Laghi di Monticchio (Southern Italy, Region Basilicata): genesis of sediments—a geochemical study

• Published in: Journal of paleolimnology Vol. 40; no. 1; pp. 529 - 556
• Main Authors: Schettler, Georg, Albéric, Patrick
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2008; Springer Nature B.V; Springer Verlag
• Subjects: Climate Change; Earth and Environmental Science; Earth Sciences; Environmental Sciences; Freshwater & Marine Ecology; Geochemistry; Geology; Global Changes; Lakes; Original Paper; Paleontology; Physical Geography; Sciences of the Universe; Sedimentology; Sediments; Studies; Italy; Geochemistry; Genesis; Lacustrine sediments; Geochemistry Genesis
• ISSN: 0921-2728; 1573-0417
• DOI: 10.1007/s10933-007-9180-4

The sedimentation record of Lago Grande di Monticchio (LGM) is one of the most prominent paleoclimatic archives in the non-glaciated areas of Europe. However, the modern lake system has never been the subject of intense limnological studies. On the basis of hydrochemical water profiles, detailed investigations of sediment short cores and in situ pore water profiles from the littoral to the profundal zone, we elucidate spatial variations of sediment genesis within the lake basin and the importance of various depth sections for the lake’s internal nutrient cycling. Sediments from the smaller meromictic Lago Piccolo di Montichio are discussed as a reference. Our study demonstrates: (i) distinctly higher sediment accumulation for the centre of the lake basin by focussing of the settling particle flux; (ii) decline of carbonate from the littoral to the profundal zones; (iii) non-synchronous change of calcite net-accumulation for various water depths; (iv) exceptionally high cation release from sediments covering the steeply inclining sector of the lake basin; (v) relatively constant dissolved silica concentrations in the pore waters (SiO 2 ∼42 mg/l) independent of water depth and sediment composition; (vi) influx of oxygen-bearing groundwater into the anoxic hypolimnion after heavy rainfall and the associated precipitation of Fe-oxihydroxides; (vii) higher release of NH 4 by anaerobic degradation of organic matter at a water depth of 23 m than for sediments at a maximum water depth of 32 m, whereby the latter reflects the importance of seasonal sediment re-oxidation for anaerobic degradation of organic debris; (viii) although seasonal re-oxidation of sediments from various water depths is quite different, Oxygen Index values of LGM sediments fall in a small range, which reflects rapid microbial consumption of seasonally re-generated easily bio-degradable organic molecules.