Marine Ecology Progress Series | |
Contribution of N2 fixation to new production in the western North Pacific Ocean along 155°E | |
Ken Furuya1  Taketoshi Kodama1  Takuhei Shiozaki1  Shigenobu Takeda1  | |
关键词: New production; N2 fixation; Nitrate assimilation; ƒ-ratio; Western North Pacific Ocean; | |
DOI : 10.3354/meps07837 | |
学科分类:海洋学与技术 | |
来源: Inter-Research | |
【 摘 要 】
ABSTRACT: Nitrogen (N2) fixation and nitrate assimilation activities were examined simultaneously using a 15N tracer in February and March 2007 along the 155°E meridian from the equator to 44°N in the western North Pacific Ocean. N2 fixation was detected only to the south of 28°N, where the nitrate + nitrite (N+N) concentration was <30 nM in the upper mixed layer; the concentration ranged from 12.8 to 152 µmol N m–2 d–1. High N2 fixation rates were observed from 16°N to 24°N, where relatively high dust depositions and low concentrations (<100 nM) of soluble reactive phosphorus (SRP) were observed. The depth-integrated nitrate assimilation in the euphotic zone showed no significant latitudinal trend, varying between 184 and 349 µmol N m–2 d–1 in the area from the equator to 24°N, where the water column was stable. Toward the north of 28°N, nitrate assimilation was enhanced, while N2 fixation became insignificant. The contribution of N2 fixation to new production (= N2 fixation + nitrate assimilation) ranged from 2 to 37%, and the highest contribution was observed at 24°N at the center of the subtropical gyre, where the highest N2 fixation occurred. From the equator to 24°N, the coefficient of variation of nitrate assimilation was 20%, while that of N2 fixation was 80%, indicating that the latter is more responsible for the latitudinal variation in the contribution of N2 fixation to new production.
【 授权许可】
Unknown
【 预 览 】
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RO201912010133071ZK.pdf | 735KB | download |