Iron concentrations in selected groundwater samples from the lower Friulian Plain,northeast Italy: importance of salinity

High amounts of iron, up to 14 mg/L, were found in groundwater samples from Marano Lagoon in the Friuli Venezia Giulia Plain (northeast Italy). In order to characterize groundwater hydrochemistry in the area, an investigation has been conducted on 35 wells that were monitored since 2006. Leaching tests were performed (under anaerobic conditions with deionized and saline waters) on two core samples in the area to study the iron release from soils to groundwater. Collected data indicated the main role of salinity in metal leaching and highlighted spatial correspondence between high levels of chloride and iron. To understand the mechanism of groundwater salinization, sulphate/chloride ratio has been investigated and a statistical relation between salinity, pH and iron was found. These data do not show any relation between past activities and high iron groundwater contents. High iron concentrations are diffuse in the whole area and therefore comparable to background values. Consequently, the study states that no remediation plan should have been made for iron concentrations in this area.     

The maximum momentum of particles accelerated at cosmic ray modified shocks

Particle acceleration at non-relativistic shocks can be very efficient, leading to the appearance of non-linear effects due to the dynamical reaction of the accelerated particles on the shock structure and to the non-linear amplification of the magnetic field in the shock vicinity. The value of the maximum momentum, p _max, in these circumstances cannot be estimated using the classical results obtained within the framework of test-particle approaches. We provide here the first attempt at estimating p _max in the cosmic ray modified regime, taking into account the non-linear effects mentioned above.     

Impulses of activity and the Solar cycle

Extreme-ultraviolet data from EIT/SOHO (1996–2002), soft X-ray data from Yohkoh (1991–2001), and magnetic field data from MDI/SOHO (1996–2002) and Kitt Peak Observatory, NSO/NOAO (1991–2002) are analyzed together in the form of synoptic maps for the investigation of solar cycle variations of the corona and their relation to the magnetic field. These results show new interesting relations between the evolution of the topological structure of the corona, coronal heating and the large-scale magnetic field. The long-lived coronal structures are related to complexes of solar activity and display quasi-periodic behavior (in the form of impulses of coronal activity) with periods of 1.0–1.5 year, in the axisymmetric distribution of EUV and X-ray fluxes during the current solar cycle 23. In particular, during the second maximum of this cycle the solar corona became somewhat hotter than it was in the period of the first maximum.     

On the measure of the structure around the last kam torus before and after its break-up

We review theorems for proving non-integrability of Hamiltonian dynamical systems, which are based on properties of the variational equations in real or complex time or on the destruction of the resonant tori of an integrable system under a perturbation.     

Measurement of the Sunyaev–Zel'dovich increment in massive galaxy clusters

We have detected the Sunyaev–Zel'dovich (SZ) increment at 850 μm in two galaxy clusters (Cl 0016+16 and MS 1054.4−0321) using the Submillimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Fits to the isothermal β model yield a central Compton y parameter of  (2.2 ± 0.7) × 10⁻⁴  and a central 850-μm flux of  Δ I ₀= 2.2 ± 0.7 mJy beam⁻¹  in Cl 0016. This can be combined with decrement measurements to infer   y = (2.38 ±^0.36_0.34) × 10⁻⁴  and   v _pec= 400±¹⁹⁰⁰₁₄₀₀ km s⁻¹  . In MS 1054 we find a peak 850-μm flux of  Δ I ₀= 2.0 ± 1.0 mJy beam⁻¹  and   y = (2.0 ± 1.0) × 10⁻⁴  . To be successful such measurements require large chop throws and non-standard data analysis techniques. In particular, the 450-μm data are used to remove atmospheric variations in the 850-μm data. An explicit annular model is fit to the SCUBA difference data in order to extract the radial profile, and separately fit to the model differences to minimize the effect of correlations induced by our scanning strategy. We have demonstrated that with sufficient care, SCUBA can be used to measure the SZ increment in massive, compact galaxy clusters.     

全球寒武-奥陶系界线划分对比的标志和纽带——中国北方小阳桥剖面的启示

根据对中国小阳桥剖面高精度生物、层序、化学和磁性地层学综合研究的新成果及其与绿岬全球界线层型剖面(GSSP)的详细对比,进一步厘定了加拿大绿岬"金钉子"剖面所定义的奥陶系底界划分与对比的标志,并指出:(1)与所定义的全球标准奥陶系底界相当的界线位于小阳桥剖面块状叠层石灰岩之上19.9 m处的薄层纹层灰岩中(BD-24层...     

Assessment of magnetite as a magnetic tracer for sediments in the study of ephemeral gully erosion: Conditioning factors of magnetic susceptibility

In gully erosion, the detached soil can be transported over long distances along the landscape. The eroded material can be redistributed and/or deposited on the soil surface along the landscape and then eventually be buried by newly eroded and deposited sediment. There can be significant variability of the soil conditions (e.g., texture and moisture content) over which the eroded material travels. The eroded material can be detected through the use of magnetic tracers attached to or mixed with the eroded soil. In this study we evaluated the degree to which the magnetic signal of the magnetite is conditioned by (i) burial depth of tracer, (ii) condition of soil covering the tracer and (iii) tracer concentration. In the laboratory containers were filled with a specific soil. In the filling process, a 0.5-cm layer of a soil–magnetite mixture was interspersed in the soil profile at a certain depth. Experiments encompassed three different soil–tracer concentrations (1000:1, 200:1, 100:1), four burial depths of tracer (0 cm, 3 cm, 5 cm and 10 cm from soil surface), and two different soils. In each case, the magnetic susceptibility was measured with a susceptometer. Experiments were repeated with different soil moisture contents. If the tracer is located under the soil surface, a minimum soil–tracer concentration of 200:1 is required for its correct detection. The intensity of the magnetic signal decreases dramatically with the vertical distance of the tracer from the soil surface. The maximum detection depth for the tracer's magnetic signal is strongly dependent on the natural magnetic susceptibility of the soil, which masks the tracer's signal. Variation in soil moisture content does not significantly affect the magnetic signal. For extensive field studies, the soil–tracer volume to be handled would be very high and therefore, it is necessary to explore new tracer application techniques.