As one of the areas with numerous lakes on the Tibetan Plateau, the Hoh Xil region plays an extremely important role in the fragile plateau eco-environment. Based on topographic maps in the 1970s and Landsat TM/ETM+ remote sensing images in the 1990s and the period from 2000 to 2011, the data of 83 lakes with an area above 10 km² each were obtained by digitization method and artificial visual interpretation technology, and the causes for lake variations were also analyzed. Some conclusions can be drawn as follows. (1) From the 1970s to 2011, the lakes in the Hoh Xil region firstly shrank and then expanded. In particular, the area of lakes generally decreased during the 1970s-1990s. Then the lakes expanded from the 1990s to 2000 and the area was slightly higher than that in the 1970s. The area of lakes dramatically increased after 2000. (2) From 2000 to 2011, the lakes with different area ranks in the Hoh Xil region showed an overall expansion trend. Meanwhile, some regional differences were also discovered. Most of the lakes expanded and were widely distributed in the northern, central and western parts of the region. Some lakes were merged together or overflowed due to their rapid expansion. A small number of lakes with the trend of area decrease or strong fluctuation were scattered in the central and southern parts of the study area. And their variations were related to their own supply conditions or hydraulic connection with the downstream lakes or rivers. (3) The increase in precipitation was the dominant factor resulting in the expansion of lakes in the Hoh Xil region. The secondary factor was the increase in meltwater from glaciers and frozen soil due to climate warming.

Boron is a moderately volatile element with two stable isotopes ¹¹B and ¹⁰B. As much as 10% relative mass difference between the two isotopes leads to significant variation in boron isotopic composition from -70‰ to +75‰ in nature. Boron is always bound to oxygen forming tetrahedral (BO₄) and trigonal (BO₃) coordination structures. The isotope fractionation between¹⁰B and ¹¹B is mainly controlled by their partition between the two structures. In this study, we gave a comprehensive review on the advances in equilibrium fractionation of boron isotopes in various processes. In solution, the boron isotope fractionation factor between B(OH)₃ and ${B(OH)^{-}_{4}}$ (α_3-4) is controlled by pH and thermodynamic p-T conditions. At ambient conditions, the α_3-4 values ranged from 1.0194 to 1.0333 by experimental and theoretical approaches. In addition to p-T-pH controls, boron isotope fractionation, caused by mineral surface adsorption between minerals (carbonates, clay minerals (montmorillonite and illite), goethite, hydromanganese, borate, etc.) and solution, is significant at low temperature. In medium and high temperature processes, boron isotope fractionation during illitization of smectite, tourmaline and muscovite minerals and in hydrothermal fluids or silicate melts and fluids are controlled by boron coordination, chemical composition, and physicochemical conditions. With further understanding of boron isotope fractionation mechanisms in individual process and isotopic distribution in various geological reservoirs, boron isotopes may be considered as sensitive indices for tracing ore-forming material sources, exploring ore-forming processes and genesis models, as well as reconstructing physicochemical conditions during ore formation. To better constrain geological concerns using boron isotopes in ore deposit geochemistry, the remaining challenges are to achieve fine characterizations of boron coordination and isotopic compositions in different host phases, such as fluids, minerals and melts.