HISTORICAL CHANGES IN PHOSPHORUS ACCUMULATION IN A SMALL LAKE

Isotopes like Pb-210 and Cs-137 effective tools for determining chrono logy in lake sediments. Once the chronology is established, environmen tal changes in lakes can be investigated, and the causes for those cha nges can often be inferred. Pb-210 and Cs-137 profiles were constructe d for the sediments of Crystal Lake, Connecticut, USA. The geochronolo gy was used to determine the historical changes in organic matter and P accumulation in the sediment. Those profiles showed two significant periods of sedimentation which correlate with major precipitation even ts. Decreasing P accumulation in the sediments of the lake in the last decade was also correlated with increasing eutrophication as document ed by increases in epilimnetic P and decreases in transparency.