Spatial Variability of Sampling: Grid Size Impact on Atmospheric Metals and Trace Elements Deposition Mapping with Mosses     

Géraldine Amblard-Gross  Armand Maul  Jean-François Férard  Francine Carrot  Sophie Ayrault 《Journal of Atmospheric Chemistry》2004,49(1-3):39-52

This paper deals with the spatial heterogeneity structure and the influence of the precision of moss data on results interpretation as real spatial variations of atmospheric heavy metal deposition. Different sizes of map mesh net (unit I of 30 × 30 km, unit II of 10 × 10 km, unit III of 3 × 3 km) have divided an area of 90 × 90 km. The protocol used is a nested design with three levels and random draws. The statistical method of components of variance analysis estimates the associated variability for each mesh size. Our results show the poor precision of this biological tool for map purposes on a little scale (unit III). Furthermore, the high residual variance of As, Ba, Cd, Co, Cu, La, Ti, and U hides the spatial variations associated with mesh sizes. In order to obtain useful maps, it should be reasonable to use a 30 × 30 km mesh size, or even larger, to build spatial variation maps of Pb, Sb and with more caution for Cu, Sr, Rb and Zn. For V, As and Cd, the residual variability of moss data was too important to guarantee any spatial origin to the mapped variations. The cost–benefit study shows that the sampling effort has to be concentrated on unit I of 30 × 30 km to optimize future campaigns, and with a particular stress on the sampling repetitions for Cu, Pb, and Sb.  相似文献   

Reconstruction of Middle to Late Quaternary sea level using submerged speleothems from the northeastern Yucatán Peninsula     

Simon D. Steidle  Sophie F. Warken  Nils Schorndorf  Julius Förstel  Andrea Schröder-Ritzrau  Gina E. Moseley  Christoph Spötl  Jeronimo Aviles  Wolfgang Stinnesbeck  Norbert Frank 《第四纪科学杂志》2021,36(7):1190-1200

We examined 14 subaerially deposited speleothems retrieved from submerged caves in the northeastern Yucatán Peninsula (Mexico). These speleothems grew during the Middle to Late Quaternary and were dated by ²³⁰Th-U techniques to provide upper depth limits for past sea levels. We report the first relative sea-level limits for Marine Isotope Stages (MIS) 11 and 6, and present new evidence for sea-level oscillations during MIS 5 and early MIS 1. For the latter periods, the origin of growth interruptions is evaluated by combining petrographic methods with trace element analyses. The MIS 5c sea-level highstand probably occurred between 103.94 ± 0.58 ka and 96.82 ± 0.42 ka and must have exceeded -10.8 m (relative to present-day local sea level). The minimum average rate of sea-level fall over a 9.4 ka-long period during the MIS 5e/5d transition is calculated from stalagmite and published coral data at 1.74 ± 0.37 m/ka. For the early Holocene, previous discrepancies with respect to a potential multimetre oscillation of local sea level were found to be challenging to reconcile with the existing speleothem data from the area.  相似文献   

Erosion and Drainage Well Blowout in the Foundation of the Plavinas Powerhouse: Case History     

Sophie Messerklinger 《Geotechnical and Geological Engineering》2012,30(6):1421-1433

The Plavinas run-off river scheme in Latvia is founded on fine-grained deposits with artesian aquifers. These aquifers are drained with free flowing wells to assure the stability of the structures. In March 1979, one of these wells suddenly discharged high amounts of solids together with the drainage water. After a few days the water discharge stopped, the artesian pressures in the foundation increased and dirty water flew from the bottom of the tailrace channel area. Foundation failure could be mitigated by turning piezometers into free flowing relief wells. However, it was a critical situation for the powerhouse and caused significant permanent displacements of the concrete structures. A root-cause analysis was performed which is presented in this paper. It was found that caverns at the interface of alluvial and fine-grained deposits formed due to erosion of the fine fractions of the alluvium through the drainage wells. Such a cavern collapsed which caused the well blowout and the plugging of the drainage well resulting in increasing pore water pressures and local liquefaction of the powerhouse foundation.  相似文献   

Diurnal and tidal patterns of carbon uptake and calcification in geniculate inter‐tidal coralline algae          下载免费PDF全文

Sophie J. McCoy  Catherine A. Pfister  Gerard Olack  Albert S. Colman 《Marine Ecology》2016,37(3):553-564

Research on coralline algal responses to ocean acidification and other environmental stressors has increased in recent years as coralline algae is thought to stand a higher chance of being affected by acidification stress than other macroalgae. To provide context and enhance the existing eco‐physiological framework for climate change studies, it is important to understand the effects of non‐extreme stressors experienced regularly by inter‐tidal coralline algae. In this study, we tested the potentially interacting effects of diurnal and tidal treatments on calcification in the geniculate coralline algae Corallina frondescens and Corallina vancouveriensis using ¹³C‐labeled bicarbonate. Both species deposited more calcium carbonate during the day than at night, and also when submerged (high tide) compared with when emerged (low tide) in their apical and mature segments (intergenicula). These results indicate that inter‐tidal coralline algae do in fact pay a cost for living inter‐tidally at the edge of an adaptive zone.  相似文献   

Summer air temperature,reconstructions from the last glacial stage based on rodents from the site Taillis-des-Coteaux (Vienne), Western France     

Aurélien Royer  Christophe Lécuyer  Sophie Montuire  Jérôme Primault  François Fourel  Marcel Jeannet 《Quaternary Research》2014

The oxygen isotope composition of phosphate from tooth enamel of rodents (δ¹⁸O_p) constitutes a valuable proxy to reconstruct past air temperatures in continental environments. This method has been applied to rodent dental remains from three genera, Arvicola sp., Microtus sp. and Dicrostonyx sp., coming from Taillis-des-Coteaux, Vienne, France. This archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole Upper Palaeolithic, including seven stratigraphic layers dated from 35 to 17 cal ka BP. The abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation of the site. Differences between δ¹⁸O_p values of Arvicola sp. and Microtus sp. teeth are interpreted as the result of heterochrony in tooth formation as well as differences in ecology. Mean δ¹⁸O_p values of Microtus sp. are preferentially used to reconstruct summer air temperatures, which range from 16.0 ± 3.7 to 19.1 ± 3.1°C throughout the sedimentary sequence; however, the highest variability is observed during the last glacial maximum.  相似文献   

Geodynamic and climate controls in the formation of Mio–Pliocene world-class oxidized cobalt and manganese ores in the Katanga province, DR Congo     

Sophie Decrée  Étienne Deloule  Gilles Ruffet  Stijn Dewaele  Florias Mees  Christian Marignac  Johan Yans  Thierry De Putter 《Mineralium Deposita》2010,45(7):621-629

The Katanga province, Democratic Republic of Congo, hosts world-class cobalt deposits accounting for ~50% of the world reserves. They originated from sediment-hosted stratiform copper and cobalt sulfide deposits within Neoproterozoic metasedimentary rocks. Heterogenite, the main oxidized cobalt mineral, is concentrated as “cobalt caps” along the top of silicified dolomite inselbergs. The supergene cobalt enrichment process is part of a regional process of residual ore formation that also forms world-class “manganese cap” deposits in western Katanga, i.e., the “black earths” that are exploited by both industrial and artisanal mining. Here, we provide constraints on the genesis and the timing of these deposits. Ar–Ar analyses of oxidized Mn ore and in situ U–Pb SIMS measurements of heterogenite yield Mio–Pliocene ages. The Ar–Ar ages suggest a multi-phase process, starting in the Late Miocene (10–5 Ma), when the metal-rich substratum was exposed to the action of meteoric fluids, due to major regional uplift. Further oxidation took place in the Pliocene (3.7–2.3 Ma) and formed most of the observed deposits under humid conditions: Co- and Mn-caps on metal-rich substrata, and coeval Fe laterites on barren areas. These deposits formed prior to the regional shift toward more arid conditions in Central Africa. Arid conditions still prevailed during the Quaternary and resulted in erosion and valley incision, which dismantled the metal-bearing caps and led to ore accumulation in valleys and along foot slopes.  相似文献   

Comparative Analysis of Stability—Genetic Diversity in Seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) Meadows Yields Unexpected Results     

Sophie Arnaud-Haond  Núria Marbà  Elena Diaz-Almela  Ester A. Serrão  Carlos M. Duarte 《Estuaries and Coasts》2010,33(4):878-889

The diversity–stability relationship is the subject of a long-standing debate in ecology, but the genetic component of diversity has seldom been explored. In this study, we analyzed the interplay between genetic diversity and demographic responses to environmental pressures. This analysis included 30 meadows formed by the Mediterranean endemic seagrass, Posidonia oceanica, showing a wide range of population dynamics ranging from a near equilibrium state to steep decline due to strong environmental pressures close to aquaculture installations. Our results show that sedimentation rates are much better predictors of mortality than clonal or genetic components. An unexpected positive trend was observed between genotypic diversity and mortality, along with a negative relationship between allelic richness and net population growth. Yet such trends disappeared when excluding the most extreme cases of disturbance and mortality, suggesting the occurrence of a threshold below which no relationship exists. These results contrast with the positive relationship between genotypic diversity and resistance or resilience observed in previous manipulative experiments on seagrass. We discuss the reasons for this discrepancy, including the difficulties in designing experiments reflecting the complexity of natural meadows.  相似文献   

Reply to Letter to the Editor by J. Rodríguez     

Sophie Montuire 《Quaternary Research》2000,54(3)

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