Multiple sediment cores collected from Little Rock Lake, Wisconsin, prior to experimental acidification show that total sulfur accumulation rates increased during the past century, with most of the increase occurring in the nonacid-volatile inorganic and organic fractions. The increased sulfur accumulation is a result of diagenetic processes within the sediments, rather than changes in seston deposition rates or terrestrial inputs. This enrichment has occurred because atmospheric sulfate deposition rates have increased over the past century, resulting in increased lake-water sulfate concentrations, which has, in turn, increased the diffusional flux to the sediments and increased the extent of diagenetic immobilization. Individual cores had markedly different sulfur accumulation rates, demonstrating the importance of collecting multiple cores to determine lakewide sediment accumulation.Processes that retain sulfate are of considerable interest in the context of lake acidification because they are important in regulating the alkalinity of many soft-water ' Present address: % U.S. EPA Environmental Research Laboratory, 200 SW 35th St., Corvallis, Oregon 97333.
AcknowledgmentsWe thank Linda Shane for contributing to the pollen analysis, Peter Appleby for the gamma spectroscopy analysis, and Susan Christie for editorial assistance. The use of the University of Wisconsin's Trout Lake Field Station is appreciated. Carol Kelly, Richard Holdren, and Noel Urban reviewed an earlier draft of this paper and made numerous suggestions.