1. Weathering Sources in the Kaoping River Catchment, Southwestern Taiwan: Insights From Major and Trace Elements, Sr Isotopes and Rare Earth Elements C.-F. You, K.-F. Huang, C.-H. Chung and R.-M. Wang Department of Earth Sciences Also at Earth Dynamic System Research Center National Cheng Kung University

2. Ching et al., 2007 Liu et al., 2007

3. Outlines Sr isotopes Non-conventional high precision Sr isotopic measurement Major and trace elements REEs

4. Strontium Isotopes: 84 Sr (0.56 %) 86 Sr (9.86 %) 87 Sr (6.99 %) 88 Sr (82.54 %) 87 Rb  87 Sr ＋ β - ＋ anti-neutrino ＋ energy (t 1/2 ＝ 4.88× 10 10 years)

5. Geological Applications: 1. Geo-chronometer : Rb-Sr dating Seawater curve 2. 87 Sr/ 86 Sr Tracer: a. River water --- weathering process b. Sediments--- provenance and transportation c. Biogenic carbonate---seawater evolution 3. Environmental proxy SST or SSS

6. Sr Isotopic Composition of Earth Systems Dissolved load in river 0.7119 Detrital load in river 0.7178 Sediment 0.724 Seawater 0.708 Hydrothermal vent 0.7035 Oceanic crust 0.702

7. Geochemical Behaviors of Sr in the “Water World” 1.River water: (a) Reflect the Rb/Sr ratio and “age” of the source rocks; (b) Sources derived from silicate and carbonate weathering 2. Seawater: (a) Chemically and isotopically “uniform” because of its long residence time (~2 Ma); (b) Small but considerable regional difference in flux and ICs occurred on time-scales shorter than the residence time; (c) Non-conservative mixing in estuaries due to dynamic exchanges

8. Total mass of Sr in seawater= 1.25×10 17 mol After Basu et al., 2001 Oceanic Sr Budget 1, Steady or not? 2, How Sr ICs change with time? (Assuming an average seawater concentration of 91.3  M)

9. Sampling Sites Reference sites- ST-1 (NEC) and St-C (SCS)

10. South China Sea Sample Locality April Aug.

11. Modern Hydrography Typhoon Toraji Liang et al., 2003 WRA., 2003

12. Wang et al., 2002 200-300 m Kuroshio NPTW SCS 100 m NPIW PDW 400-600 m >1300 m Kao-Ping Canyon Sea Water Masses RW 0 100 Water massDepth SCS NPTW 200 SCS 400 SCS NPIW 600 NPDW 1300 bottom

13. High-Precision Sr Isotopic Measurement P- TIMS 3N HNO38N HNO3 3N HNO3 0.05N HNO3 Seawater ORI 679_S6-10 m 1.0.709196±03 2.0.709197±02 ORI 679_S3-10 m 1.0.709195±03 2.0.709195±02 SB_09-12 (10.5 m) 1.0.709195±03 2.0.709193±02 Recovery> 99.5% TRITON TI

14. Δ 87 Sr (ppm) The surface distributions of Sr ICs in the KPE After Typhoon Toraji

15. Other Hydrographic Evidences (Lin et al., 2003)

16. Δ 87 Sr= -39.11*S+1338.7 r 2 =0.80 Δ 87 Sr= -10.82*S+377.08 r 2 =0.70 EM-1 EM-2 EM-3 9.3 ppm (33.99‰) Salinity (psu) Δ 87 Sr (ppm) Freshening Surface Seawater Sr ICs vs. Salinity EM-1: Most radiogenic Sr IC--- (1) intense water-sediment interaction caused by flood plume (2) release radiogenic Sr from silicates due to stronger erosion EM-2: Normal discharge of the Kao-ping river after heavy rainfalls 2σ2σ

17. Sr Isotopic Characteristics of the Taiwan River Δ 87 Sr (ppm)

18. Mixing processes of the Water masses --- Evidence from the vertical profiles of the Sr ICs at the SOT SOT S1 S6 S3 0.7091760.709182 0.709176 Seawater Sr ICs is “not” isotopic uniform in the open ocean and marginal sea, but it seems to have a similar pattern in the same region.

20. (a)

23. (b) (c)

24. Summary High precision Sr isotopic measurement can be applied as a new sensitive tracer for studying water mass mixing near estuary Rather large variation in  87 Sr, >60 ppm, was detected in the Kao-ping estuary and possibly were affected by flood plume, river discharge and surface seawater mass Vertical seawater Sr ICs is “not” isotopic uniform in the open ocean and marginal sea Dynamic exchange among freshwater, groundwater and seawater are occurring in the Kaoping River estuary and canyon

25. Summary (continue) High dissolved B and Sr in the Kaoping River emphasize the potential impact of mountainous island to the global oceanic chemical budget The dissolved REE patterns of the Kaoping River at different tributaries show similar negative Ce anomaly and HREE enrichment Strong positive Gd anomaly supports an anthropogenic pollution in the river. The Sr isotopic variations are rather large, 0.712649~ 0.713592, and show systematically decreasing ratios with distance from the coastal region

26. THANKS FOR YOUR ATTENTION EDSRC-NCKU, Taiwan