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  • Online Resource  (3)
  • Geography  (3)
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  • Geography  (3)
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  • 1
    Online Resource
    Online Resource
    Wiley ; 1980
    In:  Soil Science Society of America Journal Vol. 44, No. 6 ( 1980-11), p. 1326-1327
    In: Soil Science Society of America Journal, Wiley, Vol. 44, No. 6 ( 1980-11), p. 1326-1327
    Abstract: Steam distillation of NH 3 is commonly used to quantify the amount of mineral N in soil and plant materials. A problem with NO 3 ‐ recovery by this method was encountered in an NH 3 volatilization study. When NH 4 NO 3 solutions were collected in acid and analyzed for NH 4 + ‐N and NO 3 ‐ ‐N, incomplete recovery of NO 3 ‐ occurred. As the volume or normality of H 2 SO 4 added to the distilling solution increased, more of the MgO used to raise the pH of the distilling solution was solubilized, which caused NO 3 ‐ recovery in the first 25ml of distillate to decrease. Only 80% NO 3 ‐ ‐N recovery was obtained with 20 ppm of Mg 2+ in the distilling solution. Soils with 3 meq exchangeable Mg 2+ /100 g depressed NO 3 ‐ ‐N recovery by 15% using the standard distillation procedure. An interaction between Mg 2+ and Devarda's alloy evidently inhibits NO 3 ‐ reduction.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 1980
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2004
    In:  Sedimentology Vol. 51, No. 4 ( 2004-08), p. 885-897
    In: Sedimentology, Wiley, Vol. 51, No. 4 ( 2004-08), p. 885-897
    Abstract: Clastic sedimentary rocks, deposited on eastern North America in response to the Taconian Orogeny, commonly have Sm/Nd isotope relationships indicating substantial isotope disturbance near or subsequent to the time of sedimentation that may be associated with severe depletion in light rare earth elements (LREE). Affected units [Normanskill Formation (Austin Glen and Pawlet Members), Frankfort Formation and Perry Mountain Formation] are widely separated both geographically (western New York to western Maine) and stratigraphically (Middle Ordovician to Silurian). A model is proposed for the most likely explanation of the observed REE and Sm/Nd isotope relationships involving a two‐stage process. In the first stage, REE are redistributed on a mineralogical scale (dissolution/precipitation on a sample scale) often with the involvement of REE‐enriched trace phases such as apatite and monazite. This stage typically takes place during diagenesis but may also take place later during metamorphism and/or recent weathering, and results in isotope re‐equilibration on a sample scale. The second stage occurs when one or more of these phases is redissolved and REE are transported on large advective scales. Where LREE‐enriched phases are involved, this gives rise to LREE depletion in whole rocks. The timing of this second stage cannot be constrained from Sm/Nd isotope data and may take place at any time subsequent to the isotope re‐equilibration. Such complex histories of REE redistribution may result in serious errors in estimating Nd model ages but not in estimating the Nd isotope composition at the age of sedimentation. Thus, Sm/Nd ratios even of unmetamorphosed sedimentary rocks have to be carefully evaluated before the calculation of depleted mantle model ages for the provenance.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2004
    detail.hit.zdb_id: 2020955-1
    detail.hit.zdb_id: 206889-8
    SSG: 13
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Wiley ; 1987
    In:  Soil Science Society of America Journal Vol. 51, No. 1 ( 1987-01), p. 124-128
    In: Soil Science Society of America Journal, Wiley, Vol. 51, No. 1 ( 1987-01), p. 124-128
    Abstract: Reliable field measurements of NH 3 volatilization are necessary for evaluating N‐fertilizer efficiency for sod crops and conservation crop production systems. This study was conducted to compare NH 3 loss measurements under field conditions using a forced‐draft technique and recovery of urea‐ 15 N. Measurements were made from urea solution applied at a rate of 100 kg N ha −1 to a bare or mulched Cecil sandy loam soil (Typic Hapludult). In an adjacent area, microplots were established to which urea enriched with 15 N was added. Ammonia losses from the bare and mulched soil were 49 and 72% of the applied N by the forced‐draft technique, and 14 and 46% of the applied N by 15 N recovery. The air flow rate with the forced‐draft technique was shown to exceed the actual wind speed near the soil surface 10 and 50% of the time for bare and mulched soil, respectively. These results raise serious questions about the validity and accuracy of the forced‐draft technique. The usefulness of the forced‐draft technique may be limited to relative comparisons of N sources, N rates, and various management practices.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 1987
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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