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Age of Soil

The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform

N. Elmegaard – 1st expert on this subject based on the ideXlab platform

  • Toxicity and Bioaccumulation of Copper to Black Bindweed (Fallopia convolvulus) in Relation to Bioavailability and the Age of Soil Contamination
    Archives of Environmental Contamination and Toxicology, 2000
    Co-Authors: M. Bruus Pedersen, C. Kjær, N. Elmegaard

    Abstract:

    The use of ecotoxicity test results obtained in the laboratory for prediction of effects of potentially toxic concentrations of chemicals in the field is hampered by several factors differing between the laboratory and the field situations. One important factor is the binding of test chemicals to Soil, which is affected by the Age of the contamination and Soil type. The present study investigated the effect of contamination Age by introducing an aging period of 1 to 12 weeks between mixing the test substance, copper sulfate, in with Soil and introducing the test plant, Fallopia convolvulus (L.) A. Löve. Copper accumulation, emergence of cotyledons, and growth were assessed and related to total (boiling with HNO_3) and 0.01 M CaCl_2- and DTPA-extractable Soil copper concentrations. Aging of the copper-contaminated Soil had only small effects on bioaccumulation of copper, copper toxicity, and extractable Soil copper fractions. Soil copper had no effect on emergence of cotyledons. Estimated EC_50 values for shoot and root growth averAged 280 mg Cu/kg. Effects on growth in these laboratory-treated Soils were much more severe than in a study performed in Soil from an old copper-contaminated field site. Neither CaCl_2- nor DTPA-extractable copper fractions could explain all of the differences in effects between Aged spiked Soil and field Soil. The accumulation pattern for roots and shoots of F. convolvulus indicated that excessive copper was accumulated and adsorbed mainly by the fine roots, whereby the copper concentrations of other plant parts were kept low until the plant was no longer able to maintain this regulation. An internal threshold for effects on growth of about 20 mg Cu/kg shoot dry weight was estimated, coinciding with a Soil copper concentration of approximately 200 mg/kg.

  • toxicity and bioaccumulation of copper to black bindweed fallopia convolvulus in relation to bioavailability and the Age of Soil contamination
    Archives of Environmental Contamination and Toxicology, 2000
    Co-Authors: Bruus M Pedersen, C. Kjær, N. Elmegaard

    Abstract:

    The use of ecotoxicity test results obtained in the laboratory for prediction of effects of potentially toxic concentrations of chemicals in the field is hampered by several factors differing between the laboratory and the field situations. One important factor is the binding of test chemicals to Soil, which is affected by the Age of the contamination and Soil type. The present study investigated the effect of contamination Age by introducing an aging period of 1 to 12 weeks between mixing the test substance, copper sulfate, in with Soil and introducing the test plant, Fallopia convolvulus (L.) A. Love. Copper accumulation, emergence of cotyledons, and growth were assessed and related to total (boiling with HNO3) and 0.01 M CaCl2- and DTPA-extractable Soil copper concentrations. Aging of the copper-contaminated Soil had only small effects on bioaccumulation of copper, copper toxicity, and extractable Soil copper fractions. Soil copper had no effect on emergence of cotyledons. Estimated EC50 values for shoot and root growth averAged 280 mg Cu/kg. Effects on growth in these laboratory-treated Soils were much more severe than in a study performed in Soil from an old copper-contaminated field site. Neither CaCl2- nor DTPA-extractable copper fractions could explain all of the differences in effects between Aged spiked Soil and field Soil.

C. Kjær – 2nd expert on this subject based on the ideXlab platform

  • Toxicity and Bioaccumulation of Copper to Black Bindweed (Fallopia convolvulus) in Relation to Bioavailability and the Age of Soil Contamination
    Archives of Environmental Contamination and Toxicology, 2000
    Co-Authors: M. Bruus Pedersen, C. Kjær, N. Elmegaard

    Abstract:

    The use of ecotoxicity test results obtained in the laboratory for prediction of effects of potentially toxic concentrations of chemicals in the field is hampered by several factors differing between the laboratory and the field situations. One important factor is the binding of test chemicals to Soil, which is affected by the Age of the contamination and Soil type. The present study investigated the effect of contamination Age by introducing an aging period of 1 to 12 weeks between mixing the test substance, copper sulfate, in with Soil and introducing the test plant, Fallopia convolvulus (L.) A. Löve. Copper accumulation, emergence of cotyledons, and growth were assessed and related to total (boiling with HNO_3) and 0.01 M CaCl_2- and DTPA-extractable Soil copper concentrations. Aging of the copper-contaminated Soil had only small effects on bioaccumulation of copper, copper toxicity, and extractable Soil copper fractions. Soil copper had no effect on emergence of cotyledons. Estimated EC_50 values for shoot and root growth averAged 280 mg Cu/kg. Effects on growth in these laboratory-treated Soils were much more severe than in a study performed in Soil from an old copper-contaminated field site. Neither CaCl_2- nor DTPA-extractable copper fractions could explain all of the differences in effects between Aged spiked Soil and field Soil. The accumulation pattern for roots and shoots of F. convolvulus indicated that excessive copper was accumulated and adsorbed mainly by the fine roots, whereby the copper concentrations of other plant parts were kept low until the plant was no longer able to maintain this regulation. An internal threshold for effects on growth of about 20 mg Cu/kg shoot dry weight was estimated, coinciding with a Soil copper concentration of approximately 200 mg/kg.

  • toxicity and bioaccumulation of copper to black bindweed fallopia convolvulus in relation to bioavailability and the Age of Soil contamination
    Archives of Environmental Contamination and Toxicology, 2000
    Co-Authors: Bruus M Pedersen, C. Kjær, N. Elmegaard

    Abstract:

    The use of ecotoxicity test results obtained in the laboratory for prediction of effects of potentially toxic concentrations of chemicals in the field is hampered by several factors differing between the laboratory and the field situations. One important factor is the binding of test chemicals to Soil, which is affected by the Age of the contamination and Soil type. The present study investigated the effect of contamination Age by introducing an aging period of 1 to 12 weeks between mixing the test substance, copper sulfate, in with Soil and introducing the test plant, Fallopia convolvulus (L.) A. Love. Copper accumulation, emergence of cotyledons, and growth were assessed and related to total (boiling with HNO3) and 0.01 M CaCl2- and DTPA-extractable Soil copper concentrations. Aging of the copper-contaminated Soil had only small effects on bioaccumulation of copper, copper toxicity, and extractable Soil copper fractions. Soil copper had no effect on emergence of cotyledons. Estimated EC50 values for shoot and root growth averAged 280 mg Cu/kg. Effects on growth in these laboratory-treated Soils were much more severe than in a study performed in Soil from an old copper-contaminated field site. Neither CaCl2- nor DTPA-extractable copper fractions could explain all of the differences in effects between Aged spiked Soil and field Soil.

Susan E. Trumbore – 3rd expert on this subject based on the ideXlab platform

  • Age of Soil organic matter and Soil respiration radiocarbon constraints on belowground c dynamics
    Ecological Applications, 2000
    Co-Authors: Susan E. Trumbore

    Abstract:

    Radiocarbon data from Soil organic matter and Soil respiration provide pow- erful constraints for determining carbon dynamics and thereby the magnitude and timing of Soil carbon response to global change. In this paper, data from three sites representing well-drained Soils in boreal, temperate, and tropical forests are used to illustrate the methods for using radiocarbon to determine the turnover times of Soil organic matter and to partition Soil respiration. For these sites, the averAge Age of bulk carbon in detrital and Oh/A-horizon organic carbon ranges from 200 to 1200 yr. In each case, this mass-weighted averAge includes components such as relatively undecomposed leaf, root, and moss litter with much shorter turnover times, and humified or mineral-associated organic matter with much longer turnover times. The averAge Age of carbon in organic matter is greater than the averAge Age predicted for CO2 produced by its decomposition (30, 8, and 3 yr for boreal, temperate, and tropical Soil), or measured in total Soil respiration (16, 3, and 1 yr). Most of the CO 2 produced during decomposition is derived from relatively short-lived Soil organic matter (SOM) components that do not represent a large component of the standing stock of Soil organic matter. Estimates of Soil carbon turnover obtained by dividing C stocks by hetero- trophic respiration fluxes, or from radiocarbon measurements of bulk SOM, are biased to longer time scales of C cycling. Failure to account for the heterogeneity of Soil organic matter will result in underestimation of the short-term response and overestimation of the long-term response of Soil C storAge to future changes in inputs or decomposition. Comparison of the 14 C in Soil respiration with Soil organic matter in temperate and boreal forest sites indicates a significant contribution from decomposition of organic matter fixed.2 yr but ,30 yr ago. Tropical Soil respiration is dominated by C fixed ,1 yr ago. Monitoring the 14 C signature of CO2 emitted from Soils give clues as to the causes of

  • Radiocarbon Dating of Soil Organic Matter
    Quaternary Research, 1996
    Co-Authors: Yang Wang, Ronald Amundson, Susan E. Trumbore

    Abstract:

    Radiocarbon Ages of Soil organic matter are evaluated with a model which incorporates the dynamics of the14C content of Soil organic matter. Measured14C Ages of Soil organic matter or its fractions are always younger than the true Ages of Soils due to continuous input of organic matter into Soils. Differences in Soil C dynamics due to climate or Soil depth will result in significantly different14C signatures of Soil organic matter for Soils of the same Age. As a result, the deviation of the measured14C Age from the true Age of Soil formation could differ significantly among different Soils or Soil horizons. Our model calculations also suggest that14C Ages of Soil organic matter will eventually reach a steady state provided that no climatic or ecological perturbations occur. Once a Soil or a Soil horizon has reached a steady state,14C dating of Soil organic matter will provide no useful information regarding the Age of the Soil. However, for Soils in which steady state has not been reached, it is possible to estimate the Age of Soil formation by modeling the measured14C contents of Soil organic matter. Radiocarbon dating of buried Soils could, in general, overestimate the true Age of the burial by as much as the steady-state Age of the Soil or Soil horizon.

  • factors and processes governing the 14c content of carbonate in desert Soils
    Earth and Planetary Science Letters, 1994
    Co-Authors: Ronald Amundson, Oliver A Chadwick, Susan E. Trumbore, Leslie D. Mcfadden, Eric V. Mcdonald, Steven Wells, Michael J Deniro

    Abstract:

    EPSL ELSEVIER Earth and Planetary Science Letters 125 (1994) 385-405 Factors and processes governing the 14C content of carbonate in desert Soils Ronald Amundson a Yang Wang a, Oliver Chadwick b Susan Trumbore c, Leslie McFadden d, Eric McDonald d, Steven Wells e, Michael DeNiro f a Division of Ecosystem Sciences, 108 Hilgard, University of California, Berkeley, CA 94720, USA b Earth Sciences Division, Jet Propulsion Laboratory, Pasadena, CA 91109, USA c Department of Geosciences, University of California, Irvine, CA 92717, USA d Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA e Department of Earth Sciences, University of California, Riverside, CA 92521, USA f Department of Geological Sciences, University of California, Santa Barbara, CA 93106, USA Received 1 September, 1993; revision accepted 14 April 1994 Abstract A model is presented describing the factors and processes which determine the measured 14C Ages of Soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with Soil CO 2. Carbon dioxide in Soils is a mixture of CO 2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing Soil humus. The relative proportion of these two CO z sources can greatly affect the initial 14C content of pedogenic carbonate: the greater the contribution of humus-derived CO 2, the greater the initial 14C Age of the carbonate mineral. For any gwen mixture of CO 2 sources, the steady-state CO 2 distribution vs. Soil depth can be described by a production/diffusion model. As a Soil Ages, the 14C Age of Soil humus increases, as does the steady-state 14C Age of Soil CO 2 and the initial 14C Age of any pedogenic carbonate which forms. The mean 14C Age of a complete pedogenic carbonate coating or nodule will underestimate the true Age of the Soil carbonate. This discrepancy increases the older a Soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured 14C Age and true Age. Although the production/diffusion model qualitatively explains the 14C Age of pedogenic carbonate vs. Soil depth in many Soils, other factors, such as climate change, may contribute to the observed trends, particularily in Soils older than the Holocene. 1. Introduction R a d i o c a r b o n d a t i n g o f s e d i m e n t a r y d e p o s i t s in d e s e r t s is h i n d e r e d by a lack o f o r g a n i c carbon. Paradoxically, most o f the d e p o s i t s in t h e s e re- [MK] gions a r e b l a n k e t e d with i n o r g a n i c c a r b o n in the f o r m o f p e d o g e n i c c a r b o n a t e . Since t h e early 1960s, 14C Ages have b e e n c a l c u l a t e d for t h e s e c a r b o n a t e s [1]. Fig. 1 illustrates t h a t an a p p r o x i – m a t e 1 : 1 r e l a t i o n s h i p exists b e t w e e n 14C Ages of Soil c a r b o n a t e a n d coexisting o r g a n i c m a t e r i a l s a n d Ages d e t e r m i n e d by o t h e r m e a n s (see also [2,3]). T h e s e r e l a t i o n s h i p s a r e n o t perfect: s o m e c a r b o n a t e is y o u n g e r t h a n i n d e p e n d e n t Ages sug- 0012-821X/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0012-821X(94)00097-I