Dissolved and labile particulate Zr,Hf, Nb,Ta, Mo and W in the western North Pacific Ocean |
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Authors: | M Lutfi Firdaus Kazuhiro Norisuye Yusuke Nakagawa Seiji Nakatsuka Yoshiki Sohrin |
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Institution: | (1) Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan |
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Abstract: | Dissolved and labile particulate Zr, Hf, Nb, Ta, Mo and W were determined at stations K1 (51°N, 165°E), K2 (47°N, 160°E),
KNOT (44°N, 155°E) and 35N (35°N, 160°E) in the western North Pacific Ocean. A portion of seawater for dissolved species (D)
was passed through a 0.2 μm Nuclepore filter and acidified to pH 2.2 with HCl and HF. A portion of seawater for acid-dissolvable species (AD) was acidified
without filtration. Labile particulate (LP) species is defined as AD minus D, which represents a chemically labile fraction
of particulate species. D-Zr, Hf and Ta increase with depth, Nb shows a slight depletion in surface water, whereas Mo and
W have a conservative vertical profile. The concentration range of D-Zr, Hf, Nb, Ta and W is 31–275, 0.14–0.95, 4.0–7.2, 0.08–0.29
and 40–51 pmol kg−1, respectively, whereas that of Mo is 97–105 nmol kg−1. LP-species of Zr, Hf and Ta account for 10–14% of AD in average and increase up to 25% below 4000 m, whereas those for Mo
and W are negligible. In contrast, LP-Nb shows maxima (up to 27%) in surface water. We also found that D-Zr/Hf, Nb/Ta and
Mo/W mole ratios generally increase in the order continental crust < river water < coastal sea < open ocean. |
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Keywords: | Zirconium hafnium niobium tantalum molybdenum tungsten seawater North Pacific Ocean speciation |
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