Characteristic analysis on oxygen isotopic tracer in the East China Sea and waters to east of the Ryūkyū-guntō

Samples of O isotopic tracer were mlleMed at Sections P₃, P₂₅, P_cM-t/2-E and P_CM-1/2.w in both the Fast China Sea and the area to the east of the Ryūkyū-guntō during October-November, 1991.
Analytical results of the δ¹⁸O are as follows: (1) In the Kuroshio area, the δ¹⁸O isolines are almost parallel to the 200 m isobath.The value of δ¹⁸O is negative and reaches minimum mt the main axis of the Kuroshio, and increases on both sides. (2) In the Taiwan Warm Current (TWC) area there is a high δ¹⁸O tongue extending to the northeast. (3) In the area near the coast, the distribution of δ¹⁸O isoline shows that the Changjiang River runoff diffuses seaward and the land-ocean isotopic effect from the nearshore to the offshore. (4) The values of δ¹⁸O are from -1.0×10^-3 to -0.5×10^-3 in the shelf. (5) There is a low mre of δ¹⁸O value (<-1.6×10^-3) at the 600 m layer in the Kuroshio area, which is quite in accord with the existence of a low salinity mre (S G 34.30) between the 600 and 800 m layers in the same area.Finally, the mrrelations of the δ¹⁸O with the salinity and temperature, the upwelling and so on are discussed.