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Transition of low‐salinity water in the Western Pacific Warm Pool recorded in the nitrogen isotopic ratios of settling particles
Author(s) -
Yoshikawa Chisato,
Nakatsuka Takeshi,
Kawahata Hodaka
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl023103
Subject(s) - salinity , settling , oceanography , nitrate , nitrogen , hydrology (agriculture) , surface water , geology , environmental science , ecology , chemistry , biology , geotechnical engineering , organic chemistry , environmental engineering
We analyzed nitrogen isotopic ratio (δ 15 N) of settling particles at four sites in the western and central equatorial Pacific from January to November 1999, together with the δ 15 N of nitrate above 200 m depth in December 1999. The δ 15 N values of settling particles at the two western sites (station 1 and 2) were about 3.0 ‰ more depleted than that at the most eastern site (station 9). In March 1999, the δ 15 N values rose from 3.7 ‰ to 7.2 ‰ at station 3 located at 0°N 145°E. During this month, the salinity at this site also increased by 0.4 psu, suggesting that low‐salinity water had shifted to the west. The relationship between salinity and δ 15 N of nitrate in surface water suggested that the depleted δ 15 N reflects river discharge, atmospheric deposition and/or nitrogen fixation. Thus, we were able to reconstruct the transition of low‐salinity water in the WPWP based on the δ 15 N values of settling particles.