Climatic and anthropogenic influence on the stable isotope record from bulk carbonates and ostracodes in Lake Neuchâ, Switzerland, during the last two millennia

摘要: Lake Neuchatel is a medium sized, hard-water lake, lacking varved sediments, situated in the western Swiss Lowlands at foot of Jura Mountains. Stable isotope data (δ18O and δ13C) from both bulk carbonate ostracode calcite an 81 cm long, radiocarbon-dated sediment core represent last 1500 years Neuchatel's environmental history. Comparison between this isotopic other palaeolimnologic (mineralogical, geochemical, palynological, etc.) helps to differentiate anthropogenic natural factors most recently affecting lake. An increase lacustrine productivity (450–650AD ca), inferred positive trend δ13C values carbonate, related medieval forest clearances associated nutrient budget changes. A negative δ18O approximately 1300 1500AD, tentatively interpreted as due cooling mean air temperature transition Medieval Warm Period Little Ice Age. Negative trends through uppermost which have no equivalent values, are concomitant with recent onset eutrophication Isotopic disequilibrium during precipitation, probably kinetic periods high postulated mechanism explain trends, although effect shift precipitation towards warmer months cannot be excluded.