Nonhomogeneous seawater Sr isotopic composition in the coastal oceans: A novel tool for tracing water masses and submarine groundwater discharge

作者：Huang Kuo Fang^*; You Chen Feng; Chung Chuan Hsiung; Lin In Tian

来源：Geochemistry Geophysics Geosystems, 2011, 12(5): Q05002.

DOI：10.1029/2010GC003372

• seawater Sr isotope
• water mass mixing
• submarine groundwater discharge

Here we present high-precision (2 sigma = +/- 3 ppm) (87)Sr/(86)Sr measurements in coastal waters, together with salinity, to evaluate water mass mixing and the influence of submarine groundwater discharge (SGD) in coastal waters and marginal seas. Nonhomogeneous Sr isotopic variations in water columns were documented in the Southern Okinawa Trough (SOT), South China Sea, and Kao-ping Canyon (KPC), where seawater (87)Sr/(86)Sr varied up to 70 ppm. Seawater Sr isotopic composition changes only slightly in the upper 200 m of the SOT but was detectable and highly correlated with salinity, indicating a mixing between radiogenic North Pacific Tropical Water (high (87)Sr/(86)Sr and high salinity) at 100-150 m and a less radiogenic component with low (87)Sr/(86)Sr and low salinity at similar to 200 m. Vertical profiles of seawater (87)Sr/(86)Sr along the KPC show significant variations, suggesting dynamic mixing affected by continental inputs (i.e., river runoff and SGD) in this region. These results highlight the potential use of seawater Sr isotopes as a powerful tracer for determining mixing ratios and the dynamic mixing of oceanic water masses, especially in coastal and marginal seas.

• 出版日期2011-5-7