Four sediment cores were collected from the lower Fox River, Wisconsin, USA, to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) using a chemical mass balance model. The cores, ...which were obtained in 1995 from areas close to Green Bay, Wisconsin, USA, had total PAH concentrations between 19.3 and 0.34 ppm. To determine historical trends of PAH inputs, 210Pb and 137Cs dating was used, and elemental carbon particle analysis was done to characterize particles from the combustion of coal, wood, and petroleum. Source fingerprints were taken from the literature. Our results indicate that coke oven emissions, highway dust, coal gasification, and wood burning are likely sources of PAHs in the lower Fox River. Coke oven emissions are in the range of 40 to 90% of total PAHs, and this fraction decreases from 1930 to 1990, except in core Fox River–A (FR‐A). The overall highway dust (HWY) contribution is between 10 and 75%, and this fraction increases from 1930 to present, except in core FR‐A. The wood burning (WB) contribution (i.e., wood burning or coal gasification) is less than 7% in cores FR‐B, FR‐C, and FR‐D. In core FR‐A, a maximum (≈23%) is found around 1960. The contribution of wood burning has changed from less than 6% in 1950 to between 3 and 10% in 1995. Evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene, with a half‐life of approximately 0.5 years has been found at the site of core FR‐D, which is the shallowest (1.1 m) of the four core sites.
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The lifetime of the 3 P 0 state of Bi − has been measured by selective photodetachment in a cryogenic ion-beam storage ring. By measuring the lifetime as a function of applied laser powers and ...extrapolating to zero laser power, a lifetime of 16.0±0.5 s is deduced for electric quadrupole decay of the excited state to the ground sate. The result provides a stringent test of recent state-of-the art theoretical calculations.
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A factor analysis (FA) model with non-negative constraints is used to apportion historical records of polycyclic aromatic hydrocarbon (PAH) sources in seven sediment cores (CLM-A, C, D, E, F, G, and ...H) from the central Lake Michigan (CLM) area. Source apportionment of PAHs is important for environmental modeling and management. Instead of PAH compound concentrations, averages of total PAH fluxes (the sum of sixteen PAHs) into sediments during 5-year periods are used in the FA model. As a consequence, apportionment results indicate historical input records of sources. A data matrix, based on unmixed and focus-corrected total PAH fluxes of seven sediment cores and seven time periods, was used in the FA model. From the FA results, modified Wisconsin petroleum and coal consumption records are identified for the first and the second factors, respectively. The predicted and the Wisconsin coal profiles exhibit similar trends with peaks for the 1946–1951 and 1968–1973 periods. The patterns of predicted and actual profiles for petroleum are also similar, however, predicted values are lower than actual values after 1964. Results from the petroleum profile analysis may indicate a limitation of the FA model when coefficients of variation are not constant over the entire period of study. Factor score results show the separation of the cores into two groups. Cores A, C, D, and E are affected significantly (>36%) by coal and to some extent petroleum point sources (Port Washington and Milwaukee) whereas cores F, G, and H, are impacted mainly (>76%) by diffuse petroleum sources with a weak coal component. This is consistent with the prevailing southwestern wind direction and chemical mass balance (CMB) model results for individual PAHs.
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A chemical mass balance (CMB) model, applied to polycyclic aromatic hydrocarbon (PAH) compounds, is used to apportion PAH sources in a group of seven sediment cores in the Milwaukee Basin of the ...central Lake Michigan area. PAH apportionment results indicate the dominance of coke oven emissions from 1925-1976, and of highway inputs from 1983-1992 for most of the seven cores. This is consistent with results of carbon particle analysis from the same basin. Milwaukee and Port Washington appear to be primary contributors of point source inputs of PAHs from coke ovens and highway dust. Wood burning is a minor source (<13%). These findings are supported by an independent factor analysis study. Historical PAH records are also determined for the seven sediment cores. The records are unmixed and averaged over the basin. The resulting average record is then used as measured profile in a CMB model to determine PAH sources. Source profiles are historical records of the consumption of coal, petroleum, and wood, including coal used for coke production. A cubic spline technique is developed and applied for the curve fitting of original data points for all of the cores. Unmixed profiles reveal a number of features that are not seen in the original data. Wood burning, coke oven emissions, and highway dust profiles are found to resemble the national consumption records. Coal burning is a very small PAH source (<1%).
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DOBA, FGGLJ, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The properties of atomic negative ions are to a large extent determined by electron-electron correlation which makes them an ideal testing ground for atomic many-body physics. In this paper, we ...present a detailed experimental and theoretical study of excited states in the negative ion of iridium. The ions were stored at cryogenic temperatures using the double electrostatic ion ring experiment facility at Stockholm University. Laser photodetachment was used to monitor the relaxation of three bound excited states belonging to the Xe 4f(14)5d(8)6s(2) ionic ground configuration. Our measurements show that the first excited state has a lifetime much longer than the ion-beam storage time of 1230 +/- 100 s. The binding energy of this state was measured to be 1.045 +/- 0.002 eV. The lifetimes of the second and third excited states were experimentally determined to be 133 +/- 10 and 172 +/- 35 ms, respectively. Multiconfiguration Dirac-Hartree-Fock calculations were performed in order to extract binding energies and lifetimes. These calculations predict the existence of the third excited bound state that was detected experimentally. The computed lifetimes for the three excited bound states agree well with the experimental results and allow for a clear identification of the detected levels.
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Six sediment cores were collected from Green Bay, Wisconsin, in order to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) by a chemical mass balance (CMB) model. The cores which ...were obtained in 1995 had total PAH concentrations between 8.04 and 0.460 ppm.
210Pb and
137Cs dating was used to determine historical trends of PAH inputs, and elemental carbon particle analysis was done to characterize particles from combustion of coal, wood and petroleum. The results show that coke burning, highway dust, and wood burning are likely sources of PAHs to Green Bay. The contribution of coke oven emissions (CB) for the Green Bay cores is in the range of 5 to 90%. The overall highway dust (HWY) contribution is between 5 and 70%. There is a maximum (∼67%) contribution of HWY around 1988 which is in agreement with the historical US petroleum consumption. The wood burning (WB) contribution is between 1 to 30%, except in core GB-A where a maximum (∼50%) is found around 1994. The average relative errors of measurement for x
2 equal to the number of degrees of freedom, are 52.5, 56.2, 36.2, 52.3, and 42.8 (df = 3) for the Green Bay cores A, B, C, E, and F, respectively. The sums of the contribution factors are less than one, indicating gain of inert biological or other bulk material between source and receptor. The results of carbon particles for Green Bay core D show that coal, oil, and wood burning are consistent with the CMB modeling results.
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In recent decades, scholars have argued that the Roman Republic's political culture was essentially democratic in nature, stressing the central role of the 'sovereign' people and their assemblies. ...Karl-J. Hlkeskamp challenges this view in Reconstructing the Roman Republic, warning that this scholarly trend threatens to become the new orthodoxy, and defending the position that the republic was in fact a uniquely Roman, dominantly oligarchic and aristocratic political form.
Carbon particle analysis is carried out on four sediment cores from Lake Michigan (CLM-I), Green Bay (GB-D), and the Fox (FR-C) and Kinnickinnic Rivers (KK-6) to explore the inputs of pollution from ...incomplete combustion of fossil fuels. Elemental carbon content is determined by CHN analyzer, and carbon particle type (from burning of coal, wood, and petroleum), abundance, and size are determined through scanning electron microscopy. Carbon contents are between 0 and 1.0% except for core KK-6, where high values (3−33%) appear to be linked to a now defunct coke and coal gasification plant. Maxima are found in the 1950s (CLM-I) or during 1940−1962 (FR-C). The abundance of coal particles is between 40 and 95% in all four cores. The wood fraction is between 0 and 40% with the highest value in the central Lake Michigan core (CLM-I), indicating long-range transport of small diameter (18−22 μm) wood particles with a minimum during 1960−1970 in agreement with the U.S. consumption record. The fraction of oil particles increases in the top layers of KK-6, FR-C, and CLM-I, reflecting increasing emissions from automobile traffic since 1920−1940. Core GB-D shows the opposite tend since 1953, demonstrating reduced significance of Green Bay as a commercial port. PAH data for these areas, obtained by others, generally support our results.
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