On the Neogene-Quaternary debate     

Lucas J. Lourens 《《幕》》2008,31(2):239-242

A proposed resolution to the current Neogene-Quaternary debate involves independent, non-overlapping status for the two units and harks back to Lyell＇s original denotation of the terms Older and Newer Pliocene.  相似文献   

Mineralogy and Geochemistry of Rural Road Dust and Nearby Mine Tailings: A Case of Ignored Pollution Hazard from an Abandoned Mining Site in Semi-arid Zone     

Del Rio-Salas  Rafael  Ayala-Ramírez  Yessi  Loredo-Portales  René  Romero  Francisco  Molina-Freaner  Francisco  Minjarez-Osorio  Christian  Pi-Puig  Teresa  Ochoa–Landín  Lucas  Moreno-Rodríguez  Verónica 《Natural Resources Research》2019,28(4):1485-1503

Natural Resources Research - Abandoned mine tailings are considered as one of the main sources of potentially toxic elements. Because of the lack of supervision, particularly from small-scale or...  相似文献   

Coupled rainfall and water vapour stable isotope time series reveal tropical atmospheric processes on multiple timescales     

Niels C. Munksgaard  Costijn Zwart  Jordahna Haig  Lucas A. Cernusak  Michael I. Bird 《水文研究》2020,34(1):111-124

High-frequency stable isotope data are useful for validating atmospheric moisture circulation models and provide improved understanding of the mechanisms controlling isotopic compositions in tropical rainfall. Here, we present a near-continuous 6-month record of O- and H-isotope compositions in both water vapour and daily rainfall from Northeast Australia measured by laser spectroscopy. The data set spans both wet and dry seasons to help address a significant data and knowledge gap in the southern hemisphere tropics. We interpret the isotopic records for water vapour and rainfall in the context of contemporaneous meteorological observations. Surface air moisture provided near-continuous tracking of the links between isotopic variations and meteorological events on local to regional spatial scales. Power spectrum analysis of the isotopic variation showed a range of significant periodicities, from hourly to monthly scales, and cross-wavelet analysis identified significant regions of common power for hourly averaged water vapour isotopic composition and relative humidity, wind direction, and solar radiation. Relative humidity had the greatest subdiurnal influence on isotopic composition. On longer timescales (weeks to months), isotope variability was strongly correlated with both wind direction and relative humidity. The high-frequency records showed diurnal isotopic variations in O- and H-isotope compositions due to local dew formation and, for deuterium excess, as a result of evapotranspiration. Several significant negative isotope anomalies on a daily scale were associated with the activity of regional mesoscale convective systems and the occurrence of two tropical cyclones. Calculated air parcel back trajectories identified the predominant moisture transport paths from the Southwest Pacific Ocean, whereas moisture transport from northerly directions occurred mainly during the wet season monsoonal airflow. Water vapour isotope compositions reflected the same meteorological events as recorded in rainfall isotopes but provided much more detailed and continuous information on atmospheric moisture cycling than the intermittent isotopic record provided by rainfall. Improved global coverage of stable isotope data for atmospheric water vapour is likely to improve simulations of future changes to climate drivers of the hydrological cycle.  相似文献   

Towards semantic‐aware multiple‐aspect trajectory similarity measuring     

Lucas May Petry  Carlos Andres Ferrero  Luis Otavio Alvares  Chiara Renso  Vania Bogorny 《Transactions in GIS》2019,23(5):960-975

The large amount of semantically rich mobility data becoming available in the era of big data has led to a need for new trajectory similarity measures. In the context of multiple‐aspect trajectories, where mobility data are enriched with several semantic dimensions, current state‐of‐the‐art approaches present some limitations concerning the relationships between attributes and their semantics. Existing works are either too strict, requiring a match on all attributes, or too flexible, considering all attributes as independent. In this article we propose MUITAS, a novel similarity measure for a new type of trajectory data with heterogeneous semantic dimensions, which takes into account the semantic relationship between attributes, thus filling the gap of the current trajectory similarity methods. We evaluate MUITAS over two real datasets of multiple‐aspect social media and GPS trajectories. With precision at recall and clustering techniques, we show that MUITAS is the most robust measure for multiple‐aspect trajectories.  相似文献   

Comparative reproductive biology of two southwestern Atlantic populations of the hermit crab Pagurus exilis (Crustacea: Anomura: Paguridae)     

Mariana Terossi  Lucas S. Torati  Ivana Miranda  Marcelo A. Scelzo  Fernando L. Mantelatto 《Marine Ecology》2010,31(4):584-591

Pagurus exilis (Benedict, 1892) is an endemic South Atlantic hermit crab with a distribution ranging from Rio de Janeiro State, Brazil, to Buenos Aires Province, Argentina. The present study analyzed the reproduction of two populations at the extremes of this geographical distribution, and compared their reproductive period, fecundity, and changes in egg size and egg volume during the incubation period in order to assess the variability over this latitudinal range. Hermit crabs were collected monthly over a 2‐year period. In total, 108 females were analyzed for Brazil (44 non‐ovigerous and 64 ovigerous), and 141 for Argentina (87 non‐ovigerous and 54 ovigerous). Reproduction in Brazil occurs year‐round, with peaks in the fall and winter seasons; in Argentina reproduction occurs only in spring and summer. The Brazilian ovigerous females were significantly larger than the Argentina ones (Brazil: SL = 5.33 ± 1.45 mm; Argentina: SL = 4.15 ± 0.52 mm; P < 0.001). The fecundity was 1447 ± 831 eggs (317 to 2885) in Brazil and 987 ± 711 eggs (114 to 2665) in Argentina, with a trend towards higher fecundity in Brazil. Eggs in the Argentina population were larger than those in Brazil for all the three stages investigated, and no changes in egg volume were found during egg development for both populations. The reproductive traits of the two populations showed some important differences, which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Argentine waters. The strategy adopted by the Argentina population involves a lower production of larger eggs compared to the population in Brazil; this lower production is associated with reproduction in cold‐water regions.  相似文献   

Tracing of dissolved organic matter from the Sepetiba Bay (Brazil) by PARAFAC analysis of total luminescence matrices   总被引：2，自引：0，他引：2  

Luciani X  Mounier S  Paraquetti HH  Redon R  Lucas Y  Bois A  Lacerda LD  Raynaud M  Ripert M 《Marine environmental research》2008,65(2):148-157

Fluorescent excitation-emission matrices (FEEM) of the fluorescent dissolved organic matter (FDOM) are widely used for DOM characterization and tracing. In this work, a set of FEEM from sampling campaigns in the Sepetiba Bay (Brazil) was decomposed into independent components using the parallel factor analysis (PARAFAC) algorithm. Four independent components were extracted describing the total fluorescence of the FDOM. The well described peaks A, C, M, B and T were found, and a new peak, A', linked to the C peak, was detected. Relative contribution of each of four components to the total fluorescence confirms that the coastal water has DOM of terrestrial origin, except for the 275Ex/400-500Em range (nm), which primarily occurs in marine waters.  相似文献   

Spatialities of ageing: The co-construction and co-evolution of old age and space   总被引：1，自引：0，他引：1  

Tim Schwanen  Irene Hardill  Susan Lucas 《Geoforum》2012,43(6):1291-1295

This editorial introduction to the themed issue is divided into four parts. We begin with outlining five reasons for more sustained attention to ageing and old age in human geography and go onto discuss two major challenges for geographical inquiry into ageing and later life. One of these is examining embodiment in ways that keep both its social/cultural aspects and its biological/physiological dimensions in sharp focus; the other concerns the challenge of considering time, or rather spatiotemporality, in all its facets. With regard to the latter we argue that the life-course concept can be helpful in this regard, especially if attention is paid to transitions as well as to slow, difficult-to-identify forms of change and if life-courses are understood in terms of folds. Thinking in these terms opens up a perspective according to which ageing and space can be analysed as entwined becomings. We conclude by positioning the contributions in this issue vis-à-vis the perspective developed in this piece.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000887     

Gerald Grellet-Tinner  Michael B.Thompson  Lucas E.Fiorelli  Eloísa Argaaraz  Laura Codorniú  E.Martín Hechenleitner 《地学前缘(英文版)》2014,5(6):759-765

The increasing number of fossil pterosaur eggs sheds light on nesting environments and breeding be- haviors of these extinct flying reptiles. Here we report the first partial three-dimensional egg of the pterosaur, Pteroduustro guinazui, from central Argentina. The specimen was discovered from the same Albian deposits as the exceptional R guinazui embryo described in 2004. Microscopic characterizations indicate a pristine preservation of the 50 Bm thick calcium carbonate, which differs significantly from the soft shell of Chinese pterosaur eggs. Estimate of the eggshell conductance implies that the nest had a minimum moisture content of 75%. This moisture estimate, combined with geological and taphonomical data, suggests that P. guinazui may have adopted a nesting strategy similar to those of grebes and flamingos rather than being buried on land, as previously hypothesized. Moreover, our results demon- strate that the nesting paleoenvironment of this pterosaur species was closely linked to a mesohaline lacustrine ecosystem in a basin governed by regional tectonic subsidence, a setting characteristic for the feeding and reproduction of modern flamingos.  相似文献   

Geochemical tracing and hydrogeochemical modelling of water–rock interactions during salinization of alluvial groundwater (Upper Rhine Valley,France)     

Y. Lucas  A.D. Schmitt  F. Chabaux  A. Clément  B. Fritz  Ph. Elsass  S. Durand 《Applied Geochemistry》2010

In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves that a small contribution of calcite precipitation/dissolution takes places whereas other secondary mineral precipitation or host rock mineral dissolution do not play a significant role in the geochemical signature of the studied groundwater samples. Application of the model demonstrates that it is necessary to consider the pollution history to explain the important Cl, Na and Ca concentration modifications in groundwater samples taken over 2 km downstream of waste heaps. Additionally, the model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer.  相似文献   

It starts at home? Climate policies targeting household consumption and behavioral decisions are key to low-carbon futures     

Ghislain Dubois  Benjamin Sovacool  Carlo Aall  Maria Nilsson  Carine Barbier  Alina Herrmann  Sébastien Bruyère  Camilla Andersson  Bore Skold  Franck Nadaud  Florian Dorner  Karen Richardsen Moberg  Jean Paul Ceron  Helen Fischer  Dorothee Amelung  Marta Baltruszewicz  Jeremy Fischer  Françoise Benevise  Valérie R. Louis  Rainer Sauerborn 《Chemie der Erde / Geochemistry》2010

Through their consumption behavior, households are responsible for 72% of global greenhouse gas emissions. Thus, they are key actors in reaching the 1.5 °C goal under the Paris Agreement. However, the possible contribution and position of households in climate policies is neither well understood, nor do households receive sufficiently high priority in current climate policy strategies. This paper investigates how behavioral change can achieve a substantial reduction in greenhouse gas emissions in European high-income countries. It uses theoretical thinking and some core results from the HOPE research project, which investigated household preferences for reducing emissions in four European cities in France, Germany, Norway and Sweden. The paper makes five major points: First, car and plane mobility, meat and dairy consumption, as well as heating are the most dominant components of household footprints. Second, household living situations (demographics, size of home) greatly influence the household potential to reduce their footprint, even more than country or city location. Third, household decisions can be sequential and temporally dynamic, shifting through different phases such as childhood, adulthood, and illness. Fourth, short term voluntary efforts will not be sufficient by themselves to reach the drastic reductions needed to achieve the 1.5 °C goal; instead, households need a regulatory framework supporting their behavioral changes. Fifth, there is a mismatch between the roles and responsibilities conveyed by current climate policies and household perceptions of responsibility. We then conclude with further recommendations for research and policy.  相似文献