The identification of conceptual hydrological models for surface water acidification     

H. S. Wheater  K. H. Bishop  M. B. Beck 《水文研究》1986,1(1):89-109

Ambiguity in parameter identification represents a potentially serious limitation to the application of models of surface water acidification. Previous work has concentrated on manipulation of two of the three factors affecting model identifiability, namely model structure and estimator properties. A new technique is proposed which uses different modes of response within the data to improve parameter identification. Preliminary results, obtained using the Birkenes model of surface water acidification, appear to show promise. The technique is robust in recovering model parameters from synthetic data, with and without error, and in assimilating problems of structural error.  相似文献   

The late Quaternary sedimentary infill of Lake Annecy (northwestern Alps): an overview from two seismic-reflection surveys     

Christian Beck  Pieter Van Rensbergen  Marc De Batist  Fernand Berthier  Serge Lallier  Frédéric Manalt 《Journal of Paleolimnology》2001,25(2):149-161

The sedimentary fill of Lake Annecy (northwestern Alps) - related to the last glacial/post-glacial episode - was investigated through high resolution (sparker) and very high resolution (2.5 kHz) seismic-reflection surveys. A seismostratigraphic approach led to subdivision of a 150 m-thick pile (maximum thickness in axial part) into five units. Basal units (1 and 2) represent an imbrication of subglacial and glacio-lacustrine deposits, close to the grounding line of the glaciers' fronts (respectively at the northern and southern terminations of the lake). The first acoustically well-stratified unit (3) developed during a fast retreat of the glaciers fronts far from the lake basin, and a progradational alluvial regime, with abundant underflows, in a lake larger than the present one. Unit 4 represents the progressive decrease of this clastic input mixed with the progressive development of in situ bio-induced production. As in many other alpine lakes, a topmost unit (5), relatively thin (about 8-10 m) and with a conspicuous drape configuration, is the signature of the Holocene interglacial climatic conditions with a sedimentation rate of about 1 mm/yr. On the lacustrine basin slopes, slumps and debris flow occurred mainly within Unit 3; they may be due to, either climate-induced high rate terrigenous sedimentation, or/and to a period of increased seismo-tectonic activity.  相似文献   

The environmental significance of magnetic measurements of Late Pleistocene and Holocene sediments from the Grand Lac d'Annecy, eastern France     

Yuguan Hu  Frank Oldfield  Frédéric Manalt  Christian Beck 《Journal of Paleolimnology》2001,25(2):193-203

The results of a series of magnetic measurements on sediment samples are illustrated by means of examples selected from a more specialized parallel publication (Hu & Oldfield, submitted). They are interpreted in terms of magnetic components, notably, 'magnetite' of varying grain size/domain state, haematite, goethite and greigite. Wherever possible, some indication is given of changes in the relative importance of the various magnetic grain size and mineral phases through time. The main components of the magnetic assemblage are described for each of the main lithological units identified in the long core which is considered elsewhere in this volume. These assemblages are related to source areas and to depositional processes, especially in the pre-Holocene parts of the core. In the Holocene sediments, the magnetic properties cannot be interpreted solely in terms of shifts in detrital mineral sources. Evidence is presented for the presence of both biogenic magnetite and authigenic greigite. The most recent sediments point to renewed catchment erosion, probably as a result of human activity during historical times.  相似文献   

Investigation of Possible Contamination of Shallow Ground Water by Deeply Injected Liquid Industrial Wastes     

Suzanne Lesage  Richard E. Jackson  Mark Priddle  Paul Beck  Ken G. Raven 《Ground Water Monitoring & Remediation》1991,11(1):151-159

The objective of this study was to assess the possible impact of deep well disposal operations, conducted between 1958 and 1974, on the ground water quality in a shallow fresh water aquifer beneath Sarnia, Ontario, Canada. Because of the breakout of formation fluids in Sarnia and Port Huron, Michigan, in the early 1970s, it had been hypothesized that liquid waste from the disposal zone in bedrock had leaked through numerous abandoned oil, gas, and salt wells in the area up to the shallow fresh water aquifer and from there to the surface.
A monitoring well network of 29 5cm (2 inch) diameter piezometers was established in the thin sand and shale aquifer system, which exists between 30 and 70m (100 and 230 feet) below ground surface. In addition, a 300m (1000 foot) deep borehole was drilled and instrumented with a Westbay multilevel casing, which permitted sampling of the disposal zone.
Ground water samples from the shallow monitoring wells and the Westbay multilevel casing were analyzed for volatiles by GC/MS. Those volatile aromatics that were conspicuously present in the deep disposal zone, e.g., ethyl toluenes and trimethyl benzene, were not detected in the shallow monitoring wells. Thus, if contaminants from the disposal zone did indeed migrate to the shallow aquifer, contamination was not widespread and probably consisted mostly of displaced chloride-rich formation waters.  相似文献   

Hydrogeologic controls on peatland development in the Malloryville Wetland, New York (USA)     

J.P. McNamara  D.I. Siegel  P.H. Glaser  R.M. Beck 《Journal of Hydrology》1992,140(1-4):279-296

The Malloryville Wetland Complex, a small kettle-hole peatland, contains a diversity of peatland types. The wetland has a ‘rich’ side that contains wetland vegetation associated with solute-rich, near-neutral pH (minerotrophic) water, and a ‘poor’ side containing vegetation that grows in solute-poor and acidic (ombrotrophic) water. Vertical head gradients at piezometer clusters located in the rich side clearly show that groundwater is moving upwards towards the land surface, consistent with the vegetation types and surface water quality. In contrast, vertical head gradients also show that groundwater is moving upward in the poor side even though the vegetation and surface water chemistry are not minerotrophic. An incipient raised bog in the center of the poor side is the only site where groundwater moves consistently downward.

A peat core collected at the bog center shows that the bog site was initially covered by minerotrophic vegetation, typically found in groundwater discharge zones, which was later replaced by ombrotrophic bog vegetation. Theoretical computer simulation experiments of the bog hydrogeologic setting through time suggest that the direction of vertical groundwater flow at the bog site permanently changed from up to down when a water table mound developed under a convex-shaped fen peat mound that probably formed because of differential peat accumulation. Ombrotrophic conditions and bog vegetation probably began when the fen water table mound grew sufficiently large enough to divert the upward movement of regional groundwater. The transition from rich to poor environments probably occurred when the wetland water table was substantially below the elevation of the surrounding regional water table.  相似文献   

Hydrogeologic Factors Affecting New Sinkhole Development in the Orlando Area, Florida   总被引：2，自引：0，他引：2  

William L. Wilson  Barry F. Beck 《Ground water》1992,30(6):918-930

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A comparison of greenness measures in two semi-arid grasslands   总被引：5，自引：0，他引：5  

Louisa R. Beck  Charles F. Hutchinson  Jeffery Zauderer 《Climatic change》1990,17(2-3):287-303

A field experiment was conducted during 1988 in a semi-arid grassland along a portion of the U.S./Mexico border in which the utility of NDVI-transformed data for estimating green vegetation amount and cover was explored. Results showed that, although there was significant difference in green and total biomass between the U.S. and Mexico sites, we were unable to find any correlation between either these vegetation parameters and NDVI values calculated from reflectance measurements. Based on these results, it would appear that semi-arid perennial grasslands can pose problems for remote sensing analysis due to their erectophile structure, the likelihood of significant accumulation of senescent biomass, and dominance of soil background in sparsely vegetated areas. Therefore, if remotely-sensed data, and indices derived from them, are to be used in global change models, it is critical to establish if these indices are sufficiently sensitive to distinguish long-term change from the seasonal and spatial variability in vegetation biomass normally found within these perennial grassland communities.  相似文献   

Gold mineralisations in the SW Iberian Pyrite Belt     

G. K. Strauss  J. S. Beck 《Mineralium Deposita》1990,25(4):237-245

The occurrence and distribution of gold in the massive sulfide orebodies of the upper Palaeozoic volcano-sedimentary environment of the SW Iberian Pyrite Belt have long been assumed to be quite uniform. Recent investigations in several working mines indicate that the gold content of the ores varies between ore types, and is controlled by physico-chemical and time factors during deposition. Above-average gold grades occur in the following ore types: lead-zinc-rich ores, situated laterally and on top of the massive sulfide lenses; copper-rich siliceous basal ore facies; footwall stringer sulfides; and gangue-rich massive sulfides (siliceous, carbonate-rich, baryte bearing, or carbonaceous matrix). Exploration possibilities therefore are promising in foot- and hanging-wall environments within an orebody, as well as in disseminated and stringer ores in its footwall.  相似文献   

Multiproxy record for the last 4500 years from Lake Shkodra (Albania/Montenegro)     

Giovanni Zanchetta  Aurelien Van Welden  Ilaria Baneschi  Russell Drysdale  Laura Sadori  Neil Roberts  Marco Giardini  Christian Beck  Vincenzo Pascucci  Roberto Sulpizio 《第四纪科学杂志》2012,27(8):780-789

A multi‐proxy record is presented for approximately the last 4500 cal a BP from Lake Shkodra, Albania/Montenegro. Lithological analyses, C/N ratio and δ¹³C of the organic and inorganic carbon component suggest that organic matter and bulk carbonate are predominantly authigenic. The δ¹⁸O record of bulk carbonate indicates the presence of two prominent wet periods: one at ca. 4300 cal a BP and one at ca. 2500–2000 cal a BP. The latter phase is also found in southern Spain and Central Italy, and represents a prominent event in the western and central Mediterranean. In the last 2000 years, four relatively wet intervals occurred between ca. 1800 and 1500 cal a BP (150–450 AD), 1350–1250 (600–700 AD), 1100–800 (850–1150 AD), and at ca. 90 cal a BP (1860 AD). Between ca. 4100 and 2500 cal a BP δ¹⁸O values are relatively high, with three prominent peaks indicating drier conditions at ca. 4100–4000 cal a BP, ca. 3500 and at ca. 3300 cal a BP. Four additional drier events are identified at 1850 (ca. 100 AD), 1400 (ca. 550 AD), 1150 (800 AD) and ca.750 cal a BP (1200 AD). The pollen record does not show changes in accordance with these episodes owing to the poor sensitivity of vegetation in this area, which is dominated by an orographic rainfall effect and where changes in altitudinal vegetation belts do not affect the pollen rain in the lake catchment. However, since ca. 900 cal a BP a significant decrease in the percentage arboreal pollen and in pollen concentrations suggest major deforestation produced by human activities. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Geotechnical Behavior and Physico-Chemical Changes of Lime-Treated and Cement-Treated Silty Soil     

Bouras  Fawzi  Al-Mukhtar  Muzahim  Tapsoba  Nouffou  Belayachi  Naima  Sabio  Serge  Beck  Kévin  Martin  Mylène 《Geotechnical and Geological Engineering》2022,40(4):2033-2049

Geotechnical and Geological Engineering - An investigation performed on the interactions of silty soil treated with cement or lime demonstrates the strong relationship between microstructural...  相似文献