Image analysis in sedimentology as application for high-resolution grain size analysis: a case study of lake sediments from Tangra Yumco (Tibetan Plateau)

Abstract HKT-ISTP 2013 B

Heavy rainfall events recorded in sediments of the TT Lake (southern-central Tibetan Plateau) since AD 440

Abstract HKT-ISTP 2013 B

Applicability of electrical resistivity tomography monitoring to coarse blocky and ice-rich permafrost landforms

The inversion and interpretation of electrical resistivity tomography (ERT) data from coarse blocky and ice-rich permafrost sites are challenging due to strong resistivity contrasts and high contact resistances. To assess temporal changes during ERT monitoring (ERTM), corresponding inversion artefacts have to be separated from true subsurface changes. Appraisal techniques serve to analyse an ERTM data set from a rockglacier, including synthetic modelling, the depth of investigation index technique and the so-called resolution matrix approach. The application of these methods led step by step to the identification of unreliable model regions and thus to the improvement in interpretation of temporal resistivity changes. An important result is that resistivity values of model regions with strong resistivity contrasts and highly resistive features are generally of critical reliability, and resistivity changes within or below the ice core of a rockglacier should therefore not be interpreted as a permafrost signal. Conversely, long-term degradation phenomena in terms of warming of massive ground ice at the permafrost table are detectable by ERTM

Biogeochemical evidence for freshwater periods during the Last Glacial Maximum recorded in lake sediments from Nam Co, south-central Tibetan Plateau

Improved knowledge of deglaciation processes during the termination of the Last Glacial Maximum on the Tibetan Plateau can provide important information for understanding deglaciations in climate-sensitive high-altitude ecosystems. Little, however, is known about this time interval because most lacustrine sediment records from the Tibetan Plateau are younger than 19,000 years. This study focused on a lake sediment record from Nam Co, south-central Tibetan Plateau, covering the interval from *23.7 to 20.9 cal ka BP. We analysed the distribution and compound-specific hydrogen isotope composition (dD) of sedimentary n-alkanes, as well as the bulk sediment TOC, TN, d13Corg and d15N composition, to infer lake system development. Pronounced changes in environmental conditions between *21.6 and 21.1 cal ka BP, as well as between 23.1 and 22.5 cal ka BP (Greenland Interstadial 2), were inferred from increased aquatic nalkane amounts and decreased dDn-C23 values within these time intervals, respectively. Freshwater inputs, which most likely resulted from enhanced glacier melting, caused these changes. Our results suggest that mountain glacier retreat on the Tibetan Plateau started earlier than previously assumed. The required energy for thawing was probably provided by temperature changes caused by reorganization of atmospheric circulation, which has also been recorded in Greenland ice records

Late quaternary hydrological changes at Tangra Yumco, Tibetan Plateau: a compound-specific isotope-based quantification of lake level changes

Lake level fluctuations are important features in paleo-reconstructions that can be linked to past climate changes. Closed-basin lakes on the southcentral Tibetan Plateau record the balance between monsoonal precipitation and evaporative loss. To date, most studies provide only qualitative estimates of past hydrological changes. For the first time, we applied hydrogen isotopes (dD) of aquatic and terrestrial nalkanes to quantify lake volume changes of Tangra Yumco and compared values to newly calculated lake volumes of Nam Co. We also used carbon isotopes of sedimentary n-alkanes to reveal past climate and environmental conditions around the lake. The water volume of Tangra Yumco changed by 146 km3 in the past 17.42 cal ka. Lake volume increased in two steps, the first mainly initiated by glacial meltwater input after 16 cal ka BP, and to a minor extent by first strengthening of the Asian Summer Monsoon (ASM). The second increase was caused by intensified summer monsoon precipitation at 11.45 cal ka BP. After 8.0 cal ka BP, lake volume decreased because of arid conditions, until an increase at 0.8 cal ka BP that was probably linked to a wet spell during the Little Ice Age. The lake level changes of Tangra Yumco and Nam Co were affected simultaneously by the ASM, although their amplitudes differed because of different local conditions, such as basin morphology or the blocking effect of neighboring mountains, which influences the rainout of air masses and wind-induced evaporation

Forest Shink Plan Using a Carbon Offset System

In April 2005, Canada announced the introduction of new systems that could make the best use of market mechanisms, such as the Climate Fund, the Large Final Emitter System, and the Carbon Offset System, in order to achieve the reductions quota during the first commitment period (2008-2012). The Carbon Offset System has very high potential as a system able to push forward the forest sink policy, as it can help companies obtain credits for the GHG sink through forest sink activities recognized by the Kyoto Protocol (Paragraph 3 and 4, Clause 3). It also enables companies to trade GHG sink credits through the domestic emissions trade market. If the Carbon Offset System, which fully uses market mechanisms, is to be applied in Korea during the second commitment period (2013-2017) when Korea will have to deal with the obligations to reduce GHG emissions, it will be applied mostly to the expansion of the forest sink, through active forest management activities, such as afforestation, reforestation, and deforestation － given Korea has far fewer forest areas than Canada. In this case, it will be possible to increase the efficiency of the system by designing and operating it in a manner suitable for the conditions in Korea, including issuing domestic GHG sink credits to each sink developed through forest management, purchasing the credits, or providing additional subsidies. Forest owners might receive economic incentives through this, and it can also encourage new outside investments, such as forestry investments made by enterprises as part of their social contribution efforts