Late holocene high resolution multi-proxy climate and environmental records from Lake Van, Eastern Turkey

Lake Van is the largest alkaline lake in the world characterized by varved sediments. It is located in eastern Anatolian plateau of Turkey. This study highlights the use of a multi-proxy approach toward understanding paleoenvironmental changes and sedimentation processes in Lake Van. We specifically focuse on climate records of the last 3500 years at centennial resolution. Compare the results with other studies in Anatolia, Near East and Europe. This study uses multi-proxy analyses of four interface sediment cores from different parts of the Lake. The multi-proxy data include ostracod counts, µ-XRF elemental, total organic (TOC) and inorganic carbon, C-N elemental and stable isotopes. For the age model of the core, we use radionuclide (210Pb and 137Cs) analysis and varve counting. Accelerator Mass Spectrometry (AMS) 14C dates from total organic carbon (TOC) indicates large differences with the corresponding varve ages, suggesting significant reservoir ages, which range from 1.2 to 3.8 ka BP. Double energetic window method by LSC which relies on the direct determination of 210Pb without waiting for the in growth of 210Po from 210Pb was used to construct the past environmental conditions of Lake Van in eastern Turkey. The results show that the sedimentation rate varies significantly among the four study sites, ranging between 0.3 and 0.7 mm.year-1.Varve counting of annually laminated sediments of Lake Van using digital X-ray radiographic images provided another means of dating the cores. Our study shows that varve counting method detects and counts fine-scale laminae, and produces robust varve ages that are comparable with independently determined 210Pb and 137Cs ages for the upper part of the core. All multi-proxy parameters including ostracods population, C/N ratio, stable isotope values, organic matter, Ti/Ca ratio showed 16 consistent periods varying between 100 and 350 years corresponding to alternation of cold/dry and warm/wet periods during the last 3500 years. The Lake Van climate records are conformable with the Lake Nar and the Sofular speleothem records as well as the European historical climate periods including Roman Warm Period (RWP), Dark Age Cold Period (DACP), Medieval Warm Period (MWP) and Little Ice Age (LIA), indicating teleconnections with the North Atlantic system. μ-XRF heavy metal profiles along the Lake Van cores show antropogenic inputs since 1960s. A significant increase occurred in metals such as Zn, Pb, Ni, and Co in the last 30-60 years in Lake Van cores. Especially increases in Zn and Pb in the upper parts of the cores indicate that important agricultural and industrial pollution began in the 1960s.