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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Environmental science & technology 22 (1988), S. 178-182 
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    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] Nadelhoffer et al. reply — Jenkinson et al. and Sievering are justifiably concerned that our 15N additions to forest floors do not account for the potential uptake of nitrogen input by forest canopies. We agree that canopies can remove nitrogen from the ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Humans have altered global nitrogen cycling such that more atmospheric N2 is being converted (‘fixed’) into biologically reactive forms by anthropogenic activities than by all natural processes combined. In particular, nitrogen oxides emitted during fuel combustion and ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Extensive studies of precipitation chemistry during the last 20 yr have clearly shown that highly polluted precipitation falls over large areas of Scandinavia, and that this pollution is increasing in severity and geographical extent. Precipitation in southern Norway, Sweden, and Finland contains large amounts of H+, SO= 4, and NO− 3 ions, along with heavy metals such as Cu, Zn, Cd, and Pb, that originate as air pollutants in the highly industrialized areas of Great Britain and central Europe and are transported over long distances to Scandinavia, where they are deposited in precipitation and dry-fallout. In Norway the acidification of fresh waters and accompanying decline and disappearance of fish populations were first reported in the 1920s, and since then in Sørlandet (southernmost Norway) the salmon have been eliminated from several rivers and hundreds of lakes have lost their fisheries. Justifiably, acid precipitation has become Norway's number-one environmental problem, and in 1972 the government launched a major research project entitled ‘Acid precipitation — effects on forest and fish’, (the SNSF-project). Studies of freshwater ecosystems conducted by the SNSF-project include intensive research at 10 gauged watersheds and lake basins in critical acid-areas of southern Norway, extensive surveys of the geographical extent and severity of the problem over all of Norway, and field and laboratory experiments on the effect of acid waters on the growth and physiology of a variety of organisms. Large areas of western, southern, and eastern Norway have been adversely affected by acid precipitation. The pH of many lakes is below 5.0, and sulfate, rather than bicarbonate, is the major anion. Lakes in these areas are particularly vulnerable to acid precipitation because their watersheds are underlain by highly resistant bedrock with low Ca and Mg contents. Apart from the well-documented decline in fish populations, relatively little is known about the effects of acid precipitation on the biology of these aquatic ecosystems. Biological surveys indicate that low pH-values inhibit the decomposition of allochthonous organic matter, decrease the species number of phyto-and zooplankton and benthic invertebrates, and promote the growth of benthic mosses. Acid precipitation is affecting larger and larger areas of Norway. The source of the pollutants is industrial Europe, and the prognosis is a continued increase in fossil-fuel consumption. The short-term effects of the increasing acidity of freshwater ecosystems involve interference at every trophic level. The long-term impact may be quite drastic indeed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 72 (1994), S. 297-315 
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Manipulations with whole catchments were initiated in Norway in 1983 (RAIN project Reversing Acidification In Norway) to obtain direct experimental evidence relating to the reversibility of soil and water acidification, rate of change, and the relative roles of sulfur and nitrogen. We present here results for soil and runoff chemistry during 8 years of acid addition at Sogndal, a pristine acid-sensitive site in central Norway characterized by gneissic bedrock, thin and patchy soils, and alpine vegetation. Catchment SOG2 receives 100 meq m−2 yr−1 H2SO4, catchment SOG4 receives a 1∶1 mixture of H2SO4 and HNO3, while catchments SOG1 and SOG3 serve as untreated controls. Acid is applied to the snowpack in April and in 5 portions of 11 mm of pH 3.2 acidified lakewater during the snowfree period. The 8-years of acid addition have caused major changes in runoff chemistry. Concentrations of sulfate and base cations have increased while acid neutralizing capacity (ANC) has decreased. Henriksen's F-factor (change in concentration of non-marine Ca+Mg divided by change in concentration of non-marine SO4) is about 0.35, but is expected to decrease as soil acidification proceeds. Runoff is acidic, aluminum-rich, and toxic to fish and other aquatic organisms. Repeated soil sampling indicates no dramatic trends related to treatment. Year-to-year variations are large, and mask changes expected. The input-output budgets indicate that over the 8-yr period Ca has been depleted by about 5% of the total soil pool of exchangeable Ca. The observed trends are consistent with response predicted by MAGIC, a process-oriented model of soil and water acidification. The gradual increase in nitrate flux from catchment SOG4 may be the first indication of ‘nitrogen saturation’ induced simply by increasing nitrogen deposition.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-0629
    Keywords: Key words: climate change; boreal forest; greenhouse; catchment; vegetation; soil; water; temperature; carbon dioxide.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: ABSTRACT To evaluate the effects of climate change on boreal forest ecosystems, both atmospheric CO2 (to 560 ppmv) and air temperature (by 3°–5°C above ambient) were increased at a forested headwater catchment in southern Norway. The entire catchment (860 m2) is enclosed within a transparent greenhouse, and the upper 20% of the catchment area is partitioned such that it receives no climate treatment and serves as an untreated control. Both the control and treatment areas inside the greenhouse receive deacidified rain. Within 3 years, soil nitrogen (N) mineralization has increased and the growing season has been prolonged relative to the control area. This has helped to sustain an increase in plant growth relative to the control and has also promoted increased N export in stream water. Photosynthetic capacity and carbon–nitrogen ratio of new leaves of most plant species did not change. While the ecosystem now loses N, the long-term fate of soil N is a key uncertainty in predicting the future response of boreal ecosystems to climate change.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 101 (1983), S. 1-12 
    ISSN: 1573-5117
    Keywords: forest water ecosystems ; acid precipitation ; Norway ; chemical budgets ; sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Precipitation and streamwater volume and chemical composition have been measured since 1974 at Langtjern, a small, acid (pH 4.6–4.8) lake on granitic-gneissic bedrock in coniferous forest located ca. 100 km north of Oslo, Norway. The area receives acid precipitation (weighted average pH 4.28). The 7-year input-output budgets for major ions at two terrestrial subcatchments indicate that for Na, K, SO4 and Cl outputs approximately equal inputs, for H+, NH4 and NO3 outputs are much less than inputs, and for Ca, Mg and Al outputs greatly exceed inputs. The sulfate budgets (which include estimated dry deposit) indicate that the terrestrial catchment retains about 20% of the incoming sulfate, perhaps due to absorption in the soil, plant uptake, reduction and storage in peaty areas or reduction and release of H2S to the atmosphere. The budgets for Langtjern lake itself indicate that for most components output equals inputs to within 10%, i.e. these compounds simply pass through the lake. For H+, and possibly NH4 and NO3, inputs exceed outputs. Because gaseous phases are not measured the N budgets are uncertain. A mechanism that leads to ‘retention’ of both H+ and SO4 is sulfate reduction and incorporation of sulfides in the lake sediments. Such has been documented in the experimentally-acidified Lake 223, Experimental Lakes Area, Ontario, Canada. Although there is no evidence suggesting the development of anoxic bottom waters at Langtjern, such reduction might occur at the water-sediment interface and in the sediments. The budgets for the pollutant components H+ and SO4 at Langtjern differ substantially from those at the relatively unaffected Lake 239, in the Experimental Lakes Area.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1435-0629
    Keywords: Key words: catchment; global change; forest; nitrogen; runoff; acid deposition; Norway.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: ABSTRACT CLIMEX (Climate Change Experiment) is an integrated, whole-ecosystem research project that focuses on the response of forest ecosystems at the catchment scale to increased CO2 and temperature. KIM catchment (860 m2) is completely enclosed by a transparent greenhouse, receives deacidifed “clean” rain, and has elevated CO2 (560 ppmv) and elevated air temperature (3°–5°C above ambient). The uppermost 20% of the catchment is partitioned off, is not subject to changed CO2 or temperature, and serves as an untreated control. Fluxes of nitrate and ammonium in runoff from KIM catchment increased from 2 mmol m− 2 y− 1 each in the 3 years before treatment to 6 and 3 mmol m− 2 y− 1, respectively, in the 3 years after treatment (May 1994–April 1997), despite a 15 mmol m− 2 y− 1 decrease in N dry deposition due to the sealing of the walls to the enclosure. N flux in runoff from three reference catchments and the control section did not change. The net loss of inorganic N was thus about 20 mmol m− 2 treated soil y− 1. There were no changes in organic N or total organic carbon in runoff. The ecosystem switched from a net sink to a net source of inorganic nitrogen (N). The increased loss of N may be due to accelerated decomposition of soil organic matter induced by higher temperature. Due to many decades of N deposition from long-range transported pollutants, the ecosystem prior to treatment was N saturated. If global change induces persistent losses of inorganic N on a regional scale, the result may be a significant increase in nitrate concentrations in fresh waters and N loading to coastal marine ecosystems. In regions with acid sensitive waters, such as southern Norway, the increased nitrate release caused by global change may offset improvements achieved by reduced sulfur and N deposition.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-515X
    Keywords: acidification ; forest ecosystems ; models ; Sitka spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A new model for simulating nitrogen leaching fromforested ecosystems has been applied to data from anexperimentally manipulated 30-year-old Sitka sprucestand. The manipulation experiment (at Aber, in north-western Wales, UK) was part of the European NITREXproject and involved five years of additions ofinorganic nitrogen to the spruce stand. The model(MERLIN) is a catchment-scale, mass-balance model thatsimulates both biotic and abiotic processes affectingnitrogen in ecosystems. The structure of MERLIN includes representationsof the inorganic soil, one plant compartment and twosoil organic compartments. Fluxes in and out of thesimulated ecosystem and transfers between compartmentsare regulated by atmospheric deposition, hydrologicaldischarge and biological processes such as plantuptake, litter production, immobilization,mineralization, nitrification and denitrification.Rates of nitrogen uptake, cycling and release amongpools are regulated by carbon productivity, inorganicnitrogen availability and the C:N ratios of theorganic pools. Inputs to the model are temporalsequences of carbon fluxes and pools, hydrologicaldischarge and external sources of nitrogen. The NITREX experiment at Aber began in 1990 withweekly additions of ammonium nitrate(NH4NO3) at a rate of 35 kg N ha-1 yr-1.Data were collected from both control andtreatment plots within the stand. The site-intensivedata from the control plots at Aber were augmented bydata taken from a chronosequence of 20 Sitka sprucestands and data from a survey of 5 moorland catchmentsin the same region to providecalibration data for the model. The data were used toestablish current conditions at the Aber site and toreconstruct historical sequences of carbon fluxes andpools from 1900 to the present day with which to drivethe model. The reconstructed sequences included anincrease in nitrogen deposition and a vegetationchange from moorland to plantation forest in 1960. Thecalibrated model was then used to predict the effectsof the experimental nitrogen additions begun in 1990. MERLIN successfully reproduced the observedincrease in NO3 leaching from aging spruce standsthat results from forest maturation and increasednitrogen deposition (as inferred from thechronosequence and forest survey data in the region).MERLIN also correctly predicted the increases insoilwater NO3 concentrations, the changes innitrogen content of tree and soil organic matterpools, and the changes in nitrogen fluxes that occurin spruce stands in response to increased nitrogeninputs (as observed in the nitrogen additionexperiment).
    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 Soil and stream water responses to ‘clean rain’ treatments at three roof covered forest ecosystems in Norway, Sweden and Denmark were modelled by the MAGIC model. The model outputs were compared with measured responses. Over the wide span in site conditions among the three sites MAGIC successfully reproduced the observed effects in the ‘clean rain’ treatments. Seasalt influence caused single year discrepancies but the long term trends were well reproduced. In particular the significant decreases in SO4 output were well reproduced. A simultaneous change in base cation leaching was observed, which in the long run will be the basis for the recovery of these acidified systems. The rate of recovery at the 3 studied sites was very slow.
    Type of Medium: Electronic Resource
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