Author(s): E. Dinelli; I. Vasumini; S. Toller

Linked Author(s):

Keywords: Ridracoli lake; Surface sediments; Geochemical characterization; Sedimentological analysis; Organic carbon

Abstract: This work is aimed at the characterization of the surface sediments of the Ridracoli lake in Emilia-Romagna, Italy. Ridracoli lake is an artificial lake that is part of Foreste Casentinesi, Monte Falterona, Campiglia National Park, between Romagna and Tuscany. The lake, formed by the construction of a dam operating since 1982 for drinking water storage and hydropower generation, covers an area of 1082 km2, reaches a maximum depth of 88 m, and can store a maximum of 33.06 106 m3 of water. As regard the geology of this area, there is a massive presence of sandstones, and in a minor way of marls and clays. Surface sediments of the lake, sediments transported from the tributaries and sediments of the surrounding water courses were sampled and analyzed for their chemical and textural composition. Sediment samples were taken from 27 stations within the lake using a grab, collecting the upper 10 centimeters. The sampling survey covered the whole lake, from a maximum depth of 71 meters to a minimum of 8, and of about 1 meter for samples collected from tributaries. Sediments were analyzed for their total composition by means of X-ray fluorescence (XRF) spectrometry and for their pseudo-total composition with aqua regia digestion followed by ICP-MS analysis. The Corg and N content were evaluated using an elemental analyzer. The grain size distribution has been evaluated by sieving, and sedigraph analysis on the <60 µm fraction. Sediments from the lake are dominated by silt and clay with only local dominance of sand, where sand and silt are the main type of sediment. On the other hand, the bedload sediment sampled in the tributaries is predominantly composed by sand. The sediment is a mixture of silicoclastic and carbonate material, according to the bedrock geology of the area, which is dominated by sandstones and marls. It is important to note the high concentration of Corg (from 0.37 to 6.40 wt%) that record the highest concentrations in the inflowing rivers and an increasing concentration toward the northern portion of the lake, closer to the dam.

DOI: https://doi.org/10.3850/978-981-11-2731-1_345-cd

Year: 2018