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  • Articles  (2)
  • Florida lakes  (2)
  • Springer  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 143 (1986), S. 55-61 
    ISSN: 1573-5117
    Keywords: paleolimnology ; Florida lakes ; trophic state ; sediment chemistry ; accumulation rate ; 210Pb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We describe statistical relationships between chemical aspects of surficial sediments from 34 Florida lakes, and trophic state of the overlying waters. Trophic state is expressed by Carlson's TSI-Chl a. The objectives of the study are two-fold: 1) to understand processes that govern the transfer of material across the mudwater interface, and 2) to develop transfer functions for inferring historical TSI measures in chemically analyzed, 210Pb-dated cores. Simple regression of organic matter content or nutrient (C, N, P) concentration in surface sediments vs. TSI yields nonsignificant or weak positive correlations. However, using a novel application of 210Pb assay, net accumulation rates of the materials are estimated and show a better correlation with trophic state. Cation (Ca, Mg, Fe, K) and sulfur concentrations in surface muds are poorly related to corresponding TSI's. Net accumulation rates of these elements (Ca, Mg, Fe, K, S) are positively correlated (P 〈 0.01) with TSI-Chl a. Chemical data from the Florida surficial sediment survey suggest that inferred levels of past trophic state should be based on net accumulation rates of chemical constituents rather than their simple sediment concentrations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: paleolimnology ; eutrophication ; trophic state ; 210Pb ; transfer functions ; Florida lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transfer functions relating trophic state (Carlson's TSIchlorophyll-a) to present day accumulation rate of (1) nutrients, (2) cations, and (3) organic sediment, are computed using Binford's 210Pb-dilution method. As computed from surficial sediments of 27 lakes, former trophic states are reconstructed for recent (210Pb-dated) sedimentary histories of 14 lakes. Of the three kinds of models potentially available, model (3) (TSI vs. organic accumulation) is the weakest statistically, and may be unduly influenced by exceptional deposition and/or preservation of allochthonous organic matter. At present, however, it is the only model applicable to all 14 of the histories tested. Results are encouraging in that model accurately predicts observed TSI's in several mesotrophic and eutrophic lakes. Clearly significant increases (accelerations) are inferred only for a of the most eutrophic lakes of the set, while the model consistently overpredicts TSI's of the 7 most oligotrophic lakes. As Whitmore's diatom-assemblage index is a better predictor of TSI than is model (3) in the one eutrophic lake in which it has been tested, we expect more persuasive results when models (1) and (2) can be tested within a more complete set of analytical data. We were surprised to find 3 severely disturbed lakes among the 12 that show little or no acceleration in rate of eutrophication in recent decades, but we defer attempts at explanation until former nutrient loading can be tested by model (1).
    Type of Medium: Electronic Resource
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