Texture‐based image segmentation applied to the quantification of superficial sand in salmonid river gravels     

Patrice E. Carbonneau  Normand E. Bergeron  Stuart N. Lane 《地球表面变化过程与地形》2005,30(1):121-127

The presence of ?ne sediment in river gravels is widely recognized as being detrimental to salmonid habitat quality. In order to facilitate quanti?cation of sand presence at larger scales, this paper presents an application of image processing allowing for rapid and accurate assessments of super?cial sand presence in dry exposed ?uvial gravels. Images for the process are acquired with a 35 mm SLR ?lm camera and then scanned with a desktop scanner. Texture‐based segmentation is then applied to differentiate between sand and clast areas. Results show that the method is accurate and therefore it offers an alternative to bulk sampling in cases where rapid assessments of sand presence are required. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Effet de la privation de nourriture sur la teneur en ADN de la larve de sole (Solea solea L.)     

Bergeron  Jean-Pierre; Boulhic  Michel; Galois  Robert 《ICES Journal of Marine Science》1991,48(1):127-134

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Contrasting years in the Gironde estuary (Bay of Biscay, NE Atlantic) springtime outflow and consequences for zooplankton pyruvate kinase activity and the nutritional condition of anchovy larvae: an early view   总被引：3，自引：0，他引：3  

Bergeron  Jean-Pierre 《ICES Journal of Marine Science》2004,61(6):928-932

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Tectonic Significance of the Taitung Canyon, Huatung Basin, East of Taiwan   总被引：1，自引：0，他引：1  

Jean-Claude Sibuet  Shu-Kun Hsu  Alain Normand 《Marine Geophysical Researches》2006,27(1):77-79

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Mobility of palladium chloride complexes in mafic rocks: insights from a flow-through experiment at 25 °C using air-saturated, acidic, and Cl-rich solutions     

S. A. Wood  C. Normand 《Mineralogy and Petrology》2008,92(1-2):81-97

Summary A flow-through chromatographic experiment was carried out to determine the ability of an oxidized, acidic, chloride-bearing solution to transport Pd through a column of crushed Columbia River basalt at 25 °C. An initial plug of solution containing 13.8 mg Pd/kg H₂O was loaded onto the column of crushed basalt and eluted with an air-saturated, 1 m NaCl solution of pH 3. Even after 3606 h of elution, corresponding to a fluid-rock mass ratio of 1338, less than 10% of the Pd originally loaded on the column was recovered. On the other hand, in a similar experiment involving relatively unreactive quartz sand, the Pd was almost completely recovered after the passage of only 4 pore masses of eluent (or a fluid-rock mass ratio of approximately one), a behavior similar to that of Rb. The results suggest that unrealistically large amounts of oxidizing and acidic fluids are required to react with a given mass of basalt in order to overcome the acid- and redox-buffering capacity of the rock and to mobilize palladium as a chloride complex. On the other hand, Pd-chloride complexes can be easily transported through a rock with minimal acid- and redox-buffering capacity, such as clean quartz sandstone. The implications of this study for PGE enrichments in sediment-hosted stratiform copper (Kupferschiefer type) deposits are explored briefly. Authors’ addresses: Scott A. Wood, Department of Geological Sciences, University of Idaho, Box 443022, Moscow, Idaho 83844-3022, USA; Charles Normand, Département des Sciences de la Terre et de l’Atmosphère, Université du Québec à Montréal, Case postale 8888, Succursale Centre-ville, Montréal (Québec), H3C 3P8 Canada  相似文献   

The Relationship Between Fracture Traces and Joints in a Tertiary Basin, Southwest Montana     

Noel C. Krothe  Marcel P. Bergeron 《Ground water》1981,19(2):138-143

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Hydraulic geometry and changes in flow velocity at a river confluence with coarse bed material     

Andr G. Roy  Ren Roy  Normand Bergeron 《地球表面变化过程与地形》1988,13(7):583-598

A survey of flows was conducted at a river confluence with coarse bed material. Bridges were installed on both tributaries, at the confluence and farther downstream on the receiving stream. At these stations, flow velocities were measured over a dense grid for seven conditions ranging from very low flows to the bankfull stage. Hydraulic geometry relationships established at all four stations revealed that flow is accelerated through the confluence as stage rises. At bankfull discharge, average velocity is 1.6 times higher at the confluence than on either tributary. Flow acceleration occurs at and above intermediate flow stages and is concentrated at the centre of a linear pool located at the confluence. The development of a zone of high shear stress is also associated with the cell of high flow velocity. Flow acceleration is dissipated at the exit of the pool where water surges over boulder ribs. The acceleration is not related to the development of flow separation zones as observed by Best and Reid (1984) for wide junction angles, nor is it explained by the reduction of the friction exerted by the banks. Acceleration is associated with the plan geometry of the confluence, with the lateral slopes which permit water to converge, and with a reduction in grain roughness at the confluence. Owing to the curvature of the tributary and to the acute angle of entry, relative power losses through the confluence decrease with increasing stages.  相似文献   

Coniferization of the mixed‐wood boreal forests under warm climate     

Ccile C. Remy  Dominic Senici  Han Y. H. Chen  Yves Bergeron  Martin Lavoie  Laure Paradis  Adam A. Ali 《第四纪科学杂志》2019,34(7):509-518

Mixed‐wood boreal forests are characterized by a heterogeneous landscape dominated by coniferous or deciduous species depending on stand moisture and fire activity. Our study highlights the long‐term drivers of these differences between landscapes across mixed‐wood boreal forests to improve simulated vegetation dynamics under predicted climate changes. We investigate the effects of main climate trends and wildfire activities on the vegetation dynamics of two areas characterized by different stand moisture regimes during the last 9000 years. We performed paleofire and pollen analyses in the mixed‐wood boreal forest of north‐western Ontario, derived from lacustrine sediment deposits, to reconstruct historical vegetation dynamics, which encompassed both the Holocene climatic optimum (ca. 8000–4000 a bp ) and the Neoglacial period (ca. 4000 a bp ). The past warm and dry period (Holocene climatic optimum) promoted higher fire activity that resulted in an increase in coniferous species abundance in the xeric area. The predicted warmer climate and an increase in drought events should lead to a coniferization of the xeric areas affected by high fire activity while the mesic areas may retain a higher broadleaf abundance, as these areas are not prone to an increase in fire activity. Copyright © 2019 John Wiley & Sons, Ltd.  相似文献   

Impacts of diverted freshwater on dissolved organic matter and microbial communities in Barataria Bay, Louisiana, U.S.A     

Bianchi TS  Cook RL  Perdue EM  Kolic PE  Green N  Zhang Y  Smith RW  Kolker AS  Ameen A  King G  Ojwang LM  Schneider CL  Normand AE  Hetland R 《Marine environmental research》2011,72(5):248-257

Here we present results of an initial assessment of the impacts of a water diversion event on the concentrations and chemical composition of dissolved organic matter (DOM) and bacterioplankton community composition in Barataria Bay, Louisiana U.S.A, an important estuary within the Mississippi River Delta complex. Concentrations and spectral properties of DOM, as reflected by UV/visible absorbance and fluorescence, were strikingly similar at 26 sites sampled along transects near two western and two eastern areas of Barataria Bay in July and September 2010. In September 2010, dissolved organic carbon (DOC) was significantly higher (568.1-1043 μM C, x=755.6+/-117.7 μM C, n=14) than in July 2010 (249.1-577.1 μM C, x=383.7+/-98.31 μM C, n=14); conversely, Abs254 was consistently higher at every site in July (0.105-0.314) than in September (0.080-0.221), averaging 0.24±0.06 in July and 0.15±0.04 in September. Fluorescence data via the fluorescence index (FI450/500) revealed that only 30% (8 of 26) of the July samples had an FI450/500 above 1.36, compared to 96% (25 of 26) for the September samples. This indicates a more terrestrial origin for the July DOM. Bacterioplankton from eastern sites differed in composition from bacterioplankon in western sites in July. These differences appeared to result from reduced salinities caused by the freshwater diversion. Bacterioplankton communities in September differed from those in July, but no spatial structure was observed. Thus, the trends in bacterioplankton and DOM were likely due to changes in water masses (e.g., input of Mississippi River water in July and a return to estuarine waters in September). Discharge of water from the Davis Pond Freshwater Diversion (DPFD) through Barataria Bay may have partially mitigated some adverse effects of the oil spill, inasmuch as DOM is concerned.  相似文献   

Downscaling the hydrological cycle in the Mackenzie basin with the Canadian regional climate model     

Murray D. MacKay  Ronald E. Stewart  Guy Bergeron 《大气与海洋》2013,51(3):179-211

Abstract

The Canadian Regional Climate Model (CRCM) has been nested within the Canadian Centre for Climate Modelling and Analysis ‘ second generation General Circulation Model (GCM), for a single month simulation over the Mackenzie River Basin and environs. The purpose of the study is to assess the ability of the higher resolution CRCM to downscale the hydrological cycle of the nesting GCM. A second 1‐month experiment, in which the CRCM was nested within analyzed fields of a global data assimilation system, was also performed to examine the sensitivity of the basin moisture budget to atmospheric lateral boundary forcing.

We have found that the CRCM can produce realistic lee cyclogenesis, preferentially in the Liard sub‐basin, along with associated circulation and precipitation patterns, as well as an improved rainshadow in the lee of the Rocky Mountains compared to the GCM. While these features do quantitatively affect the monthly average climate statistics, the basin scale moisture budgets of the models were remarkably similar, though some of this agreement is due to compensating errors in the GCM. Both models produced excessive precipitation compared to a recent climatology for the region, the cause of which is traced to lateral boundary forcing. A second experiment, identical to the first except that the CRCM was forced with analyzed fields at the lateral boundaries, produced a qualitatively different basin moisture budget, including a much more realistic precipitation field. Errors in the moisture budget of the first experiment appear to be associated with the poor representation of the Aleutian Low in the GCM, and do not appear to be strongly connected to (local) surface processes within the models. This suggests that an effective strategy for modelling the hydrological cycle of the Mackenzie Basin on the fast climate timescale ‐ a major requirement of the Mackenzie GEWEX Study ‐ will involve nesting the CRCM within analyzed (or re‐analyzed) atmospheric fields.  相似文献