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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 329 (1987), S. 27-32 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Strong empirical evidence links deposition of strong acids from the atmosphere to acidification of freshwaters and loss offish populations. Chemical processes in soils explain the composition of soil solution and surface waters and when coupled with input-output fluxes these processes, in ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 343 (1990), S. 53-55 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The RAIN project comprises two parallel large-scale manipulations in which acid deposition is experimentally changed at whole catchments4. At Sogndal in western Norway, a 7,200-m2 pristine headwater catchment (SOG2) is artificially acidified by the addition of 70-100 meq m~2 yr"1 H2SO4. At ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-2932
    Keywords: acid deposition ; Adirondacks ; integrated assessment ; lake acidification ; mathematical model ; reduced-form modelling ; soil acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A reduced-from modelling approach is used to predict soil and lake acidification as part of an integrated assessment of acid deposition effects and control strategies. The reduced-form model is based upon the mechanistic, lumped parameter watershed chemistry model, MAGIC (Model of Acidification of Groundwater in Catchments). Recent improvements to MAGIC are described, and its reduced-form representation in the Tracking and Analysis Framework (TAF), an integrated assessment model for decision and uncertainty analysis, is presented. Reduced-form models are developed for lake acid neutralising capacity (ANC), calcium, pH, and aluminium; and for soil base saturation. The model for lake ANC incorporates long-term depletion of the watershed acid neutralisation fraction, as is predicted to occur with MAGIC. In test calibrations for 33 representative watersheds in the Adirondacks, the resulting reduced-form model provides a close approximation to MAGIC, with average root mean square errors of 0.79 μeq l-1 for ANC, 1.09 μeq l-1 for calcium, 0.16 for pH, 2.52 μeq l-1 for aluminium, and 0.09% for soil base saturation. In addition, improved fish viability models are incorporated in the integrated assessment model, and predictions are demonstrated for a future deposition reduction scenario for the Adirondack region.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 105 (1998), S. 643-659 
    ISSN: 1573-2932
    Keywords: acid deposition ; acidification ; aluminium ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Although the increased mobilization of aluminum from soils to surface waters is widely recognized as one of the most important ecological effects of acidic deposition, lumped-parameter mathematical models of acidification response typically overestimate the change in Al concentration under changing deposition by a considerable margin. The assumption of equilibrium with gibbsite (Al(OH)3) in the MAGIC model and other models of acid-base chemistry is shown to be inconsistent with measured values for a large variety of lake and stream databases. A modified algorithm for predicting Al concentration, based on empirical relationships evident in field data, provided superior estimates of changes in Al concentration in three long-term monitoring data sets and under experimental conditions at two experimental watershed manipulation sites.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-2932
    Keywords: Acidification ; modelling ; nitrogen ; land-use ; MAGIC-WAND
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The Galloway region of Southwest Scotland has been subject to decades of acidic deposition which has resulted in damage to soils, surface waters and aquatic biota. A survey of lochs was conducted in 1979, 1988, and 1993, over which time there have been dramatic changes in total sulphur and nitrogen deposition. The MAGIC model successfully reproduced the major chemical changes in water chemistry from 1979 to 1988 during which time there was a rapid decline in sulphur deposition. A new coupled sulphur and nitrogen model (MAGIC-WAND) has been used to evaluate the regional hydrochemical response to changing patterns of N & S deposition from the period 1988 to 1993. Details of the model structure and parameterisation are discussed. The model under-predicts the response of non-marine sulphate in the region suggesting that there has been a slight increase in deposition over this period. Future hydrochemical responses to different nitrogen deposition scenarios are presented, indicating that the potential increase of nitrogen in surface waters is closely linked to the age and extent of different mosaics of commercial afforestation within the individual catchments.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 2607-2612 
    ISSN: 1573-2932
    Keywords: acidification ; model testing ; modeling ; acid deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Strategies to control the emission of atmospheric pollutants such as sulfur and nitrogen, are generally based in large part on projections using models that simulate the influence of sulfur and/or nitrogen deposition on the acid-base chemistry of surface waters. One of the principal models used throughout Europe and North America for such assessment is the Model of Acidification of Groundwater in Catchments (MAGIC). All watershed models are simplified representations of reality, and as such require careful testing to establish their veracity prior to use for making policy projections. This is particularly true where the use of these model projections has the potential for serious environmental or economic consequences. During the past five years, we have tested the MAGIC model in a large variety of settings and under quite varying environmental conditions. This work has included comparing model hindcast simulations with diatom-inferences of historical acidification, sensitivity analyses to examine the response of the model to alternative assumptions and formulations, and detailed testing of model forecasts by comparing simulated chemistry with the results of catchment-scale and plot-scale experimental acidification and deacidification. Our analyses have elucidated a number of potentially-important deficiencies in model structure and method of application. These have resulted in changes to the model and its calibration procedures. Our work has included in-depth evaluation of issues related to regional aggregation of soils data, background sulfur deposition, natural organic acidity, and aluminum mobilization. The result has been an improved and more thoroughly-tested version of MAGIC. The process we have followed to improve and confirm the MAGIC model has been iterative and time consuming. It required the availability of large volumes of data from experimental manipulation and paleolimnological studies. We believe that such model testing and confirmation efforts should be a critical prerequisite for regional or national assessment activities that are based largely on the results of environmental models.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 30 (1986), S. 367-380 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In sensitive areas receiving acidic deposition, paleolimnolgical data indicate changes in lake pH over 1 to 3 decades during the past century. Estimates of deposition of SOx and NOx over this same period suggest that deposition rates changed (1) earlier and (2) more slowly than did changes in lake chemistry. Clearly chemical and biological processes in the terrestrial catchment damp, delay, and moderate the response of surface water pH to deposition of acidifying compounds. This response is controlled by key terrestrial processes that include chemical weathering, sulfate adsorption, cation exchange, dissolution and precipitation of Al compounds, and dissolution and dissociation of inorganic C. MAGIC (Model of Acidifcation of Groundwater In Catchments) provides a tool by which these processes can be simultaneously and quantitatively linked to examine the impact of acid deposition on surface water chemistry. We have applied MAGIC to 4 lakes from which paleolimnological reconstructions are available — Big Moose Lake in the Adirondacks, Loch Grannoch in Scotland, Lake Gårdsjøn in Sweden, and Lake Hovvatn in Norway. The results indicate that the processes linked in MAGIC can account for temporal trends in pH and alkalinity such as those obtained from paleolimnological data.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-2932
    Keywords: nitrogen ; acidification ; Adirondack Mountains ; atmospheric deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Assessments of the aquatic effects of acidic deposition have focused on sulfur, as have recent efforts to control the emissions of acidifying compounds. Nitrogen dynamics were excluded from most acidic deposition modeling studies because it was believed that terrestrial ecosystems strongly retain N and because modeling N is a more formidable task than modeling S due to the influence of complex biological processes on N cycling. Re-examination of available data for the Adirondack Mountains of New York suggests that N deposition may be contributing to both chronic and episodic acidification of freshwaters to a greater extent than is generally believed. Previous research concluded that N has played a limited role in acidification processes in these lakes, based on regional averages of chronic chemistry. However, it is now known that historic acidification responses have been spatially variable within the Adirondack Mountains and that the declines in lakewater pH have been less than previously believed. Lakewater NO3 − concentrations are commonly in the range of 5 to 25 μeq L−1 on a chronic basis in portions of the Adirondack region that have experienced significant chronic acidification. These NO3 − concentrations correspond in magnitude to inferred historical acidification. Furthermore, the relative importance of NO3 − as an agent of acidification increases dramatically during snowmelt when conditions are most toxic to fish. The consequence of not addressing N in formulating acidification recovery strategies for the Adirondacks includes the likelihood that we will overestimate the response of surface water to the mandated sulfur emissions reductions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-2932
    Keywords: Gypsy moth ; Forest defoliation ; Stream-water composition ; Stream-water acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Infestation by the gypsy moth (Lymantria dispar) can alter biogeochemical conditions in affected catchments. Stream-water concentration data obtained over the period of 1980–1993 for White Oak Run, a stream in Shenandoah National Park, Va., indicate that change in catchment acid-base status is associated with forest defoliation by the moth larva. Stream-water concentration changes following defoliation included increasing concentrations of strong-acid anions, base-cations, and hydrogen ion, as well as decreasing concentrations of acid-neutralization capacity (ANC) and sulfate. The largest change was in the concentration of nitrate; annual discharge-weighted mean concentrations increased from predefoliation levels consistently less than 5 μeq L−1 to postdefoliation levels greater than 50 μeq L−1. An intensification of acidification was indicated by record-high hydrogen ion concentrations and record-low ANC concentrations. The long-term biogeochemical implications of the infestation are uncertain due to the nonlinearity of the observed responses and unknown patterns of recovery and recurrence.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-2932
    Keywords: nitrogen ; acidification ; Adirondack Mountains ; atmospheric deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Assessments of the aquatic effects of acidic deposition have focused on sulfur, as have recent efforts to control the emissions of acidifying compounds. Nitrogen dynamics were excluded from most acidic deposition modeling studies because it was believed that terrestrial ecosystems strongly retain N and because modeling N is a more formidable task than modeling S due to the influence of complex biological processes on N cycling. Re-examination of available data for the Adirondack Mountains of New York suggests that N deposition may be contributing to both chronic and episodic acidification of freshwaters to a greater extent than is generally believed. Previous research concluded that N has played a limited role in acidification processes in these lakes, based on regional averages of chronic chemistry. However, it is now known that historic acidification responses have been spatially variable within the Adirondack Mountains and that the declines in lakewater pH have been less than previously believed. Lakewater NO3 - concentrations are commonly in the range of 5 to 25 μeq L-1 on a chronic basis in portions of the Adirondack region that have experienced significant chronic acidification. These NO3 - concentrations correspond in magnitude to inferred historical acidification. Furthermore, the relative importance of NO3 - as an agent of acidification increases dramatically during snowmelt when conditions are most toxic to fish. The consequence of not addressing N in formulating acidification recovery strategies for the Adirondacks includes the likelihood that we will overestimate the response of surface water to the mandated sulfur emissions reductions.
    Type of Medium: Electronic Resource
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