PRIMARY MINERAL SOURCE AND THE BUDGET OF PHOSPHORUS IN THE HUBBARD BROOK EXPERIMENTAL FOREST, NEW HAMPSHIRE
LEE, Lai Man. ('97), KELLER, Dianne and APRIL, Richard H. Dept. of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346.

llee@center.colgate.edu

Phosphorus is a major nutrient for biological growth, and the only source of new phosphorus for biological cycling is in the weathering of primary minerals. Previous studies have estimated the amount of phosphorus available for plant growth by measuring phosphorus concentrations in soil solutions. In the current investigation, samples were collected at the Hubbard Brook Experimental Forest sandbox experiment, specifically the Red Pine sandbox and the barebox. Point count analysis was employed to quantify an absolute amount of phosphorus minerals per sandbox. Instrumentations used in this investigation includes the scanning electron microscope (SEM), the energy dispersive analyzer (EDS) and the petrographic microscope. SEM/EDS analysis revealed that the primary phosphorus- bearing mineral is apatite. Calculations converting point count data to kilograms per hectare showed that the results from this study for the Red Pine sandbox are significantly higher than published values. Furthermore, the amount of apatite increased with depth, indicating intense weathering of apatite minerals in the upper horizons which was unexpected due to young age of the soil in the sandbox experiment.

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