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1.
O. S. Chauhan B. S. Sukhija A. R. Gujar P. Nagabhushanam A. L. Paropkari 《Geo-Marine Letters》2000,20(2):118-122
Down-core variations in illite, chlorite, smectite and kaolinite (the major clays) in two 14C-dated cores collected along the SW continental margin of India show that illite and chlorite have enhanced abundance during
20–17, 12.5, 11–9.5, and 5–4.8 ka b.p., whereas smectite accumulation is higher between 17 and 12.5, and after 9 ka b.p. The climate may have been predominantly arid at 17 (20–17), 12.5, 10.5 (11–9.5), and 4.8 ka b.p. The first three dates correspond to the last glacial maximum, Bolling-Allerod, and Younger Dryas events, respectively. The
SW monsoon was variable between 17 and 15 ka b.p., and it was more stable and intense after the Younger Dryas until about 6 ka b.p.
Received: 2 December 1999 / Revision accepted: 11 April 2000 相似文献
2.
Observed variations in dissolved oxygen and in total carbon dioxide were found to be consistent with the organic decomposition
model ofRedfield, Ketchum, andRichards (1963), if the effects on the total carbon dioxide of processes other than decomposition are compensated for. 相似文献
3.
Yuzo Komaki 《Journal of Oceanography》1970,26(5):283-295
A considerable number ofEuphausia similis
G. O. Sars were found to be infected with a parasite in the samples collected in the summer of 1969 in Suruga Bay. The same species
was also parasitized by an ellobiopsid,Thalassomyces fagei (Boschma), but it was rare in occurrence. The former parasite is slightly oval in shape with the longer diameter ranging between 1.0
and 1.5 mm, average diameter 1.35 mm. It infests cardiac region, rarely gastric region, of the host. It has been preliminarily
identified by Drs.T. Oshima andT. Shimazu of the Shinshu University as the progenetic metacercaria of a trematode species very closely related toPseudopecoelus japonicus; its adult was originally reported to infest several bathypelagic fishes and the encysted stage was also found in jack mackerel
from Suruga Bay byYamaguti (1938). The occurrence of the metacercaria inE. similis from the area may be new to science, althoughG. O. Sars (1885) has reported the immature forms ofDistomum filiferum
G. O. Sars inNematoscelis megalops
G. O. Sars andThysanoessa gregaria
G. O. Sars and the crustaceans of wide variety have been proved to serve as the second intermediate host of various trematodes. The
euphausiids infected with the metacercaria were concentrated in the innermost part of the bay. This might suggest the presence
of the euphausiid population which is confined to the geographical area for some period. The metacercaria may be used as a
“biological tag” to trace the migratory range of the host when the life history of the parasite is elucidated. The finding
ofT. fagei in the area may be the first record of occurrence of the species in the western North Pacific, andE. similis is now recorded as the fourteenth known host euphausiid of the ellobiopsid. 相似文献
4.
Based on new and existing data on oxygen isotopes, alkenone-surface seawater temperature trends, planktonic foraminifers,
lithology, and clay mineral composition of piston cores, a distinct cooling event has been identified around 8,200 cal a b.p. in the middle Okinawa Trough, northwest Pacific. This corresponds to the 8,200 a b.p. cooling event recorded in many places of the Northern Hemisphere. During this event, the local temperature decreased by
1°C, and the δ18O value increased by 0.6‰. A strengthened Asian winter monsoon is the most probable cause for this event, which thus adds
further credibility to the contention that we are dealing here with a global phenomenon. 相似文献
5.
Kenzo Takano 《Journal of Oceanography》1974,30(4):205-206
A wrong finite difference form is used for the rotation of the Coriolis force in the vorticity equation with bottom topography in a series of papers byEndoh. 相似文献
6.
Origin of pockmarks and chimney structures on the flanks of the Storegga Slide,offshore Norway 总被引:2,自引:1,他引:2
Seafloor pockmarks and subsurface chimney structures are common on the Norwegian continental margin north of the Storegga
Slide scar. Such features are generally inferred to be associated with fluid expulsion, and imply overpressures in the subsurface.
Six long gravity and piston cores taken from the interior of three pockmarks were compared with four other cores taken from
the same area but outside the pockmarks, in order to elucidate the origins and stratigraphy of these features and their possible
association with the Storegga Slide event. Sulfate gradients in cores from within pockmarks are less steep than those in cores
from outside the pockmarks, which indicates that the flux of methane to the seafloor is presently smaller within the pockmarks
than in the adjacent undisturbed sediments. This suggests that these subsurface chimneys are not fluid flow conduits lined
with gas hydrate. Methane-derived authigenic carbonates and Bathymodiolus shells obtained from a pockmark at >6.3 m below the seafloor indicate that methane was previously available to support a
chemosynthetic community within the pockmark. AMS 14C measurements of planktonic Foraminifera overlying and interlayered with the shell-bearing sediment indicate that methane
was present on the seafloor within the pockmark prior to 14 ka 14C years b.p., i.e., well before the last major Storegga Slide event (7.2 ka 14C years b.p., or 8.2 ka calendar years b.p.). These observations provide evidence that overpressured fluids existed within the continental margin sediments off Norway
during the last major advance of Pleistocene glaciation. 相似文献
7.
We investigated the biogenic components (biogenic opal, calcium carbonate, and organic carbon) of the marine sediments in core TY99PC18 recovered from the southeastern part of the Ulleung Basin, East Sea (Japan Sea). Our results indicate that primary productivity by diatoms increased after the last glaciation (15,000 14C years b.p.) probably because of the onset of vertical mixing of seawater and nutrient supply from the deep water. Between 5,000 and 10,000 14C years b.p. a shift in the dominant primary producer, i.e. from diatoms to coccolithophores, coincides with decreased productivity, which could be related to the influx of warm, low-nutrient waters at that time. During the late Holocene (after 5,000 14C years b.p.) the productivity of diatoms increased once more probably due to renewed ventilation and vertical mixing. 相似文献
8.
K��r?ad Kadir Eri? M. N. ?a?atay Sena Ak?er Luca Gasperini Yosi Mart 《Geo-Marine Letters》2011,31(1):1-18
The late glacial to Holocene sedimentary record of the northern shelf of the Sea of Marmara (SoM) has been documented by detailed
seismo-, chrono-, and biostratigraphic analyses using sub-bottom (Chirp) profiles and sediment cores. During MIS 3 and the
main part of MIS 2 (60–15 14C ka b.p.), disconnection from the Mediterranean and Black seas together with a dry climate resulted in a regression in the SoM, when
the Sea was transformed into a brackish lake. The river incisions below 105 m water depth along the northern shelf took place
during the last glacial maximum, when the lake level was modulated by stillstands at −98 and −93 m. The post-glacial freshwater
transgressive stage of the Marmara ‘Lake’ occurred between 15 and 13.5 14C ka b.p., leading to a rise in water level to −85 m by 13.0 14C ka b.p., as evidenced by broad wave-cut terraces along the northern shelf. Since 12 14C ka b.p., high-frequency sea-level fluctuations have been identified at the SoM entrance to the Strait of İstanbul (SoI). Thus, wave-cut
terraces have been recorded at water depths of −76 and −71 m that, according to an age model for core MD04-2750, have ages
of 11.5 and 10.5 14C ka b.p., respectively. Ancient shoreline at −65 m along the northern shelf presumably formed soon after the Younger Dryas (YD) at
ca. 10.1 14C ka b.p. Moreover, there is compelling evidence of Holocene outflow from the Sea of Marmara to the Black Sea. At the SoM entrance
to the SoI, the existence of bioherms on the reflector surface together with abundant Brizalina spathulata and Protoglobulimina pupoides in a core suggests a return to higher salinities due to strong Mediterranean water incursion into the SoM at ∼8.8 14C ka b.p. This finding is consistent with earlier suggestions that, after the YD, the Black Sea was flooded by outflow from the SoM
as a result of global sea-level rise. 相似文献
9.
Masaaki Murano 《Journal of Oceanography》1970,26(3):137-150
A list of the 21 species represented in the collection by the bottom-net is given. Of these, 5 are impossible to be identified
with the already known species, especially 2 are reserved as their genera are undecided. It is found that there are 2 races
inHolmesiella affinis
Ii, the large-sized and the small-sized, as like as the most related species,H. anomala
Ortmann. As to a species,Pteromysis amemiyai
Ii, the development of the marsupium is discussed on the basis of an adult female collected by the ORI-net. The occurrence of
2 species,Petalophthalmus oculatus
Illig andPseudomma calloplura
Holt andTattersall, is a new record in the Pacific. For the former species, moreover, an ecological property of the habitat is discussed. 相似文献
10.
以I.A.M.收集的培养基Ⅱ为基本培养基,采用单因子和L16(45)正交设计法,进行了舟形藻BT001对N、P、Fe、Si四种营养盐最适需求的研究,并在此基础上,研究了尿素对正交优化组合的影响以及以尿素作为氮源对正交优化组合的影响。结果表明,N、P、Fe、Si四种营养盐最佳单因子水平为:KNO3,300mg/L;Na2HPO4·12H2O,40mg/L;FeCl3,4mg/L;Na2SiO3·9H2O,200mg/L。四种营养盐正交组合水平为:KNO3,150mg/L;Na2HPO4·12H2O,40mg/L;FeCl3,4mg/L;Na2SiO3·9H2O,200mg/L。在正交组合水平基础上,添加16mg/LCO(NH2)2,可更好的促进该藻的生长和繁殖。在8天的培养中,最大细胞相对生长率可达0.1577。在等摩尔氮源的条件下,以CO(NH2)2代替正交优化水平组合中的KNO3对舟形藻BT001进行11天的培养。结果表明,以CO(NH2)2为氮源的藻细胞最大生长密度可达2.69×105cell/ml,明显地高于硝酸钾作为氮源培养的藻细胞密度。 相似文献
11.
We report records of land plant-derived long-chain n-alkanes since 37 ka b.p. from a sediment core in the middle Okinawa Trough, East China Sea. The data show the content and carbon preference index
(CPI; degree of freshness) of n-alkanes generally decreasing as sea level rose, which could be explained by coastline retreat resulting in an increased transport
route of n-alkanes toward the study site. The n-alkane CPI returned to higher values during the Holocene highstand, however, suggesting sea-level rise was not the only cause
for the decline of freshness of n-alkanes. Paleovegetation changes in terms of C3 vs. C4 contributions inferred from n-alkane δ13C are overall consistent with published marine and terrestrial records during two distinct intervals: from 37.0 to 15.2 ka
b.p., and from 7.6 ka b.p. to the present. However, n-alkane δ13C excursions from 15.2 to 7.6 ka b.p. are difficult to reconcile with terrestrial signatures. This disagreement, along with other possible causes for the decline
of freshness of n-alkanes, and the higher-energy sedimentary environment inferred from increased mean grain sizes and silt/clay ratios during
this time period, is consistent with existing knowledge of offshore transport of materials previously stored on the extensive
continental shelf during the post-glacial transgression. We therefore suggest that n-alkane records from the Okinawa Trough should be used only cautiously to infer deglacial vegetation and sea-level changes. 相似文献
12.
The high frequency part (10 Hz50 Hz) of the one-dimensional wave spectrum was measured in a wind-wave channel under accurately controlled conditions. The results are compared with the spectral forms for the capillary range that have been proposed recently byPierson andStacy (1973) andToba (1973). In a general sense, fairly good agreement is found between the present results and those ofPierson andStacy (1973) and ofToba (1973). The spectrum in the capillary range is clearly wind speed dependent, and the spectral density in that range increases with increasing wind speed.However, closer examination shows systematic deviations of the present results from those previously proposed, particularly for high speed winds. 相似文献
13.
Kunio Kutsuwada 《Journal of Oceanography》1982,38(3):159-171
The wind-stress field in the North Pacific Ocean during 1961–75 is computed from nearly five million ship reports. With a drag coefficient having a linear relation to wind speed, annual mean and monthly mean wind-stress fields are obtained, and their features are described.Compared with the stress fields obtained byHellerman (1967) andWyrtki andMeyers (1976), the eastward component of the stress in the present study is larger in magnitude and the northward one smaller in magnitude, especially in the trade wind region. Differences in the drag coefficient do not have a pronounced effect on the estimated stress field. Long-period inter-annual variations in the wind field are the most likely cause of the discrepancies between the present study and those of the above authors.The maximum of the wind-stress curl, estimated from the annual mean wind-stress fields, is as large as 1.0×10–8dyn cm–3 around 30°N, and is larger than that estimated byEvenson andVeronis (1975). The discrepancy is considered to be mainly due to differences in the computed stress field itself rather than due to differences in the grid size used in the stress computations.The Sverdrup transports integrated from the eastern boundary on the basis of the present stress field have a maximum greater than 40×10–12cm3 s–1 (Sv.) near the western boundary around 30°N. This value is closer to the observed transport of the Kuroshio than that based on Hellerman's stress field. 相似文献
14.
15.
16.
Keisuke Taira 《Journal of Oceanography》1972,28(5):187-202
This paper presents the results of observation on the development of wind-waves which were generated in a lake water about 420 cm deep with a fetch 12 km long. Measurements of surface elevation were carried out at the end of an observational pier where the water depth was 80 cm. The wave momentum flux, i.e., the growth rate of the wave momentum, was estimated from both significant waves and power spectral densities for the wave records. The values obtained by the two ways accorded fairly well and they were 57 % as large as the wind stress measured simultaneously. The exponential growth rate of spectral densities for a frequency component was in good accord with that observed bySnyder andCox (1966) and by others. If these growth rates are applied to all the components of the spectrum, the wave momentum flux must exceed the wind stress. This cannot explain the experimental results nor can be physically accepted. The difference of spectral densities between the two successive runs showed that the increase of spectral densities was. limited in several bands of frequency. The phenomena are discussed in relation with the overshoot-undershoot effects studied byBarnett andSutherland (1968).Observational results suggest that the spectral growth of a certain component is closely related to the spectral densities of other components. Energy exchange among componented waves has not been considered in the theories for generation and development of wind-waves established by Phillips, Miles and others.New generation mechanism suggested byLonguet-Higgins (1969) was found to be able to describe the observed growth rates of the form(f)={(1/2)(t–t1/2)}2: the spectral density(f) was proportional to the square of durationt. However, the mechanism can not explain the overshoot-undershoot effects peculiar to the equilibrium spectrum of windwaves.Three frequencies characterizing the discrete distributions of frequency bands where spectral densities increased were examined and three waves corresponding to these frequencies were found to be satisfying the resonance conditions for the wave-wave interactions among three sinusoidal wave trains as studied byPhillips (1960),Longuet-Higgins (1962) andBenny (1962). The interactions are suggested to predict well both the spectral growth proportional to squares of duration and the ceaseless oscillations of spectral densities in an equilibrium spectrum. 相似文献
17.
掺铝氧化锌厚膜制备及其对三甲胺和海产品鲜度的敏感性 总被引:2,自引:0,他引:2
用烧结法制备掺铝氧化锌厚膜,把氧化锌粉末分别同0%,1%,3%,5%的Al2O3粉末机械研磨混合均匀,在1100℃下烧3h,再同粘合剂,有机溶剂混合制成浆料,用刮刀法在氧化铝基片上浆料制成膜,在100℃下烘干后再经1100℃烧结2h。膜的灵敏度的测量方法是将膜放在玻璃管内加热到测量温度,测量膜暴露在一定浓度TMA气体或由牡蛎放出的气体时电阻值的变化。测量温度为200,250,300℃和400℃,T 相似文献
18.
The Helgoland mud area in the German Bight is one of the very few sediment depocenters in the North Sea. Despite the shallowness of the setting (<30 m water depth), its topmost sediments provide a continuous and high-resolution record allowing the reconstruction of regional paleoenvironmental conditions for the time since ~400 a.d. The record reveals a marked shift in sedimentation around 1250 a.d., when average sedimentation rates drop from >13 to ~1.6 mm/year. Among a number of major environmental changes in this region during the Middle Ages, the disintegration of the island of Helgoland appears to be the most likely factor which caused the very high sedimentation rates prior to 1250 a.d. According to historical maps, Helgoland used to be substantially bigger at around 800 a.d. than today. After the shift in sedimentation, a continuous and highly resolved paleoenvironmental record reflects natural events, such as regional storm-flood activity, as well as human impacts at work at local to global scales, on sedimentation in the Helgoland mud area. 相似文献
19.
20.
提要以伊红染色法检测样品精子存活率为依据,研究了4℃下5种保存液及Ca2 、Mg2 离子对中华绒螯蟹精子体外保存效果的影响。5种保存液分别为人工海水(ASW)、2倍钙离子人工海水(2×Ca2 -ASW)、无镁离子人工海水(Mg2 -FASW)、无钾离子人工海水(K -FASW)、无钙离子人工海水(Ca2 -FASW),经4天保存后,各保存液中精子样品的存活率和精子密度均出现明显差异,K -FASW、ASW及2×Ca2 -ASW三种保存液中的精子因发生顶体反应而大量死亡,而Mg2 -FASW、Ca2 -FASW的保存效果较好。在此基础上,进一步探讨了不同Mg2 和Ca2 浓度对精子存活率的影响,结果发现,经24h保存后各实验组精子存活率均随着两种离子浓度的增加而明显下降。上述结果表明:K -FASW、ASW及2×Ca2 -ASW不适合精子保存,而Mg2 -FASW和Ca2 -FASW均可作为该蟹精子的保存液;Ca2 因可引起精子顶体反应而造成保存液中精子的大量死亡,其浓度与存活率呈明显的负相关;无K 的保存液中,Ca2 、Mg2 的存在与否对精子的保存效果起关键作用;无Mg2 人工海水之所以具有较好的保存效果,可能与Mg2 的缺乏而导致Ca2 逆浓度差转运受阻,避免了因Ca2 进入而诱发顶体反应有关。 相似文献