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Decreased surface salinity in the Sea of Okhotsk during the last glacial period estimated from alkenones
Author(s) -
Seki Osamu,
Kawamura Kimitaka,
Sakamoto Tatsuhiko,
Ikehara Minoru,
Nakatsuka Takeshi,
Wakatsuchi Masaaki
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl022177
Subject(s) - glacial period , salinity , oceanography , geology , alkenone , interglacial , period (music) , sea ice , last glacial maximum , sea surface temperature , climatology , geomorphology , physics , acoustics
Studies of sediment cores from the Sea of Okhotsk, which is characterized by seasonal sea ice, have shown a large variability of sea ice indicators during the glacial‐interglacial cycles. In this study, we apply the relative abundance of the C 37:4 alkenone to total C 37 alkenones (%C 37:4 ) as a molecular indicator of salinity and water masses to further investigate surface oceanographic condition in the Sea of Okhotsk in the glacial period. We found a large fluctuation of %C 37:4 (4–35%) with higher values (20∼35%) during the last glacial period and lower values (<8%) during warm periods, suggesting a decreased surface salinity in the glacial period. The variation of %C 37:4 was found to be consistent with the ice rafted debris (IRD) in the sediment core (correlation coefficient (r 2 ) between %C 37:4 and IRD: 0.72). This suggests that the duration of seasonal sea ice was longer in the glacial period than today. The lowered surface salinity in the glacial might also have been seriously affected by the close‐off of the shallow Soya Strait, which currently transports massive volumes of saline water from the Sea of Japan to the Sea of Okhotsk.