RECENT SULFUR ENRICHMENT IN THE SEDIMENTS OF LITTLE-ROCK LAKE, WISCONSIN

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 lake-wide sediment accumulation.