Abstract |
The investigation was undertaken to determine major, minor and trace element levels and their variation with depth in recent sediment cored from a small medi-Michigan lake. The objective was to identify chemical gradients in the unconsolidated sediment and correlate them with human activity in the area. During the geologically recent human occupation of the region, it was expected that certain metals introduced into the lake water would become incorporated in some fashion into the sedimentary column. Concentration profiles with depth show increases in the uppermost layer for sodium, potassium and manganese when compared to concentration means from the 20 to 60 cm depth. The percentage increases for Na, K, and Mn are 56%, 84% and 48% respectively. Thorium shows a 47% decrease in concentration. Since it is likely that diffusion into the sediment is taking place and that redistribution of the elements is taking place as decay of the organic material proceeds, it is not possible to calculate with any accuracy the total burden of these elements that has been imposed upon the lake. (Modified author abstract) |