A PALEOLIMNOLOGICAL STUDY OF THE STRANGE CASE OF LONG POND (GA, USA) : HIGH PHOSPHORUS INPUTS WITH A LACK OF EUTROPHICATION
Evidence of abundant algae, phytoplankton, and diatoms in the lower depths of the core (500-300cm) suggests eutrophication was not prominent in most of the lake’s history. The absence of eutrophication still holds, despite a steady increase of the P concentrations in the upper sediments of the core (suggesting an influx of P from modern farming practices) to levels which would normally result in an increase of eutrophication markers.
The purpose of this study is to ascertain the nature of the correlation between P and Al as well as its origin and potential role as a detrital signal through the history of the lake sediment. To that purpose, the mineralogical profile of the lake sediments, as well as the mineralogical profile of surrounding sediments feeding into the lake, will be combined with paleo pH-proxies to provide a paleolimnological analysis of the lake. Preliminary XRD analysis of sediments collected throughout the core have indicated a typical mineralogy for the area, which is mostly dominated by quartz, along with minerals containing Fe, Mg, Mn, Ti, and Zn. Further XRD analysis of the clay fraction of samples will be conducted to determine the presence and nature of an aluminophosphate phase and examine its diagenesis. Findings from this work will elucidate the relationship between the P and Al in Long Pond and help explain the lack of eutrophication. These findings could be useful in preventing eutrophication in areas where human activities increase the runoff of P into the fragile ecosystems of lakes and ponds.