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1.
The sedimentation system of the bottom contour current over the continental slope of Bear Island in the Norwegian Sea is considered. The nepheloid layer that provides the high horizontal flux of sedimentary material represents the main source of matter for the bottom sediments. The vertical particulate matter flux is largely formed in the nepheloid layer; the flux from higher layers of the water column is insignificant. Horizontal and vertical fluxes of sedimentary matter show a positive correlation. The flux of the matter from the bottom sediment into the nepheloid matter and the residence time of particles in the latter are estimated.  相似文献   

2.
The basic parameters of the sedimentation environment are considered: the Western Boundary Deep Current that transports sedimentary material and distributes it on the survey area; the nepheloid layer, its features, and the distribution of the concentrations and particulate standing crop in it; the distribution of the horizontal and vertical fluxes of the sedimentary material; and the bottom sediments and their absolute masses. The comparison of the vertical fluxes of the particulate matter and the absolute masses of the sediments showed that the contemporary fluxes of sedimentary material to the bottom provided the distribution of the absolute masses of the sediments in the survey area during the Holocene.  相似文献   

3.
Oceanology - New data are presented on sedimentary matter fluxes and its main components along a meridional transect (59°30′ N) in the North Atlantic under the effect of multidirectional...  相似文献   

4.
分析了南海62个表层沉积物样品中生源(有机质、碳酸钙和蛋白石)和非生源(岩源物质)组分的含量变化和分布特征,并以沉积学分区为基础,结合5个沉积物捕获器站位,将南海划分为N、C-NE、SW和S 4个区域,对比分析了各区表层沉积物和水柱中沉降颗粒物中各组分含量、沉积通量分布特征和变化,探讨了表层沉积物的输出生产力、沉降颗粒物的初级生产力及真光层下100 m输出生产力三者之间的对应关系.结果显示:南海4个海域表层沉积物中各组分平均含量多数低于沉降颗粒物中的平均含量,而碳酸钙、岩源物质的沉积通量却多数高于沉降颗粒物中的沉积通量,分析得出表层沉积物中各组分平均含量和沉积通量不仅受水柱中各组分输出量影响,还受到陆源物质输入、溶解作用和上层水体营养盐影响.南海表层沉积物中生源组分沉积通量大小对应其输出生产力的大小.但是,由于陆源有机质、生源颗粒侧向漂移的影响,表层沉积物的输出生产力大小分布并不完全对应沉降颗粒物的初级生产力大小分布,尽管南海真光层下100 m输出生产力与沉降颗粒物的初级生产力比值与世界大洋"f"比平均值基本一致,但是,明显低于表层沉积物的输出生产力大小,只有在沉降颗粒物的初级生产力较高区域,真光层下100 m输出生产力大小才最接近表层沉积物的输出生产力大小.  相似文献   

5.
The CTD and nephelometric sounding data are considered along with the parameters of the nearbottom currents and particulate fluxes measured by a subsurface mooring station in the northern part of the Bear Island Trough. It is shown that the near-bottom current is characterized by highly variable parameters, while the distribution of suspended particulate matter demonstrates surface and bottom maximums. The horizontal and vertical fluxes of sedimentary matter in the nepheloid layer are studied.  相似文献   

6.
Organic-rich black shale of the Upper Yangtze Basin from the Late Ordovician and Early Silurian is considered an excellent source rock in South China. The formation and preservation conditions of this resource are revealed by its geochemical characteristics in this study. Geochemical indices, including redox indices (V/(V + Ni), V/Cr, V/Sc, and Ni/Co) and primary productivity indices (P/Ti and Ba/Al), and paleoclimate, clastic flux and sedimentary rate analyses are presented to investigate the accumulation mechanism of organic matter. Redox indices suggest that a stagnant, anoxic environment predominated in the Upper Yangtze Basin during accumulation of Wufeng and Longmaxi formations. In contrast, ventilated and oxygenated marine conditions pervaded the Upper Yangtze Basin during deposition of Linxiang and Guanyinqiao formations. The concentrations of V and U demonstrate that accumulation of organic matter was mainly controlled by redox conditions. Besides, such factors as clastic fluxes, fresh water inflows or a mixed deposition with a rapid sedimentary rate cannot be ignored due to their influences on organic matter enrichment and preservation. However, weak co-variance relationship of TOC content and productivity proxies, including P/Ti and Ba/Al, demonstrates that the accumulation of organic matter was not controlled by primary productivity. Results of the present study suggest a depositional model that stresses the importance of tectonic movements and glacial events on the accumulation and preservation of organic matter. The model shows that the Upper Yangtze Basin was a semi-restricted basin system influenced by the isolation of Xuefeng, but also it implies that oxygen-depleted bottom water of the basin favored the accumulation and preservation of sedimentary organic matter, resulting in the formation of organic-rich black shale.  相似文献   

7.
A simple construction of the MSL-110 sediment trap developed at the Laboratory of Physical-Geological Research of the Shirshov Institute of Oceanology, Russian Academy of Sciences, is presented. The trap is easily assembled from standard parts available at stores. The trap is easy to use, reliable, and inexpensive. It is applied for determination of sedimentary matter fluxes and their components in water columns of seas, lakes, and other water reservoirs.  相似文献   

8.
A one year study of downward particle fluxes conducted in the northwestern Mediterranean Sea is presented. Two mooring lines equipped with sediment traps and current meters were deployed at around 1000 m depth on the northeastern continental slope of the Gulf of Lions, one inside the Grand-Rhône canyon and the other outside on the adjacent open slope. Mean total mass fluxes increased slightly with trap depth inside the canyon, a feature quite typical of fluxes in continental margin environments. The near-bottom trap inside the canyon collected more material than its counterpart deployed at equivalent depth on the open slope, indicating a preferential transport of material within the canyon. Major biogeochemical constituents (organic and inorganic carbon, opal, and siliciclastic residue) revealed a marked difference in particle composition between the sub-surface (80 m) and deeper traps, suggesting the existence of at least two sources of material. The two shallower traps showed a clear biological signal: flux peaks were related to periods of surface biological production, especially perceptible in summer and autumn. The particulate matter trapped at deeper levels in the canyon and on the open slope was characterized by a more stable composition with a major lithogenic contribution, originating from sedimentary material most probably resuspended on the upper- or mid-slope. The seasonal variability was dominated by the summer/winter alternation; the latter period was characterized by a weak stratification of the water column and an enhanced current variability favoring vertical exchanges. The present results are compared with those obtained previously in the Lacaze-Duthiers canyon on the southwestern side of the Gulf of Lions. The comparison shows strong differences between the NE entrance and the SW exit of the gulf, with respect to the general along-slope circulation of water masses, both in terms of intensity of particulate fluxes and transport processes.  相似文献   

9.
Data on the mineral composition of sedimentary matter and its fluxes in the sediment system of the Caspian Sea are presented. River runoff, aerosols, particulate matter from sediment traps, and the upper layer (0–1 cm) of bottom sediments are considered. The contents of detrital minerals (quartz, albite, and K-feldspar), clay minerals (illite, chlorite, and kaolinite), and carbonates (calcite, Mg-calcite, dolomite, aragonite, and rhodochrosite) are determined. Gypsum was found in bottom sediments but is absent in the other object of the sediment system.  相似文献   

10.
Fluxes of amino acids and hexosamines to the deep South China Sea   总被引：2，自引：0，他引：2  
Settling particles collected by sediment traps deployed between 1987 and 1999 in the northern, central and southwestern South China Sea (SCS) were analysed to study seasonal, interannual and spatial variations in the composition and flux of labile particulate matter. Results were combined with remote-sensing and surface-sediment data in order to describe the factors controlling the preservation of organic matter en route from the upper ocean to the seafloor. Organic carbon, amino acid and hexosamine fluxes generally follow the fluxes of total particulate matter, with maxima during the SW and NE monsoon periods. During non-El Niño conditions spectral amino acid distributions show that degradation of organic matter in the water column decreases as the flux rates increase. This is suggested to be the combined result of enhanced primary productivity, greater input of lithogenics serving as ballast to increase settling rates, and sorption of labile components to clay minerals. During El Niño conditions, in contrast, the degree of organic matter degradation is at very high and comparable levels at all trap sites. Flux component seasonality is strongly reduced except for the coastal upwelling areas, particularly off central Vietnam, which show significantly higher fluxes of organic carbon and lithogenic matter as compared to the open SCS. This suggests that the fluxes are affected by lateral advection of reworked organic matter from riverine sources or resuspended sediments from the nearby shelf/slope. Comparison of the measured organic carbon fluxes in 1200 m depth with those accumulating in surface sediments results in a more than 80% loss of organic matter before final burial in the sediments. The degree of organic matter preservation in the surface sediments of the deep SCS is distinctly lower than in other monsoonal oceans. This may be due to varying lithogenic input and almost complete dissolution of protective biogenic mineral matrices at greater water depth.  相似文献   

11.
In this paper, the results of long-term studies of the nepheloid layer in the Norwegian Sea in the Komsomolets test area are considered. Its principal characteristics such as its thickness, the particulate matter concentration in the nepheloid layer, and its standing crop are presented. The nepheloid layer is formed by the near-bottom current, which, together with the particulate standing crop, determines the horizontal flux of the sedimentary matter over the continental slope. Also presented are data about the currents in different years of observations as well as estimates of the horizontal fluxes.  相似文献   

12.
We conducted a multi-year sediment-trap experiment in Saanich and Jervis Inlets, British Columbia, Canada. Moorings with traps positioned at three depths were placed near the mouth and toward the head of each fjord, and deployments were monthly. We present fluxes of total mass, biogenic silica (BSi), particulate organic carbon (POC) and aluminium (Al), as well as the δ13C signal of the POC, and we compare the sediment-trap fluxes to primary-production measurements made during the experiment.Diatomaceous silica and aluminosilicates were the primary components of the settling flux, while organic matter from marine (largely diatoms) and terrestrial sources was occasionally a significant portion of the sinking material. Fluxes of BSi and POC were highest in the spring and summer, tracing maxima in local primary production. These fluxes decreased, increased or remained constant with depth due to water-column remineralisation and variability in processes that cause fluxes to increase with depth. Al fluxes followed local precipitation and river runoff at the landward stations, and with remarkable faithfulness in Saanich Inlet. Near the mouths, there was little seasonality in Al flux, and the increases of flux with depth reveal sedimentary plumes at each fjord’s sill. Tidal and deepwater-renewal components of the plumes are evident, and the plume in Saanich Inlet was particularly intense. Fluxes of Al to deep sediment traps associated with renewal flows were also observed toward the head of each fjord.Marine δ13C endmembers are estimated from relationships between δ13C and BSi concentrations, and measures of soil δ13C from each fjord were available. These endmembers are used with the δ13C record to quantify marine and terrigenous contributions to the POC flux. Marine POC composed 54-72% of the total POC caught by shallow sediment traps in spring and summer, and 36-54% in fall and winter. Primary production and sediment-trap fluxes are used to estimate annually averaged export ratios (shallow-trap flux:autotrophic assimilation) for marine POC and Si. POC export ratios (0.092-0.14) were low for these productive waters, but they compare with other results based on sediment-trap fluxes from coastal waters where terrigenous OC has been subtracted. Export ratios of Si were calculated using an estimated Si:C assimilation ratio and, therefore, are susceptible to error, but the high results (>0.8) suggest that BSi was exported more efficiently than POC. The possibility that POC was preferentially lost after interception by sediment traps is also considered. Primary production and settling fluxes were higher in Saanich Inlet than in Jervis Inlet, while export ratios of OC and Si were similar in both fjords, away from the nepheloid layer near the sill of Saanich Inlet.  相似文献   

13.
Results are presented from particle flux studies using sediment trap and current meter moorings along a transect at the European continental margin at 49°N within the EU-funded Ocean Margin Exchange (OMEX) project. Two moorings were placed, at the mid- and outer slope in water depths of 1500 and 3660 m, with traps at 600 and 1050 m and at 580, 1440 and 3220 m, respectively. Residual currents at the mid-slope follow the slope contour, whereas seasonal off-slope flow was registered at the outer slope. At 600 m on the slope fluxes are similar to those in the abyssal North Atlantic. The flux of all components (bulk dry weight, particulate organic and inorganic carbon, lithogenic matter and opal) increased with water depth. Highest fluxes were recorded at 1440 m at the outer slope, where off-slope residual currents mediate particle export. The injection of biogenic and lithogenic particles below the depth of winter mixing results in the export of particles from shallower waters. Calculated lateral fluxes of particulate organic carbon exceed the primary flux by over a factor of 2 at 1440 m on the outer slope. Estimated lateral fluxes of suspended particulate matter in the water column and intermediate nepheloid layers at the outer slope are potentially large compared to sinking fluxes measured by sediment traps. A comparison is made of particle flux at three continental margin sites and two sites in the adjacent open North Atlantic, from which it is seen that bulk and organic matter flux increases exponentially with proximity to the shelf break. The percentage contribution of particulate organic carbon to biogenic fluxes increases from a mean of 5.7% in the abyssal N. Atlantic to 13.9% at the continental margins.  相似文献   

14.
Sediment trap experiments were carried out 39 times during the years from 1977 to 1981 in Funka Bay, Hokkaido, Japan. The observed total particulate flux varies seasonally, that is, the particulate fluxes in winter and spring are larger than those in summer. The fluxes in all seasons increased with depth. Major components of settling particles are aluminosilicate in winter, biogenic silicate in spring and organic matter and terrestrial material in summer, respectively. The fluxes of each chemical component observed with sediment traps are normalized to that of Al by assuming that the actual flux of Al is equal to the accumulation rate onto the sediment surface. Vertical changes of the normalized flux of each chemical component indicate the following: Fe was not regenerated from the settling particles in the water column. Mn was regenerated from the settling particles in the lower layer exclusively between 80 m depth and the sediment surface. Cd was actively regenerated in the upper layer above 80 m depth. Phosphate was regenerated in the upper layer, while biogenic silicate was in the lower layer. The silicate regeneration, therefore, occurs after phosphate regeneration. The material decomposing in the water column below 40 m has an atomic ratio of P ∶ Si ∶ C = 1 ∶ 52 ∶ 128.  相似文献   

15.
The flux and compositions of solvent-extractable lipid fractions were measured in particulate matter collected periodically by moored sediment traps in the Santa Monica Basin from 1985–1988. The purpose was to assess the compositional changes during settling, the carbon dynamics in the basin and to estimate the impacts of energy-related by-products on the surface sediments. Sediment traps recorded consistently high lipid fluxes in the eastern slope relative to the central basin, reflecting elevated terrigenous carbon inputs possibly from land-based human activities. Generally, lipid fluxes decrease offshore but increase vertically with water depth below 500m, implying lateral transport of particles. The steep decline of flux in the top 500m of the water is related to the rapid decomposition and mineralization of the marine-derived cellular carbon compounds. Less than 5% of the marine lipid components reach the seabed. In contrast, preferential preservation of terrigenous lipid is clearly evident from the chemistry of deeper traps and surface sediments.The lateral transport of particles is reflected in the presence of higher plant-derived lignin phenols and sewage-derived coprostanol and epicoprostanol in the deep trap material as well as in surface sediment throughout the basin. Petroleum triterpanes characteristic of natural seepage also permeates through the entire basin. Based on the data collected from both the trap particulte matter and surface sediments, a carbon budget for the Santa Monica Basin has been constructed.  相似文献   

16.
Synchronous measurement of the total suspended organic and mineral particulate matter, together with vertical sedimentary matter flux, carried out in various areas of Yarnyschnaya Inlet (Murmansk coast of the Barents Sea) and Chupa Inlet (Karelian coast of the White Sea) revealed that the seston organic component plays no part in sedimentation, being almost completely utilized in the water column, while the majority of mineral matter is transported out of the bay. The total amount of suspended matter and its components in the water column is estimated, as well as the total flux of sedimentary matter to the bottom of Chupa and Yarnyschnaya inlets.  相似文献   

17.
Deep slope currents and particulate matter concentrations were studied on the Barcelona continental margin in and around the Foix submarine canyon from May 1993 to April 1994. This year-long moored experiment revealed that near-bottom slope currents are strongly influenced by the bottom topography, being oriented along isobaths and along the canyon axis. The deep slope current fluctuations are controlled by the local inertial motion (18.3 h) and also by low-frequency oscillations at periods of 6–10 days, related to the passage of atmospheric pressure cells. Particulate matter concentrations recorded during the experiment do not show a clear seasonal variability, except outside the canyon, where significant peaks of particulate matter concentrations were recorded only during the winter-fall deployment. In addition, the temporal evolution of suspended particulate matter concentration is not linked to changes in the cross-slope or along-slope current components and did not show a clear relationship with river avenues or wave storm events. This suggests that suspended particulate matter exported from the shelf is dispersed on the slope by advective processes, which attenuate the signal of the shelf-slope sediment transfer. Mean particulate matter concentrations differed among sampling sites, but the magnitude of the mean horizontal suspended particle flux reflects a quite similar value in the whole study area, ranging from 2.53 to 4.05 mg m−2 s−1. These horizontal suspended particle fluxes are 27 (canyon head) to 360 (open slope) times higher than the settling particle fluxes measured at the same sampling sites, indicating that the suspended particulate transport on the Barcelona continental slope dominates over the settling particle fluxes, even inside the Foix submarine canyon.  相似文献   

18.
Time-series data from sediment trap moorings intermittently deployed during 1991–1999 show that the fluxes of biogenic material (carbonate, opal and organic matter, including amino acids) and other related parameters are temporally and spatially distinct across the Western Pacific Warm Pool (WPWP). These variations resulted from the El Niño and La Niña conditions, which alternately prevailed over the equatorial Pacific Ocean during the mooring deployments. The westernmost WPWP (a hemipelagic region) recorded relatively high average total mass and amino acid fluxes during the El Niño event. This was in sharp contrast to the eastern part of the WPWP (oligotrophic and weak upwelling regions) which recorded higher flux values during the La Niña event. Settling particulate organic matter was rich in labile components (amino acids) during La Niña throughout the study area. Relative molar ratios of aspartic acid to β-alanine together with relative molar content of non-protein amino acids β-alanine and γ-aminobutyric acid) suggested that organic matter degradation was more intense during La Niña relative to that during El Niño in the WPWP. This study clearly shows that during an El Niño event the well documented decrease in export flux in the easternmost equatorial Pacific is accompanied by a significant increase in export flux in the westernmost equatorial Pacific Ocean.  相似文献   

19.
Marine snow from upper and mid-water (i.e., pelagic) depths on the California margin is texturally and compositionally different from that traveling in the nepheloid layer. Transmission electron microscopy shows that pelagic marine snow consists primarily of bioclasts (e.g., diatom frustules, foram tests), organic matter, and microbes. These components are entrained as discrete particles or small aggregates μm in diameter) in a loose network of exocellular, muco-polysaccharide material. Clays are infrequent but, when present, are constituents of comparatively compact organic-rich microaggregates. Microbes are abundant and appear to decrease in number with increasing water depth. In contrast, marine snow aggregates collected from just above the sea floor in the nepheloid layer are assemblages of clay particles, clay flocs, and relatively dense clay–organic-rich microaggregates in an exocellular organic matrix. Bioclasts and microorganisms occur only rarely. The prevalence of clay–organic-rich aggregates in the nepheloid layer suggests that, prior to final deposition and burial, marine snow from the pelagic zone is subject to disaggregation and recombination with terrigenous detrital material near or at the sea floor. Results have significant implications for the accumulation and burial rates of organic carbon on continental margins and the aging and bioavailability of sedimentary organic matter. Samples examined were collected offshore of northern and central California.  相似文献   

20.
Spatial and temporal variations in the vertical fluxes of amino acids and hexosamine were studied at coastal sites in the south of the Chukchi Sea, Otsuchi Bay, and the center and the entrance of Funka Bay. Amino acid fluxes were higher in the upper trap than in the lower trap material, but hexosamine fluxes were opposite to amino acid fluxes. The ratios between protein amino acids (Asp, Glu and Arg) and their decomposition products (β-Ala, γ-Aba and Orn) indicate that the labile organic matter was more abundant in the upper traps than in the lower ones and increased during periods of enhanced amino acid fluxes. The ratios of Ser/Gly did not vary temporally and spatially and were nearly constant, indicating that Ser and Gly were preserved in a stable form within sinking particles. Hexosamine/amino acid ratios of these particles were higher in the lower sediment trap than in the upper trap material. This implies that the sinking particles derived from zooplankton are relatively more abundant in deep layers than in the surface layer in the water column. We suggest that the difference in amino acid flux and the composition between the upper and lower trap material is influenced by the processes of microbial decomposition and zooplankton consumption of sinking particulate organic matter. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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