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21.
Roles of Biogeochemical Processes in the Oceanic Carbon Cycle Described with a Simple Coupled Physical-Biogeochemical Model 总被引:1,自引:0,他引:1
Masahiko?FujiiEmail author Motoyoshi?Ikeda Yasuhiro?Yamanaka 《Journal of Oceanography》2005,61(5):803-815
To evaluate the contribution of biogeochemical processes to the oceanic carbon cycle and to calculate the ratio of calcium
carbonate to organic carbon downward export, we have incorporated biological and alkalinity pumps in the yoked high-latitude
exchange/interior diffusion-advection (YOLDA) model. The biogeochemical processes are represented by four parameters. The
values of the parameters are tuned so that the model can reproduce the observed phosphate and alkalinity distributions in
each oceanic region. The sensitivity of the model to the biogeochemical parameters shows that biological production rates
in the euphotic zone and decomposition depths of particulate matters significantly influence horizontal and vertical distributions
of biogeochemical substances. The modeled vertical fluxes of particulate organic phosphorus and calcium carbonate are converted
to vertical carbon fluxes by the biological pump and the alkalinity pump, respectively. The downward carbon flux from the
surface layer to the deep layer in the entire region is estimated to be 3.36 PgC/yr, which consists of 2.93 PgC/yr from the
biological pump and 0.43 PgC/yr from the alkalinity pump, which is consistent with previous studies. The modeled rain ratio
is higher with depth and higher in the Pacific and Indian Oceans than in the Atlantic Ocean. The global rain ratio at the
surface layer is calculated to be 0.14 to 0.15. This value lies between the lower and higher ends of the previous estimates,
which range widely from 0.05 to 0.25. This study indicates that the rain ratio is unlikely to be higher than 0.15, at least
in the surface waters. 相似文献
22.
Monthon?Ganmanee Teruyoshi?Narita Hideo?SekiguchiEmail author 《Journal of Oceanography》2004,60(6):1071-1083
Based on our long-term data from megabenthos sampling from 1993 to 2002 in Ise Bay, central Japan, we examined spatio-temporal variations in taxon composition, species richness and its distribution of megabenthos in the bay in relation to the occurrence of the oxygen-poor water (i.e. oxygen content less than 3 ppm) in bottom waters of the bay. A total of 261 species were identified including 6 cnidarians, 1 tentaculate, 5 annelids, 71 molluscs, 72 crustaceans, 16 echinoderms, 12 urochordates and 78 pisces. Of the most abundant 10 megabenthos species, the following 4 species of echinoderms made up more than the half of megabenthos biomass: Luidia quinaria, Echinocardium cordatum, Asterias amurensis and Astropecten scoparius. Species richness of megabenthos varied significantly between seasons and among stations. The severity and period of occurrence of the oxygen-poor water developing every summer play an important role in determining spatial distributions of species richness in the bay. 相似文献
23.
东海大陆架沉积物中的放射虫 总被引:5,自引:0,他引:5
利用海洋沉积物中放射虫的研究资料来判別海底地层和解决与海洋学有关的问題, 系探索海洋资源的手段之一。近年来,一些国家对世界大洋的调查研究工作进展很快,目前,除北冰洋外;几乎对各大洋的大部分海域都进行了钻探取样。其中,用放射虫沉积岩样结合地层学进行分析划带的工作已有很大进展。东海大陆架范围辽阔,资源丰富,亟待开发利用,但对其海底情况过去了解较少。为配合当前渔场调查和海底矿产资源的探测,对海底沉积物及有关方面进行调查研究是急需的。本文就东海大陆架部分地区(东经121°30′-127°,北纬26°30′-32°30′;图1)海底沉积物中的放射虫进行研究整理、以供作海洋开发的基础资料。 相似文献
24.
Organic matter origin and distribution in suspended particulate materials and surficial sediments from the western Adriatic Sea (Italy) 总被引:5,自引:2,他引:5
T. Tesi S. Miserocchi M.A. Goi L. Langone A. Boldrin M. Turchetto 《Estuarine, Coastal and Shelf Science》2007,73(3-4):431-446
In this study, organic carbon (OC), total nitrogen (TN), stable carbon isotopic (δ13COC) and CuO reaction product compositions were used to identify the sources of organic matter (OM) and to quantify the relative importance of allochthonous and autochthonous contributions to the western Adriatic Sea, Italy. Suspended particulate material (195 samples) and surficial sediments (0–1 cm, 70 samples) from shallow cross-shelf transects were collected in February and May 2003, respectively. Vertical water column profiles were acquired along the same transects. Data include depth, potential temperature, salinity, density and chlorophyll fluorimetry.Along the western Adriatic shelf in the near-shore region, the phytoplankton growth was influenced by dynamics of the buoyant plumes from the Po and Appennine rivers. A small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope. High variability in the bulk composition was detected in the Po prodelta surficial sediments, whereas the western Adriatic shelf, although a larger area, exhibited a narrower range of values.A significant decoupling was observed between suspended particles in the water column and surficial deposits. The organic material collected in the water column was compositionally heterogeneous, with contributions from marine phytoplankton, riverine–estuarine phytoplankton and soil-derived OM. Frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine OC, resulting in the observed accumulation and preservation of refractory soil-derived OC delivered by the Po and Appennine rivers. 相似文献
25.
Tatsuya?IwataEmail author Yoshiko?Shinomura Yuta?Natori Yasumasa?Igarashi Rumi?Sohrin Yoshimi?Suzuki 《Journal of Oceanography》2005,61(4):721-732
We investigated the water structure and nutrient distribution in the Suruga Bay from April 2000 to July 2002, especially the Offshore Water, which occupies a large part of the bay. The maximum salinity in the upper 200 m varied between 34.49 and 34.71, indicating a temporal change in the influence of Kuroshio Water on the Offshore Water. Seasonal variation in nutrient concentrations was largest from surface to 50 m. On the other hand, the variance in nutrient concentrations within each season was largest in the subsurface layer of 100–300 m in spring, summer and fall. In the Offshore Water, the change of nutrients was negatively correlated with that of salinity in each season. This suggests that an increasing intrusion of saline water brings about a lower nutrient concentration in the Offshore Water. Likewise, negative correlations were observed between the change of the maximum salinity and chlorophyll a (Δ [chl.a-int])/nutrients integrated in the upper 200 m. Δ[chl.a-int] was significantly correlated with the changes of nitrate and phosphorus, but there were no significant correlations between Δ[chl.a-int] and the change of silicate. These results suggest that the concentrations of chlorophyll a and nutrients in the Offshore Water were decreased due to the increasing intrusion of Kuroshio Water. The Offshore Water is likely to be related to the regulation of primary production by nitrate. 相似文献
26.
Surface waves are the roughness element of the ocean surface. The parameterization of the drag coefficient of the ocean surface is simplified by referencing to wind speed at an elevation proportional to the characteristic wavelength. The dynamic roughness is analytically related to the drag coefficient. Under the assumption of fetch limited wave growth condition, various empirical functions of the dynamic roughness can be converted to equivalent expressions for comparison. For datasets covering a wide range of the dimensionless frequency (inverse wave age), it is important to account for the variable rate of wave development at different wave ages. As a result, the dependence of the Charnock parameter on wave age is nonmonotonic. Finally, the analysis presented here suggests that the significant wave steepness is a sensitive property of the ocean surface and a single variable normalization of the dynamic roughness using a wavelength or wave height parameter actually produces more robust functions than bi-variable normalizations using wave height and wave slope. 相似文献
27.
Mohamed?IsmailEmail author Tadashi?Kimura Yumiko?Suzuki Makoto?Tsuchiya 《Journal of Oceanography》2005,61(3):631-644
Total mass flux, size distribution of sediment particles and some chemical components such as total carbon (TC), total nitrogen (TN) and calcium carbonate (CaCO3) were monitored monthly using a multi-cup sediment traps at seven coral reef sites (6 reef flat and 1 reef slope) of the Marine Protected Areas around Ishigaki, Kohama, Kuroshima and Iriomote Islands in the southern Ryukyus, Japan from September 2000 to September 2001. The size distribution of trapped sediments revealed mostly uni-modal fine sand to mud in the reef flat and gravelly to coarse sand in the reef slope. The total mass flux ranged between 0.54 to 872 gm−2d−1, and showed a pronounced seasonality (high in summer-autumn and low in spring) at each site, which was consistent with the rainfall and typhoon regime. Exceptionally high values were observed on the reef slope (Iriomote) in February–March 2001 (1533 gm−2d−1) owing to a large amount of bottom sediment re-suspension. On the reef flat (Todoroki South and North; Ishigaki), values obtained in July–August 2001 (872 gm−2d−1) and August–September 2001 (800 gm− 2d−1) indicate the high terrestrial discharge from Todoroki River. Trapped sediment particles consist of CaCO3 (1.2–27.1%) and a non-carbonate fraction (98.8–72.9%), which contains total carbon (4.9–26%), carbonate carbon (CO2-C) (0.2–3.1%) and non-carbonate carbon (NC-C) (7.9–25.6%). Total nitrogen content was in the range 0.02–0.48%. TN is contained mainly in the carbonate fraction and NC-C may be contained in the non-carbonate fraction. The low TN/OC ratio of the trapped sediments suggests that they were mostly of terrestrial origin and that both fractions migrated. The high total mass flux derived from Todoroki River exceeded the threshold at which a lethal effect on coral community is caused. The results stress the importance of conducting seasonal studies of sedimentation over more than one year and at more than one location in south Japan coral reef ecosystems to gain an understanding of the processes controlling the total mass fluxes and their nutrients content, also to develop an awareness of how to prevent the damage of coral reef ecosystems and, if it does occur, to allow mitigation measures to be undertaken. 相似文献
28.
Yoichi?ShimadaEmail author Atsushi?Kubokawa Kay?I.?Ohshima 《Journal of Oceanography》2005,61(5):913-920
Recent observations suggest that the annual mean southward transport of the East Sakhalin Current (ESC) is significantly larger
than the annual mean Sverdrup transport. Motivated by this observational result, transport of a western boundary current has
been investigated using a simple numerical model with a western slope. This transport is defined as the instantaneous barotropic
transport integrated from the western boundary to the offshore point where the barotropic velocity vanishes. The model, forced
by seasonally varying wind stress, exhibits an annual mean of the western boundary current transport that is larger than that
of the Sverdrup transport, as observed. The southward transport from October to March in the model nearly equals the instantaneous
Sverdrup transport, while the southward transport from April to September decreases slowly. Although the Sverdrup transport
in July vanishes, the southward transport in summer nearly maintains the annual mean Sverdrup transport, because the barotropic
Rossby wave cannot intrude on the western slope. This summer transport causes the larger annual mean. Although there are some
uncertainties in the estimation of the Sverdrup transport in the Sea of Okhotsk, the seasonal variation of the southward transport
in the model is qualitatively similar to the observations. 相似文献
29.
于1992年4-10月在山东省青岛市黄岛前湾育苗场和胶南市红石崖镇邵家村养殖场,采用载玻片挂片和对中国对虾现场取样的方法,研究中国对虾育苗池和养成池载玻片挂 表面和对体表微型污着生物群落的组成和发展。 相似文献
30.
Riccardo?Geletti Emanuele?LodoloEmail author Anatoly?A.?Schreider Alina?Polonia 《Marine Geophysical Researches》2005,26(1):17-28
The structural framework of the southern part of the Shackleton Fracture Zone has been investigated through the analysis of
a 130-km-long multichannel seismic reflection profile acquired orthogonally to the fracture zone near 60° S. The Shackleton
Fracture Zone is a 800-km-long, mostly rectilinear and pronounced bathymetric lineation joining the westernmost South Scotia
Ridge to southern South America south of Cape Horn, separating the western Scotia Sea plate from the Antarctic plate. Conventional
processing applied to the seismic data outlines the main structures of the Shackleton Fracture Zone, but only the use of enhanced
techniques, such as accurate velocity analyses and pre-stack depth migration, provides a good definition of the acoustic basement
and the architecture of the sedimentary sequences. In particular, a strong and mostly continuous reflector found at about
8.0 s two-way traveltime is very clear across the entire section and is interpreted as the Moho discontinuity. Data show a
complex system of troughs developed along the eastern flank of the crustal ridge, containing tilted and rotated blocks, and
the presence of a prominent listric normal fault developed within the oceanic crust. Positive flower structures developed
within the oceanic basement indicate strike-slip tectonism and partial reactivation of pre-existing faults. Present-day tectonic
activity is found mostly in correspondence to the relief, whereas fault-induced deformation is negligible across the entire
trough system. This indicates that the E–W-directed stress regime present in the Drake Passage region is mainly dissipated
along a narrow zone within the Shackleton Ridge axis. A reappraisal of all available magnetic anomaly identifications in the
western Scotia Sea and in the former Phoenix plate, in conjunction with new magnetic profiles acquired to the east of the
Shackleton Fracture Zone off the Tierra del Fuego continental margin, has allowed us to propose a simple reconstruction of
Shackleton Fracture Zone development in the general context of the Drake Passage opening. 相似文献