On convergence of an asymmetrical body potential expansion in spherical harmonics

The gravity potential of an arbitrary bodyT is expanded in a series of spherical harmonics and rigorous evaluations of the general termV _n of the expansion are obtained. It is proved thatV _n decreases on the sphere envelopingT according to the power law if the body structure is smooth. For a body with analytic structure,V _n decreases in geometric progression. The exactness of these evaluations is proved for bodies having irregular and analytic structures. For the terrestrial planetsV _n =O (n ^–5/2).

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I I V _n IV _n I . . IV _n I . I. IV _n =O(n ^–5/2 )

     

Potential of anthracite,dolomite, limestone and pozzolan as reactive media for de-icing salt removal from road runoff

De-icing salt (NaCl) application is a common practice during winter road maintenance in northern countries, compromising ecosystem services. Ecoengineering facilities, including reactive filter beds, are becoming an effective strategy for road runoff management. Different materials (anthracite coal, dolomite, limestone, and pozzolan) were tested as reactive media of filter beds. Characterization showed that dolomite has the best physical properties (resistance to fragmentation, porosity) for filter bed construction and maintenance, followed by limestone. NaCl removal efficiency was investigated in batch at different concentrations (150–5000 mg L^?1 Cl). Removal efficiency substantially varied depending on the element (Cl or Na), the material, and the added NaCl concentration. At the lowest NaCl concentration, Cl removal was higher onto anthracite (48 %) and dolomite (59 %); but greater Na removal was reached onto limestone (54 %) and pozzolan (67 %). At higher concentrations, Cl removal was similar (anthracite), decreased (dolomite), or increased (limestone, pozzolan); and Na removal increased (anthracite) or decreased (dolomite, limestone, pozzolan). Parallel experiments at 4 °C showed lower NaCl removal, anthracite being the most efficient. Practical applicability was evaluated in columns using synthetic runoff solution (NaCl and metals). NaCl removal efficiency was much lower in column assays with respect to batch. The highest NaCl removal was reached onto dolomite, followed by limestone. Metals were successfully removed, generally remaining over time in a wide range (41–89 % Cd, 78–97 % Ni, 44–88 % Cu, and 3–83 % Zn) depending on the material, being pozzolan the least efficient. Further studies including a combination of materials would be of high interest.     

Multi‐kilometre long pathway of geofluids migration: Clues concerning an ophiolite serpentinization setting possibly responsible for the inferred abiotic provenance of methane in thermal water outflows of the South‐West Carpathians (Romania)

Methane occurrences displaying signatures of a possible abiotic origin had previously been reported in the South‐West Carpathians (Romania). Such an accumulation, at Tisovi?a, was intercepted by a well drilled in an ophiolitic rocks massif, whereas in two other localities—situated tens of kilometres faraway—the concerned methane is released via thermal groundwater outflows that are apparently not associated with any ultramafic products. By using groundwater ionic compositions, corroborated with previously published isotopic (¹³C‐CH₄, ²H‐CH₄, ³He/⁴He) and molecular gas analyses, we assessed in more detail the conjectured abiotic provenance of methane, and quantitatively investigated the hypothesis of a progressive mixing between two, abiotic and thermogenic, methane end‐members. The corresponding geofluids behaviour was modelled by hypothesizing a “concealed” ophiolite serpentinization setting (largely similar to that at Tisovi?a), whose abiotic methane production was “diverted” towards remote discharges at ground surface, via a ~20‐km‐long flowpath supposedly generated by recently operating extensional tectonics.     

Use of major and selected trace elements to describe mixing processes in a water reservoir

Data on temperature, major constituents and some trace elements, measured in the dissolved and particulate phases, were used to identify the hydrodynamics of a reservoir (the Bicaz reservoir, Romania). Results revealed that the reservoir experiences two thermal stratifications per year (summer and winter). However, the summer stratification is delayed by the high river inflow of June–July. Two layers were identified, a surface and a deep layer, whose location and impact vary with time. The surface layer originates from the river inflow (intrusion layer) and the deep current is produced by the outflow (velocity current). According to season, the river inflow either supplies the deep current or remains recordable up to the dam. Consequently, the structure of the water column, and thus the biogeochemical processes within it, are governed both by thermal stratification and by these layers.     

Morphology and environmental impact of the Colţi–Aluniş landslide (Curvature Carpathians), Romania

The May–August 2005 heavy rainstorm events in Romania triggered a large number of geomorphic hazards of great magnitude, consisting of primarily floods and landslides. Some of the most affected regions were the Curvature Carpathians and Subcarpathians. This paper addresses the effects of rainfall on slopes, especially in the middle sector of the Sibiciu basin (the Buzău Carpathians) outlining the significant landslide damage along the road connecting the Colţi and Aluniş villages. The landslides are analyzed in terms of geologic, geomorphic and engineering geologic features, focusing on the Colţi–Aluniş landslide which had the greatest impact on the road displacement. The related environmental and social impacts are also discussed.     

Landslide susceptibility assessment using the bivariate statistical analysis and the index of entropy in the Sibiciu Basin (Romania)

The Sibiciu Basin is located in Romania between the Buzău Mountains and the Buzau Subcarpathians (Curvature Carpathians and Subcarpathians). The geology of the basin consists of Paleogene flysch deposits represented by an alternation of sandstones, marls, clays and schists and Neogene deposits represented by marls, clays and sands. The area is affected by different types of landslides (shallow, medium-deep and deep-seated failures). In Romania, in the last decades, direct and indirect methods have been applied for landslide susceptibility assessment. The most utilized before 2000 were based on qualitative approaches. This study evaluates the landslide susceptibility in the Sibiciu Basin using a bivariate statistical analysis and an index of entropy. A landslide inventory map was prepared, and a susceptibility estimate was assessed based on the following parameters which influence the landslide occurrence: slope angle, slope aspect, curvature, lithology and land use. The landslide susceptibility map was divided into five classes showing very low to very high landslide susceptibility areas.     

Isotopic climate record in a Holocene stalagmite from Ursilor Cave (Romania)

The PU‐2 stalagmite from Ursilor Cave provides the first dated Romanian isotope record for the Holocene. The overall growth rate of the speleothem was 3.5 cm kyr^?1, corresponding to a temporal resolution of 142 y between each isotope analysis. The ‘Hendy’ tests indicate that isotopic equilibrium conditions occurred during the formation of PU‐2, and hence that it is suitable for palaeoclimatic studies. The relationship between δ¹⁸O and temperature was found to be positive. This can be interpreted either as rain‐out with distance from the west‐northwest ocean source of evaporation or shifts in air mass source with changing North Atlantic Oscillation indices. Applying five U–Th thermal ionisation mass spectrometric (TIMS) dates to a 17.5 cm isotope profile (δ¹⁸O and δ¹³C) along the stalagmite growth axis enabled a tentative interpretation of the palaeoclimate signal over the past 7.1 kyr. Spikes of depleted isotopic δ¹⁸O values are centred near ca. 7, ca. 5.2 and ca. 4 ka, reflecting cool conditions. The record shows two warm intervals between ca. 3.8 and ca. 3.2 ka (the maximum warmth) and from ca. 2 to ca. 1.4 ka, when the δ¹⁸O values were less negative than present. The ‘Holocene Climate Optimum’ spanning the time interval from ca. 6.8 to ca. 4.4 ka is not well expressed in the PU‐2 stalagmite. Individual spikes of lighter δ¹³C are interpreted as indicative of periods of heavy rainfall, at ca. 7, ca. 5.5, and ca. 3.5 ka. The overall trend to lighter δ¹³C in the PU‐2 stalagmite may reflect a gradual decrease in water–rock interaction. The results demonstrate that the effect of North Atlantic oceanic changes extended to the investigated area. Nevertheless, some differences in temporal correlation and intensity of stable isotopic response to these climatic events have been found, but the exact nature of these differences and the underlying mechanism is yet to be determined. Copyright © 2002 John Wiley & Sons, Ltd.