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1.
The annual flux of biologically produced organic carbon from surface waters is equivalent to annual net community production (NCP) at a steady state and equals the export of particulate and dissolved organic carbon (POC and DOC, respectively) to the ocean interior. NCP was estimated from carbon budgets of salinity-normalized dissolved inorganic carbon (nDIC) inventories at two time-series stations in the western subarctic (K2) and subtropical (S1) North Pacific Ocean. By using quasi-monthly biogeochemical observations from 2004 to 2013, monthly mean nDIC inventories were integrated from the surface to the annual maximum mixed layer depth and corrected for changes due to net air–sea CO2 exchange, net CaCO3 production, vertical diffusion from the upper thermocline, and horizontal advection. The annual organic carbon flux at K2 (1.49 ± 0.42 mol m?2 year?1) was lower than S1 (2.81 ± 0.53 mol m?2 year?1) (p < 0.001 based on t test). These fluxes consist of three components: vertically exported POC fluxes (K2: 1.43 mol m?2 year?1; S1: 2.49 mol m?2 year?1), vertical diffusive DOC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.25 mol m?2 year?1), and suspended POC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.07 mol m?2 year?1). The estimated POC export flux at K2 was comparable to the sum of the POC flux observed with drifting sediment traps and active carbon flux exported by migrating zooplankton. The export fluxes at both stations were higher than those reported at other time-series sites (ALOHA, the Bermuda Atlantic Time-series Study, and Ocean Station Papa).  相似文献   

2.
通过最新的高分辨率再分析海洋数据资料,对于东海黑潮以及琉球群岛以东海域的海流进行了研究。结果表明琉球群岛以东西边界流最大流速出现在600~1200 m深度的地形坡度最大处,大小约为0.2 m/s。由于冲绳岛以南庆良间水道的水交换对于东海黑潮流量有重要的影响,东海黑潮的平均流量从南向北逐渐递增,平均流量为28×106~35×106m3/s;琉球群岛以东的西边界流流量则比东海黑潮小一个量级,平均值小于其变化的方差;由于受庆良间水道海流的影响,冲绳岛东侧的流量要远小于奄美大岛东侧的流量。同一纬度大洋中西传的Rossby波对琉球群岛以东的西边界流有较大影响,因此琉球群岛以东西边界流的流量有大约100 d的显著变化周期。庆良间水道以南的东海黑潮由于主要受台湾以东黑潮流量的控制,也有大约100 d的显著变化周期,庆良间水道以北的东海黑潮则没有该特征。  相似文献   

3.
A shipboard high-resolution hydrographic survey in the subtropical region of the western North Pacific conducted from October to November 2008 detected part of a cyclonic eddy around 30°N, 145°E. This eddy had propagated westward in the region south of the Kuroshio extension for at least 6 months as a wavelike disturbance. Within this eddy, isopycnals shallowed between a depth of 600 m and just below the surface mixed layer. In addition, maximal dissolved oxygen concentrations were observed in the subsurface layer between depths of 50 and 100 m. Nitrate was depleted within this subsurface maximal oxygen layer. These results suggest that nutrients in the deeper layers were supplied into the euphotic layer as a result of the uplift of isopycnals in the eddy, fueling the photosynthesis of phytoplankton in the subsurface and emitting an excess of oxygen due to new production. Compared with the outside of the eddy, the enhancement of oxygen and the decrease of nitrate in the center of the eddy were estimated to be 2.7 mol O2 m?2 and 0.22 mol N m?2, respectively. The primary productivity calculated using the eddy transition speed of 5.1 km day?1 was 548 mg C m?2 day?1 at the center of the eddy. The enhanced primary productivity due to the passage of the eddy is likely to have an important role in the ecosystem and on material cycling in the subtropical region.  相似文献   

4.
While concern over anthropogenic marine litter around coastlines is increasing worldwide, information on this litter in trenches on the seafloor is very sparse. We investigated the amount of marine litter on the deep-sea bottom around the Ryukyu Islands in the Northwest Pacific, based on trawl samples. The density of litter observed in the axis of the Ryukyu Trench (7100 m) and in the basin of the Okinawa Trough ranged from 1.2 × 103 to 7.1 × 103 items km?2, or 7.5–121.4 kg km?2, which was significantly higher than that observed on the adjacent shallower continental slopes or abyssal plain (0.1 × 103 to 0.6 × 103 items km?2; 0.03–9.2 kg km?2). This suggests that trenches and troughs function as “depocenters” for anthropogenic litter because of their deeper and enclosed topographies.  相似文献   

5.
Using hydrographic data and moored current meter records and the ADCP observed current data during May–June 1996, a modified inverse method is applied to calculate the Kuroshio east of Taiwan and in the East China Sea and the currents east of Ryukyu Islands. There are three branches of the Kuroshio east of Taiwan. The Kuroshio in the East China Sea comes from the main (first) and second branches of the Kuroshio east of Taiwan. The easternmost (third) branch of the Kuroshio flows northeastward to the region east of Ryukyu Islands. The net northward volume transports of the Kuroshio through Section K2 southeast of Taiwan and Section PN in the East China Sea are 44.4×106 and 27.2×106 m3s−1, respectively. The western boundary current east of Ryukyu Islands comes from the easternmost branch of the Kuroshio east of Taiwan and an anticyclonic recirculating gyre more east, making volume transports of 10 to 15×106 m3s−1. At about 21°N, 127°E southeast of Taiwan, there is a cold eddy which causes branching of the Kuroshio there.  相似文献   

6.
The Arctic Ocean is connected to the Pacific by the Bering Sea and the Bering Strait. During the 4th Chinese National Arctic Research Expedition, measurements of carbon tetrachloride (CCl4) were used to estimate ventilation time-scales and anthropogenic CO2 (Cant) concentrations in the Arctic Ocean and Bering Sea based on the transit time distribution method. The profile distribution showed that there was a high-CCl4 tongue entering through the Canada Basin in the intermediate layer (27.6?<?σθ?<?28), at latitudes between 78 and 85°N, which may be related to the inflow of Atlantic water. Between stations B09 and B10, upwelling appeared to occur near the continental slope in the Bering Sea. The ventilation time scales (mean ages) for deep and bottom water in the Arctic Ocean (~?230–380 years) were shorter than in the Bering Sea (~?430–970 years). Higher mean ages show that ventilation processes are weaker in the intermediate water of the Bering Sea than in the Arctic Ocean. The mean Cant column inventory in the upper 4000 m was higher (60–82 mol m?2) in the Arctic Ocean compared to the Bering Sea (35–48 mol m?2).  相似文献   

7.
This modeling study investigates the impacts of increasing atmospheric CO2 concentration on acidification in the East Sea. A historical simulation for the past three decades (1980 to 2010) was performed using the Hadley Centre Global Environmental Model (version 2), a coupled climate model with atmospheric, terrestrial and ocean cycles. As the atmospheric CO2 concentration increased, acidification progressed in the surface waters of the marginal sea. The acidification was similar in magnitude to observations and models of acidification in the global ocean. However, in the global ocean, the acidification appears to be due to increased in-situ oceanic CO2 uptake, whereas local processes had stronger effects in the East Sea. pH was lowered by surface warming and by the influx of water with higher dissolved inorganic carbon (DIC) from the northwestern Pacific. Due to the enhanced advection of DIC, the partial pressure of CO2 increased faster than in the overlying air; consequently, the in-situ oceanic uptake of CO2 decreased.  相似文献   

8.
A total of 639 pink dentex Dentex gibbosus was collected in Canary Islands waters between April 1991 and September 1993. Total lengths ranged from 14,2 to 95,2 cm. Females dominated smaller size-classes and males the larger ones. The species was characterized by protogynous hermaphroditism. The overall ratio of males to females was 1 : 1,45. The reproductive period extended from April to September, spawning peaking in June/July. The total lengths at 50% maturity were 34,7 cm for females and 38,6 cm for males. The length-mass relationship for the whole sample can be described by the parameters a = 0,01014 and b = 3,0812. Fish aged 0–16 years were present in the samples. The parameters of the Von Bertalanffy growth equation were: L ∞ = 101,2 cm, k = 0,149·year?1, and t 0 = ?0,111 years. The rates of total mortality Z and natural mortality M were 0,57 and 0,28·year?1 respectively. Rates of fishing mortality F and exploitation E were 0,29 and 0,51·year?1 respectively. The estimated length at first capture (LC 50) was 17,8 cm total length.  相似文献   

9.
Turbulent mixing in the central equatorial Pacific has been quantitatively evaluated by analyzing data from microstructure measurements and conductivity temperature depth profiler (CTD) observations in a meridionally and vertically large region. The result that strong turbulent mixing with dissipation rate ε (>O(10?7) W kg?1), continuing from sea-surface mixed layer to low Richardson number region below, in the area within 1° of the equator, shows that turbulent mixing has a close relationship to shear instability. ε > O(10?7) W kg?1 and turbulent diffusivity K ρ  > O(10?3) m2 s?1 were obtained from near-surface to 85 db at stations even southwardly beyond 3°S, where it is already far from the southern boundary (~2°S) of the Equatorial Undercurrent. Turbulence-induced heat flux and salinity flux were calculated, and both had their maxima in the equatorial upwelling region, though the former was downward and the latter was upward. Accordingly, vertical velocity in the upwelling region was estimated to be similar to the results derived by other methods. These fluxes and the vertical velocity suggest the critical importance of turbulent mixing in maintaining the well-mixed upper layer. Secondly, in the intermediate region (>500 db), turbulent eddies were investigated by applying Thorpe’s method to the CTD data. A large number of overturns were detected, with spatial-averaged K ρ (700–1,000 db) being 3.3 × 10?6 m2 s?1, and the corresponding K ρ-max reaching to O(10?4) m2 s?1 in the north (3°–13°N). The results suggest that, in the intermediate region, considerable turbulent mixing occurs and moderates the properties of the water masses.  相似文献   

10.
根据Huang和Qiu 1995年的潜沉率计算公式,采用同化的海洋模式资料和海洋-大气界面的通量观测资料,计算了北太平洋副热带海域3个模态水形成区逐年的潜沉率,研究了潜沉率产生年际变化的机制.研究结果表明:西部、中部和东部3个模态水形成区潜沉率的年际变化主要周期分别为6,2~5和2 a;北太平洋副热带模态水的3个形成区的潜沉率都发现年代际的变化特征:在1985年以前,西部模态水形成区的潜沉率年际变化最为显著,但1985后年际变化振幅明显减小;在中部模态水形成区,1975~1992年间潜沉率随时间的变化的振幅较大,潜沉率在这段时间内的平均值也达到33.99 m/a,而在1970~1975年间和1993~1998年间潜沉率都小于20 m/a;西部副热带模态水形成区的潜沉率的年际变化与这里海面的净热通量的年际变化有很好的相关性,中部副热带模态水形成区潜沉率的年际变化则取决于局地Ekman流的年际变化,而在东部模态水形成区局地风应力旋度的变化直接影响潜沉率的大小.  相似文献   

11.
In this study, the inverse method is used to compute the Kuroshio in the East China Sea and southeast of Kyushu and the currents east of the Ryukyu Islands, on the basis of hydrographic data obtained during September-October, 1987 by R/V Chofu Maru. The results show that: (1)A part of the Taiwan Warm Current has a tendency to converge to the shelf break; (2) the Kuroshio flows across the section C3 (PN) with a reduced current width, and the velocity of the Kuroshio at the section C3 increases and its maximum current speed is about 158 cm/s, and its volume transport here is about 26×106m3/s; (3) the Kuroshio has two current cores at the sections C3 (PN) and B2 (at the Tokara Strait); (4) the currents east of the Ryukyu Islands are found to flow northward over the Ryukyu Trench during September-October, 1987. The velocities of the currents are not strong throughout the depths. At the section C2 east of the Ryukyu Islands, the maximum current speed is at the 699 m levei and its magnitude is 25 cm/s, and i  相似文献   

12.
The distribution of the fugacity of CO2 ( $ f_{{{\text{CO}}_{ 2} }} $ ) and air–sea CO2 exchange were comprehensively investigated in the outer estuary to offshore shallow water region (lying adjacent to the Sundarban mangrove forest) covering an area of ~2,000 km2 in the northern Bay of Bengal during the winter. A total of ten sampling surveys were conducted between 1 December, 2011 and 21 February, 2012. Physico-chemical variables like sea surface temperature (SST), salinity, pH, total alkalinity (TAlk), dissolved inorganic carbon (DIC) and in vivo chlorophyll-a along with atmospheric variables were measured in order to study their role in controlling the CO2 flux. Surface water $ f_{{{\text{CO}}_{ 2} }} $ ranged between 111 and 459 μatm which correlated significantly with the SST (r = 0.71, p < 0.001, n = 62). Neither DIC nor TAlk showed any linear relationship with varying salinity in the estuarine mixing zone, demonstrating the significant presence of non-carbonate alkalinity. An overall net biological control on the surface $ f_{{{\text{CO}}_{ 2} }} $ distribution was established during the study, although no significant correlation was found between chlorophyll-a and $ f_{{{\text{CO}}_{ 2} }} $ (water). The shallow water region studied was mostly under-saturated with CO2 and acted as a sink for atmospheric CO2. The difference between surface water and atmospheric $ f_{{{\text{CO}}_{ 2} }} $ ( $ \Updelta f_{{{\text{CO}}_{ 2} }} $ ) ranged from ?274 to 69 μatm, with an average seaward flux of ?10.5 ± 12.6 μmol m?2 h?1. The $ \Updelta f_{{{\text{CO}}_{ 2} }} $ and hence the air–sea CO2 exchange was primarily regulated by the variation in sea surface $ f_{{{\text{CO}}_{ 2} }} $ , since atmospheric $ f_{{{\text{CO}}_{ 2} }} $ varied over a comparatively narrow range of 361.23–399.05 μatm.  相似文献   

13.
Concentrations of dissolved methane in seawater and bottom sediments, as well as of methane emanating from gas seeps were measured at 18 stations including several small bays in the Sevastopol coastal area (Black Sea) during 2007–2008. Methane concentrations in surface waters ranged from 10 to 2,970 nmol l?1, and correlated well with values recorded for sediments. Methane concentrations in the water column were influenced by water depth, as well as by air and water temperatures. In the spring and summer of 2008, in situ CH4 saturation relative to air was in the range of 970–71,900%. Maximum saturation was in summer. CH4 fluxes to the atmosphere from the Sevastopol coastal area were estimated to vary from 190 to 1,550 μmol m?2 day?1. Gas bubbles escaping from the seepages contained about 57 vol% methane. Radiocarbon dating of the methane revealed an age not exceeding 150 years, implying a biogenic origin.  相似文献   

14.
Fast repetition rate fluorometry (FRRf) provides a potential means to examine marine primary productivity; however, FRRf-based productivity estimations require knowledge of the electron requirement (K) for carbon (C) uptake (K C) to scale an electron transfer rate (ETR) to the CO2 uptake rate. Most previous studies have derived K C from parallel measurements of ETR and CO2 uptake over relatively short incubations, with few from longer-term daily-integrated periods. Here we determined K C by comparing depth-specific, daily ETRs and CO2-uptake rates obtained from 24-h on-deck incubation experiments undertaken on seven cruises in Ariake Bay, Japan, from 2008 to 2010. The purpose of this study was to determine the extent of variability of K C and to what extent this variability could be reconciled with the prevailing environmental conditions and ultimately to develop a method for determining net primary productivity (NPP) based on FRRf measurements. Both daily ETR and K C of the upper layer varied considerably, from 0.5 to 115.7 mmol e? mg Chl-a ?1 day?1 and 4.1–26.6 mol e? (mol C)?1, respectively, throughout the entire data set. Multivariate analysis revealed a strong correlation between daily photosynthetically active radiation (PAR) and K C (r 2 = 0.94). A simple PAR-dependent relationship derived from the data set was used for generating K C, and this relationship was validated by comparing the FRRf-predicted NPP with the 13C uptake measured in 2007. These new observations demonstrate the potential application of FRRf for estimating regional NPP from ETR.  相似文献   

15.
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   

16.
《Marine Chemistry》2001,73(3-4):291-303
Oxygen and phosphate measurements from two sections across the Norwegian Atlantic Current, the Gimsøy-NW section from 67.5°N 9°E to 71.5°N 1°E and the Bjørnøya-W section along 74.5°N from 7 to 15°E, are used to estimate oxygen fluxes in the surface layer and between the atmosphere and the ocean. Vertical entrainment velocities of 0.9 m day−1 for the winter season and 0.1 m day−1 for the summer season are found and applied to the upper 300 m. The resulting oxygen fluxes to the surface layer driven by this vertical mixing are 0.58±0.05 and 0.27±0.02 mol O2 m−2 year−1 at the Gimsøy-NW and Bjørnøya-W sections, respectively. Oxygen fluxes to the surface layer due to phytoplankton production are 2.6 and 3.4 mol O2 m−2 year−1, which represent the net community production at the two sections. Estimated uncertainties in these numbers are ±15%. The surface water is a sink for atmospheric oxygen during fall and winter and a source during the productive season for both sections. On an annual basis there is a net uptake of oxygen from the atmosphere, 3.4±0.4 mol O2 m−2 year−1 at the Gimsøy-NW section and 4.9±0.5 mol O2 m−2 year−1 at the Bjørnøya-W. A decrease in temperature of 1°C to 1.5°C seen between the Gimsøy-NW section and the Bjørnøya-W section is the main reason for the increased atmospheric flux of oxygen at the latter section. An oxygen budget made for the area bounded by the two sections gives a net advective flux of oxygen out of the area of approximately 10 mol O2 m−2 year−1. The increased concentration of oxygen corresponding to the decrease in surface layer temperatures going northwards in the Norwegian Atlantic Current is mainly attributed to the air–sea oxygen exchange and phytoplankton production in this area.  相似文献   

17.
The life history of Plesionika edwardsi (Brandt, 1851) around the Canary Islands in the Eastern Central Atlantic was investigated, based on a total of 11 434 shrimps ranging in length between 8 and 40 mm carapace length (CL). The species carries out seasonal migrations; they concentrate in deep water during winter, move shallower in summer and return to deep water again in autumn. Ovigerous females occur throughout the year, but a spawning peak was determined between April and September. The size at maturity for females was approximately 26 mm CL. Shrimp size generally increased with increasing water depth. The growth parameters for males were L ∞ = 25.75 mm CL and K = 0.55 year?1, and L ∞ = 28.28 mm CL and K = 0.66·year?1 for females. The species displays the typical reproductive pattern of tropical pandalids and is dioecious.  相似文献   

18.
Data from the first systematic survey of inorganic carbon parameters on a global scale, the GEOSECS program, are compared with those collected during WOCE/JGOFS to study the changes in carbon and other geochemical properties, and anthropogenic CO2 increase in the Atlantic Ocean from the 1970s to the early 1990s. This first data-based estimate of CO2 increase over this period was accomplished by adjusting the GEOSECS data set to be consistent with recent high-quality carbon data. Multiple Linear Regression (MLR) and extended Multiple Linear Regression (eMLR) analyses to these carbon data are applied by regressing DIC with potential temperature, salinity, AOU, silica, and PO4 in three latitudinal regions for the western and eastern basins in the Atlantic Ocean. The results from MLR (and eMLR provided in parentheses) indicate that the mean anthropogenic CO2 uptake rate in the western basin is 0.70 (0.53) mol m?2 yr?1 for the region north of 15°N; 0.53 (0.36) mol m?2 yr?1 for the equatorial region between 15°N and 15°S; and 0.83 (0.35) mol m?2 yr?1 in the South Atlantic south of 15°S. For the eastern basin an estimate of 0.57 (0.45) mol m?2 yr?1 is obtained for the equatorial region, and 0.28 (0.34) mol m?2 yr?1 for the South Atlantic south of 15°S. The results of using eMLR are systematically lower than those from MLR method in the western basin. The anthropogenic CO2 increase is also estimated in the upper thermocline from salinity normalized DIC after correction for AOU along the isopycnal surfaces. For these depths the results are consistent with the CO2 uptake rates derived from both MLR and eMLR methods.  相似文献   

19.
The geochemical composition of phosphorites and phosphatic sediments in the Baja California peninsula is studied and used to assess the environment in which phosphogenesis took place. The deposits are classified in three groups: (1) stratified phosphorites, (2) phosphatic sandy sediments from beaches and dunes, and (3) submarine sediments. Some of the elements that might have substituted Ca and PO4 during francolite mineralization were studied by means of ICP-AES. Significant differences are seen in the concentration of these metals (e.g., Cr = 72-406 μg g?1 and V = 17-198 μg g?1), indicating that their concentration is not only controlled by the P2O5 concentration, but also by paleo-environmental conditions existing during francolite precipitation. Shale normalized REE patterns suggest two main environments of formation: (1) a strong negative Ce anomaly (< ? 0.3) and La enrichment (La/Nd ≥ 1) enrichment, suggesting well oxygenated shelf environments and probably lower light REE weathering, and (2) a weak negative Ce anomaly (> ? 0.3) and La depletion (La/Nd ≤ 1) suggesting shallower waters or restricted circulation and probably LREE weathering.  相似文献   

20.
We measured dissolved isoprene (2-methyl-1,3-butadiene; C5H8) concentrations in a broad area of the southern Indian Ocean and in the Indian sector of the Southern Ocean from 35°S to 64°S and from 37°E to 111°E during austral summer 2010–2011. Isoprene concentrations were continuously measured by use of a proton-transfer-reaction mass spectrometer combined with a bubbling-type equilibrator. Concentrations of isoprene and its emission flux throughout the study period ranged from 0.2 to 395 pmol L?1 and from 181 to 313 nmol m?2 day?1, respectively, the averages being generally higher than those of previous studies. Although we found a significant linear positive relationship between isoprene and chlorophyll-a concentrations (r 2 = 0.37, n = 36, P < 0.001), the correlation coefficient was lower than previously reported. In contrast, in the high-latitude area (>53°S) we identified a significant negative correlation (r 2 = 0.59, n = 1263, P < 0.001) between isoprene and the temperature-normalized partial pressure of carbon dioxide (n-pCO2), used as an indicator of net community production in this study. This suggests that residence times and factors controlling variations in isoprene and n-pCO2 are similar within a physically stable water column.  相似文献   

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