Relazioni tra contenuto di materia organica, carbonio organico e granulometrica nei sedimenti di aree di transizione

To describe the geochemical features of the sediments in nine sicilian coastal lakes, 78 samples of surface sediments were collected in July 2005. Analyses of Nitrogen, Total Organic Carbon, Organic Matter, Carbonates and Grainsize were performed. A better correlation between the Organic Matter, evaluated through the Sequential-LOI, and TOC was found at 350 °C, rather than at 450 °C. Statistical analysis confirmed the similarities of the trends of TOC and LOI350 in the samples pooled according to the dominant grainsize, with the highest values associated to the medium sand fraction. The differences among the median values of the groups were significant (ANOVA, Kruskal-Wallis; P<0.001). The ratio LOI/TOC in the sediments were rather variable at the two temperatures. LOI350/TOC values ranged between 2 and 5, conversely the LOI450/TOC ones spanned in a wider range (2.5 - 14). The sandy samples exhibited more frequently lower values of the LOI/TOC ratio at both temperatures, while the silty samples showed the opposite, probably due to the presence of less labile organic compounds in the finest fractions.