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Roles of Continental Shelves and Marginal Seas in the Biogeochemical Cycles of the North Pacific Ocean 总被引：4，自引：0，他引：4
Chen-Tung Arthur Chen Andrey Andreev Kyung-Ryul Kim Michiyo Yamamoto 《Journal of Oceanography》2004,60(1):17-44
Most marginal seas in the North Pacific are fed by nutrients supported mainly by upwelling and many are undersaturated with
respect to atmospheric CO2 in the surface water mainly as a result of the biological pump and winter cooling. These seas absorb CO2 at an average rate of 1.1 ± 0.3 mol C m−2yr−1 but release N2/N2O at an average rate of 0.07 ± 0.03 mol N m−2yr−1. Most of primary production, however, is regenerated on the shelves, and only less than 15% is transported to the open oceans
as dissolved and particulate organic carbon (POC) with a small amount of POC deposited in the sediments. It is estimated that
seawater in the marginal seas in the North Pacific alone may have taken up 1.6 ± 0.3 Gt (1015 g) of excess carbon, including 0.21 ± 0.05 Gt for the Bering Sea, 0.18 ± 0.08 Gt for the Okhotsk Sea; 0.31 ± 0.05 Gt for
the Japan/East Sea; 0.07 ± 0.02 Gt for the East China and Yellow Seas; 0.80 ± 0.15 Gt for the South China Sea; and 0.015 ±
0.005 Gt for the Gulf of California. More importantly, high latitude marginal seas such as the Bering and Okhotsk Seas may
act as conveyer belts in exporting 0.1 ± 0.08 Gt C anthropogenic, excess CO2 into the North Pacific Intermediate Water per year. The upward migration of calcite and aragonite saturation horizons due
to the penetration of excess CO2 may also make the shelf deposits on the Bering and Okhotsk Seas more susceptible to dissolution, which would then neutralize
excess CO2 in the near future. Further, because most nutrients come from upwelling, increased water consumption on land and damming
of major rivers may reduce freshwater output and the buoyancy effect on the shelves. As a result, upwelling, nutrient input
and biological productivity may all be reduced in the future. As a final note, the Japan/East Sea has started to show responses
to global warming. Warmer surface layer has reduced upwelling of nutrient-rich subsurface water, resulting in a decline of
spring phytoplankton biomass. Less bottom water formation because of less winter cooling may lead to the disappearance of
the bottom water as early as 2040. Or else, an anoxic condition may form as early as 2200 AD.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Enhancement/reduction of biological pump depends on ocean circulation in the sea-ice reduction regions of the Arctic Ocean 总被引：1，自引：0，他引：1
Shigeto Nishino Takashi Kikuchi Michiyo Yamamoto-Kawai Yusuke Kawaguchi Toru Hirawake Motoyo Itoh 《Journal of Oceanography》2011,67(3):305-314
The biological pump is a central process in the ocean carbon cycle, and is a key factor controlling atmospheric carbon dioxide
(CO2). However, whether the Arctic biological pump is enhanced or reduced by the recent loss of sea ice is still unclear. We examined
if the effect was dependent on ocean circulation. Melting of sea ice can both enhance and reduce the biological pump in the
Arctic Ocean, depending on ocean circulation. The biological pump is reduced within the Beaufort Gyre in the Canada Basin
because freshwater accumulation within the gyre limits nutrient supply from deep layers and shelves hence inhibits the growth
of large-bodied phytoplankton. Conversely, the biological pump is enhanced outside the Beaufort Gyre in the western Arctic
Ocean because of nutrient supply from shelves and greater light penetration, enhancing photosynthesis, caused by the sea ice
loss. The biological pump could also be enhanced by sea ice loss in the Eurasian Basin, where uplifted isohaline surfaces
associated with the Transpolar Drift supply nutrients upwards from deep layers. New data on nitrate uptake rates are consistent
with the pattern of enhancement and reduction of the Arctic biological pump. Our estimates indicate that the enhanced biological
pump can be as large as that in other oceans when the sea ice disappears. Contrary to a recent conclusion based on data from
the Canada Basin alone, our study suggests that the biological CO2 drawdown is important for the Arctic Ocean carbon sink under ice-free conditions. 相似文献
3.
Michiyo Sawai Ikuo Katayama Arisa Hamada Makoto Maeda Satoru Nakashima 《Physics and Chemistry of Minerals》2013,40(4):319-330
The dehydration kinetics of serpentine was investigated using in situ high-temperature infrared microspectroscopy. The analyzed antigorite samples at room temperature show relatively sharp bands at around 3,655–3,660 cm?1 (band 1), 3,570–3,595 cm?1 (band 2), and 3,450–3,510 cm?1 (band 3). Band 1 corresponds to the Mg–OH bond, and bands 2 and 3 correspond to OH associated with the substitution of Al for Si. Isothermal kinetic heating experiments at temperatures ranging from 625 to 700 °C showed a systematic decrease of the OH band absorbance with heating duration. The one-dimensional diffusion was found to provide the best fit to the experimental data, and diffusion coefficients were determined with activation energies of 219 ± 37 kJ mol?1 for the total water band area, 245 ± 46 kJ mol?1 for band 1, 243 ± 57 kJ mol?1 for band 2, and 256 ± 53 kJ mol?1 for band 3. The results indicate that the dehydration process is controlled by one-dimensional diffusion through the tetrahedral geometry of serpentine. Fluid production rates during antigorite dehydration were calculated from kinetic data and range from 3 × 10?4 to 3 × 10?5 $ {\text{m}}_{\text{fluid}}^{ 3} \,{\text{m}}_{\text{rock}}^{ - 3} \,{\text{s}}^{ - 1} $ . The rates are high enough to provoke hydraulic rupture, since the relaxation rates of rocks are much lower than these values. The results suggest that the rapid dehydration of antigorite can trigger an intermediate-depth earthquake associated with a subducting slab. 相似文献
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Potential of submarine-cave sediments and oxygen isotope composition of cavernicolous micro-bivalve as a late Holocene paleoenvironmental record 总被引：2，自引：1，他引：1
Akihisa Kitamura Nagisa Yamamoto Tomoki Kase Shu-ichi Ohashi Mayumi Hiramoto Hitoshi Fukusawa Tsuyoshi Watanabe Tomohisa Irino Hiroshi Kojitani Michiyo Shimamura Ikuo Kawakami 《Global and Planetary Change》2007,55(4):301-316
A sediment layer (43 cm thick) and surface sediments (5 cm thick) in a submarine limestone cave (31 m water depth) on the fore-reef slope of Ie Island, off Okinawa mainland, Japan, were examined by visual, mineralogical and geochemical means. Oxygen isotope analysis was performed on the cavernicolous micro-bivalve Carditella iejimensis from both cored sediments and surface sediments, and the water temperature within the cave was recorded for nearly one year. These data show that: (1) water temperature within the cave is equal to that at 30 m deep in the open sea; (2) the biotic and non-biotic environments within the cave have persisted for the past 2000 years; (3) mud-size carbonate detritus is a major constituent of the submarine-cave deposit, and may have come mainly from the suspended carbonate mud produced on the emergent Holocene reef flat over the past two millennia; (4) the δ18O-derived temperature (Tδ18O) of C. iejimensis suggests that the species grows between April and July; (5) the Tδ18O of C. iejimensis from cored sediments implies that there were two warmer intervals, at AD 340 ± 40 and AD 1000 ± 40, which correspond to the Roman Warm Period and Medieval Warm Period, respectively. These suggest that submarine-cave sediments provide unique information for Holocene reef development. In addition, oxygen isotope records of cavernicolous C. iejimensis are a useful tool to reconstruct century-scale climatic variability for the Okinawa Islands during the Holocene. 相似文献
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