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1.
The decomposition characteristics of particulate organic matter (POM) sampled with plankton nets in Hiroshima Bay were investigated under aerobic conditions in a laboratory experiment.The POM derived from plankton consisted of both a labile fraction (70–80 % of the whole) and a refractory fraction (20–30%). The labile fraction was completely decomposed within 40 days at 20°C. Although the concentrations of particulate organic carbon (POC) decreased gradually with time, an apparent lag phase was recognized in the decomposition of particulate phosphorus (PP) at an early stage, which might result from a specific uptake of dissolved inorganic phosphorus (DIP) by bacteria. A comparison of the metabolic activity between dissolved organic matter (DOM) and POM by measuring ATP contents showed that the former was one order of magnitude larger than the latter.On the other hand, there was no significant difference among the decomposition rates of POM collected at various depths. The change of the first-order rate constant (k) for the POM decomposition by temperature was expressed ask=0.0329 exp(0.0644T), and the Q10 value was 1.94. There were fairly large variances ink values obtained from the various plankton species. Thek values averaged 0.144 day–1 and ranged from 0.078 to 0.20 day–1 at 20°C. 相似文献
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Variability in water-exchange time between Tokyo Bay and the Pacific Ocean during winter is investigated based on the results of intensive field observation from November 2000 to March 2001. Water-exchange time between Tokyo Bay and the Pacific Ocean during winter mainly depends on the strength of northerly monsoon, being about 16 days under the weak monsoon and about 12 days under the strong monsoon. Moreover, it becomes longer by about 1 day in spring tide and shorter in neap tide due to the coupling effect of estuarine circulation and vertical mixing. Water-exchange time also varies depending on the open-ocean condition. When the warm water mass approaches from the Pacific Ocean to the mouth of Tokyo Bay through the eastern channel of Sagami Bay, which connects Tokyo Bay and the Pacific Ocean, water-exchange time becomes longer by about 2 days because the warm water mass is blocked in the surface layer at the bay mouth. On the other hand, when the warm water mass approaches to the mouth of Tokyo Bay through the western channel of Sagami Bay, water-exchange time becomes shorter by about 1 day because the warm water mass intrudes into the middle or lower layers of Tokyo Bay. Such different behavior of warm water mass at the mouth of Tokyo Bay is due to the difference in density of approaching warm water masses, that is, the density of the warm water mass through the eastern channel is smaller than that of the warm water mass through the western channel of Sagami Bay.Responsible Editors: Yens Kappenberg 相似文献
3.
Boundary-Layer Meteorology - Surface shear stresses produced by wind and particle collision play a key role in aerodynamic entrainment and splash processes. The fluid shear stress at the surface... 相似文献
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Interannual salinity variations in the Tsushima Strait and its relation to the Changjiang discharge 总被引:2,自引:0,他引:2
Tomoharu Senjyu Hirofumi Enomoto Takeshi Matsuno Sigeaki Matsui 《Journal of Oceanography》2006,62(5):681-692
Interannual salinity variations in the Tsushima Strait are investigated on the basis of historical hydrographic data. The
EOF analysis revealed that the most dominant mode is the in-phase salinity variation between the eastern and western channels.
The time coefficients of the EOF first mode in summer show a negative correlation with the Changjiang discharge, which indicates
that salinity in the Tsushima Strait tends to decrease over summer, related to a large discharge of the Changjiang. The eigenvectors
of the first mode are larger in the eastern channel than those in the western channel, though the low salinity water mainly
flows through the western channel. This is because the low salinity water spreads into the eastern channel as well as the
western channel over summers with a large discharge of the Changjiang. The out-of-phase salinity variation between the channels
is extracted as the EOF second mode; this is the predominant variation in the western channel. The time coefficients of the
second mode in summer show no significant correlations to the volume transports through the western channel and the transport
differences between channels. A relationship between the EOF second mode and variations in the wind stress over the East China
Sea is suggested. 相似文献
6.
Cristina Milesi Hirofumi Hashimoto Steven W. Running Ramakrishna R. Nemani 《Global and Planetary Change》2005,47(2-4):221
Human domination of ecosystems has been pervasive over the last century, with nearly half of Earth's surface transformed by human actions. It is widely accepted that humans appropriate up to 50% of global net primary production (NPP), the energy base of all the trophic levels on the land surface. Yet, despite the important role of vegetation productivity for defining Earth habitability, the covariation of NPP and human population distribution has not been analyzed in depth. We used recently available satellite-based NPP estimates, along with gridded population at 0.5° resolution, first, to identify the global distribution of human population with reference to average NPP and to the various climatic constraints (temperature, water and cloud cover) that limit NPP, second, to analyze recent trends in global NPP in relation to population trends, and third, to identify populations that are vulnerable to changes in NPP due to interannual variability in climate. Our results indicate that over half of the global human population is presently living in areas with above the average NPP of 490 g C m−2 year−1. By 1998, nearly 56% of global population lived in regions where water availability strongly influences NPP. Per capita NPP declined over much of Africa between 1982 and 1998, in spite of the estimated increases in NPP over the same period. On average, NPP over 40% of the total vegetated land surface has shown significant correlations with ENSO-induced climate variability affecting over 2.8 billion people. 相似文献
7.
Roughness length for heat over an urban canopy 总被引:1,自引:0,他引:1
The roughness length for heat zT was evaluated over an urban canopy, using the measured sensible heat flux and radiometric temperature. To overcome thermal heterogeneity in the urban area, the measured radiometric temperature was transformed into the equivalent temperature of an upward longwave radiation flux. The equivalent temperature was found to provide an effective parameterization of the radiometric temperature. The daytime average of the resulting ln(zT/z0) was 10, where z0 is the aerodynamic roughness length. This result generally agrees with previous studies; however, the anthropogenic heat is a large uncertainty, which could cause an error at least 240% in zT. 相似文献
8.
The variation of displacement along fifteen traces of minor normal faults was measured in the multilayered Quaternary sediments of Kyushu, Japan. In the diagrams of distance along a fault trace (L) vs displacement (D) two distinct types of faults, a cone-shaped L-D pattern (C-type) and mesa-shaped one (M-type), were detected. Because the L-D pattern is subject to slip-parallel strain in the wall rocks, a D-constant pattern is ascribed to the competent (rigid) material and a D-variable pattern is found in the incompetent material. Therefore, C-type faults are characteristic of homogeneous incompetent materials, whereas M-types are representative of faults that cut through a rigid unit. However, the steep slopes in the flanking sections of M-type patterns indicate that the faulting of a rigid unit should terminate in a strain absorber of incompetent materials. The concept of lithologic control in the L-D pattern is important for the better understanding of faulting processes as well as the localization of faults. 相似文献
9.
Yoshiaki Ohsawa Hirofumi Kagaya Takeshi Koshizuka 《Journal of Geographical Systems》2002,4(3):325-342
When demand points are given as a planar map where projection method is explicitly stated, we usually know the latitudes
and longitudes of these points from the map. Then we can solve the Weber problem on the globe, and we do not suffer from errors.
This paper analyses how cylindrical projections cause distortion in the Weber problem when demands are distributed on the
Northern Hemisphere. First, we demonstrate that planar solutions are always located south of the spherical solution if the
Mercator projection, the equirectangular projections with standard parallels near the demands, or the equal-area projection
with the same characteristic is chosen. Second, we verify that this geographical tendency is inclined to hold when the demand
points, are distributed symmetrically, widely or toward the north.
Received: 15 August 2001 / Accepted: 20 April 2002
This paper was partially written while the first author was visiting the Department of Geography at the Catholic University
of Louvain, Louvain-la-Neuve, Belgium [1993–1994]. He is grateful for the hospitality of this department. An earlier version
of this paper was presented in 1994 at the Seventh Meeting of the European Operational Research Working Group on Locational
Analysis in Brussels, and in 1996 at the Fifth World Congress of the Regional Science Association International in Tokyo.
The authors would also like to thank the participants as well as three anonymous referees for their constructive comments. 相似文献
10.
Snowmelt and the hydrological interaction of forest–grassland ecosystems in Central Yakutia,eastern Siberia
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M. L. Lopez Caceres F. Takakai G. Iwahana A. N. Fedorov Y. Iijima R. Hatano M. Fukuda 《水文研究》2015,29(14):3074-3083
In the last two decades the major focus of study in forest water and carbon balances in eastern Siberia has been on the effect of rain during the growing season. Little attention has been paid to the contribution of snowmelt water. The results of the present study indicate that weather conditions during the snowmelt period as well as the soil moisture conditions carried from the previous year's growing season strongly determined the water availability for the forest ecosystem at the beginning of the next growing season. In the forest–grassland intermingled ecosystem of lowland Central Yakutia, gradual snowmelt water flow from the forest into the adjacent grassland depressions increased when soil moisture was high and air temperature was low, whereas low soil moisture and high air temperatures accelerated soil thawing and consequently snowmelt water infiltration into the forest soil. We found that snow depth did not determine the volume of snowmelt water moving to the grassland depression since the thermokarst lake water level in the adjacent grassland was about 25 cm lower in 2005 than in May 2006, even though maximum snow depth reached 57 cm and 43 cm in the winter of 2004–05 and 2005–06, respectively. The contribution of snowmelt water to forest growth as well as the flow of water from the forest to the grasslands showed a strong annual variability. We conclude that warmer springs and high variability in precipitation regimes as a result of climate change will result in more snowmelt water infiltration into the forest soil when the previous year's precipitation is low while more snowmelt water will flow into the thermokarst lake when the previous year's precipitation is high. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献