Historical loading record of sulfur in an Adirondack Lake

Autor: G. Matisoff, G. R. Holdren
Rok vydání: 1993
Předmět:
Zdroj: Journal of Paleolimnology. 9:243-256
ISSN: 1573-0417
0921-2728
Popis: A model for the distribution of sulfur in the sediments of a lake in the Adirondack Mountains, New York, is developed to gain insight into the timing and magnitude of anthropogenic increases in sulfur loading. Surficial sulfur concentrations are about 3500 µg g−1, increase to 6000–7000 µg g−1 at a depth of about 6 cm, and then decrease downcore to background levels of about 2500 µg g−1. Sulfate concentrations are about 60–80 µM in the overlying water and decrease rapidly below the sediment-water interface. This reflects assimilatory reduction and/or dissimilatory reduction of sulfate and incorporation into the inorganic and/or organic solid-phase fractions of the sediment. A mathematical model is constructed assuming sulfur is incorporated into sediments by burial of detrital organic matter and by diffusion of sulfate from the overlying water with subsequent fixation in the sediment. Several historical scenarios of atmospheric sulfate loading rates were examined as model boundary conditions. Model results are compared with observed sedimentary sulfur profiles. The observed sediment sulfur profiles are best described using model boundary conditions showing increases in lake water sulfate concentrations since about 1940. Assuming as much as a decade of retention of sulfate within the terrestrial portion of the ecosystem, this suggests that significant increases in sulfate deposition rates began sometime after 1930 in this relatively remote area.
Databáze: OpenAIRE
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