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1.
Results of organic carbon, total nitrogen, amino acid and hexosamine analyses of samples collected during time-series sediment trap investigations in the Arabian Sea are presented. Samples were taken over a period of years at two depths at each of three locations in the western, central and eastern part of the basin. Seasonal changes in amino acid contents and their spectral distributions show that degradation of organic matter in the water column is reduced during the monsoons, which are the high-flux periods in the western and central Arabian Sea. At the eastern site more degraded material of possibly recycled marine or terrestrial origin reaches the traps during the late summer peak fluxes. The results of hexosamine analyses suggest that bacterial biomass is relatively enriched on particles sinking in the water column and, to a larger extent, at the sediment-water interface. Decomposition between intermediate and deep water results in a loss of 30–40% of total organic carbon and more than 40% of amino acids. Comparison of the measured accumulation rates of organic carbon in sediment traps with those of organic carbon preserved in sediments show that more than 85% is lost before final burial in the sediments. Organic matter preservation in the Arabian Sea is higher than the average for the open ocean; this maybe due to the abundance of refractory organic matter of recycled marine or terrestrial origin.  相似文献   

2.
Sinking matter collected by sediment traps, which were deployed in the equatorial Pacific Ocean at 175°E for about 11 months during 1992–1993, were analyzed for their flux and labile components in terms of amino acids and hexosamines. The samples provided a temporal resolution of 15 days and were collected from 1357 (shallow trap) and 4363 m (deep trap) depths where sea floor depth was 4880 m. Particle flux along with major components (carbonate, organic matter, biogenic opal and lithogenic material) and amino acid parameters showed distinct temporal variations, which were more pronounced in the shallow trap relative to deep trap. A coupling between the fluxes in the shallow and deep traps was more evident during the period of maximum particle flux, which seems to be connected with the short reappearance of non-El Niño conditions in equatorial Pacific during the 1991–1993 El Niño event. The biogeochemical indicators C/N, Asp/Bala, Glu/Gaba, Bala+Gaba mol%, THAA-C% and THAA-N% implied that the increase in sinking flux was associated with upwelling and enhanced surface production. Degradation of sinking particulate organic matter between the shallow and deep traps was also evident. Occasionally higher mass and major component fluxes in the deep trap relative to the shallow trap are attributed to contribution of resuspended particulates from sea floor (nepheloid layer) or to laterally advected particulates from nearby areas. Carbonate and opal composition of the sinking flux showed a predominance of calcareous plankton; however, Asp/Gly mol ratio and Ser+Thr mol% indicated enhanced occurrence of diatoms during the periods of higher flux.  相似文献   

3.
A time-series sediment trap was deployed from December 1994 to February 2002 at the mouth of Tokyo Bay (35°03′ N, 139°40′ E; water depth, 850 m). Sinking particles were obtained with a time interval of one week at a depth of approximately 100 m above the sea floor. Observed total mass fluxes varied from 3.3 to 226.7 g/m2/day with an average of 28.0 g/m2/day. Concentrations of rare earth elements, Al, Ca and Si in particulate materials were measured. The combustible fraction at 450°C is assumed to be equivalent to the organic matter content. Contents of biogenic materials, namely organic matter, opal and calcium carbonate, were about 30% and the content of lithogenic material was about 70%. Using La/Yb ratios of particles from the sediment trap and Tama-gawa River and surface sediment of Tokyo Bay, it was estimated that about 50% of the lithogenic particles collected in the sediment trap at the mouth of Tokyo Bay originated from resuspended surface sediment in Tokyo Bay. An increasing trend of Opal/CaCO3 ratio in the sinking particles was found in the spring season. It is suggested that the relative increase of diatoms is due to the decreasing dissolved inorganic nitrogen input into Tokyo Bay.  相似文献   

4.
We investigated amino acids and pigments in particles settling through the water column of the Southern Ocean and showed that spatial and temporal differences in phytoplankton source and consumer population influence sinking particle composition. Sediment traps were deployed along 170°W from November 1996 to March 1998 as part of the United States Joint Global Ocean Flux Study (US JGOFS) Antarctic Environment Southern Ocean Process Study (AESOPS) program. Peak fluxes of amino acids and pigments occurred during austral spring and summer (November–April) and were highest in the Antarctic Circumpolar Current (ACC). Compositional changes in pigments and total hydrolyzed amino acids demonstrate how the source of sinking particles varies with latitude and suggest that sinking material was most degraded in relatively diatom-depleted regions and toward the end of the high-flux period (February–March). At the Subantarctic Front, high proportions of pheophytin and β-alanine illustrate the important role of microbes in degradation. Further south at the Antarctic Polar Front, glycine, pyropheophorbide, and pheophorbide enrichments reflected a greater contribution of diatoms and greater processing by zooplankton grazers. Even further south in the ACC, enrichments of the diatom pigment fucoxanthin, diatom cell wall indicators glycine and serine, and diatom frustule-bound amino acids suggested the settling of empty frustules and aggregates. Despite being protected by the mineral, diatom-bound amino acids were not preferentially preserved between shallow and deep traps, possibly because of silica dissolution and a relatively small amount of organic carbon remineralization. Our results show that organic matter at diatom-rich stations is removed by mechanisms that do not result in the appearance of organic matter degradation indicators. Recent observations that calcium carbonate has a higher carrying capacity for sinking organic matter than silica may be related to diatom silicification, physiological status and decomposition pathway.  相似文献   

5.
Prompted by recent data analyses suggesting that the flux of particulate organic carbon sinking into deep waters is determined by fluxes of mineral ballasts, we undertook a study of the relationships among organic matter (OM), calcium carbonate, opal, lithogenic material, and excess aluminum fluxes as part of the MedFlux project. We measured fluxes of particulate components during Spring and Summer of 2003, and Spring of 2005, using a swimmer-excluding sediment trap design capable of measuring fluxes both in a time-series (TS) mode and in a configuration for obtaining particle settling velocity (SV) profiles. On the basis of these studies, we suggest that distinct OM–ballast associations observed in particles sinking at a depth of 200 m imply that the mechanistic basis of the organic matter–ballast association is set in the upper water column above the Twilight Zone, and that the importance of different ballast types follows the seasonal succession of phytoplankton. As in other studies, carbonate appears to enhance the flux of organic matter over opal. Particles must be at least half organic matter before their settling velocity is affected by ballast concentration. This lack of change in ballast composition with SV in particles with <40% OM content suggests that particle SV reaches a maximum because of the increasing importance of inertial drag. Relative amounts of OM and opal decrease with depth due to decomposition and dissolution; carbonates and lithogenic material contribute about the same amount to total mass, or increase slightly, throughout the water column. The high proportion of excess Al cannot be explained by its incorporation into diatom opal or reverse weathering, so Al is most likely adsorbed to particulate oxides. On shorter time scales, dust appears to increase particle flux through its role in aggregation rather than by nutrient inputs enhancing productivity. We suggest that the role of dust as a catalyst in particle formation may be a central mechanism in flux formation in this region, particularly when zooplankton fecal pellet production is low.  相似文献   

6.
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   

7.
The transfer of material through the twilight zone of the ocean is controlled by sinking particles that contain organic matter (OM) and mineral ballast. During the MedFlux field program in the northwestern Mediterranean Sea in 2003, sinking particulate matter was collected in time series (TS) and settling velocity (SV) traps and analyzed for amino acids, lipids, and pigments (along with ballast minerals) [Lee, C., Armstrong, R.A., Wakeham, S.G., Peterson, M.L., Miquel, J.C., Cochran, J.K., Fowler, S.W., Hirschberg, D., Beck, A. Xue, J., 2009b. Particulate matter fluxes in time series and settling velocity sediment traps in the northwestern Mediterranean Sea. Deep-Sea Research II, this volume [doi:10.1016/j.dsr2.2008.12.003]]. The goal was to identify how organic chemical compositions of sinking particles varied as a function of their in-situ settling velocity. The TS record was used to define the biogeochemical character and temporal pattern in flux during the period of SV trap deployment. Temporal variations in organic and mineral compositions are consistent with particle biogeochemistry being driven by the seasonal succession of phytoplankton. Spring diatom bloom conditions led to a high flux of rapidly sinking aggregates and zooplankton fecal matter; summer oligotrophy followed and was characterized by a higher proportion of slowly sinking phytoplankton cells. Bacterial degradation is particularly important during the low-flux summer period. Settling velocity traps show that a large proportion of particulate organic matter sinks at 200–500 m d−1. Organic compositions of this fast-sinking material mirrors that of fecal pellets and aggregated material that sinks as the spring bloom terminates. More-slowly sinking OM bears a stronger signature of bacterial degradation than do the faster-sinking particles. The observation that compositions of SV-sorted fractions are different implies that the particle field is compositionally heterogeneous over a range of settling velocities. Thus physical and biological exchange between fast-sinking and slow-sinking particles as they pass down the water column must be incomplete.  相似文献   

8.
Four year-long time-series sediment trap experiments were conducted along the equatorial Pacific Ocean in order to understand the biogeochemistry of particulate organic matter (POM) on the basis of amino acid (AA) and hexosamine (HA) compositions of the settling particles. Total mass flux in the study area varied over 4 orders of magnitude without a common seasonality among all trap sites. Planktonic blooms were apparent in terms of total mass and AA fluxes at the easternmost end of the Niño-4 region. AA fluxes closely followed the total mass flux profiles, suggesting that increased particle flux delivered a greater amount of labile OM to the deep ocean. A labile OM index (LI)-based classification showed that during the El Niño conditions in 2002, the eastern side of the equatorial Pacific transported relatively more labile OM than the western equatorial Pacific. An overall change in AA and HA composition of settling particles could be revealed with the help of discriminant analysis, suggesting that settling particles during El Niño were compositionally different from those settling during La Niña condition in the equatorial Pacific.  相似文献   

9.
Stable carbon and nitrogen isotopic composition of zooplankton, suspended particulate organic matter (SPOM), and sinking particles collected using sediment traps were measured for samples obtained from the southeastern Bering Sea middle and outer shelf during 1997–1999. The quantity of material collected by the middle shelf sediment trap was greater in both spring and late summer and fall than in early and mid-summer. The δ15N of SPOM, sinking material and zooplankton showed greater inter-annual variability at the middle shelf site (M2) than at the outer shelf site (M3). Zooplankton and sinking organic matter collected by M2 sediment traps became more depleted in 15N from 1997 through 1999, associated with a change from unusually warm to unusually cold conditions. Suspended and sinking organic matter and zooplankton collected from M3 decreased only slightly in δ15N from 1998 to 1999. SPOM, zooplankton, and sediment trap samples collected at M2 were usually enriched in δ15N and δ13C over those from M3. However, in 1999 sediment trap samples from the middle shelf were enriched in 13C over M3 material, but the δ15N of samples from the two sites was similar. The geographic pattern could be explained greater productivity over the middle shelf, associated with either isotopically heavy nitrogen being regenerated from sediments, or with utilization of a greater fraction of the available inorganic nitrogen pool during most years.  相似文献   

10.
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   

11.
Four types of sediment traps which are different in their shapes were simultaneously deployed in Funka Bay, Hokkaido or open ocean, in order to compare the quantity and quality of settling particles collected at the same time. In Funka Bay, the larger total particulate fluxes were observed with the sediment traps having the larger height to width ratios. The settling particles collected with the narrower sediment traps were somewhat similar to suspended particle enriched in organic matter, phosphorus and Mn. These results suggest that the narrower sediment trap more effectively collects fine and light particles similar to suspended particles.  相似文献   

12.
The flux and composition of material caught using two different upper ocean sediment trap designs was compared at the Bermuda Atlantic Time-series Study site (BATS). The standard surface-tethered trap array at BATS was compared to a newly designed neutrally buoyant sediment trap (NBST). Both traps used identical cylindrical collection tubes. Of particular concern was the effect of horizontal flow on trap collection efficiency. In one experiment, mass, particulate organic carbon (POC) and particulate organic nitrogen (PON) fluxes were slightly lower (20–30%) in the NBST than in the standard BATS trap. In contrast, 234Th and fecal pellet fluxes were up to a factor of two to three lower in the NBST. In a second experiment, mass and POC fluxes decreased significantly with depth in the BATS surface-tethered trap, but not in the NBST. Different brine treatments had no measurable effect on collection efficiencies. A striking observation was that the swimmer “flux” was much larger in the standard BATS traps than in the NBST. Overall, these results show that different components of the sinking flux can be collected with differing efficiencies, depending upon how traps are deployed in the ambient environment.  相似文献   

13.
To understand the transport process of lithogenic particles in the ocean, we measured the grain size distributions of lithogenic particles and measured the opal, La, Yb, Th, and Sc concentrations of the settling particles collected from time-series sediment traps at Sta. KNOT (44°N, 155°E, water depth 5320 m) from June 2002 to May 2004. The annual mean lithogenic particle flux observed at the lower sediment trap (5100 m) was twice as high as that at the upper sediment trap (770 m). The contribution of Asian loess estimated by the La/Yb and the Th/Sc ratios in the lower layer was greater than that in the upper layer. The fluxes of small lithogenic particles with sizes of 3–4 μm at the lower layer (5 to 65 mg/m2/day) were approximately four times larger than that at the upper layer (0.6 to 27 mg/m2/day). These results indicate that the horizontal addition of small particle sizes of Asian loess is a main factor in the increase of lithogenic particles at the lower layer. The temporal variations in the small lithogenic particle flux at the lower layer had a positive correlation with those at the upper layer (r = 0.71). The small lithogenic particle fluxes showed a strong positive correlation with the opal fluxes (r = 0.9). We therefore conclude that the small lithogenic particles were laterally transported and scavenged by the formation of aggregates with opal.  相似文献   

14.
Downward fluxes of microbial assemblages associated with sinking particles sampled in sediment traps deployed at nominal depths of 1000 m (trap A), 3000 m (trap B) and 4700 m (trap C) were measured between October 1995 and August 1998 on the Porcupine Abyssal Plain (PAP, NE Atlantic). The goal of the study was to provide detailed information on the microbial contributions to the particulate organic carbon and DNA fluxes. Bacterial fluxes associated with settling particles in the PAP area were generally low and significantly lower than bacterial fluxes reported from the same area during 1989–90. Marked seasonal pulses in the microbial assemblages were observed in all years that were associated with particle flux maxima in April–June. No significant differences were found in microbial fluxes between 1000 and 4700 m depth, but both the bacterial biomass flux and the frequency of dividing bacteria increased with depth, suggesting that organic matter turnover and conversion into bacterial biomass increased in the deeper traps. The structure of microbial assemblages displayed clear changes with increasing depth; the ratios of bacteria to both flagellates and cyanobacteria increased up to 4-fold between 1000 and 4700 m, showing a marked increase in bacterial dominance in the deeper layers of the water column. A parallel increase of the bacterial contribution to particulate organic carbon (POC) and DNA fluxes was observed. Total microbial contribution to the POC flux in the PAP area was about 2%, whereas the contribution of cyanobacteria was negligible. Fluxes of microbial assemblages were significantly correlated with DNA fluxes and on average the bacteria accounted for 5% of DNA fluxes. Data reported here confirm that the “rain” of particulate bacterial DNA may represent an important source of nucleotides for deep-sea bacteria, but also suggests that a much larger pool of detrital DNA is potentially available to deep-sea micro-organisms.  相似文献   

15.
Sediment traps were deployed at 5 depths of 100 through 5,250 m to collect suspended sediments in the northern North Pacific (47°51.1'N; 176°20.6'E, 5,300 m deep) in the summer of 1978. Fatty acid composition was determined in the samples of phytoplankton, particulate matter, trap sediment and bottom sediment.Fatty acid composition of the trap sediments revealed no significant vertical trend throughout the water column from depths of 100 to 5,250 m, and were also similar to those of the phytoplankton and the particulate matter from the euphotic layer. However, a marked difference in the fatty acid composition was observed between the trap sediments and the particulate matter from deep waters. Therefore, it can be concluded that the source of fatty acids in the trap sediments is the particulate matter from the euphotic layer but not from deep waters.Unsaturated fatty acids highly susceptible to biological agents were rather abundant in the trap sediments as well as in the phytoplankton and particulate matter from the euphotic layer, however no unsaturated fatty acid was found in the particulate matter from deep waters. From these findings, it is clear that the particulate matter of the euphotic layer is transported to deep waters very rapidly. As the sinking rate of fecal pellets produced by zooplankton is in the range of ten to hundreds of meters a day, fecal pellets are assumed to be the most likely carrier of rapid-transport of organic matter including fatty acids from the euphotic layer to deep waters.  相似文献   

16.
Time-series Mark 7 sediment traps were deployed at three stations at 0°N, 13°N and 48°N along 175°E to investigate seasonal and spatial variations of particulate material flux. Chemical analysis of particulate material was performed for four major chemical components, viz. opal, CaCO3, organic material and clay minerals, Cd and P in the particulate material were also determined. We discuss the characteristics of particulate material at each site and the transportation of Cd and P to deep water by the particulate material. The total mass fluxes and variation of fluxes at each site reflect oceanographic conditions, such as biological productivity and kind of major planktonic organisms. At the northern site, large mass fluxes with a spring bloom and high ratios of opal are characteristic. Relatively small mass fluxes with high ratios of CaCO3 are distinct, and dissolution of CaCO3 due to sinking is recognized in the middle latitude and 0°N sites. The larger flux at the lower trap than the upper trap at the equatorial site suggests influence by lateral transport in the deep water. Distinctive decreasing Cd/P ratio and CaCO3 concentrations in the particulate material with increasing depth suggests that the change of Cd/P ratio in the intermediate and deep water occurs through the dissolution of CaCO3. The dissolved Cd/P ratios in the deep water are proportional to the age of the deep water in the Atlantic but not in the Pacific. This is explained by the difference of kinds of particulate material transporting Cd and P in the deep water between the oceans. That is, the major planktonic organisms are planktons of CaCO3 tests in the Atlantic Ocean and diatoms of opal tests in the North Pacific Ocean.  相似文献   

17.
在南极普里兹湾外开阔海域布放时间系列沉积物捕获器,研究沉降颗粒物中生源组分(生物硅、有机质、碳酸钙)通量、组成、来源及元素的摩尔比值的生物地球化学意义,结果表明Ⅲ-1+站在1000m处颗粒物总通量的变化为13.00~334.59mg/(d·m2),颗粒物中以生物硅为主,占总通量的80%以上;各组分通量呈现明显的季节性变化.结合罗斯海沉降颗粒物通量和元素的摩尔比值的对比研究表明,研究海域1000m深的沉降颗粒物中生物硅与有机碳元素摩尔比值、无机碳与有机碳的元素摩尔比值较高,表明研究海域生物硅与有机碳生物地球化学循环过程是非耦合的,生物活动有效地将CO2由表层水中移出.  相似文献   

18.
Sinking particulate matter were obtained from twelve depths using free-drifting sediment trap arrays which were deployed in the upper 2,000 m water column of the Izu Trench, northwest Pacific Ocean. The largest flux of 146 mgC m–2 day–1 was observed at 150 m depth. The flux generally decreased with depth below the maximum, however, minor flux peaks occurred at 1,000 and 1,250 m depth (>30 mgC m–2 day–1). Sinking large particles (>100 µm) were composed of fecal pellets typical of crustaceans, macroscopic aggregates, and planktonic organisms and their fragments. Three major components constituted 19%, 20% and 29%, respectively, of the total carbon flux (averaged from the fluxes at five depths; 50, 100, 150, 1,000 and 2,000 m). Among them, fecal pellet flux and large organism flux were well correlated with the total flux. The close correspondence between the fecal flux and the total carbon flux suggests that the latter is derived from a group of variables including other biogenic matter, among which fecal pellet is one of the leading factors controlling total flux, though the latter is only a minor covariable in quantity. Vertical flux profiles of fecal pellets and their internal constituents revealed some new inputs of feces occurring through the water column. This phenomenon implies that downward transportation of organic material is characterized by feeding and egestion activities of zooplankton, including overlapping processes of sinking and dispersion of large fecal particles and repackaging of dispersed small particles.  相似文献   

19.
Purine and pyrimidine bases in marine environmental particles collected in Harima-Nada, the Seto Inland Sea, Japan, were investigated by high performance liquid chromatography.Purines and pyrimidines concentrations varied from 0.3 to 9.3 μg l−1 (n=20) for suspended matter, and 0.3 to 0.6 mg g−1 (n=10) for sinking particles. A good correlation was found between chlorophyll a and purine+pyrimidine bases in suspended matter, indicating that these bases contained in suspended matter originated from phytoplankton.A comparison between several compositional data of the suspended matter and the sinking particles, namely CN ratio, composition of purines and pyrimidines, and percentages of the nitrogen bases relative to total particulate organic nitrogen, demonstrates that the sinking particles were different from suspended matter. Also, from the variety of purine and pyrimidine concentrations of marine particle samples, it was estimated that the decomposition rate of these bases seemed more rapid than decomposition rates of amino acids reported in our earlier study.  相似文献   

20.
The characteristics of the ratios between cadmium (Cd) and phosphorus (P) in settling particles collected from the Okinawa Trough in the East China Sea were examined using a sediment trap, moored at a depth of 811 m for one year. The Cd/P ratios varied within a narrow range throughout the year, in spite of the large seasonal change in the total dry mass, Cd, and P fluxes. The average Cd/P ratio of settling particles was 0.062 (nmol/μmol), which was obviously lower than that of surface seawater around the study site (0.16). This lower ratio in the Okinawa Trough particles collected using the 811 m-moored trap certainly reflected the mixture of biologically produced organic matter around the study site and other components that were mainly transported as lateral flux from the shelf edge and slope area of the East China Sea.  相似文献   

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