TY - JOUR
T1 - Late-Holocene salinity changes in Lake Ogawara, Pacific coast of northeast Japan, related to sea-level fall inferred from sedimentary geochemical signatures
AU - Nara, Fumiko Watanabe
AU - Watanabe, Takahiro
AU - Matsunaka, Tetsuya
AU - Yamasaki, Shin ichi
AU - Tsuchiya, Noriyoshi
AU - Seto, Koji
AU - Yamada, Kazuyoshi
AU - Yasuda, Yoshinori
N1 - Funding Information:
This work was partly supported by the cooperative research program of the Institute of Nature and Environmental Technology, Kanazawa University (Accept No. 18023 and 19045), and the 2012 Joint Research Program (No. A-1, 2012) of the International Research Institute of Disaster Science (IRIDeS), Tohoku University, Japan. We are grateful to the editor Shucheng Xie as well as to two anonymous reviewers whose thorough reviews considerably improved this article. We are grateful to M. Saito-Kato (National Museum of Nature and Science) and K. Gotanda (Chiba University of Commerce) for their kind support in collecting the lake sediment sample, T. Omori (Tokyo University) for his helpful comments on 14C age model, Y. Asahara (Nagoya University) for his help to improve the manuscript, T. Yokoyama (JAEA) for the XRD measurements and Y. Yamamoto (JAEA, seconded from KOBELCO research institute. Inc) for the portable XRF measurements.
Funding Information:
This work was partly supported by the cooperative research program of the Institute of Nature and Environmental Technology, Kanazawa University (Accept No. 18023 and 19045 ), and the 2012 Joint Research Program (No. A -1, 2012 ) of the International Research Institute of Disaster Science (IRIDeS), Tohoku University, Japan. We are grateful to the editor Shucheng Xie as well as to two anonymous reviewers whose thorough reviews considerably improved this article. We are grateful to M. Saito-Kato (National Museum of Nature and Science) and K. Gotanda (Chiba University of Commerce) for their kind support in collecting the lake sediment sample, T. Omori (Tokyo University) for his helpful comments on 14 C age model, Y. Asahara (Nagoya University) for his help to improve the manuscript, T. Yokoyama (JAEA) for the XRD measurements and Y. Yamamoto (JAEA, seconded from KOBELCO research institute. Inc) for the portable XRF measurements.
Publisher Copyright:
© 2022 The Authors
PY - 2022/4/15
Y1 - 2022/4/15
N2 - This study aimed to provide important insights into Pacific Ocean sea-level changes by clarifying salinity changes in Lake Ogawara on the Pacific coast of northeast Japan, which became brackish in the late Holocene. Radiocarbon (14C) dating, tephrochronology, and geochemical signatures, including bromine (Br), iodine (I), total sulfur (TS), total organic carbon (TOC), and total nitrogen (TN), were applied to continuous sediment core from Lake Ogawara to estimate salinity changes. The core has two tephra layers, the Towada eruption (To-a; approximately 915 CE) and the Changbaishan eruption (B-Tm; 946 CE). An age model for the core was established using plant macro remain 14C ages constrained by a B-Tm tephra. The depletion of marine-derived elements (Br, I, and TS) was observed in 2200–2000 cal BP layers, indicating a paleosalinity change from saline to brackish conditions caused by falling sea levels during the late Holocene. Variations in Br, I, TOC, and TN concentrations were significantly changed compared to those below the B-Tm layer. High correlations between Br and TOC and I and TOC above the B-Tm tephra layer to the surface indicated an organic source for the halogens post the Changbaishan eruption, indicating a change to the hydrological system of the lake's watershed. The increasing variation in the C/N atomic ratio in the post-B-Tm sediments also supported this hydrological change. Two recorded significant volcanic eruptions could have triggered these changes to the Lake Ogawara water inflow system.
AB - This study aimed to provide important insights into Pacific Ocean sea-level changes by clarifying salinity changes in Lake Ogawara on the Pacific coast of northeast Japan, which became brackish in the late Holocene. Radiocarbon (14C) dating, tephrochronology, and geochemical signatures, including bromine (Br), iodine (I), total sulfur (TS), total organic carbon (TOC), and total nitrogen (TN), were applied to continuous sediment core from Lake Ogawara to estimate salinity changes. The core has two tephra layers, the Towada eruption (To-a; approximately 915 CE) and the Changbaishan eruption (B-Tm; 946 CE). An age model for the core was established using plant macro remain 14C ages constrained by a B-Tm tephra. The depletion of marine-derived elements (Br, I, and TS) was observed in 2200–2000 cal BP layers, indicating a paleosalinity change from saline to brackish conditions caused by falling sea levels during the late Holocene. Variations in Br, I, TOC, and TN concentrations were significantly changed compared to those below the B-Tm layer. High correlations between Br and TOC and I and TOC above the B-Tm tephra layer to the surface indicated an organic source for the halogens post the Changbaishan eruption, indicating a change to the hydrological system of the lake's watershed. The increasing variation in the C/N atomic ratio in the post-B-Tm sediments also supported this hydrological change. Two recorded significant volcanic eruptions could have triggered these changes to the Lake Ogawara water inflow system.
KW - B-Tm tephra
KW - Brackish lake
KW - C
KW - Halogens
KW - Sea-level changes
KW - Tohoku
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U2 - 10.1016/j.palaeo.2022.110907
DO - 10.1016/j.palaeo.2022.110907
M3 - Article
AN - SCOPUS:85126028408
SN - 0031-0182
VL - 592
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
M1 - 110907
ER -