Summary: | Progress Code: completed Purpose To determine the total organic carbon content of marine sediment samples taken as part of the Davis Sewage Treatment Project around Davis Station during the 2009/10 austral summer. Total Organic Carbon A 2 g homogenised wet sediment sub-sample from each core was weighed into a pre-combusted crucible and dried at 105 degrees C. The dried sample was reweighed before being analysed for total carbon by mass loss on ignition at 550 degrees C, the sample was placed in the muffle furnace for 4 hours. Samples 56698, 57062, 56837, 57058, and 580792 were analysed in triplicate to assess the reproducibility of the analytical procedure. (Total number of analyses was 117). - TOC - For the 107 samples: - Mean and SD: 3 plus or minus 4 % DMB, range: 0.16-15 %, n=107 - Considering the mean values for the 27 site locations: - Range: 0.33-14 % DMB, mean and SD: 3.3 plus or minus 3.7 % DMB, n=27 - Analytical uncertainty - Analytical precision: 5 samples analysed in triplicate: - RSD = 6 plus or minus 5% range 1-11%, n=5 - Site heterogeneity: reproducibility (RSD) of mean data from site replicate samples was 26% (mean, SD 15%, range 10-57%, n=27) - From the limited data on reproducibility summarised above, it can be concluded that site heterogeneity contributes most to the uncertainty of the TOC data for the site locations. - DMF - For the 107 samples: - Mean and SD: 0.57 plus or minus 0.23 %, range: 0.09-0.85, n=107 - Considering the mean values for the 27 site locations: - Range:0.17-0.83, mean and SD: 0.57 plus or minus 0.22, n=27 - Analytical uncertainty - Analytical precision: 5 samples analysed in triplicate: - RSD = 2 plus or minus 2% range 0.8-5%, n=5 - Site heterogeneity: reproducibility (RSD) of mean data from site replicate samples (mostly quadruplicates) was 10% (mean, SD 10%, range 1-37%, n=27) - From the limited data on reproducibility summarised above, it can be concluded that site heterogeneity contributes most to the uncertainty of the DMF data for the site locations. Collection ...
|