Assessing climatic exposure of grassland-based livestock systems with seasonal-scale indicators     

Marion Sautier  Roger Martin-Clouaire  Robert Faivre  Michel Duru 《Climatic change》2013,120(1-2):341-355

Research aiming to reduce the vulnerability of agricultural systems to climate variability and change requires practical appraisal of their climatic exposure. We propose a method to map local climatic conditions over a given period to a set of productivity and management-related indicators that are specific to grassland-based livestock systems. Our method based on a reference system balances herbage production and feed requirements over a long period (≥ 30 years) and provides boundaries for productivity-defined seasons and indicators for surplus or shortage of herbage at seasonal and annual scales. This exposure-assessment method was applied to five climatically contrasting locations in south-western France. The trends and variability of the exposure indicators were analysed for past (1980–2010) and future (2035–2065) periods, considering the A1B scenario of the IPCC. Despite high year-to-year variability and the heterogeneity of the climatic situations studied, we show that climate change can modify the boundaries of productivity-defined seasons and seasonal herbage surplus or shortage. Moreover, the exposure indicators succeed in detecting climate-induced changes and distinguishing situations where a classical exposure indicator, such as annual forage production, could not. The exposure indicators highlight the forage productivity and the timing of production associated with local climatic conditions. These features fit the temporal scale at which farmers consider farm management and are highly suitable for identifying adaptation strategies that reduce the vulnerability of grassland-based livestock systems.  相似文献   

The phase 0/A study of the ESA M3 mission candidate EChO     

Ludovic Puig  Kate Isaak  Martin Linder  Isabel Escudero  Pierre-Elie Crouzet  Roger Walker  Matthias Ehle  Jutta Hübner  Rainer Timm  Bram de Vogeleer  Pierre Drossart  Paul Hartogh  Christophe Lovis  Giusi Micela  Marc Ollivier  Ignasi Ribas  Ignas Snellen  Bruce Swinyard  Giovanna Tinetti  Paul Eccleston 《Experimental Astronomy》2015,40(2-3):393-425

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Arsenic species in weathering mine tailings and biogenic solids at the Lava Cap Mine Superfund Site,Nevada City,CA     

Foster AL  Ashley RP  Rytuba JJ 《Geochemical transactions》2011,12(1):1

Background  

A realistic estimation of the health risk of human exposure to solid-phase arsenic (As) derived from historic mining operations is a major challenge to redevelopment of California's famed "Mother Lode" region. Arsenic, a known carcinogen, occurs in multiple solid forms that vary in bioaccessibility. X-ray absorption fine-structure spectroscopy (XAFS) was used to identify and quantify the forms of As in mine wastes and biogenic solids at the Lava Cap Mine Superfund (LCMS) site, a historic "Mother Lode" gold mine. Principal component analysis (PCA) was used to assess variance within water chemistry, solids chemistry, and XAFS spectral datasets. Linear combination, least-squares fits constrained in part by PCA results were then used to quantify arsenic speciation in XAFS spectra of tailings and biogenic solids.  相似文献   

Tritium�Chelium groundwater age used to constrain a groundwater flow model of a valley-fill aquifer contaminated with trichloroethylene (Quebec, Canada)     

Samantha Murphy  Thomas Ouellon  Jean-Marc Ballard  Ren�� Lefebvre  Ian D. Clark 《Hydrogeology Journal》2011,19(1):195-207

Tritium?Chelium groundwater dating was carried out in a trichloroethylene (TCE)-contaminated valley-fill aquifer system in Quebec, Canada, where a numerical groundwater flow model was developed. Forty seven discrete groundwater and dissolved gas samples were obtained along two flow paths originating from known TCE source zones whose related plumes converge down gradient to form a single plume. Sampling points in monitoring wells were projected onto vertical sections showing particle tracks along the two flow paths. At these points, simulated advective ages obtained from particle tracking were matched to tritium?Chelium ages using different porosity values; the best match was 0.35. Ages were also obtained above and below a prodeltaic silty aquitard in a portion of the aquifer where some source zones are located, which provide groundwater and TCE transit times through the aquitard as well as a mean vertical hydraulic conductivity that agrees with previous estimates used in the model. In certain locations, anomalously old ages associated with high terrigenic ⁴He indicate areas where groundwater from the underlying proglacial unit flows upward into the deltaic sand aquifer through aquitard windows. Upflow locations correspond with increased TCE concentrations, suggesting significant TCE provenance through the proglacial unit originating from a previously unrecognized TCE source zone.  相似文献   

New constraints on the Messinian sealevel drawdown from 3D seismic data of the Ebro Margin,western Mediterranean     

Roger Urgeles  Angelo Camerlenghi  Daniel Garcia‐Castellanos  Ben De Mol  Miquel Garcés  Jaume Vergés  Ian Haslam  Martin Hardman 《Basin Research》2011,23(2):123-145

We present new 3D seismic and well data from the Ebro Margin, NW Mediterranean Sea, to shed new light on the processes that formed the Messinian Erosion Surfaces (MES) of the Valencia Trough (Mediterranean Sea). We combine these data with backstripping techniques to provide a minimum estimate of the Messinian sea level fall in the EBRO Margin, as well as coupled isostasy and river incision and transport modeling to offer new constraints on the evolution of the adjacent subaerial Ebro Basin. Four major seismic units are identified on the Cenozoic Ebro Margin, based on the seismic data, including two major prograding megasequences that are separated by a major unconfirmity: the MES. The 3D seismic data provide an unprecedented view of the MES and display characteristic features of subaerial incision, including a drainage network with tributaries of at least five different orders, terraces and meandering rivers. The Messinian landscape presents a characteristic stepped‐like profile that allows the margin to be subdivided in three different regions roughly parallel to the coastline. No major tectonic control exists on the boundaries between these regions. The boundary between the two most distal regions marks the location of a relatively stable base level, and this is used in backstripping analysis to estimate the magnitude of sea level drop associated with the Messinian Salinity Crisis on the Ebro Margin. The MES on the Ebro Margin is dominated by a major fluvial system, that we identify here as the Messinian Ebro River. The 3D seismic data, onshore geology and modeling results indicate that the Ebro River drained the Ebro Basin well in advance of the Messinian.  相似文献   

An unexpected outburst from A0535+262     

A. B. Hill  A. J. Bird  A. J. Dean  V. A. McBride  V. Sguera †  D. J. Clark  M. Molina  S. Scaringi  S. E. Shaw 《Monthly notices of the Royal Astronomical Society》2007,381(3):1275-1279

A0535+262 is a transient Be/X-ray binary system which was in a quiescent phase from 1994 to 2005. In this paper we report on the timing and spectral properties of the INTEGRAL detection of the source in 2003 October. The source is detected for ∼6000 s in the 18–100 keV energy band at a luminosity of  ∼3.8 × 10³⁵ erg s⁻¹  ; this is compatible with the high end of the range of luminosities expected for quiescent emission. The system is observed to be outside of the centrifugal inhibition regime and pulsations are detected with periodicity,   P = 103.7 ± 0.1 s  . An examination of the pulse history of the source shows that it had been in a constant state of spin-down since it entered the quiescent phase in 1994. The rate of spin-down implies the consistent presence of an accretion disc supplying torques to the pulsar. The observations show that the system is still active and highly variable even in the absence of recent Type I or Type II X-ray outbursts.  相似文献   

On the origin of the absorption features in SS 433     

A. D. Barnes  J. Casares  P. A. Charles  J. S. Clark  R. Cornelisse  C. Knigge  D. Steeghs 《Monthly notices of the Royal Astronomical Society》2006,365(1):296-302

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Acoustic detections of blue whale (Balaenoptera musculus) and fin whale (B. physalus) sounds during a SURTASS LFA exercise     

Clark  C.W. Altman  N.S. 《Oceanic Engineering, IEEE Journal of》2006,31(1):120-128

Acoustic data collected on the R/V Cory Chouest in February and March 1996 during an active operation of the U.S. Navy's surveillance-towed-array-sensor-system low-frequency-active (LFA) sonar were analyzed for blue whale (Balaenoptera musculus) and fin whale (B. physalus) sounds. Operational monitoring and mitigation protocols were implemented throughout the exercise to reduce the chances of an acoustic impact on marine mammals and sea turtles. The operational schedule did not include intentional "control" periods without transmissions but did include periods when the LFA sonar was not operating for other reasons (e.g., repairs). There were insufficient detections of blue whales for further analysis. Fin whale acoustic detection probabilities were calculated from the postprocessed data. A local-linear-regression analysis was used to compare fin whale detection probabilities from 2065 11-min intervals under conditions when the LFA sonar was and was not transmitting. There was an indication of a slightly higher probability of detecting fin whale sounds during periods when there were no LFA transmissions than during periods with transmissions. This may be the result of the following: 1) Reduced vocal activity by whales in response to LFA transmissions; 2) the effect of the mitigation protocols; or 3) some combination of 1) and 2). The data presently available do not allow one to distinguish definitively between these explanations, mainly because there were not enough data recorded for periods without LFA transmissions.  相似文献   

Young star clusters immersed in intermediate-age fields in the Small Magellanic Cloud     

Andrés E. Piatti  Ata Sarajedini  Doug Geisler  David Clark  Juan Seguel 《Monthly notices of the Royal Astronomical Society》2007,377(1):300-316

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Paul Pellas (1924–1997)     

Brigitte Zanda  Roger H. Hewins  Jean-Pierre Bibring 《Meteoritics & planetary science》1997,32(6):983-984

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