Suivis temporels comparés de la structure thermique d'eaux côtières libanaises (Batroun) et françaises (Marseille) entre juin 1999 et octobre 2002

Vertical temperature profiles were recorded from June 1999 to October 2002 (at least once a month) at two Mediterranean sites, in the eastern basin (Batroun, Lebanon; 0–100 m) and in the northwestern basin (Marseilles, France; 0–55 m). At the two sites, the thermal seasonal evolution and the thermocline time dynamics are quite identical. But in the Lebanese waters, at comparable water depths, temperatures are currently 4 to 5?°C higher than in the French waters, the thermocline is longer (more than 6 months), permanent and deeper (40–50 m) than in Marseilles (20–30 m). The latter frequently disappears in summer due to northwest winds inducing cold waters. This is principally due to differences in prevailing wind regimes at each site. Such evaluation, coupled with long-term observations of temporal evolution of coastal water at the regional level of the Mediterranean basins, will shed light on temperature regime fluctuations and their consequences in the context of global warming of the Mediterranean. To cite this article: M. Abboud-Abi Saab et al., C. R. Geoscience 336 (2004).     

The favelas of Rio de Janeiro: A temporal and spatial analysis

A spatial and temporal analysis, at a city wide scale, is given of the main type of informal housing (favelas) in Rio de Janeiro. Rapid change in the number and distribution of favelas and their inhabitants (favelados) over time is seen as the outcome of two opposing sets of factors. Demand-led housing factors, including population growth and variations in levels of poverty in the city, have constantly outstripped the supply side of the housing equation where inadequate housing policies and investment, together with restricted building land have been characteristic. Added to these factors are a set of more specific developments which shape the favela geography, including the timing and location of urban redevelopment, favela eradication and recognition, transport development and access by the favelados to employment sources. Evidence shows that the contemporary distribution of favelas in the city does not conform to spatial models of this urban form, and that any interpretation of the Rio favelas, including their growth, development and diversity, needs to be space and time specific. This revised version was published online in July 2006 with corrections to the Cover Date.     

Probabilistic hazard analysis of Citlaltépetl (Pico de Orizaba) Volcano, eastern Mexican Volcanic Belt

Citlaltépetl or Pico de Orizaba is the highest active volcano in the North American continent. Although Citlaltépetl is at present in repose, its eruptive history reveals repetitive explosive eruptions in the past. Its relatively low eruption rate has favored significant population growth in areas that may be affected by a potential eruptive activity. The need of some criteria for hazards assessment and land-use planning has motivated the use of statistical methods to estimate the time and space distribution of volcanic hazards around this volcano. The analysis of past activity, from late Pleistocene to historic times, and the extent of some well-identified deposits are used to calculate the recurrence probabilities of eruptions of various size during time periods useful for land-use planning.     

The Use of Reference Materials: A Tutorial

Any review of the analytical literature shows that, while reference materials are routinely used in laboratories world-wide, not all uses follow ISO Guide 33 (1989), which outlines best practices. Analytical data quality can suffer as a result. This paper reviews the various uses that the geoanalytical community has made of reference materials from a historical perspective, and suggests improvements in practice that would more closely follow ISO Guide 33 recommendations.     

福建龙海明溪两区玄武质火山岩钾-氩年龄和Nd、Sr、Pb同位素

本文给出了福建龙海明溪两区玄武质岩石的K-Ar年龄测定结果,其中龙海为16.57～19.20Ma,属第三纪中新世的产物;明溪则均小于5Ma,为上新世至更新世所喷发。通过Sr、Nd、Pb同位素组成分析,讨论了两区玄武岩的源区特征及其成因。     

二磷酸氢钛的加压合成及对锂同位素的分离效应

用无定型磷酸钛和磷酸在175℃,约3MPa气压下,合成的晶形细微化合物,即二水合二磷酸氢钛[TI(HPO_4)_2·2H_2O],是一种层状结构的无机离子交换剂。在酸性和中性介质中其溶解度极小,对于钾、锂碱金属离子具有很好的交换吸附效应。以聚丙烯腈的二甲基甲酰胺溶液为粘合剂,压制成型,装制成色谱柱,以LiNO_3溶液为原料,HCl为洗脱剂,合理截取洗脱流分并测得~6Li和~7Li的单级分离因数为1.023,获得了文献中尚未报道过的结果。     

Determination interative des geoides altimetriques

Geoid heights measured by spatial altimetry must be corrected for systematic bias due to orbital error. This requires the solution of a very large overdetermined and underconstrained system of linear equations. We present a rigorous procedure of solution by successive iterations (block relaxation method) and define its validity on a synthetic example from the Mediterranean area.     

The specific surface of Na+-humate on the basis of coion exclusion

The activity of the coion in Na⁺ -humate sol from the membrane potential and the activity of coion in the dialyzate values is calculated. The specific surface of Na⁺ -humate sol, determined by the negative absorption of coion, is close to 2000 m²g^?1. The relationships among the specific surface, the molecular weight and the size of particles of Na⁺ -humate sol are considered.     

Modelling Thermohaline Properties in an Estuarine Upwelling Ecosystem (Ría de Vigo: NW Spain) Using Box-Jenkins Transfer Function Models

Since 1987, twice weekly, hydrological variables have been monitored at a fixed station in the Ría de Vigo (NW Spain), aiming to examine the time scales of variability and the relationships to meteorological conditions. The present paper analyses: (1) the advantage of Box-Jenkins transfer function (TF) models (single output–multiple input), a type of linear stochastic model, to describe the dynamic behaviour of the system; and (2) the coupling between the Ría and meteorological events at the time scale of autonomy of this coastal inlet affected by the Iberian coastal upwelling, approximately a fortnightly period. In order to achieve these objectives, thermohaline properties have been used to characterize the estuarine ecosystem (output variables), while wind regime, runoff in the drainage basin and incoming solar radiation have been considered as the main forcing variables (input variables). The use of the amplitude time series, derived from principal component analysis (PCA) applied to the deseasonalized meteorological variables, is also explored as a different set of input variables.When compared with standard regression models, all TF models built to describe thermohaline behaviour had reduced residual variance. Similar TF models, as well as percentage of explained variance, were also obtained when meteorological variables or the amplitude time series were used as input variables. The fitted TF models provided an insight into the ‘ inertial ’ behaviour of the system and the time scales of coupling of the system with the forcing variables. The plausible physical mechanisms which link the response of the system with the observed meteorological variability are also discussed. As could be expected, bottom thermohaline properties show a stronger inertial behaviour than the surface ones, which is particularly marked for bottom temperature. Besides, the shelf domain, by means of upwelling-downwelling events, strongly influences surface and bottom temperature, as well as bottom salinity; by contrast, surface salinity is mainly influenced by the effect of wind along the main axis of the Ría and runoff. In relation to the time scales of coupling between the system and the forcing variables, thermohaline properties show a dependance with the meteorological conditions in, at least, the immediately preceding fortnight period. It was concluded that: (1) TF models that incorporate meteorological information described the dynamic behaviour of the system adequately; and (2) this type of model can be useful as a first approximation to develop more sophisticated (deterministic) models, since, with the purpose of modelling any state variable of the system, both the coupling between different domains and the time scales of the interactions must be taken into account.