Kenneth Fortino edited ResultsOMMineralization.tex  over 7 years ago

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At the conclusion of the leached litter experiment (day ##) the sediments in the microcosms without leaf litter had a median of 13.3\% organic matter (range = 13.1\% -- 28.5\%) and the sediments in the microcosms with leaf litter had a median of 12.4\% organic matter (range = 11.8\% -- 14.3\%). The leaves in the microcosms containing leaves lost a mean ($\pm$ SD) of 30.7\% ($\pm$ 11.7) and 45.8\% ($\pm$ 8.1) of the initial organic matter mass of the leaves in the leaf--only and leaf + sediments treatments respectively. The difference in the percent of organic matter mass lost by the leaves was marginally significantly different between the microcosms with and without sediments (F = 4.936, df\textsubscript{error} = 6, p = 0.06804).  The leaves in the leached litter experiment had an initial C:N that ranged from 50.4 -- 56.5 with a median of 53.4 but by the end of the experiment the C:N had dropped significantly (F\textsubscript{2, 7} = 35.7, p = 0.0002) to between 28.9 -- 36.82 with a mean of 32.6 in the microcosms without sediments and between 23.4 -- 30.1 with a mean of 26.3 in the microcosms with leaf litter and sediments. The reduction in C:N was due to the loss of C mass but the retention of N mass from the leaves. The C mass of the leaves dropped significantly (F\textsubscript{2, 9} = 8.378, p = 0.0088) from a mean ($\pm$ range) of 0.097 g ($\pm$ 0.085 -- 0.109 g) prior to incubation in the microcosms to 0.062 g ($\pm$ 0.041 -- 0.083 g) and 0.059 g ($\pm$ 0.050 -- 0.073 g) following incubation in the microcosms without sediment and leaf litter plus sediment, respectively. Whereas the N mass was not significantly altered by the incubation and had a mean ($\pm$ range) of 0.00183 g ($\pm$ 0.00019 -- 0.00348 g) across all the leaf samples.  The sediments added to the microcosms in the leached litter SOD experiment had median dry bulk density of 0.17 g ml\textsuperscript{-1}. The organic matter content of the sediments was more variable than was seen in the previous experiments, where one of the samples had only 7.2\% organic matter and the other 2 samples had 16.7 and 16.5\% organic matter. The sediments in this experiment contained between 4.07 and 4.24 g of organic matter per microcosm. The microcosms that received leaf litter each received between 0.04 and 0.07 g of coarse organic matter which would be the equivalent of 11.5 to 21.0 g of coarse organic matter m\textsuperscript{-2}.  In the lake from which the sediments were collected we measured between 57.3 and 163.0 g coarse organic matter m\textsuperscript{-2}, so the microcosms used in the experiment contained at most 40\% of the coarse organic matter of the lake. However in the microcosms all of the leaf litter was added to the surface of the sediments, while a portion of the leaf litter in the lakes was buried within the sediment.