A Paleoenvironmental record from Lake Gosainkunda, Nepal

The Himalayan region is a key area for climate and environmental change and has experienced rapid and pronounced changes over the past decades. Paleoenvironmental studies from this region are crucial to understand natural climate variability. Here we investigate a ~150 cm long sediment core, spanning over the last ~7 cal. ka BP, from a small high-altitude Lake Gosainkunda (surface area ~2.3 km², 4300 m elevation) in the central Himalayas using a multiproxy approach. Several maxima in allochthonous elements such as Ti and K, sand, as well as white layers indicate increased erosion, possibly related to flood events. Low input of allochthonous elements and sand from ~7 to 6 cal. ka BP, and from ~5 to 1.8 cal. ka BP implies reduced erosion interpreted to be associated with low precipitation. Contemporaneously, high values of log(Si/Ti), log(Ca/Ti), BSi, and inc/coh indicate high aquatic productivity, mainly controlled by higher growing season temperature and shorter duration of ice cover. High allochthonous and sand input from ~6 to 5 cal. ka BP and from ~1.8 to 1 cal. ka BP indicate increased erosion related to high precipitation. Concurrently, low aquatic productivity and authigenic carbonate production as well as positive excursion in bulk δ¹³C and δ¹⁵N values suggest reduced growing season temperatures and longer ice-cover. In the last ~1 ka, increased allochthonous input is related to increased anthropogenic activity in the catchment. We are now aiming to apply a suite of lipid biomarkers including the compound-specific hydrogen isotopic composition of n-alkanes for paleohydrological reconstruction as well as polycyclic aromatic hydrocarbons and faecal biomarkers to investigate paleo-fires and human impacts.