Wetland Uranium Transport via Iron-Organic Matter Flocs and Hyporheic Exchange

Uranium (U) released from the M-Area at the Department of Energy Savannah River Site into Tims Branch, a seasonal wetland and braided stream system, is estimated to be 43,500 kg between 1965 and 1984. The motivation for this work is the uranium’s persistence in the wetland for decades, where it is estimated that 80% of the U currently remains in the Tims Branch wetland. U has begun to incorporate into wetland iron (Fe) and carbon cycles, associating with local Fe mineralogy and deposits of rich wetland organic matter (OM). The objective of this work is to characterize the chemical phases responsible for sequestration or mobilization of U, Fe, and C in a riparian wetland system and to understand the partitioning and lability of uranium incorporated into natural Fe and C cycles. Born from the observation of Fe-OM flocs under specific hydrologic conditions, it is hypothesized that the mobilization of Fe-OM flocs drive U transport from the wetland as U incorporates into the wetland cycles. This work first investigates the lateral distribution of U within the wetland and identifies key hotspots where U has accumulated due to hydrologic and geochemical controls. With knowledge of these hotspots, work sought to identify relationships of U to Fe and OM throughout the wetland in the water column and as a function of depth at the hotspots. Next, these relationships to Fe and OM were investigated further via parallel extraction of redox-preserved cores in oxic and anoxic atmospheres. This study determined that OM concentrations coupled with OM compound diversity heavily impact metal sequestration and availability in wetland sediments. Deep sediment layers with relatively non-labile OM accumulate metals naturally, as isotopic ratio evidence indicates that sequestration of natural U is occurring in addition to accumulation of anthropogenic depleted U. With an improved understanding of the metal inventories in the wetland, a seasonal study of metal transport allowed for initial estimates of seasonal U and Ni transport associated with Fe-OM flocs. Fluxes of U in Fe-OM flocs can be conservatively estimated to be of minimal risk to water quality, as worst-case assumptions and measurements pre- and post-storm determine that flocs would have mobilized only 132 kg U over the last 60 years. Currently, stream sediments are now hypothesized to be the primary driver of U transport from the wetland, but these U fluxes only amount to roughly 20 kg per year, based on stream flowrate data collection and stream water sampling

Transient motion of a circular plate after an impact

The transient response of a flat circular plate to a sudden impact has been studied experimentally and theoretically. High-speed electronic speckle pattern interferometry reveals the presence of pulses that travel around the edge of the plate ahead of the bending motion initiated by the strike. It is found that the transient motion of the plate is well described by Kirchhoff thin-plate theory over a time approximately equal to the time required for the initial impulse to circumvent the plate; however, a more sophisticated model is required to describe the motion after this time has elapsed

Spectrophotometric determination of chromium as the chromium-peroxo-4-(2-pyridylazo)resorcinol complex

Der ternäre Chrom-Peroxo-PAR-Komplex weist einen scheinbaren molaren Extinktionskoeffizienten von 6280 l · mol −1 · cm −1 auf, wenn er aus 0,1 M schwefelsaurer Lösung mit Ethylacetat extrahiert wird. Das Beersche Gesetz wird bis zu 6,0 μg Cr/ml befolgt. Die Bedingungen für eine optimale Farbbildung, die Zusammensetzung des Komplexes, die Wirkung verschiedener Begleitionen und die Anwendung auf Stähle werden beschrieben. The ternary complex chromium-peroxo-PAR exhibits an apparent molar absorptivity of 6280 l mol −1 cm −1 when extracted into ethyl acetate from 0.1 M sulfuric acid solution. Beer's law is followed for solutions containing up to 6.0 μg Cr ml −1 . Conditions for optimum color formation, complex composition, effects of diverse ions, and application to the determination of chromium in steels are described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46457/1/216_2004_Article_BF00480608.pd

Childhood solid tumours in relation to infections in the community in Cumbria during pregnancy and around thetime of birth

In a retrospective cohort study of all 99 976 live births in Cumbria, 1975–1992, we investigated whether higher levels of community infections during the mother's pregnancy and in early life were risk factors for solid tumours (brain/spinal and other tumours), diagnosed 1975–1993 under age 15 years. Logistic regression was used to relate risk to incidence of community infections in three prenatal and two postnatal quarters. There was an increased risk of brain/spinal tumours among children exposed around or soon after birth to higher levels of community infections, in particular measles (OR for trend=2.1, 95%CI : 1.3–3.6, P=0.008) and influenza (OR for exposure=3.3, 95%CI : 1.5–7.4, P=0.005). There was some evidence of an association between exposure to infections around and soon after birth and risk of other tumours, but this may have been a chance finding. The findings are consistent with other recent epidemiological studies suggesting brain tumours may be associated with perinatal exposure to infections

Biochemical adaptations of the retina and retinal pigment epithelium support a metabolic ecosystem in the vertebrate eye

Here we report multiple lines of evidence for a comprehensive model of energy metabolism in the vertebrate eye. Metabolic flux, locations of key enzymes, and our finding that glucose enters mouse and zebrafish retinas mostly through photoreceptors support a conceptually new model for retinal metabolism. In this model, glucose from the choroidal blood passes through the retinal pigment epithelium to the retina where photoreceptors convert it to lactate. Photoreceptors then export the lactate as fuel for the retinal pigment epithelium and for neighboring Mu ̈ ller glial cells. We used human retinal epithelial cells to show that lactate can suppress consumption of glucose by the retinal pigment epithelium. Suppression of glucose consumption in the retinal pigment epithelium can increase the amount of glucose that reaches the retina. This framework for understanding metabolic relationships in the vertebrate retina provides new insights into the underlying causes of retinal disease and age-related vision loss

Atmospheric carbon dioxide retrieved from the Greenhouse gases Observing SATellite (GOSAT): Comparison with ground-based TCCON observations and GEOS-Chem model calculations

We retrieved column-averaged dry air mole fractions of atmospheric carbon dioxide (X_CO_2) from backscattered short-wave infrared (SWIR) sunlight measured by the Japanese Greenhouse gases Observing SATellite (GOSAT). Over two years of X_CO_2 retrieved from GOSAT is compared with X_CO_2 inferred from collocated SWIR measurements by seven ground-based Total Carbon Column Observing Network (TCCON) stations. The average difference between GOSAT and TCCON X_CO_2 for individual TCCON sites ranges from −0.87 ppm to 0.77 ppm with a mean value of 0.1 ppm and standard deviation of 0.56 ppm. We find an average bias between all GOSAT and TCCON X_CO_2 retrievals of −0.20 ppm with a standard deviation of 2.26 ppm and a correlation coefficient of 0.75. One year of XCO2 was retrieved from GOSAT globally, which was compared to global 3-D GEOS-Chem chemistry transport model calculations. We find that the latitudinal gradient, seasonal cycles, and spatial variability of GOSAT and GEOS-Chem agree well in general with a correlation coefficient of 0.61. Regional differences between GEOS-Chem model calculations and GOSAT observations are typically less than 1 ppm except for the Sahara and central Asia where a mean difference between 2 to 3 ppm is observed, indicating regional biases in the GOSAT X_CO_2 retrievals unobserved by the current TCCON network. Using a bias correction scheme based on linear regression these regional biases are significantly reduced, approaching the required accuracy for surface flux inversions

Endogenous sex hormones and prostate cancer: a quantitative review of prospective studies

This paper presents a quantitative review of the data from eight prospective epidemiological studies, comparing mean serum concentrations of sex hormones in men who subsequently developed prostate cancer with those in men who remained cancer free. The hormones reviewed have been postulated to be involved in the aetiology of prostate cancer: androgens and their metabolites testosterone (T), non-SHBG-bound testosterone (non-SHBG-bound T), di-hydrotestosterone (DHT), androstanediol glucuronide (A-diol-g), androstenedione (A-dione), dehydroepiandrosterone sulphate (DHEAS), sex hormone binding globulin (SHBG), the oestrogens, oestrone and oestradiol, luteinizing hormone (LH) and prolactin. The ratio of the mean hormone concentration in prostate cancer cases to that of controls (and its 95% confidence interval (CI)) was calculated for each study, and the results summarized by calculating the weighted average of the log ratios. No differences in the average concentrations of the hormones were found between prostate cancer cases and controls, with the possible exception of A-diol-g which exhibited a 5% higher mean serum concentration among cases relative to controls (ratio 1.05, 95% CI 1.00-1.11), based on 644 cases and 1048 controls. These data suggest that there are no large differences in circulating hormones between men who subsequently go on to develop prostate cancer and those who remain free of the disease. Further research is needed to substantiate the small difference found in A-diol-g concentrations between prostate cancer cases and controls