The tributary rivers Amu Darya and Syr Darya contribute major amounts of water to the hydrological budget of the endorheic Aral Sea. Processes controlling the flow of water into rivers in the headwater systems in Tien Shan (Kyrgyzstan) and Pamir (Tajikistan) are therefore most relevant. Lake water mineralization is strongly dependent on river discharge and has been inferred from spectrometrically determined gypsum and other salt contents. Comparison of high-resolution mineralization data with tree ring data, other proxies for tracing temperature and snow cover in NW China, and accumulation rates in the Guliya Ice Core indicate that mineralization over the past ?2000 years in the Aral Sea reflects snow cover variability and glacier extent in Tien Shan and Pamir (at the NW and W edges of the Tibetan Plateau). We observed that the runoff decreased between AD 100-300, AD 1150-1250, AD 1380-1450, AD 1580-1680 and during several low frequency events after AD 1800.
We assessed the late Holocene minerogenic aerosol deposition distribution of the grain size of detrital particles and the bulk sediment flux from the Aral Sea at high resolution. Two processes are mainly relevant for the detritic input because fine silt-size fractions and Ti, Fe and K were positively correlated with Component 1 (C1), and clay-size fractions were positively correlated with Component 2 (C2). We propose that silt-size fractions and, in particular, the grain-size fraction ratio (6-32 µm/2-6 µm) are associated with airborne processes in the Aral Sea region, while the clay-size fractions (C2) are transported into the lake by sheetwash during heavy rainfalls, particularly in spring. Our results show that the bulk sediment deposition fluxes were extremely high during the Little Ice Age (LIA; AD 1400-1780), which may be related to increased dust deposition. Deposition was low during AD 1-350; between AD 720 - 1400, including the Medieval Warm Period (MWP, AD 755 – 1070), and since the AD 1940s.