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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The depletion of calcium in forest ecosystems of the northeastern USA is thought to be a consequence of acidic deposition and to be at present restricting the recovery of forest and aquatic systems now that acidic deposition itself is declining. This depletion of calcium has been inferred from ...
    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] Blum et al. reply We identified apatite as an important reservoir of calcium in the soil horizons termed Bs and C at Hubbard Brook experimental forest (HBEF) and suggested that it could exceed the size of the soil-exchange pool. Apatite has high calcium-to-strontium (Ca/Sr) ...
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  • 3
    ISSN: 1573-515X
    Keywords: acidic deposition ; magnesium deficiency ; Norway spruce ; serpentinite ; soil chemistry ; weathering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The biogeochemistry of Ca, Mg, K, and Nawere investigated in two forested catchments in theCzech Republic, one underlain by leucogranite, theother by serpentinite. High weathering rates at theserpentinite site at Pluhův Bor resultedin Mg2+ as the dominant cation on the soilexchange complex and in drainage water. Other basiccations (Ca2+, K+, Na+) showedrelatively low concentrations and outflow instreamwater. The catchment exhibited high basesaturation in mineral soils (〉70%), and nearneutral soil and stream pH, despite elevated inputsof acidic deposition. Slow growth of Norway spruceat Pluhův Bor may be caused by K deficiency, Mgoversupply and/or Ni toxicity. In contrast, thegranitic site at Lysina showed low concentrations ofbasic cations on the soil exchange complex and instreamwater. Soil and drainage water at Lysina werehighly impacted by acidic deposition. Soil pH wasextremely acidic (〈4.5) throughout the soilprofile, and the base saturation of the mineral soilwas very low (〈5%). Supplies of basic cationsfrom atmospheric deposition and soil processes wereless than inputs of SO2- 4 on anequivalence basis, resulting in low pH and highconcentrations of total Al in drainage water. Needle yellowing in Norway spruce was possibly theresult of Mg deficiency at Lysina. Because of theirextremely different lithologies, these catchmentsserve as valuable end-members of ecosystemsensitivity to elevated levels of acidicdeposition.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-515X
    Keywords: forest disturbance ; forest ecosystem ; Potassium biogeochemistry ; soil chemistry ; stream chemistry ; wet and dry deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A synthesis of the biogeochemistry of K was conducted during 1963–1992 in the reference and human-manipulated watershed-ecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. Results showed that during the first two years of the study (1963–65), which coincided with a drought period, the reference watershed was a net sink for atmospheric inputs of K. During the remaining years, this watershed has been a net source of K for downstream ecosystems. There have been long-term declines in volume-weighted concentration and flux of K at the HBEF; however, this pattern appears to be controlled by the relatively large inputs during the initial drought years. Net ecosystem loss (atmospheric deposition minus stream outflow) showed an increasing trend of net loss, peaking during the mid-1970s and declining thereafter. This pattern of net K loss coincides with trends in the drainage efflux of SO4 2− and NO3 −, indicating that concentrations of strong acid anions may be important controls of dissolved K loss from the site. There were no long-term trends in streamwater concentration or flux of K. A distinct pattern in pools and fluxes of K was evident based on biotic controls in the upper ecosystem strata (canopy, boles, forest floor) and abiotic controls in lower strata of the ecosystem (mineral soil, glacial till). This biological control was manifested through higher concentrations and fluxes of K in vegetation, aboveground litter, throughfall and forest floor pools and soil water in the northern hardwood vegetation within the lower reaches of the watershedecosystem, when compared with patterns in the high-elevation spruce-fir zone. Abiotic control mechanisms were evident through longitudinal variations in soil cation exchange capacity (related to soil organic matter) and soil/till depth, and temporal and disturbance-related variations in inputs of strong-acid anions. Marked differences in the K cycle were evident at the HBEF for the periods 1964–69 and 1987–92. These changes included decreases in biomass storage, net mineralization and throughfall fluxes and increased resorption in the latter period. These patterns seem to reflect an ecosystem response to decreasing rates of biomass accretion during the study. Clearcutting disturbance resulted in large losses of K in stream water and from the removal of harvest products. Stream losses occur from release from slash, decomposition of soil organic matter and displacement from cation exchange sites. Elevated concentrations of K persist in stream water for many years after clearcutting. Of the major elements, K shows the slowest recovery from clearcutting disturbance.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 108 (1998), S. 107-127 
    ISSN: 1573-2932
    Keywords: acid deposition ; acidification ; base cations ; Bohemian lakes ; chloride ; Czech Republic ; lake water ; nitrate ; pH ; reversibility ; sulphate ; temporal changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Temporal changes in major solute concentrations in six Czech Republic lakes were monitored during the period 1984–1995. Four chronically-acidic lakes had decreasing concentrations of strong-acid anions (CSA = SO4 2- + NO3 - + Cl-), at rates of 3.0 to 9.0 μeq L-1 yr-1. Decreases in SO4 2-, NO3 -, and Cl- (at rates up to 5.1 μeq L-1 yr-1, 3.2 μeq L-1 yr-1, and 0.6 μeq L-1 yr-1, respectively) occurred. The response to the decrease in deposition of S was rapid and annual decline of SO4 2- in lake water was directly proportional to SO4 2- concentrations in the acidified lakes. Changes in NO3 - concentrations were modified by biological consumption within the lakes. The decline in CSA was accompanied in the four most acidic lakes by decreases in AlT, increases in pH at rates of 0.011 to 0.016 pH yr- 1, and decreases of Ca2+ and Mg2+ (but not Na+) in three lakes. The acid neutralizing capacity (ANC) increased significantly in all six lakes. Increases in base cation concentrations (CB = Ca2+ + Na+ + Mg2+ + K+) were the principal contributing factor to ANC increases in the two lakes with positive ANC, whereas decrease in CSA was the major factor in ANC increases in the four chronically-acidic lakes. The continued chemical recovery of these lakes depends on the uncertain trends in N deposition, the cycling of N in the lakes and their catchments, and the magnitude of the future decrease in S deposition.
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  • 6
    ISSN: 1435-0629
    Keywords: Key words: biogeochemistry; calcium; carbon; forest ecology; Hubbard Brook; nitrogen; soil chemistry; soil solution; stream chemistry; weathering.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: ABSTRACT Chemical changes along headwater streams at the Hubbard Brook Experimental Forest in New Hampshire suggest that important differences exist in biogeochemical cycles along an altitudinal gradient within small watershed ecosystems. Using data collected during the period 1982–92, we have constructed element budgets [Ca, Mg, K, Na, Si, Al, dissolved organic carbon (DOC), S, and N] for three subcatchments within watershed 6, a forested watershed last logged around 1917–20. The biogeochemistry of the high-elevation spruce-fir–white birch subcatchment was dominated by processes involving naturally occuring organic compounds. Stream water and soil solutions in this zone had elevated concentrations of organic acidity, DOC, and organically bound monomeric aluminum (Alo), relative to lower-elevation sites. The middle-elevation subcatchment, dominated by hardwood vegetation, had the greatest net production of inorganic-monomeric aluminum (Ali), and exhibited net immobilization of DOC and Alo. The low-elevation subcatchment, also characterized by deciduous vegetation, had the highest rates of net production of base cations (Ca2+, Mg2+, K+, Na+) among the subcatchments. Living biomass of trees declined slightly in the spruce-fir–white birch subcatchment during the study period, remained constant in the middle-elevation zone, and increased by 5% in the low-elevation subcatchment. Coupling the corresponding changes in biomass nutrient pools with the geochemical patterns, we observed up to 15-fold differences in the net production of Ca, Mg, K, Na, and Si in soils of the three subcatchments within this 13.2-ha watershed. Release of Ca, Na, and dissolved Si in the highest-elevation subcatchment could be explained by the congruent dissolution of 185 mol ha−1 y−1 of plagioclase feldspar. The rate of plagioclase weathering, based on the net output of Na, increased downslope to 189 and 435 mol ha−1 y−1 in the middle-elevation and low-elevation subcatchments, respectively. However, the dissolution of feldspar in the hardwood subcatchments could account for only 26%–37% of the observed net Ca output. The loss of Ca from soil exchange sites and organic matter is the most likely source of the unexplained net export. Furthermore, this depletion appears to be occurring most rapidly in the lower half of watershed 6. The small watersheds at the Hubbard Brook Experimental Forest occupy a soil catena in which soil depth and soil-water contact time increase downslope. By influencing hydrologic flowpaths and acid neutralization processes, these factors exert an important influence on biogeochemical fluxes within small watersheds, but their influence on forest vigor is less clear. Our results illustrate the sensitivity of watershed-level studies to spatial scale. However, it appears that much of the variation in element fluxes occurs in the first 10–20 ha of drainage area.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 782-789 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: -1 ) is insufficient to replace the pool of Zn in aboveground tissues (6.87 kg ha-1). Lead, not a nutrient, has accumulated in the soil due to the combustion of leaded gasoline. Lead leached from the O horizon between 1926 and 1991 can account for 30% of the EX + IB + ORG Pb, or 14% of the labile Pb in the mineral soil.
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