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Radiocarbon Data from the Vicinity of Four South Korean Nuclear Power Plants in 2013-2014
Lee, J H,Kim, C H,Kang, J,Song, S,Yun, M H,Kim, J C UNIVERSITY OF ARIZONA 2017 RADIOCARBON Vol.59 No.3
<B>Abstract</B><P>Radiocarbon (<SUP>14</SUP>C) is a radionuclide generated mainly through neutron-induced reactions in all types of nuclear reactors. Since most of the <SUP>14</SUP>C released into the environment is in the form of gaseous emissions (CO2 and hydrocarbons), terrestrial plants are the primary indicators of increased <SUP>14</SUP>C levels near nuclear power plants (NPPs). In 2013-2014, we collected samples of silver grasses (including common reed) and pine needles within 3 km of four South Korean NPP centers and measured <SUP>14</SUP>C activities using accelerator mass spectrometry (AMS) at Seoul National University. The highest <SUP>14</SUP>C activities were observed, respectively, in Wolsong>Hanul>Kori>Hanbit [220, 143, 127, and 123% modern carbon (pMC)].</P>
Kim, Chi-Hwan,Lee, Jang Hoon,Kang, Jin,Song, Sujin,Yun, Myung-ho,Kim, Jong Chan UNIVERSITY OF ARIZONA 2017 RADIOCARBON Vol.59 No.2
<B>Abstract</B><P>Stable carbon isotope ratios were measured on the alpha-cellulose in tree rings of a pine tree (<I>Pinus densiflora</I>) from Yeongwol, Korea. We developed an annual-resolution δ<SUP>13</SUP>C series (1835-1905) by correcting the measured data for changes in δ<SUP>13</SUP>C of air to minimize non-climatic influences. To investigate the climatic signal in the δ<SUP>13</SUP>C series, we performed correlation analysis between δ<SUP>13</SUP>C and the Cheugugi climate data. The Cheugugi precipitation data were first recorded by King Sejong (1397-1450) of the Joseon Dynasty. However, the longest set of precipitation data available is the one collected in Seoul (1776-1907). Although many studies support the reliability of the Cheugugi data, no previous studies have investigated the potential of the δ<SUP>13</SUP>C signal in tree rings as paleoclimate proxy using the Cheugugi data. Recent precipitation trends in Yeongwol are quite similar to that of Seoul, and we found significant correlations between the Cheugugi data and the δ<SUP>13</SUP>C series. We suggest further studies to replicate these results and confirm whether comparing δ<SUP>13</SUP>C variations in tree rings and Cheugugi data is a useful method of investigating the potential of the δ<SUP>13</SUP>C signal as a paleoclimate proxy in or near the Korean peninsula.</P>
Choi, Yire,Kim, Kyeong Ja,Cheong, Daekyo,Kim, Yong Ha UNIVERSITY OF ARIZONA 2014 RADIOCARBON Vol.56 No.3
<P>The paleoclimatic signal of Lake Hovsgol in Mongolia was investigated using authigenic beryllium isotopes from 20 sediment samples. The beryllium isotopic records from this study indicate that there were three dry and cold periods at the lake around 9400, 12,700, and 17,100 cal yr BP. The significant <SUP>10</SUP>Be signal during the Younger Dryas (YD) period is found to be lower. This indicates that the Lake Hovsgol area was subject to a period of cold and dry conditions with minimal dust input, which manifests itself as a low <SUP>9</SUP>Be profile in this study. In warmer and wetter climatic conditions, the <SUP>10</SUP>Be concentration was found to be higher, and this agrees with the sedimentation record of this study. The climatic signals from Lake Hovsgol appear to be similar to a decreased beryllium record during the deglacial period. The results of this study confirm that the Lake Hovsgol area also experienced the global paleoclimatic change associated with the YD event around 12,700 cal yr BP. Further investigation using worldwide lake records by the analytical technique of authigenic beryllium will be useful for understanding the global paleoclimatic change pattern in conjunction with lake-level change.</P>
Nakanishi, Toshimichi,Hong, Wan,Shimoyama, Shoichi,Sato, Shin’ichi,Park, Gyujun,Lee, Jong-Geol UNIVERSITY OF ARIZONA 2017 RADIOCARBON Vol.59 No.2
<B>Abstract</B><P>To measure chronological changes in the marine reservoir effect in western Japan, 47 marine shells and 35 terrestrial plants from the same horizons in two cores of Holocene sediments were radiocarbon dated by the KIGAM AMS facility. These cores were obtained from the central and northern parts of Hakata Bay using a Geoslicer device. This drilling tool provided us continuous coverage and many samples. In order to determine the species effects on the marine reservoir effect, both filter feeders and a deposit feeder were selected for study. Based on the analysis of lithology, mollusk assemblage, and <SUP>14</SUP>C dating, two sedimentary units were determined: the upper bay floor sediment and lower estuarine sediment. Reservoir ages of 280±150 yr (<I>n</I>=17) and 340±140 yr (<I>n</I>=18) were obtained from the central and northern parts of Hakata Bay during 2000 to 10,000 cal BP, respectively. Based on these results, it is clear that a paleoenvironmental change occurred here as a result of sea-level rise during the deglacial period.</P>