A new look at an old problem: magnetotelluric modelling of 1-D structures   总被引：2，自引：0，他引：2  

Gaston Fischer  Pascal Weibel 《Geophysical Journal International》1991,106(1):161-167

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Evidence for increased ingestion of plastics by northern fulmars (Fulmarus glacialis) in the Canadian Arctic     

Jennifer F. Provencher  Anthony J. Gaston 《Marine pollution bulletin》2009,58(7):1092-1472

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Time series data for Canadian arctic vertebrates: IPY contributions to science, management, and policy     

S. H. Ferguson  D. Berteaux  A. J. Gaston  J. W. Higdon  N. Lecomte  N. Lunn  M. L. Mallory  J. Reist  D. Russell  N. G. Yoccoz  X. Zhu 《Climatic change》2012,115(1):235-258

Long-term data are critically important to science, management, and policy formation. Here we describe a number of data collections from arctic Canada that monitor vertebrate population trends of freshwater and marine fish, marine birds, marine and terrestrial mammals. These time series data cover the last ca. 30?years and capture a period from the onset of global changes affecting the Arctic up to recent years with a rapid increase in temperature. While many of these data collections were initiated through a variety of government and university programs, they also include a surge in polar research launched with the recent International Polar Year (2007?C2008). We estimated the long-term vertebrate index from our data that summarizes various taxa abundance trends within a global context and observed a continuous decline of about 30?% in population abundance since the 1990s. Though most data collections are biased towards few taxa, we conduct time-series analyses to show that the potential value of long-term data emerges as individual monitoring sites can be spread across space and time scales. Despite covering a handful of populations, the different time series data covered a large spectrum of dynamics, cyclic to non-cyclic, including coherence with the North Atlantic Oscillation, lag effects, and density dependence. We describe a synthesis framework to integrate ecological time-series research and thereby derive additional benefits to management, science, and policy. Future requirements include: (1) continuation of current observation systems; (2) expansion of current monitoring sites to include additional trophic links and taxonomic indicators; (3) expansion beyond the existing program to include greater spatial coverage into less-sampled ecosystems and key representative locations; and (4) integration of circumpolar observations and comprehensive analyses. Development of a circumpolar observation system is necessary for innovative science, large-scale adaptive management, and policy revision essential to respond to rapid global change.  相似文献   

Further Documentary Evidence of Northern Hemispheric Coverage of the Great Dry Fog of 1783     

Gaston R. Demarée  Astrid E.J. Ogilvie  De'er Zhang 《Climatic change》1998,39(4):727-730

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Remarkably uniform oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble,with special reference to Vietnamese deposits     

Anthony E. Fallick  Gaston Giuliani  Thomas Rigaudier  Adrian J. Boyce  Van Long Pham  Vincent Pardieu 《Comptes Rendus Geoscience》2019,351(1):27-36

Oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble from Vietnam and other worldwide deposits have been determined in order to characterize the O-isotope fractionation between calcite and spinel. In Vietnam, the Δ¹⁸O_cc–sp (= 3.7 ± 0.1‰ for six samples from the An Phu and Cong Troi deposits) is remarkably constant. The combination of these data with those obtained on calcite–spinel pairs of Paigutan (Nepal, n = 2), Ipanko (Tanzania, n = 1), and Mogok (Myanmar, = 2) are also consistent with an overall Δ¹⁸O_cc–sp of 3.6 ± 0.3‰ for all the spinel samples (n = 11). The straight line correlation δ¹⁸O_cc = 0.96 δ¹⁸O_sp + 4.4 is excellent despite their worldwide geographic spread. The increment method of calculating oxygen isotope fractionation gave a geologically unreasonable temperature of formation for both minerals at 1374 °C when compared to temperatures obtained by mineral assemblage equilibrium of these marble type deposits, between 610 and 750 °C. The constant Δ¹⁸O_cc–sp reflects a constant temperature for this amphibolite facies assemblage, whose current best estimate is calculated at 620 ± 40 °C, but unquantified uncertainties remain.  相似文献   

Biomass variations of estuarine macrobenthos preserved in ethanol and formalin     

G. R. Gaston  J. H. W. Bartlett  A. P. McAllister  R. W. Heard 《Estuaries and Coasts》1996,19(3):674-679

Three preservative treatments were compared for their effects on biomass of macrobenthic species collected at Biloxi Bay, Mississippi. We tested the hypothesis that biomass did not differ among treatments once specimens were fixed in 10% formalin. Two commonly used analyses, wet-weight biomass and dry-weight biomass, were tested. Wetweight variations among treatments were compared over time. Dry-weight calculations were not possible on individuals over time because specimens could be dried only once, so ratios of dry weight to wet weight were calculated on specimens at the conclusion of each treatment. Specimens were fixed in 10% formalin for 2 wk, then transferred to either 1% formalin or 70% ethanol, or left in 10% formalin. Wet-weight biomass of the three treatments was determined weekly four times, and then specimens were dried for 72 h at 60°C for dry-weight determinations. Biomass of most taxa fixed in formalin and preserved in ethanol or formalin did not vary significantly in wet weight over time. Minor variations among the treatments occurred in dry-weight biomass. Whereas previous investigators found that ethanol effected biomass when specimens were not formalin-fixed, our results supported the premise that three commonly used preservative treatments did not differ in their effects on biomass of estuarine macrobenthos. Therefore, we propose that estuarine macrobenthos be fixed in formalin, then transferred to ethanol for biomass procedures in order to avoid exposure of laboratory personnel to carcinogenic formalin.  相似文献   

Ilot de chaleur a Quebec: Cas d'ete     

Richard Leduc  Michel Ferland  Jacques Gariepy  Ghislain Jacques  Claude Lelievre  Gaston Paulin 《Boundary-Layer Meteorology》1980,19(4):471-480

This paper studies the urban heat island in Quebec City and its suburbs on one summer night. The region under study covers an area of 20 km by 20 km which streches from lake Saint-Charles on the north to Levis on the south and from the western suburb of Cap-Rouge to Beauport on the east. The total population of the region is about 400 000.On August 22, 1979 from 22:00 to 23:30 EDT, 109 measurements of wet- and dry-bulb temperatures were taken at preselected points. On that day, a large high pressure system gave clear skies to central Quebec while Quebec City Airport recorded a maximum temperature of 23 °C. The average wind measured at Duberger meteorological tower between 6 and 121 m above ground was 1.8 m s^-1 at 22:00 EDT and 0.9 m s^-1 at 23:30 EDT. Additional data were obtained from three thermographs installed at strategic points and five regular climatological stations, which were used to estimate cooling rates.During the period of measurement, the cooling rate averaged over the eight reference points was about 0.7 °C h^-1. However, the maximum cooling rate, which occured earlier, ranged from 2.2 °C h^-1 at Duberger to 4.4 °C h^-1 at Courville-de-Poissy. No relation seems to exist, in our case, between the maximum cooling rate and the heat island spatial structure. Comparison of these results with the ones given by Oke et al. (1972) shows that the eight stations behaved more like rural stations than urban ones.The temperature gradient measured between the center of old Quebec City and the suburbs averaged 6 °C while it was 9 °C for the coldest spot. Clo units were used to characterize the microclimates prevailing on the region for that night; 1 clo would be sufficient for comfort downtown while 1.5 clo is needed in the coldest spot for a slowly walking person. Large open areas like parks or the Laval University campus had a definite effect on temperature.The humidity was calculated for each point using standard psychrometric tables; no significant difference could be found over the area expect at points near or above the St. Laurent river where the average dew point was 1.5 °C higher.Each point was classified into 6 categories according to its predominant land-use as reported by the observers. A multiple regression between temperature on the one hand and altitude and land-use on the other hand was tried; it showed that temperature was significantly correlated with both. Such an equation could be used by town-planners to locate temperature gradients in future urban development over the area; land uses could be planned to enhance or reduce these gradients.This study confirms the idea that urban climate is a mosaic of interacting micro-climates. More measurements, including possibly airborne infra-red thermal imagery, will be taken during winter in order to assess the winter urban climate of Quebec City.  相似文献   

Trophic structure of macrobenthic communities in the Calcasieu estuary,Louisiana     

Gary R. Gaston  Jeanne C. Nasci 《Estuaries and Coasts》1988,11(3):201-211

Trophic groups were used to investigate broad patterns and predict species interactions of macrobenthic assemblages in Calcasieu Estuary, Louisiana. Macrobenthic assemblages of the estuary were numerically dominated by deposit-feeding species. Surface-deposit feeders were the most abundant macrobenthos of the upper estuary, subsurface-deposit feeders dominated the lower estuary, and a trophically well-mixed assemblage inhabited the middle estuary. There were periodic shifts in species dominance within each region, but the shifts were without temporal pattern and seldom led to changes in trophic structure of the region. The macrobenthic assemblages of the upper estuary were dominated by several early-colonizing species which switched feeding modes with changes in water flow, suggesting that disturbances in the upper estuary had a direct effect on macrobenthic communities. Disturbances also may have eliminated macrobenthic species before they could establish a well-mixed community. The presence of trophically mixed communities in the middle estuary probably was indicative of fewer disturbances there. The dominance by subsurface-deposit feeders in the lower estuary probably indicates that sedimentary food in Calcasieu Lake was seldom utilized at the sediment-water interface. Rather, most food became buried and was available only to subsurface-deposit feeders.  相似文献   

Rotational properties of the magnetotelluric impedance tensor: the example of the Araguainha impact crater, Brazil   总被引：3，自引：0，他引：3  

Gaston Fischer  Wilhelm Masero 《Geophysical Journal International》1994,119(2):548-560

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Ecology of Barnegat Bay,New Jersey     

Gary R. Gaston 《Estuaries and Coasts》1985,8(3):326-327

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