Open AccessNonhomogeneous seawater Sr isotopic composition in the coastal oceans: A novel tool for tracing water masses and submarine groundwater discharge
Author(s) -
Huang KuoFang,
You ChenFeng,
Chung ChuanHsiung,
Lin InTian
Publication year - 2011
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2010gc003372
Subject(s) - seawater , submarine groundwater discharge , geology , salinity , radiogenic nuclide , oceanography , water mass , groundwater , pore water pressure , geochemistry , hydrology (agriculture) , aquifer , mantle (geology) , geotechnical engineering
Here we present high‐precision (2 σ = ±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 ∼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.