FN Archimer Export Format PT J TI Changes in East Asian summer monsoon precipitation during the Holocene deduced from a freshwater flux reconstruction of the Changjiang (Yangtze River) based on the oxygen isotope mass balance in the northern East China Sea BT AF KUBOTA, Y. TADA, R. KIMOTO, K. AS 1:1,2;2:2;3:3; FF 1:;2:;3:; C1 Natl Museum Nat & Sci, Dept Geol & Paleontol, Tsukuba, Ibaraki 3050005, Japan. Univ Tokyo, Grad Sch Sci, Dept Earth & Planetary Sci, Bunkyo Ku, Tokyo 1130033, Japan. Japan Agcy Marine Earth Sci & Technol, Res Inst Global Change, Yokosuka, Kanagawa 2370061, Japan. C2 NATL MUSEUM NAT & SCI, JAPAN UNIV TOKYO, JAPAN JAMSTEC, JAPAN IN DOAJ IF 3.638 TC 38 UR https://archimer.ifremer.fr/doc/00352/46292/45946.pdf https://archimer.ifremer.fr/doc/00352/46292/45947.pdf LA English DT Article CR IMAGES 1-MD101 MD 122 / WEPAMA BO Marion Dufresne AB The delta O-18 of seawater (delta O-18(w)), an indirect indicator of sea surface salinity (SSS), in the northern East China Sea (ECS) is reconstructed for the Holocene using paired analyses of Mg/Ca ratio and delta O-18 of planktic foraminiferal tests. According to modern observation, interannual variations in SSS during summer in the northern ECS are mainly controlled by the Changjiang (Yangtze River) discharge, which reflects summer rainfall in its drainage basin. Thus, changes in the summer SSS in the northern ECS are interpreted as reflecting variations in the East Asian summer monsoon (EASM) precipitation in the Changjiang Basin. This interpretation is confirmed by a strong relationship between the SSS in the northern ECS and the Changjiang discharge during the wet season (May-October) based on instrumental salinity records from 1951 to 2000. However, it is difficult to estimate absolute salinity values in the past with high accuracy, because the past salinity-delta O-18(w) regression slope, end member salinity, and delta O-18(w) values are not well understood. Here, we conduct delta O-18(w) mass-balance calculation to estimate the freshwater contribution to the surface water of the northern ECS during the last 7 kyr by assuming a simple mixing between two end members - the seawater and the Changjiang freshwater. The result indicates that there has been no gradual decreasing secular trend in the Changjiang freshwater flux from the middle Holocene to the present day, suggesting that summer insolation in the Northern Hemisphere does not regulate the EASM precipitation in the Changjiang Basin. Instead, internal feedback appears to have been more important during the Holocene. The absence of a decreasing trend in regional summer precipitation over the Changjiang Basin since the middle Holocene is contradictory to Chinese speleothems' delta O-18 records, suggesting that it is not possible to explain orbital changes in Chinese speleothems' delta O-18 during the Holocene by changes in summer precipitation, but that such changes are related to other factors such as changes in the moisture source. PY 2015 SO Climate Of The Past SN 1814-9324 PU Copernicus Gesellschaft Mbh VL 11 IS 2 UT 000350560400011 BP 265 EP 281 DI 10.5194/cp-11-265-2015 ID 46292 ER EF