201
Seventy years of continuous encroachment substantially increases ‘blue carbon’ capacity as mangroves replace intertidal salt marshes.
No full textShifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global ‘blue carbon’ stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30 years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70 years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30 years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130 ± 18 Mg biomass km−2 yr−1 (mean ± SE), a 2.5 times higher rate than the marine embayment site (52 ± 10 Mg biomass km−2 yr−1), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230 ± 62 Mg C km−2 yr−1 (± SE) as mangrove forests developed. Over the past 70 years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283 097 Mg and belowground C stocks by over 500 000 Mg in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue carbon storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming. © 2015, John Wiley & Sons Ltd
In vivo evaluation of radiofluorinated caspase-3/7 inhibitors as radiotracers for apoptosis imaging and comparison with [18F]ML-10 in a stroke model in the rat
No full textThe first biological evaluation of two potent fluorine-18 radiolabelled inhibitors of caspase-3/7 was achieved in a cerebral stroke rat model to visualize apoptosis © Springer Natur