An Experimental Study of the Statistics of Temperature Fluctuations in the Atmospheric Boundary Layer

A statistical characterization for two-point temperature fluctuations in the planetary boundary layer (PBL) is analyzed and its implications on the long-standing closure problem discussed. Despite the non-triviality of the dynamics of temperature fluctuations, our analysis supports the idea that the most relevant statistical properties can be captured solely in terms of two scaling exponents. They turned out to be weakly dependent on the stability properties of the PBL. Its statistics have been investigated by collecting data from a field experiment carried out in the urban area of Turin (Italy) from January 2007 to March 2008. Our results confirm those from a large-eddy simulation (LES) analysis carried out for the convective PBL with different level of convection. We extend the scenario to the stable PBL, a regime much more difficult to simulate when exploiting LES.     

Mutual Interference of Two Debris Flow Deposits Delivered in a Downstream River Reach

We investigate experimentally the depositions of two contiguous debris flows flowing into a main river reach.The aim of the present experimental research is to analyze the geometry and the mutual interactions of debris flow deposits conveyed by these tributaries in the main channel.A set of 19 experiments has been conducted considering three values of the confluence angle,two slopes of the tributary,and three different triggering conditions（debris flows occurring simultaneously in the tributaries,or occurring first either in the upstream or in the downstream tributary）.The flow rate along the main channel was always kept constant.During each experiment the two tributaries had the same slope and confluence angle.The analysis of the data collected during the experimental tests indicates that the volume of the debris fan is mainly controlled by the slope angle,as expected,while the shape of the debris deposit is strongly influenced by the confluence angle.Moreover,in the case of multiple debris flows,the deposit shape is sensitive to the triggering conditions.Critical index for damming formation available in literature has been considered and applied to the present case,and,on the basis of the collected data,considerations about possible extension of such indexes to the case of multiple confluences are finally proposed.     

Dredging displaces bottlenose dolphins from an urbanised foraging patch

The exponential growth of the human population and its increasing industrial development often involve large scale modifications of the environment. In the marine context, coastal urbanisation and harbour expansion to accommodate the rising levels of shipping and offshore energy exploitation require dredging to modify the shoreline and sea floor. While the consequences of dredging on invertebrates and fish are relatively well documented, no study has robustly tested the effects on large marine vertebrates. We monitored the attendance of common bottlenose dolphins (Tursiops truncatus) to a recently established urbanised foraging patch, Aberdeen harbour (Scotland), and modelled the effect of dredging operations on site usage. We found that higher intensities of dredging caused the dolphins to spend less time in the harbour, despite high baseline levels of disturbance and the importance of the area as a foraging patch.     

Analysis of Titan CH4 3.3 μm upper atmospheric emission as measured by Cassini/VIMS

After molecular nitrogen, methane is the most abundant species in Titan’s atmosphere and plays a major role in its energy budget and its chemistry. Methane has strong bands at 3.3 μm emitting mainly at daytime after absorption of solar radiation. This emission is strongly affected by non-local thermodynamic equilibrium (non-LTE) in Titan’s upper atmosphere and, hence, an accurate modeling of the non-LTE populations of the emitting vibrational levels is necessary for its analysis. We present a sophisticated and extensive non-LTE model which considers 22 CH₄ levels and takes into account all known excitation mechanisms in which they take part. Solar absorption is the major excitation process controlling the population of the v₃-quanta levels above 1000 km whereas the distribution of the vibrational energy within levels of similar energy through collisions with N₂ is also of importance below that altitude. CH₄-CH₄ vibrational exchange of v₄-quanta affects their population below 500 km. We found that the ν₃ → ground band dominates Titan’s 3.3 μm daytime limb radiance above 750 km whereas the ν₃ + ν₄ → ν₄ band does below that altitude and down to 300 km. The ν₃ + ν₂ → ν₂, the 2ν₃ → ν₃, and the ¹³CH₄ν₃ → ground bands each contribute from 5% to 8% at regions below 800 km. The ν₃ + 2ν₄ → 2ν₄and ν₂ + ν₃ + ν₄ → ν₂ + ν₄ bands each contribute from 2% to 5% below 650 km. Contributions from other CH₄ bands are negligible. We have used the non-LTE model to retrieve the CH₄ abundance from 500 to 1100 km in the southern hemisphere from Cassini-VIMS daytime measurements near 3.3 μm. Our retrievals show good agreement with previous measurements and model results, supporting a weak deviation from well mixed values from the lower atmosphere up to 1000 km.     

Fault zone structure and fluid–rock interaction of a high angle normal fault in Carrara marble (NW Tuscany,Italy)

We studied the geometry, intensity of deformation and fluid–rock interaction of a high angle normal fault within Carrara marble in the Alpi Apuane NW Tuscany, Italy. The fault is comprised of a core bounded by two major, non-parallel slip surfaces. The fault core, marked by crush breccia and cataclasites, asymmetrically grades to the host protolith through a damage zone, which is well developed only in the footwall block. On the contrary, the transition from the fault core to the hangingwall protolith is sharply defined by the upper main slip surface. Faulting was associated with fluid–rock interaction, as evidenced by kinematically related veins observable in the damage zone and fluid channelling within the fault core, where an orange–brownish cataclasite matrix can be observed. A chemical and isotopic study of veins and different structural elements of the fault zone (protolith, damage zone and fault core), including a mathematical model, was performed to document type, role, and activity of fluid–rock interactions during deformation. The results of our studies suggested that deformation pattern was mainly controlled by processes associated with a linking-damage zone at a fault tip, development of a fault core, localization and channelling of fluids within the fault zone. Syn-kinematic microstructural modification of calcite microfabric possibly played a role in confining fluid percolation.     

Hydrogeochemical analysis on Italian bottled mineral waters: Effects of geology

The use of bottled mineral waters use is increasingly becoming popular and the need for better knowledge of their chemical composition is a key issue for defining their quality, particularly for those elements that are not monitored on a regular basis. The link between geology and water chemistry is well known and can lead to extreme differences in element distribution and is an issue that needs to be addressed. Such an opportunity has been provided by a project of the EuroGeoSurvey Geochemistry Expert Group aimed at the characterization of groundwater geochemistry using bottled mineral waters purchased in supermarkets all over Europe. On these waters pH, conductivity and concentrations of 69 elements and ions were measured at the BGR geochemical laboratories. On a total of 1785 “samples”, 158 represent waters bottled in Italy in 126 different sites scattered throughout the country. Most of the purchased mineral water is packaged in PET bottles. In this paper, the dataset concerning Italy has been used to provide an overview on the relationship between natural concentration of the determined chemical elements in groundwater and geo-lithological features. These relationships have been investigated mostly taking into account the surface geology and other information available on water sources. Application of R-Mode factor analysis to the data set allowed the determination of the possible relationship between the distribution of individual elements and lithology or other surface enrichment phenomena. In particular waters draining through volcanic rocks are enriched in elements such as As, B, Br⁻, Cl⁻, Cs, I, K, Li, Na, NO₃⁻, PO₄³⁻, Rb, Sc, SiO₂, Sr, Te, Ti, and V up to 3 orders of magnitude higher than waters draining through other lithologies. REE and Y show significant difference in median concentration due to interaction of waters with plutonic rocks. Many elements have a large spread of concentrations, which reflects natural variations and interaction with particular lithologies. One of the five R-mode factor analysis associations, recognized as being representative of elements analysed shows high nitrate and V loadings along with As, PO₄³⁻ and Se. The latter association probably reflects a sign of anthropogenic contribution in some aquifers in volcano-sedimentary or silico-clastic deposits and in intensively cultivated areas.