HR: 0800h
AN: GC51A-0150    [Abstracts]
TI: Coral Geochemical Proxy Records Of The East Asian Winter Monsoon And Hydrological Conditions In The Central Vietnam From 1978-2004 AD
AU: * Chang, C
EM: r94224205@ntu.edu.tw
AF: Department of Geosciences , National Taiwan University, No.1, Sec. 1, Roosevelt Road, Taipei, 106, Taiwan
AU: Shen, C
EM: river@ntu.edu.tw
AF: Department of Geosciences , National Taiwan University, No.1, Sec. 1, Roosevelt Road, Taipei, 106, Taiwan
AU: Chen, Y
EM: ygchen@ntu.edu.tw
AF: Department of Geosciences , National Taiwan University, No.1, Sec. 1, Roosevelt Road, Taipei, 106, Taiwan
AU: Chiang, H
EM: d91224004@ntu.edu.tw
AF: Department of Geosciences , National Taiwan University, No.1, Sec. 1, Roosevelt Road, Taipei, 106, Taiwan
AU: Lam, D D
EM: ddinhlam@yahoo.com
AF: Institute of Geological Science, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet Str., Nghia Do, Cau Giay, Hanoi, 084, Viet Nam
AU: Ngai, N
EM: ngaind@yahoo.com
AF: Marine Biological Resources and Ecology Department, Hai Phong Institute of Marine Environment and Resources, 246 Danang Street, Hai Phong, 084, Viet Nam
AB: Monthly-resolution geochemical proxies, including δ¹⁸O, δ¹³C, Sr/Ca, and Ba/Ca, in a living Porites coral head, collected from Son Tra Island, a near-shore island located at the north tip of Vung Da Nang Bay, central Vietnam (16°12'59.4", 108°1'57.1"), was used to quantitatively reconstruct records of sea surface temperature (SST), sea surface salinity (SSS), seasonality of rainfall, and regional terrestrial input during a period of 1978-2004 AD. By comparing the 1/4-century geochemical data, five features are exhibited. (1) The coral Sr/Ca-inferred summer SSTs correspond well with the 1°x1° instrumental data to suggest that the regional SST record can be retrieved from this local coral head. (2) Interannual variation of coral winter SST data does not follow regional instrumental values. The harmonic phenomenon between coral inferred winter SST dynamic and the surface pressure difference, between the southern South China Sea (SCS) (0-10°N, 105-115°E) and the northern SCS (22.5-32.5°N, 112-122°E), indicating that the cold local SST induced by East Asian winter monsoon was addressed in the Son Tra coral. (3) 1‰ seasonal anomaly of δ¹⁸O residual (Δδ¹⁸O) suggests a 2-4-psu seasonal salinity change between dry and wet seasons. (4) The synchronous intra-annual changes of δ¹⁸O and Ba/Ca data suggest that the rainy season is from late summer to winter, which is consistent with the meteorological record. (5) The high Ba/Ca background level of 10 μmol/mol in 1992-2004, 2-3 times larger than the averaged value of 4 μmol/mol in 1978-1992, indicates an enhanced terrestrial sediment discharge into the bay over the past 10 years. Ba records probably reflect an impact of human activity on hydrological change since the Vietnam War.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1632 Land cover change
DE: 1834 Human impacts
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting