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1.
Loess deposition in Asia: its initiation and development before and during the Quaternary 总被引:3,自引:0,他引:3
Andrey E. Dodonov Liping Zhou 《《幕》》2008,31(2):222-225
Dust is important in the Earth environment system. However; the role of dust in climate change remains largely unknown. A better understanding of the temporal and spatial variability of the dust accumulation in Asia forms an important step towards establishing the link between dust deposition and climate change. Here, a summary is given for the timing of the onset and expansion of loess deposition in Asia beginning in the early, Miocene. Recent progress on some aspects of loess chronology and palaeoenvironmental reconstruction is also reviewed. 相似文献
2.
Andrey Andreev Makio Honda Yuichiro Kumamoto Masashi Kusakabe Akihiko Murata 《Journal of Oceanography》2001,57(2):177-188
Excess CO2 and pHexcess showing an increase in dissolved inorganic carbon and a decrease in pH from the beginning of the industrial epoch (middle of the 19th century) until the present time have been calculated in the intermediate water layer of the northwestern Pacific and the Okhotsk Sea. It is concluded that: (1) The Kuril Basin (Okhotsk Sea) and the Bussol' Strait areas are characterized by the greatest concentrations of excess CO2 at isopycnal surfaces due to the processes of formation and transformation of intermediate water mass. (2) The largest difference in excess CO2 concentration between the Okhotsk Sea and the western subarctic Pacific (about 8 µmol/kg) is found at the = 27.0. (3) The difference in excess CO2 between the western subarctic Pacific and subtropical regions is significant only in the upper part of the intermediate water layer ( = 26.7–27.0). (4) About 10% of the excess CO2 accumulation in the subtropical north Pacific is determined by water exchange with the subarctic Pacific and the Okhotsk Sea. 相似文献
3.
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
4.
Maps of the boundary topography for anaerobic waters in the Black Sea are plotted for the summers of the 1920s and 1980s. The mean depths of the H2S boundary for this period are determined. It is shown that the variation in the distribution and average location of the hydrogen sulphide zone has remained constant for the last 60 years.Translated by Mikhail M. Trufanov. 相似文献
5.
This paper discusses the conclusion derived during a joint U.S—Turkey expedition on the R/VKrorr on the dramatic variations of the O2–H2S zone in the Black Sea observed over the last 20 years. This conclusion is shown to be invalid since it was based on a comparison of data obtained at two stations only (in 1969 and 1988) that was made in various regions and in different seasons. Examples are provided for the inter-seasonal and mesoscale variations of hydrophysical and hydrochemical characteristics in the O2–H2S zone which, as to their scales, are comparable to or even exceed the variations registered during the expedition ofKrorr.Translated by Mikhail M. Trufanov. 相似文献
6.
7.
Peculiarities of the dynamics and the structure formation in the estuary run-off lenses have been analysed based on field data obtained at the Guinean coast (the central eastern Atlantic Ocean). Attention was paid to the processes of restratification, internal mixing, and exchange in the areas of the frontal zone of the run-off lens and the tidal frontal zone. The stabilization of the front of the estuary run-off lens by means of the periodic washing out of its forepart by tidal upwelling is described. The mechanisms of the energy transformation in the leading part of the lens have been revealed. Effects of run-off and loczalization of transformed waters in the small-scale frontal zones are found. The energy estimations represented will be useful in considering analogous phenomena in other coastal regions.Translated by Mikhail M. Trufanov. 相似文献
8.
A. A. Bezborodov S. L. Gokchen V. N. Eremeev I. T. Konuk A. K. Saidam E. M. Tirasin 《Physical Oceanography》1991,2(3):227-231
The hydrological and hydrochemical structures of the upper 300 m water column of the Black Sea in autumn 1988 have been studied. Regularities in the distribution of the physico-chemical characteristics in the zone of interaction between aerobic and anaerobic waters as well as the topography of the H2S zone boundary and its connection with a certain density gradient have been found.Translated by Mikhail M. Trufanov. 相似文献
9.
Gated communities of the Moscow green belt: newly segregated landscapes and the suburban Russian environment 总被引:3,自引:0,他引:3
The transition from the Soviet to the post-Soviet period in and near Moscow manifested itself in increasing production of
segregated space both in the urban core and suburban areas outside of the beltway to accommodate the preferences of the new
Russian business and governmental elite. This paper focuses on the residential single-family housing inside old and new settlements,
which are frequently gated. Approximately 260 of such suburban communities have been developed within 30 km of the beltway
during the past few years, of which a majority have some form of exclusion mechanism in place, typically tall solid fences,
gates, closed-circuit video surveillance and guarded entry checkpoints. The difference in exclusivity varies from the most
exclusive older communities inside Moscow Serebryany Bor enclave and Rublevskoe highway mansions to less exclusive new developments
along Novorizkhskoe and Dmitrovskoe highways. Despite high rates of construction, based on sociological surveys in 2003, only
about 11% of Russia’s upper class claimed to live in such new “cottages,” with the rest owning condos and luxury apartments
in the inner city or older detached homes in villages and small towns. Therefore, not all the needs have been accommodated
and more development is certain to take place. The environmental impact of such developments is profound. Based on preliminary
LANDSAT image analysis, almost 22% of suburban “green belt” forested land within 30 km zone has been converted to new construction
from 1991 to 2001. New construction is now focusing on the remaining fragments of natural vegetation, which will likely lower
air quality and water quality available for the city. Ironically, the new developments advertise themselves as “clean and
green” with massive investments in unnatural landscaping (seeded lawns, exotic shrubs, river and lake shore “improvements”).
This investment highlights the well-known paradox of development in which people move out of town to live near nature, while
destroying the wild nature they come to enjoy.
“We left city for the weekend
It was raining, saw no stars
There were fences everywhere
Our chiefs behind the bars.”
Gennady Shpalikov 相似文献
10.
A consideration of the dune:antidune transition in fine gravel 总被引:1,自引:0,他引:1
Hydraulic data defining the dune:antidune transition in fine gravel are compared with potential flow theory, and information is drawn from published experiments and field‐based studies. Attention is given to both transitional bedforms and the development of downstream‐migrating antidunes. In the latter case, most data pertain to sand beds and not to gravel. Empirical data provide some weak support for the theoretical notion that the transition occurs at progressively lower Froude numbers at greater relative depths. Although a critical Froude number of 0·84 may reasonably be applied for the beginning of the dune to antidune transformation, lag effects (and a possible depth limitation) ensure that transitional bedforms may persist across a broad range of Froude numbers from 0·5 to 1·8. This latter observation has great relevance for palaeohydraulic estimates derived from outcrop data. Whereas the application of theoretical bedform existence fields, based upon potential flow theory, to fine gravel was previously purely speculative, the addition of experimental and field data to these plots provides a degree of confidence in applying stability theory to practical geological problems. For the first time, laboratory data pertaining to downstream‐migrating gravel antidunes are compared with theory. These bedforms have been reported from certain experimental near‐critical flows above sand or gravel beds, but have been observed infrequently in natural streams. However, there are no detailed studies from natural rivers and only a few contentious identifications from outcrops. Nevertheless, the limited hydraulic data conform to theoretical expectations. 相似文献