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  • 1
    Electronic Resource
    Electronic Resource
    Nitrogen flows in Louisiana Gulf Coast salt marsh: Spatial considerations (1989)
    Springer
    Biogeochemistry 8 (1989), S. 25-37 
    Details
    ISSN: 1573-515X
    Keywords: nitrogen budget ; denitrification ; nitrogen fixation ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen flux data was synthesized in developing a nitrogen flow budget for a Louisiana Barataria BasinSpartina alterniflora salt marsh. Results demonstrate the importance of spatial consideration in developing a nitrogen budget for coastal marshes. Using a mass balance approach nitrogen inputs balanced nitrogen sinks or losses from a marsh soil-plant system with a specific rooting depth. However, per unit areas on a local scale, marshes serve as a large sink for nitrogen due to rapid accretion which removes 17.O g N m−2yr−1 through subsidence below the root zone. On a larger spatial scale (regional) it is shown that the marshes do not serve as a large nitrogen sink. The rapid marsh deterioration currently occurring in the rapidly subsiding marshes of the Mississippi River deltaic plain account for a net regional loss of 12.5 g N m−2yr−1. Thus, regionally the net sink is equivalent to only 5 g N m−2yr−1 as compared to 17.0 g N m−2yr−1 on a local scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02180165
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Salinity and flooding level as determinants of soil solution composition and nutrient content inPanicum hemitomum (1989)
    Springer
    Plant and soil 114 (1989), S. 197-204 
    Details
    ISSN: 1573-5036
    Keywords: speciation ; leaf metal content ; GEOCHEM ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment was conducted to examine the effects of salinity and flooding level on interstitial solute speciation and solute uptake byPanicum hemitomum grown on intact marsh substrates. The experimental set-up consisted of a factorial arrangement of treatments (5 salinity levels×3 flooding levels) with 4 replications. Salinity treatments with the addition of salt (Instant Oceanr) successfully increased interstitial pore water conductivities and resulted in significantly different treatment means. Redox potentials and proton activities were significantly higher in the drained treatment, with only minor differences between the two flooded treatments. There was not a significant pH effect due to salinity, although a significant interaction between salinity and flooding level was observed. Analysis of variance suggested that electro-chemical and interstitial solute behaviour could significantly be described by salinity and flooding treatments. GEOCHEM calculations were performed in order to relate leaf concentrations to ion activities in interstitial soil solutions. Leaf contents of Mg, Ca, K, Mn, and Cu were significantly correlated with the activities of corresponding ions in the interstitial pore water. However, most of the variabilitiy in leaf metal content could be accounted for by treatment effects. Regression analysis showed that the ion activities explained less than 25% of the variability in leaf metal content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220798
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogen accumulation by H2-uptake negative strains of Rhizobium (1985)
    Springer
    Plant and soil 85 (1985), S. 77-84 
    Details
    ISSN: 1573-5036
    Keywords: Hydrogen production ; Hydrogen uptake negative strains ; Medicago sativa ; Pisum sativum ; Rhizobium leguminosarum ; Rhizobium meliloti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Hydrogen evolution from root nodules has been reported to decrease the efficiency of the nitrogen fixing system. Mutants ofRhizobium meliloti andRhizobium leguminosarum were selected which were deficient in H2-uptake capacity (Hup−). The relative efficiency of the nitrogen fixation for both species assessed with C2H2 reduction was 0.66. The hydrogen production was monitored using a simple root incubation method. As such, hydrogen production up to 3.83 and 15.57 ml.day−1.g−1 plant dry weight were recorded forPisum sativum — Rhizobium leguminosarum 4.20 Hup− andMedicago sativa — Rhizobium meliloti 1.5 Hup− respectively. In a closed container (250 ml), hydrogen concentrations up to 20% (v/v) could be reached in the root phase ofMedicago sativa in a time period of 320 hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197802
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Sulfur cycling in a dutch moorland pool under elevated atmospheric S-deposition (1989)
    Springer
    Water, air & soil pollution 44 (1989), S. 215-234 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Atmospheric S deposition, sulfate reduction and the accumulation of reduced S components were investigated in sediments of a Dutch moorland pool. Laboratory 35SO42− tracer experiments indicated that the variation in reduction rate with depth in the sediment could be described by an exponential fit, suggesting first order kinetics. Sulfate reduction rates calculated from a kinetic transport model were highest in June and July (〉0.6 mmol m−2 day−1), and decreased towards the end of the summer (〈0.2 mmol m−2 day−1). Winter reduction rates were low, but increased towards the beginning of the spring. Concentrations of total, organic and inorganic S decreased with depth, consistent with an increasing depositional flux of S over the last century. Increased atmospheric sulfate deposition rates and consumption in the upper sedimentary layers caused a continuous increase in subsurface S concentrations. Present day S-immobilization rates were estimated between 25 to 30 mmol S in−2 yr−1, in the order of the annual input of S from wet atmospheric deposition. Sulfate metabolism in anaerobic moorland pool sediments may be the most important mechanism of long-term S-accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00279256
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    Paper (German National Licenses)
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