共查询到20条相似文献，搜索用时 203 毫秒
1.
孔压探杆贯入及潮汐作用下超孔压响应规律研究 总被引：1，自引：0，他引：1
Excess pore water pressure is an important parameter that can be used to analyze certain physical characteristics of sediment. In this paper, the excess pore water pressure of subseafloor sediment and its variation with tidal movement was measured following the installation of a wharf in Qingdao, China by using a fiber Bragg grating(FBG) piezometer. The results indicated that this FBG piezometer is effective in the field. The measured variation of excess pore water pressure after installation is largely explained by the dissipation of excess pore water pressure. The dissipation rate can be used to estimate the horizontal consolidation coefficient, which ranged from1.3×10~(–6) m~2/s to 8.1×10~(–6) m~2/s. The measured values during tidal phases are associated with the variability of tidal pressure on the seafloor and can be used to estimate the compressibility and the permeability of the sediment during tidal movement. The volume compression coefficient estimated from tidal oscillation was approximately2.0×10~(–11) Pa~(–1), which was consistent with the data from the laboratory test. The findings of this paper can provide useful information for in situ investigations of subseafloor sediment. 相似文献
2.
The petrophysical properties of sediment drill core samples recovered from the Sardinian margin and the abyssal plain of the
Southern Tyrrhenian Basin were used to estimate the downhole change in porosity and rates of deposition and mass accumulation.
We calculated how the deposited material has changed its thickness as a function of depth, and corrected the thickness for
the compaction. The corresponding porosity variation with depth for terrigenous and pelagic sediments and evaporites was modelled
according to an exponential law. The mass accumulation rate for the Plio-Quaternary is on average 4.8×104 kg m−2 my−1 on the Sardinian margin and for the Pliocene in the abyssal plain. In the latter area, the Quaternary attains its greatest
thickness and a mass accumulation rate of 11–40×104 kg m−2 my−1. The basement response to sediment loading was calculated with Airy-type backstripping. On the lower part of the Sardinian
margin, the basement subsidence rate due to sediment loading has decreased from a value of 300 m my−1 in the Tortonian and during the Messinian salinity crisis (7.0–5.33 Ma) to about 5 m my−1 in the Plio-Quaternary. In contrast, on the abyssal plain this rate has changed from 8–50 m my−1 during the period 3.6–0.46 Ma, to 95–130 m my−1 since 0.46 Ma, with the largest values in the Marsili Basin. The correlation between age and the depth to the basement corrected
for the loading of the sediment in the ocean domain of the Tyrrhenian Basin argues for a young age of basin formation. 相似文献
3.
The big Comacchio lagoons (NW Adriatic coast) have been experiencing a super-dense, long-term bloom of picocyanobacteria (PCB)
since 1985. This bloom has caused profound transformations in their ecosystem and has resulted in the loss of valuable fish
and clam resources. The composition, density and seasonal dynamics of this bloom and its impact on the ecosystem were studied
between spring and autumn 1995 and in the summer of 2001. The density of the blooming phytoplankton assemblages varied from
8 to 35 × 106 cells ml−1, and biomass from 20 to 40 g m−3, thus demonstrating a quasi-stable status since 1993. The share of pico + nanocyanobacterial fraction of the total phytoplankton
biomass was 98% in spring to early summer, and 92% in autumn. The remaining 0.2–5% comprised eukaryotic nano-algae. All components
of the animal food web were found to be drastically depleted in the lagoons. Their biomass range in the open lagoons areas
were: 2 to 20 mg m−3 of microzooplankton, 10 to 40 mg m−3 mesozooplankton, and 5 to 12 g m−2 macrozoobenthos. The share of filtering fauna in the whole ecosystem metabolism was less than 2%. The malfunction of the
deteriorated animal food web resulted in the hyper-accumulation of non-grazed microplankton biomass and detritus in the water
column and in bottom sediments. The sequence brought the acceleration of sulfide production and the accumulation of acid soluble
sulfides in the upper sediment layer of up to 700–800 mg S dm−3 of wet silt. The results of this study provide evidence that the state of ecological collapse continues in the lagoons since
1993. 相似文献
4.
The paper shows that, by virtue of the specific water circulation in the south-eastern Indian Ocean, thermal influx within
the 0–200 m layer exceeds the efflux by 13.5×1015 MJ per year, which, being recalculated for the entire area, is equivalent to about 2200 MJ m−2. Computations of the heat fluxes through the sea surface in that part of the ocean indicate that thermal efflux to the atmosphere
is larger than the influx of solar heat by about 1500 (on average, for the entire area), rather than by 2200 MJ m−2 per year. Hence, about 700 MJm−2 penetrate through the lower boundary of the layer and warm up the deeper ocean layers.
Translated by Vladimir A. Puchkin. 相似文献
5.
This study presents an analysis of the CTD data and the turbulent microstructure data collected in 2014, the turbulent mixing environment above the Atlantic Water(AW) around the Chukchi Borderland region is studied.Surface wind becomes more efficient in driving the upper ocean movement along with the rapid decline of sea ice,thus results in a more restless interior of the Arctic Ocean. The turbulent dissipation rate is in the range of4.60×10~(–10)~(–3.31×10~(–9) W/kg with a mean value of 1.33×10~(–9) W/kg, while the diapycnal diffusivity is in the range of1.45×10~(–6)–1.46×10~(–5)m~2/s with a mean value of 4.84×10~(–6) m~2/s in 200–300 m(above the AW). After investigating on the traditional factors(i.e., wind, topography and tides) that may contribute to the turbulent dissipation rate, the results show that the tidal kinetic energy plays a dominating role in the vertical mixing above the AW. Besides, the swing of the Beaufort Gyre(BG) has an impact on the vertical shear of the geostrophic current and may contribute to the regional difference of turbulent mixing. The parameterized method for the double-diffusive convection flux above the AW is validated by the direct turbulent microstructure results. 相似文献
6.
The circulation of intermediate and deep waters in the Philippine Sea west of the Izu-Ogasawara-Mariana-Yap Ridge is estimated
with use of an inverse model applied to the World Ocean Circulation Experiment (WOCE) Hydrographic Program data set. Above
1500 m depth, the subtropical gyre is dominant, but the circulation is split in small cells below the thermocline, causing
multiple zonal inflows of intermediate waters toward the western boundary. The inflows along 20°N and 26°N carry the North
Pacific Intermediate Water (NPIW) of 11 × 109 kg s−1 in total, at the density range of 26.5σθ–36.7σ2 (approximately 500–1500 m depths), 8 × 109 kg s−1 of the NPIW circulate within the subtropical gyre, whereas the rest is conveyed to the tropics and the South China Sea. The
inflow south of 15°N carries the Tropical Salinity Minimum water of 35 × 109 kg s−1, nearly half of which return to the east through a narrow undercurrent at 15–17°N, and the rest is transported into the lower
part of the North Equatorial Countercurrent. Below 1500 m depth, the deep circulation regime is anti-cyclonic. At the density
range of 36.7σ2, – 45.845σ4 (approximately 1500–3500 m depths), deep waters of 17 × 109 kg s−1 flow northward, and three quarters of them return to the east at 16–24°N. The remainder flows further north of 24°N, then
turns eastward out of the Philippine Sea, together with a small amount of subarctic-origin North Pacific Deep Water (NPDW)
which enters the Philippine Sea through the gap between the Izu Ridge and Ogasawara Ridge. The full-depth structure and transportation
of the Kuroshio in total and net are also examined. It is suggested that low potential vorticity of the Subtropical Mode Water
is useful for distinguishing the net Kuroshio flow from recirculation flows.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
2002年春季吕宋海峡海流:观测与改进逆模式计算 总被引：10，自引：1，他引：9
基于2002年春季航次在吕宋海峡海域锚碇测流站(20°49'57"N,120°48'12"E)200,500与800m处锚碇测流以及CTD观测,采用改进逆方法对调查海域进行海流计算.(1)主要观测的结果:1)在200m处,观测期间海流平均速度为(47.4cm/s,346°).在500m处,海流观测期间平均速度为(20.3cm/s,350°).这些都表明黑潮在吕宋海峡锚碇测流站200和500m处向西北方向入侵南海.2)在800m处,海流观测期间平均速度为(1.2cm/s,35°),它的方向为东北向.比较每层实测流结果,表明800m层海流状况与200和500m层流况不同.3)在观测期间,200,500和800m处,日平均流速在4月皆比3月时要强.4)在调查海区西部的中间区域存在一个高密、冷水中心(HDCW),其中心位置位于断面A的水文站3附近.5)在调查海区东南区域存在一个低密、暖水(LDWW)中心,其中心位置位于断面B的水文站8附近.(2)主要计算结果:1)通过断面B的偏北方向与偏南方向的流量分别为32.48×106m3/s(包括反气旋涡的流量)与3.34×106m3/s.因此通过断面B的净北向流量为29.14×106m3/s.2)通过断面A的东向与西向的流量分别为16.71×106m3/s与8.57×106m3/s(包括气旋涡的流量).因此,通过断面A的净东向流量为8.14×106m3/s.3)通过断面M北向的净流量为24.68×106m3/s.4)黑潮通过断面M后分为主流和一个支流,其主流,流量为16.54×106m3/s,流向断面C的东部分.主流通过断面C的东部分后,最后流向台湾以东海域.而其一个分支,净流量为8.14×106m3/s,在一个高密、冷水中心(HDCW)的区域以东作气旋式弯曲,然后向西北方向通过断面C的西部.因此,黑潮在断面C有两个流核.5)比较计算得到的在锚碇测流站M附近流方向与在200与500m处观测流方向为西北向,它们甚为一致.6)在断面B西侧位于550m以深水层南海水可能缓慢地从西北流向东南,通过断面B的南向流量大约为3.34×106m3/s. 相似文献
8.
琼州海峡冬末春初潮余流场特征 总被引：18，自引：1，他引：18
1995年2月26日至3月6日,在琼州海峡的新海一四塘断面上,大小潮期间进行15条船同步测流.该断面上涨潮流速普遍大于落潮流速,实测最大涨潮流速为172cm/s,最大落潮流速为142cm/s;大潮期间北部6个站全层平均余流速度为18.4cm/s.海峡中间3个站0～20m层平均流速为18.3cm/s,南部6个站平均余流速度为10.2m/s.中间和北部诸站余流方向指向W一S范围,南部6个站因受地形影响,流向指向NE.用数值计算方法,再现了大小潮期间琼州海峡整个潮流场.大潮期间,通过西断面(灯楼角──玉苞角)落潮流总通量为4.73×1010m3,涨潮流总通量为4.29×1010m3;通过东断面(东营──龙塘镇)落潮流总通量为5.22×1010m3,涨潮流总通量为4.90×1010m3,其净通量,西、东断面分别为0.43×1010和0.32×1010m3,其方向指向西. 相似文献
9.
Mohammed Rasheed Saber Al-Rousan Riyad Manasrah Fuad Al-Horani 《Journal of Oceanography》2006,62(1):83-89
The role of deep sediment in supporting nutrient budget in the Gulf of Aqaba has been investigated by estimating the flux
of inorganic nitrogen, phosphate and silicate. Fluxes were calculated directly by pore water profiles and indirectly by chamber
incubations carried out onboard the RV Meteor cruise. The results showed that maximum potential fluxes calculated by chamber
incubations were higher than those calculated by porewater profiles for all nutrients (6.4–28.5 fold). This has been attributed
to the additional flux due to bioturbation and flux from advective porewater exchange in the case of chamber incubation, while
porewater fluxes represent diffusive ones. Using a rough estimation considering flux results in addition to the sediment area
and water mass of the Gulf of Aqaba, we estimate that 3.3 × 105, 6.4 × 104 and 6.5 × 106 kg year−1 of inorganic nitrogen, phosphate and silicate respectively are effused from deep sediments to the water column. This quanitity
would certainly support the primary productivity in the oligotrophic water in the Gulf of Aqaba. 相似文献
10.
渤海、黄海沿岸几种经济贝类及其生存环境中的异养细菌 总被引：10，自引：0，他引：10
报道渤海、黄海6个重点沿岸海域(吕四、青岛、北戴河、盘锦、大连、庄河)海水和沉积物及经济贝类样品中的异养细菌总数检测结果.结果表明,整个渤海、黄海沿岸海域经济贝类体内异养细菌总数的变化范围为2.0×103～1.6×106cfu/g湿重,平均值为2.7×105cfu/g湿重,其中异养细菌总数最高的样品是在吕四沿岸3号站采集的四角蛤蜊(1.6×106cfu/g湿重),其次分别在北戴河沿岸2号站采集的杂色蛤(1.2×106cfu/g湿重)和毛蚶(1.1×106cfu/g湿重),而异养细菌总数最低样品是在青岛沿岸采集的镜蛤(2.0×103cfu/g湿重)和在大连沿岸采集的太平洋牡蛎、紫贻贝和皱纹盘鲍(≤5.0×103cfu/g湿重).该海区表层海水中异养细菌总数变化范围为2.5×105～1.0×108cfu/dm3,全海域平均值为1.2×107cfu/dm3.表层沉积物中异养细菌数量变化范围为2.8×103～7.5×105cfu/g干重,全海域平均值为1.3×105cfu/g干重.根据上述结果和欧共体委员会(93/51/EEC)指令要求,对各海区贝类卫生质量进行了初步评价.这在国内尚属首次. 相似文献
11.
We collected surface water along the 142nd E meridian from Tasmania to Antarctica in December 1999. We measured temperature,
salinity and total chlorophyll a; additionally, we collected suspended particle size fractions and used fluorometric analysis to determine the quantity of
chlorophyll a in each of four cell size classes: picoplankton (<3 μm), two nanoplankton fractions (3–10 μm and 10–20 μm) and microplankton
(> 20 μm). Changes in temperature and salinity show that we crossed 6 water masses separated by 5 fronts. We found low abundance
(<0.2 mg m−3) of chlorophyll in all size classes, with the exception of higher values near the continent (0.2 to 0.4 mg m−3). Lowest chlorophyll values (<0.1 mg m−3) were found in the Polar Frontal Zone (51° to 54°S). Microplankton made up the largest portion of total chlorophyll throughout
most of the region. We conclude that biomass of all phytoplankton fractions, especially pico-and nanoplankton, was constrained
by limiting factors, most probably iron, throughout the region and that ecosystem dynamics within a zone are not circumpolar
but are regionalized within sectors. 相似文献
12.
Through the water areas extracted from remote sensing images and the combination of the methods for establishing the formula for calculating tidal influx with tidal data, the tidal influx of the Haikou Bay, Hainan Province was found to be 5.14×107m3 in 1990, 5.80×107m3 in 1984 and 5.05×107m3 in 1965, respectively.After the analysis of the morphological and tidal range factors which determine tidal influx, this paper presents the trend of the changes in tidal influx caused by the changes in the morphological factors of the Haikou Bay.It is found that a decreasing trend was shown with a depressive rate of 2×10-3during the period from 1965 to 1984, and an increasing trend with an incremental rate of 1×10-3 during the period of 1984-1990.The main reason for the appearance of the decreasing trend before 1984 is the natural deposition and silting-up of the bay sediments; after 1984, the dredging and expansion of the Haikou Port and the Haikou New Port which caused an increase in water area at the mean low tide are the leading factor which causes the increase in tidal influx. 相似文献
13.
P. R. Vogt J. Gardner K. Crane E. Sundvor F. Bowles G. Cherkashev 《Geo-Marine Letters》1999,19(1-2):97-110
Numerous small (50- to 300-m-diameter) strong-backscatter objects were imaged on the 1200- to 1350-m deep crest of Vestnesa
Ridge (Fram Strait) and along the 900- to 1000-m deep northeast margin of the Storegga slide valley. Ground-truthing identified
most of these objects as 2- to 10-m-deep pockmarks, developed within soft, acoustically stratified silty clays (typical wet
bulk density: 1400–1600 kg m-3; sound speed: 1480– 1505 m s-1; porosity, 65–75%; shear strength: 5–10 kPa; water content: 80–120%; and thermal conductivity: 0.8–0.9 W m-1 deg C-1 in the top 3 m). Gas wipeouts, enhanced reflectors, and reflector discontinuities indicate recent or ongoing activity, but
the absence of local heat flow anomalies suggests that any upward fluid flows are modest and/or local. 相似文献
14.
微微型浮游植物是水环境生态碳汇的重要基石之一,也是初级生产的重要执行者。选取了一个典型的陆海交界关键带环境——海南东寨港入海口水域,采集了东寨港红树林保护区开阔水域、入港河流和新埠海海端的微微型浮游植物的样品,通过流式细胞仪分析技术对样品进行分析,以探究它们在东寨港水域中的丰度、分布及环境指示意义。结果表明,冬季水域微微型浮游植物以真核浮游植物(Eukaryote,Euk)和聚球藻(Synechococcus,Syn)两大类群为主,其中聚球藻有两个亚群,分别为富含藻蓝蛋白聚球藻(Phycocyanin-rich,PC)和富含藻红蛋白聚球藻(Phycoerythrin-rich,PE)。Syn-PC、Syn-PE和Euk在东寨港水域表层水体的平均丰度分别为(2.61×104±1.09×104)、(3.06×104±7.05×103)、(1.56×105±8.03×104) cells/m L,底层水体的平均丰度分别为(2.64×104±... 相似文献
15.
In the southwestern Okhotsk Sea off Hokkaido we observed chemical components related to the carbonate system for 1 year from
August 1997 to June 1998. Using the conservative components salinity and water temperature, we confirmed the existence of
two water masses flowing into the intermediate layer of the Okhotsk Sea, the East Sakhalin Current Water (ESCW) which becomes
denser by mixing of brine water, and the Forerunner of Soya Warm Current Water (FSWW) which becomes denser due to cooling
of the saline Kuroshio water. The ΔNTCx values were calculated by comparing the ESCW and the FSWW with the Pacific Deep Water (PDW). The ΔNTCx values obtained are 100–110 μmol/kg and 70–100 μmol/kg for the ESCW and the FSWW off Hokkaido, respectively, which are considerably
larger than that of the Kuroshio water. These large ΔNTCx values may be due to both low DIC concentration in the surface water and intense gas exchange under the cold and stormy winter
conditions for the ESCW and the cooling of the FSWW as it flows northward. Since the flow rates of dense waters concerned
with the ESCW and the FSWW have previously been estimated as 0.9 Sv and 0.2 Sv, respectively, the amount of atmospheric CO2 absorbed and transported to the intermediate layer turns out to be 3.9−4.1 × 1013 gC/yr. This flux is small on a global scale, but the flux divided by the surface layer of the Okhotsk Sea is 30 gC/m2/yr, which is 5 times greater than the mean absorption flux of anthropogenic CO2 in the world's oceans. It is thus considered that atmospheric CO2 is efficiently absorbed in the Okhotsk Sea.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Chiho Sukigara Toshio Suga Toshiro Saino Katsuya Toyama Daigo Yanagimoto Kimio Hanawa Nobuyuki Shikama 《Journal of Oceanography》2011,67(1):77-85
A profiling float equipped with a fluorimeter, a dissolved oxygen (DO) sensor, and temperature and salinity sensors was deployed
in the subtropical mode water (STMW) formation region of the North Pacific. It acquired quasi-Lagrangian, 5-day-interval time-series
records from March to July 2006. The time-series distribution of chlorophyll showed a sustained and sizable subsurface maximum
at 50–100 m, just above the upper boundary of the STMW, throughout early summer (May–July). The DO concentration in this lower
euphotic zone (50–100 m) was almost constant and supersaturated in the same period, becoming more supersaturated with time.
On the other hand, the DO concentration at 100–150 m near the upper boundary of the STMW decreased much more slowly compared
with the main layer of STMW below 150 m, even though oxygen consumption by organisms was expected to be larger in the former
depth range. The small temporal variations of DO in the lower euphotic zone and near the upper boundary of the STMW were reasonably
explained by downward oxygen transport because of large diapycnal diffusion near the top of the STMW. Assuming that the oxygen
consumption rate at 100–150 m was the same as that in the main layer of STMW and compensated by the downward oxygen flux,
the diapycnal diffusivity was estimated to be 1.7 × 10−4 m2 s−1. Nitrate transport into the euphotic zone by the same large diffusion was estimated to be 0.8 mmol N m−2 day−1. All of the transported nitrate could have been used for photosynthesis by the phytoplankton; net community production was
estimated to be 5.3 mmol C m−2 day−1. 相似文献
17.
The global VDM database, which was later supplemented by new determinations published in the world literature (a total of
3194 determinations), is used as the basis for addressing the VDM behavior in the Phanerozoic (0–542 Ma) and up to 580 Ma.
The results revealed a positive linear trend to higher VDM values from 3.5 × l022 Am2 to 5.7 × l022 Am2. Against this background, fluctuations of the mean VDMs occur with a periodicity of about 40 Myr. In the Phanerozoic, prominent
minima of the intensity are found in the time intervals of 510–520, 420–460, 340–370, 290–300, 240–270, 190–210, 165–140 Ma
(chrons M17–M43), 130–120 Ma (chrons M2–M10), 100–110 Ma (chron C34), 75–85 Ma (chrons C33 and the beginning of chron C34),
70–60 Ma (chrons C31–C27), and 40–15 Ma (chrons C18–C5AD). The distribution of the VDMs appears to reflect the paleomagnetic
field behavior and may be taken into account in a magnetization model for the reversely magnetized oceanic crust. 相似文献
18.
19.
The Luzon Strait transport variations during 1997~2000 总被引：1，自引：0，他引：1
1IntroductionTheSouthChinaSea(SCS)isthelargestmarginalseainSoutheastAsia.TheSCSiscon-nectedtotheopenoceanthroughseveralstraitsbetweenthesurroundinglandmassesandis-lands.TheLuzonStrait(seeFig.1)islocatedinthenortheastoftheSCSbetweenTaiwanIslandandthePhilippineIslands,whichisabout380kmwideanditslargestdepthismorethan2500m.Sincetheotherstraitsareveryshallow,theLuzonStraitistheonlymajorchannelallowingeffectivewaterexchangewiththewesternNorthPacific. Wyrtki(1961)firstlyassocia… 相似文献
20.
The research was performed along a transect from the Yamal Peninsula coast towards the outer shelf of the southwestern part
of the Kara Sea in September 2007. 130 phytoplankton species have been identified, among which 63 were found in the area for
the first time. The total phytoplankton numbers varied within the range of 0.2 to 11.3 × 109 cells/m2, while biomass within the range of 43 to 1057 mgC/m2. A well pronounced cross-shelf zoning in the phytoplankton communities was ascertained. The inner shelf zone about 30 km
wide with depths down to 30 meters was characterized by the predominance of diatoms (up to 80% of the total algae numbers
and biomass). The second group by value was dinoflagellates. Seaward in the area of the depth increase from 30 to 140 m, the
zone of the Yamal Current was located, which was 40 km wide and notable for its active water dynamics. The total cell numbers
in the zone reached a maximum for the entire investigated area: up to 11.3 × 109 cells/m2. The leading group in the phytoplankton was autotrophic flagellates, whose share in the total numbers reached 56–82%. Further
than 70 km from the shore, the outer shelf zone was found with the water column rigidly stratified. The highest for the whole
area phytoplankton biomass was identified here (up to 1.06 gC/m9), 80% of which was concentrated above the halocline. Diatoms dominated in the phytoplankton numbers (up to 92%) and biomass
(up to 90%), which was related to the mass development of two species: Chaetoceros diadema and Leptocylindrus danicus. 相似文献