HR: 0830h
AN: V51H-0376    [PDF]
TI: Geochemical Investigation of Chemical Weathering in Taiwan: River water chemistry and Sr Isotopes
AU: * You, C
EM: cfy20@mail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Chung, S
EM: smileung@pchome.com.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Lin, P
EM: c4488129@mail.grad ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Wang, B
EM: c4488112@mail.grad ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Wang, R
EM: c4488410@mail.grad.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Hsieh, Y
EM: c4489402@ccmail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Lin, H
EM: acsio@yahoo.com.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AU: Lee, H
EM: c4490122@ccmail.ncku.edu.tw
AF: Department of Earth Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road., Tainan, 701 Taiwan
AB: Taiwan is an active tectonic island and has the highest physical denudation rate in the world. In this study, we investigate the state of chemical weathering in various river systems distributed all around the island. More than 200 water samples were collected from eight major rivers and their tributaries, including Choshui, Kaopin, Erhjen, Wu, Houlung, Hsiukuluan and Pachang. Among them, the Erhjen was visited nine times at 19 stations in two consecutive years for a detailed study of impacts due to seasonal variation. These water samples were centrifuged and analyzed for major ions (i.e., Na, K, Mg, Ca, Cl, bicarbonate and sulfate) and trace elements (Li, B, Si, Rb, Sr, Ba, and REE), as well as Sr, Pb and U isotopes. Applying factor analysis method, the most dominant factors controlling the chemical compositions are: (1) sea-salt contribution and tidal effect; (2) degree of water-ambient rock interaction; and (3) anthropogenic pollutant. Other effects including regional and seasonal variability are also detected. For instance, Sr isotopes indicate significant seasonal variation in river waters possibly reflecting source changes in ambient soils due to monsoon rain in summer. The Sr concentration and Sr isotope plot show interesting mixing among four sources. The near estuary stations display strong seawater isotopic signature. Stations at mid-stream were influenced by chemical erosion of bed-rock or ambient soils. The upstream samples were affected largely by the characteristics of tributary waters. Uranium isotopes vary largely in the Taiwanese river samples, a range of 1.14 to 2.5, possibly due to alpha recoils.
DE: 1040 Isotopic composition/chemistry
DE: 1065 Trace elements (3670)
DE: 1806 Chemistry of fresh water
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting