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Evidence of a change in oceanic fixed nitrogen with decadal climate change in the North Pacific subpolar region
Author(s) -
Watanabe Yutaka W.,
Shigemitsu Masahito,
Tadokoro Kazuaki
Publication year - 2008
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 - 10.1029/2007gl032188
Subject(s) - hydrography , oceanography , stratification (seeds) , biogeochemical cycle , phytoplankton , environmental science , climate change , nitrogen , geology , climatology , nutrient , chemistry , environmental chemistry , biology , seed dormancy , botany , germination , organic chemistry , dormancy
Using four pentadecadal hydrographic time series of biogeochemical properties over the North Pacific subpolar region, we found that the linear trends of these properties over this region due to sea surface stratification. Decadal periodicity of 18 years was also found although there were the opposite phases between the eastern and western sides. Despite decreasing trends of DO with an increase of PO 4 , N* in the subsurface water showed an increasing trend of 0.18 μ mol kg −1 y −1 . N* in the surface water had also an increase of 0.12 μ mol kg −1 y −1 with a decrease of Si/N. With considering the decease of N/P and increase of Si/N in diatoms under iron‐deficient conditions, this finding is evidence that a shift of phytoplankton has already occurred due to the progress in stratification with the depletion of iron derived from deep water, despite being a relatively high primary production region.