https://repository.kopri.re.kr/handle/201206/5100 2026-04-04T00:33:18Z https://repository.kopri.re.kr/handle/201206/6168 Title: Comparison of radiocarbon and OSL dating methods for a Late Quaternary sediment core from Lake Ulaan, Mongolia Authors: Lee, Yong Il; Lim, Hyoun Soo; Lee, Min Kyung; Yoon, Ho Il; Choi, Jeong Heon; Lee, Jae Il Abstract: Both radiocarbon and optically stimulated luminescence (OSL) dating methods were applied to test their suitability for establishing a chronology of arid-zone lacustrine sediments using a 5.88-m-long core drilled from Lake Ulaan, southern Mongolia. Although the radiocarbon and OSL ages agree in some samples, the radiocarbon ages are older than the corresponding OSL ages at the 550-cm depth horizon (late Pleistocene) and in the 100？300-cm interval (early to late Holocene). In the early to late Holocene, radiocarbon ages are consistently older than OSL ages by 4,100？5,800 years, and in the late Pleistocene by 2,700？3,000 years. Grain-size analysis of early to late Holocene sediments and one late Pleistocene sediment sample (550-cm depth) indicates that eolian processes were the dominant sediment-transport mechanism. Also, two late Pleistocene sediments samples (from 400- to 500-cm depths) are interpreted to have been deposited by both eolian and glaciofluvial processes. Accordingly, the radiocarbon ages that were older than the corresponding OSL ages during the Holocene seem to have been a consequence of the influx of 14C-deficient carbon delivered from adjacent soils and Paleozoic carbonate rocks by the westerly winds, a process that is also active today. In addition to the input of old reworked carbon by eolian processes, the late Pleistocene sediments were also influenced by old carbon delivered by deglacial meltwater. The results of this study suggest that when eolian sediment transport is suspected, especially in lakes of arid environments, the OSL dating method is superior to the radiocarbon dating method, as it eliminates a common 'old-carbon' error problem. 2011-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/8060 Title: Mt. Everest Ice Core Record of Atmospheric Cu, Zn, Cd, Pb, and Pb Isotopes Variations in Central Asia during the Past 800 Years Authors: Lee, Khanghyun; L.J.Burn-Nunes; C.Boutron; S.Hou; C Barbante; S.Hong; Hur, Soon Do Abstract: Recent century scale time records for As, Mo, Sn, Sb, Bi, U, and Cs from Mt. Everest ice cores documented that a significant perturbation in the natural cycles of these elements took place during the second half of the 20th century due to increasing emissions of anthropogenic pollutants largely from fossil fuel combustion and non-ferrous metals production in central Asia. To evaluate to what extent human activities in central Asia have affected the natural atmospheric cycles of other heavy metals over time, Cu, Zn, Cd, and Pb concentrations and Pb isotopes were determined at 143 depth intervals from high-altitude Mt. Everest ice cores, covering an 800-year time period from 1205 to 2002 AD. This is the first reliable long-term time series of changes in the occurrence of Cu, Zn, Cd, and Pb and Pb isotopes in the remote Himalayan atmosphere. Our data show that these metals were primarily of natural origin up until the 1960s and significant increases in concentrations and crustal enrichment factors are observed from the 1970s onward. Such changes are attributed to massive emissions of anthropogenic Cu, Zn, Cd, and Pb from various anthropogenic sources in India. The Pb isotopic compositions provide clear evidence that anthropogenic Pb emitted from the use of leaded gasoline and coal combustion in India has affected the remote Himalayan atmosphere. 2010-01-01T00:00:00Z