| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
1. Horizontal distributions of barium (Ba) and silicate/nitrate ratio (Si/N) along the pathway of the deep-sea thermohaline circulation in the ocean were examined at the isopicnal horizon of sigma4=45.86. Comparing to the deep water in the northern North Atlantic, Ba concentration is ca.3.5 fold and the ratio of Si/N is ca.9 fold higher in the northern North Pacific.
2. The relationship between the concentration of Ba and the ratio of Si/N was examined in the oceans which are the North Pacific (NP), Eastern Indian, Tasman Sea of the western South Pacific (TSM), East Equatorial Pacific (EEqP), Sub Antarctic Ocean (SAA) and Antarctic Ocean (AA), and also in the adjacent seas which are Okhotsk (OHT), Japan (JPN), South China (SC), Sulu (SL) and Andaman (ADM) Seas. In the basis on the analysis by the Ba-Si/N diagram, the linear relations between the two parameters were found in each basin. Those regression relations and correlation coefficients are as follows ;
NP:Ba=2.1+32.4(Si/N) R^2=0.98 (1)
EI:Ba=33.5+18.4(Si/N) R^2=0.97 (2)
TSM:Ba=32.3+23.2(Si/N) R^2=0.97 (3)
EEqP:Ba=15.6+32.4(Si/N) R^2=0.99 (4)
SAA:Ba=52.1+12.8(Si/N) R^2=0.96 (5)
AA:Ba=57.4+10.6(Si/N) R^2=0.92 (6)
OHT:Ba=17.5+24.1(Si/N) R^2=0.97 (7)
JPN:Ba=30.8+15.2(Si/N) R^2=0.85 (8)
SC:Ba=3.5+28.3(Si/N) R^2=0.99 (9)
SL:Ba=24.3+17.5(Si/N) R^2=0.98 (10)
ADM:Ba=25.9+20.2(Si/N) R^2=0.99 (11)
Consequently, the minimum slope of the relation was obtained in the Antarctic Ocean, oppositely the maximum in the North Pacific Ocean. These results demonstrate that the linear correlationship shown on the Ba-Si/N diagram in each oceanic basin is useful for reconstructing the past seawater composition, Ba vs Si/N, and serves as a pleoceanographic proxy
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