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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 407 (2000), S. 857-858 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Stoddard et al. reply Alewell et al. introduce some important factors influencing the process of ecosystem recovery from acidification. But whereas we exclusively considered aquatic acidification and recovery, they focus on soil acidification. First, Alewell ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Rates of acidic deposition from the atmosphere (‘acid rain’) have decreased throughout the 1980s and 1990s across large portions of North America and Europe. Many recent studies have attributed observed reversals in surface-water acidification at national and regional scales ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 23 (1992), S. 71-82 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Evaluations have been made of the key chemical factors in the aquatic effects upon surface waters due to acidic precipitation in eastern Canada. The region of Canada east of the Manitoba/Ontario border was divided into 22 aggregates and assessments of inorganic and organic ion chemistry appraised relative to sulphate deposition rates and distributions. Aquatic sensitivity is largely dominated by the concentration, distribution and magnitude of SO inf4 sup2- (sulphate) deposition and by the prevalent geology and derived soils found in each aggregate. The RAISON system provided an adaptable and highly flexible platform to evaluate interactively, multiple data sets of divergent characteristics. Attributes usually associated with geographical information systems are significantly augmented by quantitative numerical and stochastic capabilities that were used extensively in this study.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Environmental monitoring and assessment 23 (1992), S. 99-113 
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Changes in SO inf4 sup2- deposition predicted to occur in response to implementation of announced SO2 emission control programs in Canada and the U.S.A. have been used as input to water chemistry models thereby giving an estimate of the changes in lake acid neutralizing capacity (ANC) and pH that can be expected from these programs. Eastern Canada has been divided into 22 subregions for the purpose of this analysis. Relative to the current level (1982–86) of SO inf4 sup2- deposition (Scenario 1), the effect of the Canadian SO2 emission control program alone (Scenario 2) is compared to that obtained when controls are implemented throughout North America (Scenarios 3 and 4). SO2 emission reduction will effect a shrinkage of the high wet SO inf4 sup2- deposition field in NE North America such that under Scenario 4 conditions, almost no area will remain in Canada that receives 〉20 kg ha-1 yr-1. The greatest decrease in deposition and resulting change in lake chemistry occurs in southern Ontario and southwestern Quebec. ANC distributions shift to higher concentrations and the percentage of lakes having pH〈6 decreases in these areas. The Atlantic Provinces will obtain only a minor benefit from the control programs, i.e. experiencing only a small decrease in deposition and improvement in water quality. High sensitivity of the terrain in many parts of Atlantic Canada means that large numbers of lakes will remain acidic (i.e. ANC〈0) and/or have pH〈6 (an important biological threshold) even after full implementation of the current plans for SO2 control in Canada and the U.S.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Ion mass budgets were measured for 2 water yr (June–May, 1981–83) for a high and a ).ow elevation lake and their associated catchments. The lakes are located in the Turkey Lakes Watershed (TLW) in central Ontario, Canada, which is an undeveloped basin located on the Canadian Shield, 50 km north of Sault Ste. Marie. The ionic budgets of the lakes show that atmospheric deposition directly to the lakes' surfaces is the principal input pathway for H+ and NH4, whereas basic cations, SO4, NO3, and probably alkalinity are supplied primarily by inflow from the surrounding terrestrial basin and/or upstream lake. The lakes strongly retain H+ (i.e. output ≪ input), weakly retain the N species, and are in balance (i.e. output = input) for other ions except Ca and alkalinity which show an excess output compared to measured + estimated inputs. We hypothesize that an input of groundwater and/or seepage accounts for most of the Ca and alkalinity imbalance although the existence of within-lake alkalinity generation is probable also.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Application of a hydrological model to three Canadian watersheds forms part of a verification package to test its accuracy and portability. Agreement of model results with observed data on hydrograph, groundwater flow and snowpack is reasonably good. The model results are consistent with the observed pH and with many of the episodic events that have occurred in these acidified watersheds. Contrasts have also been made on the different calibrated coefficients at several locations in these watersheds. An attempt to relate them to the geology and soil characteristics at the site has led to realistic estimation of the soil contact times.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 18 (1982), S. 241-258 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We have measured the input and output rates of substances to and from both lakes and watersheds in the Sudbury and Muskoka-Haliburton areas of Ontario. At the former location, we have conducted mass balance studies on 5 lakes and their watersheds for 2½ yrs. At the latter site, we have measured mass balances for 6 lakes and about 30 individual watersheds for the past 5 yrs. Substances studied included SO4 2−, NO3 −, NH4 +, H+, major cations (Ca2+, Mg2+, Na+, K+) and HCO3 −. During the course of the investigation at Sudbury we have made several observations that indicate that the inputs of some substances, specifically SO4 2− or SO4 2−-precursors and strong acids, to lakes and watersheds are underestimated when measured as bulk deposition (i.e. by collection in a continuously open container): (a) The output of SO4 2− from the calibrated watersheds was substantially greater than the input measured as bulk deposition. (b) The SO4 2− concentrations of the lakes could not be explained on the basis of the measured inputs. An additional input directly to the lake surface was needed to obtain a mass balance. (c) The net input of acids measured as bulk deposition to the watersheds was much less than the acid consumed, which was estimated by the net output of Ca2+, Mg2+, Na+, K+, Al3+, and the net retention of NO3 −. (d) The major cation content of the study lakes could be explained on the basis of weathering reactions in the lakes' watersheds only if the input of strong acid had been underestimated. When these observations were quantified, they indicated a major portion of the total input of SO4 2−-precursors and of strong acid was not included in our bulk deposition measurements. Deposition of SO2 is the most likely explanation for these observations.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The results obtained by interfacing a hydrological model with a hydrogeochemical model are presented and compared to the observed data collected from the Turkey Lakes Watershed. The most prominent feature shown in the data is the progressive increase of pH, alkalinity and Ca++ + Mg++ in the downstream direction. Analysis of the model results indicates that the proportion of groundwater input to total runoff in the headwater and downstream areas plays an important role in creating these spatial gradients. The model also reproduces many of the episodic events, both temporal and spatial, shown in the observed data.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 31 (1986), S. 215-221 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The chemistry of the snowpack and snowmelt was investigated at the Turkey Lakes Watershed during the spring melt period in 1985. Ions in the snowmelt were 2 to 10 times more concentrated than those in the pre-melt snowpack and approximately 50% of the H+, SO4 and NO3 were lost from the snowpack with the first 30% of the melt. Rainfall flowed directly through the snow cover even during the early stages of the melt. Four rain events, which accounted for only 18% of the flowthrough collected, were responsible for about 50% of the H+ and SO4 and 37% of the NO3 ions exported from the snowpack. Sulphate to nitrate equivalent ratios in the pre-melt snowpack were generally about 0.6 but an enrichment of S04 relative to N03 in atmospheric deposition during the spring (SO4:NO3 〉 1) resulted in snowmelt with an increasing SO4 content relative to NO3.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This study examines certain aspects of the hydrological and chemical interaction of springmelt runoff with the terrestrial portion of a Canadian Shield catchment. Though NO3 − is the dominant anion in the snowpack for most of the winter, SO4 −2 deposition increases at the end of the winter season (March) such that it is the dominant anion in snowpack meltwater runoff. Pronounced formation office lenses in the snowpack are responsible for notable movement of H+, NO3 − and SO4 ions downslope prior to contact with the ground. Subsurface meltwater flow through the lower portion of the slope is much more acidic (pH 5.18 ) than that flowing within the subsurface in the upper slope ( pH 6.44 ).
    Type of Medium: Electronic Resource
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