Response of phenological events to climate warming in the southern and south-eastern regions of Romania

The analysis of phenological changes in vegetation is essential for the assessment of the response and adaptation of ecosystems/agro-ecosystems to climate change. This study analyses spatial and temporal changes in phenological events (phenophases) and in the climatic growing season in southern and south-eastern Romania, based on mean monthly temperature values recorded between 1961 and 2010 at 24 weather stations, spread out uniformly in the study area. By using the histophenogram method for extracting the mean phenophases length (eight in total, i.e. growing season onset, budding–leafing, flowering, fruiting, maturing, dissemination, start of leaf loss and end of leaf loss) and that of the overall growing season, this paper aims to analyse current phenological changes (in three periods, 1991–2000, 2001–2010 and 1991–2010) in relation to 1961–1990, which is the reference interval in various global climatic studies. Following the analysis of the theoretical phenology length, based on the temperature thresholds (between 5 and 25 °C) that differentiate biological cycles of vegetation, results showed an overall increase in phenological activity (especially in the past decade, 2001–2010), except for two phenophases (fruiting and dissemination), for which largely dominant length decreases were identified. Quantitatively, increases (and null changes, in a few cases) in phenological length generally range between 0–5 days/0–10% (e.g. in the budding–leafing phenophase) and 11–15 days/10.1–20% (maturing), considering the absolute changes or percentages in the three periods, compared to the reference interval 1961–1990. For the most part, the current decrease in the fruiting and dissemination phenophases falls in the interval ?1 to ?5 days/?10.1 to ?20%, compared to the reference period. At the same time, it was noticed that the entire growing season has been expanding, especially in the past decade, when numerous increase instances of up to 15 days were recorded, corresponding to a dominant interval of 0–10% from the period 1961–1990. The results can be particularly useful for adapting the different types of crops to future climate changes, considering that the study area has a high agro-ecological importance.     

Modeling piecewise planar fault discontinuities without element-partitioning in 3D reservoir-geomechanical models

Using the extended finite element method, faults can be introduced into a three-dimensional reservoir-geomechanical model without meshing to assess the potential for fault reactivation associated with industrial activities such as disposal of CO₂ or fluid extraction. The residuals to the governing equations include basis functions formed from the enrichment functions for strong and weak discontinuities. The traditional spatial integration scheme is based on an algorithm that partitions each enriched element into a collection of subtetrahedra, which is time and storage intensive. To avoid element partitioning, we adopt the homogeneous numerical integration scheme (referred as HNI hereafter) where the integration of homogeneous monomials over each polyhedron is converted into the integration of the same monomials over the one-dimensional edges of the polyhedron by using Stokes's theorem and Euler's homogeneous function theorem. The integrands for the strong and weak discontinuities are derived to implement the integration scheme in the three-dimensional reservoir-geomechanical model. An example of a jagged fault is presented to reveal the advantages of HNI scheme over the standard element partitioning approach. Several other examples that involve fluid flow, fault sliding, and fault sliding triggered by injection pressure are also presented to demonstrate that accurate and efficient computations are realized by the new integration scheme.     

Land system changes in the context of urbanisation: Examples from the peri-urban area of Greater Copenhagen

Peri-urban areas are characterised by great heterogeneity and rapid changes of land use. Furthermore, population composition changes as peri-urban areas offer attractive residential alternatives to city centres or more remote locations. The dynamic processes leave peri-urban areas in an in-between situation, neither city nor countryside and home to a range of functions, spanning from agricultural production to residential and recreational areas. The paper investigates the urbanisation of agricultural areas in the Greater Copenhagen region based on quantitative data collected on agricultural properties in nine study areas between 1984 and 2004. The overall conclusion is that agricultural land use has continued largely unaffected by the processes of urbanisation. However, most of the production is concentrated on a few very large full-time farms. In addition, the economic activities have been greatly diversified over the last three decades. The structural components of the areas (land use and landscape elements) thus appear more resilient than the socio-economic system (declining number of full-time farmers and increasing number of owners engaged in other gainful activities). However, at some point this discrepancy will disappear and rapid land use changes may be expected.     

The effect of capillary pressure on the saturation equation of two‐phase flow in porous media

A complete and accurate simulation of two‐phase flow in porous media requires knowledge of all the controlling physics (and values of physical parameters) that play a relevant role and an understanding of the effects of each one on the solution. Of particular concern here is the effect of capillary pressure and the length scale over which it is relevant. The goal of this paper is to provide guidance onto when to include the effects of capillary pressure in the model, and onto what are the resulting length scale restrictions if those effects are to be included. Copyright © 2011 John Wiley & Sons, Ltd.     

Niobium-tantalum oxide minerals in the Jezuitsk�� Lesy granitic pegmatite, Bratislava Massif, Slovakia: Ta to Nb and Fe to Mn evolutionary trends in a narrow Be,Cs-rich and Li,B-poor dike

A complex assemblage of Nb-Ta-(Sn) oxide minerals occur in a relatively narrow (~1?2 m thick) extensively albitized, Hercynian granitic pegmatite dike intruding biotite granodiorites near Bratislava, SW Slovakia. The dike shows enrichment in beryl (locally Cs-rich) but absence of Li- and B-rich phases. Compositions and textural relationships indicate complex evolutions of Nb-Ta oxide phases with several generations presenting distinct textural and compositional features. The first generation of the Nb-Ta minerals from the quartz-microcline-muscovite zone show Ta,Fe-rich compositions with Ta# [Ta/(Ta + Nb)]?=?0.52?0.70 (Ct I columbite-tantalite), 0.88?0.90 (Tap I ferrotapiolite) and 0.73?0.86 (Fw I ferrowodginite); Mn# [Mn/(Mn + Fe)]?=?0.32?0.49 (Ct I), 0.06?0.10 (Tap I) and 0.33?0.41 (Fw I). The 2nd generation is represented by ferrocolumbite to ferrotantalite (Ct II) in saccharoidal albite zone, replacement zones of Ct II in Ct I, and irregular overgrowths of ferrotapiolite (Tap II) and ferrowodginite (Fw II) on Tap I grains. The minerals of the 2nd generation show decreasing of Ta# in comparison to the 1st group: 0.10?0.60 (Ct II), 0.85?0.87 (Tap II) and 0.73?0.77 (Fw II); Mn# attains 0.30?0.45 (Ct II), 0.06?0.09 (Tap II) and 0.26?0.37 (Fw II). The 3rd generation includes fissure fillings, overgrowths and replacement zones of manganocolumbite and manganotantalite (Ct III), ferrotapiolite (Tap III) and ferrowodginite (Fw III) on the older Nb-Ta phases (Ct I, Tap I, Fw I, Fw II), in the coarse-grained unit. The 3rd population displays distinct Mn# increasing (Ct III: 0.51?0.69, Tap III: 0.11?0.24, Fw III: 0.40?0.41), Ta# values reach 0.16?0.79 (Ct III), 0.88?0.92 (Tap III) and 0.80?0.81 (Fw III). The latest, 4th generation of the Nb-Ta phases represents irregular veinlets and patches of fluorcalciomicrolite, replacing Ct I, Tap I, Fw I, Ct II and Tap III. Decrease of Ta/(Ta + Nb) values in Ct II from the saccharoidal albite unit can be explained by crystallization from the albite-rich melt, which was significantly impoverished in Ta with respect to Nb, after crystallization of Ta-rich phases from the 1st generation (ferrotapiolite I, ferrowodginite I).     

Recognition and implication of tectonic loading-induced reheating in the northern Variscan front (Belgium and northern France), based on an illite Kübler index and oxygen isotope study

Illite Kübler index (KI) and oxygen isotope (brachiopods and micrites) investigations have been performed on more than 300 Frasnian limestones sampled in one borehole and numerous outcrops in the Dinant Synclinorium (Belgium, northern France) of the northern Variscan front. The illite Kübler index and ¹⁸O data of a 3-km-thick, tectonically repeated Frasnian series from the Focant borehole are compared with their surrounding surface correspondents and document in-situ reheating induced by Variscan tectonic loading, which post-dated sedimentary burial alteration. The boundary between these two thermal processes (sedimentary burial and tectonic loading) on the Focant profile corresponds to an important location where the heat induced by the tectonic loading was equivalent to that Frasnian strata suffered during maximum sedimentary burial. Mainly based on this knowledge and on a former conodont colour alteration index study, the thickness of the eroded thrust sheet in the Focant area is estimated to be around 3,000 m. Oxygen isotopic exchange in these Frasnian closed carbonate systems, occurring under highest-grade diagenesis and anchimetamorphism, records two events. Brachiopods present a quite different and more homogeneous pattern, due to their higher resistance to heat alteration. These thermal events caused both ¹⁸O records to become increasingly lighter than the presumed original seawater signature. The comparison between KI and ¹⁸O profiles indicates that illite KI analysis is more appropriate than ¹⁸O in highlighting the temperature variations in the burial metamorphism at the periphery of orogenic belts.     

山西朔州井水位的前驱波记录及其讨论

在山西省朔州井水位动态观测的原始记录图中,发现很多远强震前的水位慢波动现象,称其为井水位的前驱波记录．本文介绍了典型的前驱波记录图象,初步分析了该井水位对前驱波的记录特征,发现38％的远大强震前有这种记录,波动周期为数分钟至数十分钟,多在震前两天内出现;讨论了前驱波的成因与传播及其井水位的响应条件,研究了井水位前驱波的科学意义及在地震预测探索中的实用价值．      

Electrochemical properties of solids at the aqueous–solid interface and heterogeneity of surfacePropriétés électrochimiques des solides à l'interface solide–eau et hétérogénéité de surface

In aqueous medium, solid surfaces are in general electrically charged. The induced electrical and chemical properties govern numerous phenomena, such as colloidal stability or transport of pollutants. Numerous industrial processes make use of these properties. The understanding of the underlying mechanisms at molecular level is of high importance in order to predict and master the behaviour of dispersed matter in the environment and in industrial processes. The present paper shows the evolution of theories and experimental methods, their recent developments and applications. To cite this article: F. Thomas et al., C. R. Geoscience 334 (2002) 633–648.     

Large intensity changes of the non-dipole field during a polarity transition

Directional and paleointensity data for the Steens Mountain geomagnetic polarity transition do not agree with the two simplest models of reversals: rotation of undiminished dipole or gradual diminution followed by change in polarity of the dipole moment. Instead, large and rapid changes in the intensity and direction of the field occur, probably as a result of non-dipole variations.     

Oxidation of titanomagnetites in mafic and felsic intrusive rocks

We report opaque mineralogical observations and magnetic properties of primary titanomagnetites in Tertiary submarine gabbros from DSDP, Legs 30 and 37 and in a late Archean, continental granitic pluton, the Shelley Lake granite. The titanomagnetites and silicates in all the submarine gabbros have been deuterically oxidized. There is no indication of subsequent low-temperature oxidation, although serpentization of olivines is pervasive in the deeper Leg 37 units. The Leg 30 samples, from a single thick sill, contain abundant coarse (≈100 μm) titanomagnetites with fully developed ilmenite exsolution lamellae. Curie temperatures are 515–550°C; there are no low Curie temperatures that would indicate surviving unoxidized titanomagnetite. The unserpentinized Leg 37 gabbros contain scarce opaques with pure magnetite Curie points that are barely resolvable microscopically; most occur as inclusions in pyroxene. In the Shelley Lake granite, on the other hand, many samples exhibit bimodal blocking-temperature spectra, with blocking temperature peaks at 250–300°C and 550–575°C. The low-blocking-temperature phase is unidentified. No pyrrhotite was seen in thin section. Optically homogeneous grains coexist with fully exsolved neighbours, but the electron microprobe indicates no titanium. The lamellae appear to be haematite, not ilmenite, and the primary composition of the opaques is pure magnetite. The oxidation state of the opaques is very inhomogeneous, even on a fine scale.