An assessment of cultural influence of lakes of south central Minnesota by short core sediment analysis

This study involved the analysis of the relationships of sediment chemistry to lake morphometric and basin descriptors. The sediment chemistry analysis involved calcium, sodium, potassium, iron, percent organic, and the chlorophyll derivative to carotenoid pigment ratios. The morphometric descriptors included area, mean depth, maximum depth, volume, volume development index, shoreline, and shoreline development index. The lake basin descriptors included soil type, soil hydrology, lake isolation and lake formation. A total of 2700 data points were created and utilized for statistical analysis of frequencies, tabulations, Pearson's product-moment correlation coefficients, and one-way analysis of variance. This study shows that there is a relationship of sediment chemistry to lake morphometry and to lake basin descriptors. This is seen in the separation of morphometric and basin descriptor strata to various chemical parameters. This relationship is not totally directional indicating that other unmeasured factors are partially involved in determining sediment chemistry. Short core chemical analyses indicate that, since European settlement, lakes have generally become slightly less productive, have maintained or increased the anoxic conditions of their sediments and/or hypolimnion,s and indicate increased deposition of erosional materials to the sediments. Although the source of the erosional materials was not determined, it appears as though it is not a direct result of runoff from the lakes drainage basin.