In-situ removal and characterisation of uranium-containing particles from sediments surrounding the Fukushima Daiichi Nuclear Power Plant

AbstractTraditional methods to locate and subsequently study radioactive fallout particles have focused heavily on autoradiography coupled with in-situ analytical techniques. Presented here is the application of a Variable Pressure Scanning Electron Microscope with both backscattered electron and energy dispersive spectroscopy detectors, along with a micromanipulator setup and electron-hardening adhesive to isolate and remove individual particles before synchrotron radiation analysis. This system allows for a greater range of new and existing analytical techniques, at increased detail and speed, to be applied to the material. Using this method, it was possible to erform detailed energy dispersive spectroscopy and synchrotron radiation characterisation of material likely ejected from the Fukushima Daiichi Nuclear Power Plant found within a sediment sample collected from the edge of the 30km exclusion zone. Particulate material sub-micron in maximum dimension examined during this work via energy dispersive spectroscopy was observed to contain uranium at levels between 19.68 and 28.35 weight percent, with the application of synchrotron radiation spectroscopy confirming its presence as a major constituent.With great effort and cost being devoted to the remediation of significant areas of eastern Japan affected by the incident, it is crucial to gain the greatest possible understanding of the nature of this contamination in order to inform the most appropriate clean-up response

Changes in abundance and infectivity of powdery mildew conidia from cucumber plants treated systemically with lithium chloride.

Systemic treatment of cucumber plants with lithium chloride reduced the numbers of conidia produced by colonies of powdery mildew, Sphaerotheca fuliginea, growing on leaves, and lowered the infectivity of conidia produced from those leaves when they were applied to leaves of untreated plants. Production of conidiophores was lower in both lithium-treated and calcium-deprived plants, and lithium slightly decreased the calcium content of leaves. When the lithium-containing growth medium was supplemented with phosphate, conidiophore production was still markedly reduced, although leaves had normal levels of calcium. Fungal development was not correlated with either the calcium or phosphorus content of leaves. It is concluded that, although severe calcium deficiency can inhibit fungal development, the inhibitory effects of lithium are not mediated through alterations in calcium or phosphorus uptake by host tissues

Asymmetric responses of adaxial and abaxial stomata to elevated CO2: impacts on the control of gas exchange by leaves.

The response of adaxial and abaxial stomatal conductance in Rumex obtusifolius to growth at elevated atmospheric concentrations of CO2 (250 μmol mol−1 above ambient) was investigated over two growing seasons. The conductance of both the adaxial and abaxial leaf surfaces was found to be reduced by elevated concentrations of CO2. Elevated CO2 caused a much greater reduction in conductance for the adaxial surface than for the abaxial surface. The absence of effects upon stomatal density indicated that the reductions were probably the result of changes in stomatal aperture. Partitioning of gas exchange between the leaf surfaces revealed that increased concentrations of CO2 caused increased rates of photosynthesis only via the abaxial surface. Additionally, leaf thickness was found to increase during growth at elevated concentrations of CO2. The tendency for these amphistomatous leaves to develop a distribution of conductance approaching that of hypostomatous leaves clearly reduced their maximum photosynthetic potential. This conclusion was supported by measurements of stomatal limitation, which showed greater values for the adaxial surfaces, and greater values at elevated CO2. This reduction in photosynthesis may in part be caused by higher diffusive limitations imposed because of increased leaf thickness. In an uncoupled canopy, asymmetrical stomatal responses of the kind identified here may appreciably reduce transpiration. Species which show symmetrical responses are less likely to show reduced transpirational rates, and a redistribution of water loss between species may occur. The implications of asymmetrical stomatal responses for photosynthesis and canopy transpiration are discussed