TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 62 (No. 5), pp. 745-752, 2006

Short Contribution

Lower Cd/P Ratio in Settling Particles than in Surface Seawater in the Okinawa Trough

Kazuo Abe1*, Kazuo Iseki2, Kazumaro Okamura3 and Yoko Kiyomoto3

1Ishigaki Tropical Station, Seikai National Fisheries Research Institute, Fukai-Ota, Ishigaki 907-0451, Japan
2Graduate School of Biosphere Science, Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8528, Japan
3Seikai National Fisheries Research Institute, Taira-cho, Nagasaki 851-2213, Japan

(Received 14 February 2006; in revised form 1 May 2006; accepted 4 May 2006)

Abstract: The characteristics of the ratios between cadmium (Cd) and phosphorus (P) in settling particles collected from the Okinawa Trough in the East China Sea were examined using a sediment trap, moored at a depth of 811 m for one year. The Cd/P ratios varied within a narrow range throughout the year, in spite of the large seasonal change in the total dry mass, Cd, and P fluxes. The average Cd/P ratio of settling particles was 0.062 (nmol/μmol), which was obviously lower than that of surface seawater around the study site (0.16). This lower ratio in the Okinawa Trough particles collected using the 811 m-moored trap certainly reflected the mixture of biologically produced organic matter around the study site and other components that were mainly transported as lateral flux from the shelf edge and slope area of the East China Sea.

*Corresponding author E-mail: abek@fra.affrc.go.jp

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