Lacustrine organic matter and the Holocene paleoenvironmental record of Lake Albano (central Italy)

A combined bulk and detailed geochemical study of the sedimentary organic m atter in Lake Albano, central Italy, provides critical data to track the re sponse of this aquatic system to the environmental changes of variable ampl itude that occurred during the Holocene. Rock-Eval pyrolysis of this predom inantly laminated, organic carbon-rich sedimentary sequence shows changes i n hydrogen and oxygen indices that are related to variations in the dominan ce of the primary producers. These variations are further confirmed by the pigments and the carbon isotopic composition of bulk organic matter showing that cyanobacteria dominated the lake waters during the early and late Hol ocene whereas diatoms have been the main producers during the middle Holoce ne. Sharp decreases in productivity, 2-3 centuries long, are identified at ca. 8.2, 6.4 and 3.8 ka. B.P. Changes in temperature and/or effective moist ure are suggested as the most probable causes, although human impact cannot be ruled out for the latest part of the Holocene.