[U-13] Advanced understanding of Quaternary and Anthropocene hydroclimate changes in East Asia:

[U13-02] Increased soil erosion since Southeast Asia economic boom recorded in Porites corals

★Invited Papers

*Xiaohua Li¹, Zhen Zeng², Yi Liu³, Ching-Chih Chang⁴, Hong-Wei Chiang⁴, Xuan-Ce Wang⁵, Weidong Sun¹, Hui-Min Yu², Fang Huang², Chung-Che Wu⁴, Tsai-Luen Yu⁴, Chun-Yuan Huang⁴, Chuan-Chou Shen⁴ (1.Institute of Oceanology, Chinese Academy of Sciences, 2.University of Science and Technology of China, 3.Tianjin University, 4.National Taiwan University, 5.Yunnan University)

Keywords:soil erosion, Porites coral, Ba/Ca, δ137/134Ba, Southeast Asia, economic boom

Soil erosion has raised public concern in Southeast Asia which has been poorly documented due to the lack of long, continuous records. Here we present two Porites coral records of monthly-resolved Ba/Ca ratios and monthly and yearly-resolved δ^137/134Ba from the Nanwan (NW), southern Taiwan, and Son Tra Island (STI), central Vietnam, to explore the extent of soil erosion. Our major finding is that erosion and sediment transport have increase substantially since the regional economic boom and resulted in Ba/Ca ratios significantly elevated during 1987-1996 and 1992-2001 for NW and STI corals, respectively, principally due to increasing pressure on land use. Due to terrestrial inputs yield a homogeneous Ba isotope composition, the δ^137/134Ba values of coral NW and STI show essentially constant with the mean isotope fractionation between coral and seawater Δ^137/134Ba_{coral - seawater} is -0.1‰, suggesting that Porties coral could be used to trace the Ba isotope composition in ambient seawater. Coupled Ba/Ca and Ba isotopes analysis on Porites coral has the potentially to provide new information about the historical soil erosion events.