Reynolds,B.C., Frank,M. and Halliday,A.N.(2006):
Silicon isotope fractionation during nutrient utilization in
the North Pacific. Earth and Planetary Science Letters,
244, 431-443.
『北太平洋における栄養素利用の間のケイ素同位体分別』
『Abstract
The distribution of silicon in the North Pacific is controlled
by the utilization of silicic acid by diatoms, a process that
fractionates silicon (Si) isotopic compositions. Silicon isotope
variations are presented for six water column profiles from the
surface mixed layer down to the deep waters of the North Pacific
Ocean. Although the observed Si isotopic variations display an
apparently simple inverse relationship with dissolved nutrient
concentrations, in fact they reflect mixing of surface waters
undergoing active Si isotope fractionation and deep-waters with
more uniform concentrations and isotope compositions. Samples
from the surface of the subtropical gyre have the lowest dissolved
Si concentrations and heaviest Si isotope compositions of marine
waters measured thus far. Fractionation in the surface waters
follows a typical Rayleigh-type distillation curve for a ‘closed’
surface water reservoir resulting from stratification of the surface
layer in the subarctic region. In contrast, an ‘open’ system prevails
within the subtropical gyre where there is significant recycling
of silicic acid in the upper water column and lateral transport
of silicon within surface currents. For deep waters, the Si isotope
composition distinguishes between the northern North Pacific Deep
Water (NPDW) and the southerly-derived bottom water. The relatively
light Si isotope compositions measured from waters within the
subarctic gyre provides evidence for isolation of the nutrient
pool in the North Pacific.
Keywords: silicon isotopes; North Pacific; nutrients』
1. Introduction
2. Samples and methods
3. Results
4. Discussion
4.1. Modeling Si isotope fractionation
4.2. Surface water Si isotope fractionation
4.3. Intermediate waters
4.4. Seep water mixing
4.5. Effect of dust dissolution
5. Conclusion
Acknowledgements
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