Geochemistry of Lago Grande di Monticchio, S. Italy
This account describes the results of bulk geochemical analysis on the uppermost 15m of a 51m profile obtained from Lago Grande di Monticchio. This section is thought to extend from historic times back into the late Pleistocene, hence including the glacial-Holocene transition.
One of the clearest changes seen occurs in the organic carbon content of the sediment, rising from modest values in lower parts of the core to values as high as 30wt% at around 8m depth. In this zone, thought to be correlated with the glacial-Holocene transition, other elements vary directly (Br) or inversely (Al, Y) with organic carbon concentration. Multivariate techniques such as principal components analysis have been used to help identify these elemental associations. Such groupings are suggested as reflecting different contributors to the sediments (eg. plant matter, clays, residual minerals). The stable isotopic composition of organic carbon displays something of a shift towards lighter values across the glacial-Holocene transition zone, but the profile as a whole is difficult to interpret without further information on the nature of the organic matter. Several elements (P, Mn, Mo) exhibit enrichments in discrete temporal zones and it is thought that these are indicative of diagenetic processes occuring in the sediment.
KeywordsElectron Spin Resonance Lake Sediment Organic Carbon Content Biogenic Silica Diagenetic Process
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