Sulfate Reduction in a Forested Catchment as Indicated by δ34S Values of Sulfate in Soil Solutions and Runoff

Abstract

In a forested catchment in the Fichtelgebirge mountains (NE-Bavaria, Germany) the long term SO₄ ^2- budget (average 1988–1994) indicated that about 40% of the input with throughfall (16.8 kg SO₄ ^2- S·ha^?1·yr^?1) was retained in the catchment. In order to identify processes acting as potential SO₄ ^2- sinks, δ³⁴S values of SO₄ ^2- in soil solutions and runoff were measured between May and November 1994. δ³⁴S values of the runoff and the fen were higher (5.8‰) than the δ³⁴S values of the soil solution of the oxic soils in the terrestrial area (3.9‰). Because there is no lithogenic S source within the catchment, it can be assumed that SO₄ ^2- deposition is the only S source in the catchment. Thus the results were interpreted as a result of SO₄ ^2- reduction within the catchment, because the uptake of ³²S is favoured during the dissimilatory SO₄ ^2- reduction and ³⁴S is consequently enriched in the soil solution. To estimate the amount of SO₄ ^2- reduced isotopic fractionation factors between ? 9‰ and ?46‰ were considered, resulting in SO₄ ^2- reduction rates of 1.8–9.3 kg SO₄ ²-S·ha^?1yr^?1. It was concluded that besides dissimilatory SO₄ ^2- reduction another sink exists in the catchment (e.g. SO₄ ^2- sorption in deep soil layers).     

Spectral and Photophysical Properties of α-carboline (1-Azacarbazole) in Aqueous Solutions

The absorption and fluorescence spectra of α-carboline, 9H-pyrido[2,3-b]indole, AC, in organic aprotic solvents containing different water proportions and in acid/base aqueous solutions inside and outside the pH range have been examined. In the organic aprotic solvents, the addition of increasing concentrations of water sequentially quenches and shifts to the red the fluorescence spectra of AC. These spectral changes have been rationalized assuming the formation, at the lower water concentrations, of a discrete ground state non-cyclic weakly fluorescent AC hydrate emitting at 376 nm that, upon increasing the water concentrations, evolves to a higher order AC poly hydrate emitting at 397 nm. The changes of the AC absorption spectra in aqueous acid/basic solutions indicate the existence of three ground state prototropic species; the pyridinic protonated cation, C (pK_a?=?4.10?±?0.05), the neutral, N (pK_a?=?14.5?±?0.2), and the pyrrolic deprotonated anion, A. Conversely, the changes of the AC fluorescence spectra in these media indicate the existence of four excited state species emitting at 376 nm, 397 nm, 460 nm and 465 nm. Since the emissions at 376 nm and 397 nm satisfactorily match those of the hydrates observed in the organic-water mixtures, they were consistently assigned to two differently hydrated ground state N species. The remaining emissions at 460 nm and 465 nm have been assigned without ambiguity, on the basis of their excitation spectra, to the C and A species, respectively. The excited-state pK_as of the prototropic species of AC have been estimated by using the Förster-Weller cycle.     

The Effect of Diet Quality on δ(13)C and δ(15)N in the Tissues of Locusts, Locusta migratoria L

Abstract Locust nymphs were raised from hatching to adult locusts on either seedling wheat (C(3)) or maize (C(4)), to determine whether relative enrichments/depletions of (15)N and (13)C within body tissues are influenced by diet. The maize contained less hexose sugars and protein per gram than wheat. The isotopic spacing between the food and the whole insect was found to differ between the two diets. The lower quality maize diet showed an overall +5.1‰ enrichment in δ(15)N compared to + 2.8‰ for wheat, possibly due to increased fractionation due to protein recycling. The maize diet resulted in increased depletion in lipid and trehalose and depletion in chitin relative to diet. The results for both δ(15)N and δ(13)C suggest that substrate recycling was occurring on the low quality maize diet. Therefore diet quality determines the enrichment/depletion in δ(15)N and δ(13)C within organisms.     

Observation of a new χ(b) state in radiative transitions to Υ(1S) and Υ(2S) at ATLAS

The χ(b)(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider at sqrt[s] = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb(-1), these states are reconstructed through their radiative decays to Υ(1S,2S) with Υ → μ+ μ-. In addition to the mass peaks corresponding to the decay modes χ(b)(1P,2P) → Υ(1S)γ, a new structure centered at a mass of 10.530 ± 0.005(stat) ± 0.009(syst) GeV is also observed, in both the Υ(1S)γ and Υ(2S)γ decay modes. This structure is interpreted as the χ(b)(3P) system.     

Variations of δ(15)N-Values and Hydrolyzable Amino Acids in Settling Particles in the Ocean

Abstract The modification of nitrogen isotopic signals during particle sedimentation in the sea is of great interest for the use of sedimentary δ(15)N-values as a paleoceanographic tool. The effect of organic matter degradation on such modification was studied by analyzing nitrogen, hydrolyzable amino acids (THAA) and δ(15)N-values in a suit of marine settling particles collected from the Bay of Bengal, Indian Ocean, by using time-series sediment traps, and in underlying sediments. The flux of settling particles showed temporal variations which are related to the monsoons, the major climatic feature of this marine region. During high flux periods settling particles are enriched in nitrogenous material that is less degraded and exhibit higher δ(15)N-values than particles showing characteristics of degradation. At the sediment surface more than 95% of the settling particulate nitrogen is lost and the δ(15)N-values of the residual sedimentary nitrogen are higher than those of settling particles. The observed increase is interpreted to be due to fractionation during degradation of organic matter.     

Determination of δ13 CV−PDB and δ15NAIR values of cocaine from a big seizure in Germany by stable isotope ratio mass spectrometry†

In this study, δ¹³C_{V? PDB} and δ¹⁵N_AIR values of 132 cocaine samples from a big seizure in Germany in 2002 were determined using elemental analyser isotope ratio mass spectrometry. The 1.2 tons of cocaine were packed in 1 kg packages and the cocaine bricks inside these packages showed certain logos. Twenty different logos could be identified. Results show a large variability among some samples, for δ¹⁵N_AIR values ranging from?17 to ?2 ‰. Furthermore, the possibility of linking samples with the same logo was checked. The results show that, in general, there is no relationship between the determined isotope ratio and a certain logo.     

Soil respiration rates and δ13C(CO2) in natural beech forest (Fagus sylvatica L.) in relation to stand structure

Soil respiration rates were studied as a function of soil type, texture and light intensity at five selected natural beech forest stands with contrasting geology: stands on silicate bedrock at Kladje and Bricka in Pohorje, a stand on quartz sandstone at Vrhovo and two stands on a carbonate bedrock in the Karstic-Dinaric area in Kocevski Rog, Snezna jama and Rajhenav, Slovenia, during the growing season in 2005-2006. Soil respiration exhibited pronounced seasonal and spatial variations in the studied forest ecosystem plots. The CO(2) flux rates ranged from minimum averages of 2.3?μmol CO(2) m(-2) s(-1) (winter) to maximum averages of about 7?μmol CO(2) m(-2) s(-1) (summer) at all the investigated locations. An empirical model describing the relationship between soil respiration and soil temperature predicted seasonal variations in soil respiration reasonably well during 2006. Nevertheless, there were also some indications that soil moisture in relation to soil texture could influence the soil CO(2) efflux rates in both sampling seasons. It was shown that spatial variability of mean soil respiration at the investigated sites was high and strongly related to root biomass. Based on the [image omitted] data, it was shown that new photoassimilates could account for a major part of the total soil respiration under canopy conditions in forest ecosystems where no carbonate rocks are present, indicating that microbial respiration could not always dominate bulk soil CO(2) fluxes. At Snezna jama and Rajhenav, the abiotic CO(2) derived from carbonate dissolution had a pronounced influence on CO(2) efflux accounting, on average, to ～17%. Further spatial heterogeneity of soil respiration was clearly affected by management practice. Higher respiration rates as well as higher variability in respiration rates were observed in the virgin forest (Rajhenav) than in the management forest (Snezna jama) and could be related to a higher amount of detritus and consequently to less pronounced influence of inorganic pool to CO(2) efflux, lower mixing with atmospheric CO(2) and higher sensitivity to environmental changes. Major differences in soil carbon dynamics among these five forest ecosystems can be explained by the influence of bedrock geology (particularly, the presence or absence of carbonate minerals) and soil texture (affecting gas exchange with overlying air and soil moisture).     

Biosorption and Biomineralization of Uranium(VI) from Aqueous Solutions by Landoltia PunctataSCIEI北大核心CSCD

The biosorption and biomineralization characteristics of uranium by the duckweed Landoltia punctata was investigated in aqueous solutions enriched with 1 to 250 mg . L-1 of U(VI) supplied as uranyl nitrate [UO2(NO3)(2) center dot 6H(2)O]. The maximum uranium removal for the plant cultivar occurred at pH 4 similar to 5 of solution and their uranium removal efficiencies exceeded 90% after 24 h. In kinetics studies, the dried powder of duckweed can finished nearly 80% adsorption within 5 min, the batch adsorption equilibrium can be reached within 24 h for the living and dried powder of duckweed, Both for the living and dried powder of duckweed, the experimental data were well fitted by the pseudo-second-order rate model with the degree of fitting (r) higher than 0.99. The adsorption isotherms could be better described by the Freundlich model than the Langmuir model. In addition, Fourier transform infrared spectroscopy (FTIR) revealed that the surface of Landoltia punctata possess many active groups such as hydroxyl, carboxyl, phosphate and amide groups, the hydroxyl, amino groups involved in adsorption of U(VI) by living and dried powder of Landoltia punctata, and the phosphate groups also participated in the adsorption behavior of U(VI) by the living Landoltia punctata. The living Landoltia punctata reduction part of U(VI) to U(IV) was observed by XPS analysis. SEM and energy dispersive X-ray spectroscopy (EDS) of duckweed from 10 similar to 200 mg . L-1 uranium treatments indeed showed root surface of living Landoltia punctata formed a significant portion of U precipitates with nanometer sized schistose structures that consisted primarily U and P, not containing C. Inorganic phosphate was released by the root cells of Landoltia punctata during the experiments providing ligands for formation of insoluble U(VI) and U(IV) phosphates. The distinct uranium peaks in the EDS spectra of the cluster on the root surface can be observed after biosorption and the uranium and phosphorus mass ratio of the cluster spot was measured to be 82.5% and 8.76% of the total component weight, respectively, and the atomic percentage of 30.89% and 25.19%, respectively. It is worth noting that the phosphorus mass ratio and the atomic rate of the control group is only 0.24% and 0.11%, respectively. But there was no similar crystals observed on the surface of dried powder of Landoltia punctata after biosorption. The present work suggests that living and dried powder of Landoltia punctata can remove more than 90% U(VI) from solution simultaneously precipitated together with phosphate by the living Landoltia punctata, and the dried powder of Landoltia punctata adsorption U(VI) is mainly through the effect of electrostatic attraction, ion exchange and complexation coordination, etc. Here, for the first time, the presence of U immobilization mechanisms within one aquatic plant is reported using Landoltia punctata.     

Seasonal variations in fish δ13C and δ15N in two West African reservoirs,Sélingué and Manantali (Mali): Modifications of trophic links in relation to water level§

Most regions in the tropics undergo high seasonal precipitation that produces cyclic patterns of riverine discharge, resulting in periods characterized by low and high water levels. Many chemical and bio-logical factors are affected by this hydrologic seasonality, and it therefore appeared to be very likely that aquatic food webs would also differ during the low and high water periods. Available carbon sources for fish are thought to be less varied during low water periods, but flooding during high water periods could bring fish into contact with a greater abundance and diversity of food sources such as terrestrial plants or the biofilms that grow on submerged terrestrial plants. At low water levels, higher fish densities may lead to more piscivory and less omnivory when compared with the high water periods. Therefore, trophic links within the fish communities may then be modified by water level changes in tropical reservoirs. To address this prediction, we performed stable isotope analyses of the most common species in Sélingué and Manantali, two large reservoirs in Mali (West Africa). Allochthonous and littoral carbon sources were shown to support fish production to a significant extent, even during low water periods. However, the allochthonous or littoral carbon contributions that sustained the top-predators production were indeed greater during the high water periods as expected. The expected higher omnivory in the high water period might have shortened the food chain when compared with the low water period. Some carnivorous fish species were shown to feed at lower trophic levels during high water periods in both reservoirs, but this was not a general pattern. Flooding did not, therefore, necessarily result in a shorter food chain when water levels were high.     

Chaotic Motion of a Nucleon in Mean Field Potential With Octupole Deformation (Ⅱ) Characteristics of Expectation Values and Uncertainty Measures of Canonical Variables in Space-Temporal Variation of Initial Coherent States

Coherent states of two dimensional asymmetrical harmonic oscillator, which prop- agate in additional octupole deformation potentials, are used to investigate the characteristics of expectation values and uncertainty measures of canonical variables in space-temporal varia- tions.The quantum chaotic system shows varying behaviors as the corresponding classical chaotic system does. Thus the characteristics of quantum chaos are associated with the geom- atric symmetry of the potential surface, specifically, the existence of the negative curvature and the magnitude of the curvature in the potential surface.     

Reduction of optical absorption at a wavelength of around 0.8 μm in LPE garnet (TmBiCa)3(FeGaPt)5O12

Liquid-phase epitaxy (LPE) garnet films (TmBiCa)₃(FeGaPt)₅O₁₂ have been grown using only Bi₂O₃ as the flux so that the film containing Bi gives high specific Faraday rotation. The film does not contain Pb, which may affect optical absorption. The optical absorption coefficient at 810 nm has been effectively reduced by doping Ca in the melt. Our data show that a minimum level of and of the anisotropy constantK _u and also the maximum of the electrical resistivity are achieved when Ca²⁺ replaces Fe²⁺. Fe²⁺ results from Pt⁴⁺ incorporation in the film due to a Bi₂O₃ flux attack on a Pt crucible. Using a compensated film, of 58 cm^–1 and a figure of merit of 9deg/dB were obtained.     

Renormalization of the electron spectrum by confined and interface phonons in a spherical nanoheterosystem (β-HgS/CdS)

The mechanisms of the electron spectrum renormalization by confined (L) and interface (I) phonons in a spherical quantum dot (QD) embedded in a semiconducting sphere are studied for the specific case of the β-HgS/CdS nanosystem. It is shown that, in view of the absence of interaction between an electron in spherically symmetric states and interface phonons forming only one bound state in a small-size QD, the shift Δ of this single level is formed only by confined phonons. As the size of the QD increases, the contribution of L and I phonons to Δ changes accordingly (L phonons slightly dominate), and the shift varies from Δ _CdS ^3D to Δ _HgS ^3D .     

Study of X(5568) in a unitary coupled-channel approximation of BK and B_sπ

The potential of the B meson and the pseudoscalar meson is constructed up to the next-to-leading order Lagrangian, and then the BK and B_sπ interaction is studied in the unitary coupled-channel approximation. A resonant state with a mass about 5568 MeV and J~P= 0~+is generated dynamically, which can be associated with the X(5568) state announced by the D0 Collaboration recently. The mass and the decay width of this resonant state depend on the regularization scale in the dimensional regularization scheme, or the maximum momentum in the momentum cutoff regularization scheme. The scattering amplitude of the vector B meson and the pseudoscalar meson is calculated, and an axial-vector state with a mass near 5620 MeV and J~P= 1~+is produced. Their partners in the charm sector are also discussed.     

K(h)α1,2 x-ray hypersatellite line broadening as a signature of K-shell double photoionization followed by outer-shell ionization and excitation

We propose a novel approach for the theoretical analysis of the photoinduced high-resolution K(h)α(1,2) x-ray hypersatellite spectra, which allows us to obtain reliable values of lifetimes of the doubly K-shell ionized states and fundamental information about the relative role of K-shell double photoionization (DPI) mechanisms. It is demonstrated for the first time that the K(h)α(1,2) hypersatellite natural line broadening observed for selected metal atoms with 20 ≤ Z ≤ 30 can be well reproduced quantitatively by taking into account the influences of the open-shell valence configuration (adopted from predictions of the band-structure method) and the outer-shell ionization and excitation following the DPI process.     

The Λ c (2940)+ as a D*N Molecule in a Constituent Quark Model and a Possible Λ b (6248)

The Λ _c (2940)⁺ is studied in a constituent quark model. The model describes the deuteron as an NN bound state and the X(3872) as a DD* molecule. We studied the meson baryon sector and found a D*N bound state consistent with the data available for the Λ _c (2940)⁺. The existence of this bound state in this picture implies the existence of a ${\bar B^* N}$ partner that we predict as a Λ _b (6248). Different decay channels for this state are also studied.