WAS DEEP-WATER FORMED IN THE NORTH PACIFIC DURING THE LATE QUATERNARY- CADMIUM EVIDENCE FROM THE NORTHWEST PACIFIC

A benthic foraminifera Cd/Ca record, dating from the last glacial peri od to the Holocene, for a high sedimentation rate core recovered from the northwest Pacific is reported. It shows that the deep water (water depth of 2700 m) cadmium concentration was about 50% lower in the las t glacial period than in the Holocene. At 15 kyr B.P., the beginning o f deglaciation, a minimum Cd/Ca is recorded which is almost the same a s that of the modern North Atlantic. Considering previously obtained c admium records from the northwesternmost and western equatorial Pacifi c, a steep gradient in the deep-water cadmium concentration between th e western equatorial Pacific and the northwest Pacific from the last g lacial to deglacial periods has been estimated. In contrast to cadmium records, benthic foraminifera deltaC-13 records in these regions show ed similar increasing trends during this time span and no large differ ence in deltaC-13 can be observed between these two regions. This disc ordance between these two nutrient tracers may come from the change in the deltaC-13-phosphate relationship in the ocean during the Late Qua ternary. Although we cannot absolutely rule out other possibilities, w e suggest that there was a convection cell in the northwest Pacific du ring the last glacial period and at the beginning of deglaciation peri od the turnover rate of this cell increased and cadmium concentration in the northwest Pacific significantly decreased.