北太平洋西部和印度洋东部及其邻近海域表层水体中137Cs的分布

对北太平洋西部海域、苏禄海及印尼海、中国南海、印度洋东部海域、孟加拉湾及安达曼海等表层水体中放射性核素137Cs的活度进行了测定。结果表明,上述海域表层水体中137Cs活度显示了较大的变化范围,最低值出现在南极附近的南大洋(1.1Bqm-3),较高的活度值则出现在北太平洋西部海域及中国南海(3Bqm-3)。在所研究水域范围内,137Cs活度的纬度分布特征并没有完全有效地反映出137Cs的全球理论大气沉降趋势及其纬度效应。综合本研究及Miyake等人(1988)的测定结果,我们计算出137Cs自表层海水中的析出速率在苏禄海及印尼海约为0.016/a,在孟加拉湾及安达曼海约为0.033/a,在中国南海约为0.029/a,这一结果明显低于西北太平洋日本沿海表层水体中137Cs的析出速率。这可能是因为在这些海域,横向及纵向的水体混合过程相对都较慢,而且颗粒物对137Cs的吸附析出过程也比较弱所致。     

239, 240Pu,137Cs and90Sr in the central North Pacific

^{239, 240}Pu,¹³⁷Cs and⁹⁰Sr concentrations were determined in sea waters from the central and western North Pacific in 1980 and 1982. The results are consistent with those reported earlier for North Pacific waters. The profiles of⁹⁰Sr and¹³⁷Cs show a monotonic decrease with depth, whilst^{239, 240}Pu shows a distinct subsurface maximum at a depth between 400 and 1,000 m. The calculated inventories of these nuclides significantly exceed the global mean fallout inputs for these latitudes. This may be due to local fallout input to the ocean at times of large-scale nuclear weapon tests in the equatorial North Pacific. The existence of measurable amounts of¹³⁷Cs and^{239, 240}Pu in deep waters suggests that these nuclides are transported by sinking particulate matter from the surface to the deep ocean.     

Artificial radionuclides in the western Northwest Pacific (I)90Sr and137Cs in the deep waters

⁹⁰Sr and¹³⁷Cs concentrations and their vertical distributions were determined in deep waters in the western Northwest Pacific, including the adjacent seas of Japan, from 1976 to 1979.The profiles of the radionuclides show distribution patterns with two parts with an exponential variation of radioisotope content with depth in both parts.Generally speaking, the inventories of⁹⁰Sr and¹³⁷Cs in the open waters of the northwestern Pacific correspond fairly well to the fallout inputs, but in some circumstances there seems to be considerable removal of radionuclides from the water column or they are diluted with water of lower radioactivity from other regions.The possibility of radioisotope remobilization from the bottom sediment or particulate matter is also discussed.     

广东近岸海域表层水中^90Sr和^137Cs的分布

本文提供了1989～1991年广东近岸表层水中~(90)Sr和~(137)Cs含量的分析结果。在调查海区,~(90)Sr含量为2.31～3.75mBq/L,平均值为3.21±0.45mBq/L。~(137)Cs含量为2.10～4.49mBq/L,平均值为3.47±0.89mBq/L。~(137)Cs/~(90)Sr放射性的比值为0.63～1.69,平均值为1.11±0.35。调查结果表明,近三年来未发现广东近岸海域有明显的人工放射性污染。目前广东近岸海水中的~(90)Sr和~(137)Cs主要仍是以往核试验所产生的放射性落下灰残余。     

Strontium concentrations and strontium-chlorinity ratios in sea water of the North Pacific and the adjacent seas of Japan

Strontium contents of 232 sea water samples collected at various stations in the North Pacific and adjacent seas of Japan were measured by the atomic absorption spectrophotometry and strontium-chlorinity ratios were determined. Mean Sr concentration is 8.08 mg/kg and mean Sr/Cl ratio is 0.425 mg/kg/Contrary to some recent reports, regional and vertical variations of Sr/Cl ratios were statistically insignificant, and presence of particulate strontium was not confirmed.     

Distribution and inventories of 90Sr, 137Cs, 241Am and Pu isotopes in sediments of the Northwest Pacific Ocean

Bottom sediments collected in the Northwest (NW) Pacific Ocean in 1997 were analysed for ⁹⁰Sr, ¹³⁷Cs, ^239,240Pu and ²⁴¹Am contents to determine their distribution patterns, inventories and sources. Enhanced inventories of ^239,240Pu and ²⁴¹Am were observed in the latitudinal belts of 10–20°N and 30–40°N, which correspond to major areas of local (tropospheric) and global (stratospheric) fallout (with a contribution from local fallout), respectively. The sediment inventory of ^239,240Pu near the Bikini Atoll exceeded its overlying water inventory, however, in the mid-latitudes, more than 70% of ^239,240Pu still remains in the water column. ²⁴¹Am inventories in sediments exceeded that of the water column for the entire NW Pacific Ocean. Higher ¹³⁷Cs and ⁹⁰Sr sediment inventories in the latitudinal belt of 30–40°N are due to global fallout, and they account for about 10% and less than 5% of the water column inventories, respectively. The observed activity ratios of ¹³⁷Cs/⁹⁰Sr, ²³⁸Pu/^239,240Pu and ²⁴¹Am/^239,240Pu in sediment were at some stations higher than the global fallout ratios due to contributions from local fallout and due to specific processes in the water column. Two end-member mixing model based on the ²⁴⁰Pu/²³⁹Pu atom ratios observed in global and local fallout yielded ∼60% contribution of the local fallout in the bottom sediments near the Bikini Atoll. The upward decrease in the ²⁴⁰Pu/²³⁹Pu atom ratios in the sediment column indicates a decrease in the contribution of local fallout to the Pu inventory with time. ²⁴¹Am and ²⁴¹Pu dating of sediment layers was utilized to explain a hiatus in sediment accumulation in the deep seafloor.     

大亚湾不同介质中137Cs和90Sr的含量及行为特征

分别用ＨＰＧｅγ谱方法和放化分离β计数方法测量了大亚湾海水、沉积物和海洋生物样品的人工放射性核素＾１３７Ｃｓ和＾９０Ｓｒ。计算了海洋生物对＾１３７Ｃｓ和＾９０Ｓｒ的浓集因子及其在沉积物和海水中的分配系数,对＾１３７Ｃｓ和＾９０Ｓｒ的含量水平,＾１３７Ｃｓ和＾９０Ｓｒ及其与样品中天然放射性核素含量相关性,海洋生物对＾１３７Ｃｓ和＾９０Ｓｒ的浓集,以及＾１３７Ｃｓ和＾９０Ｓｒ的地球化学进行了讨论。     

Iron, manganese and aluminum in upper waters of the western South Pacific Ocean and its adjacent seas

Total dissolvable iron, manganese and aluminum distributions in upper waters were determined in the western South Pacific, Solomon Sea, Coral Sea, and Tasman Sea. In these oceanic regions, the surface aluminum distributions well reflect the atmospheric deposition pattern of mineral dust in the western South Pacific reported previously. Surface manganese distributions derive mainly from lateral transportation from the coastal sediments of western tropical islands. Compared to Mn and Al, the Fe distributions reflect the nutrient cycle in upper waters. Iron limitation over the vast South Pacific, as revealed by physiological features of phytoplankton, seems to be caused by low atmospheric dust deposition and low Fe:N ratios in deep waters. In the western South Pacific, with its unique geographic and oceanographic settings, the local sources of trace metals might considerably affect their biogeochemical cycles.     

Radium isotopes in coastal and open ocean surface waters of the Western North Pacific

Using manganese-impregnated fiber extraction and high-efficiency gamma counting techniques, we measured the distribution of ²²⁸Ra and ²²⁶Ra in surface waters near the coast of Japan and in the western North Pacific. There is no evidence in our data that any significant amount of ²²⁸Ra is added to open ocean surface waters from the coastal waters around Tokyo Bay. High ²²⁸Ra concentrations (> 10 dpm/10³ kg), were observed along the Kuroshio Current as compared to < 2.5 dpm/10³ kg between 10° and 30°N of the central gyre, and hence the major source of ²²⁸Ra in the surface water is likely to be the East Asian continental shelf zones. A simple one-dimensional eddy diffusion and advection model is used to explain the observed decrease of ²²⁸Ra from coast to the open ocean. The model results indicate two mixing regimes across the Kuroshio Current System with apparent eddy diffusion coefficients of K_y = 4 × 10⁵ cm² s⁻¹ at distance y < 200 km from the coast, and K_y = 4 × 10⁷ cm² s⁻¹ at y > 200 km. Along 40°N where an eastward flow of the ‘Kuroshio Extension’ prevails, an advective flow of > 0.1 knot is consistent with the observation of nearly constant ²²⁸Ra along the track.The geographical distribution pattern of ²²⁸Ra is clearly different from that of atmospherically derived ²¹⁰Pb. Thus the ²²⁸Ra in surface water serves as a useful tracer that accompanies fluvially and coastally derived elements during their subsequent lateral transport toward the central gyre.     

Zonal discrepancy of iodine in the West Pacific Ocean and its adjacent seas

The species of iodine in the water samples collected from the west Pacific Ocean and its adjacent seas were analysed. Results show that the concentration of total inorganic iodine appears higher in the south than that in the north of the Equator. The iodide concentration is distributed symmetrically on both sides of the Equator in tropic and subtropic zones and it decreases away from the Equator. Around the Antarctic Divergence iodide concentration approaches its minimum in the surface waters .which only accounts for 10% of the total iodine. The dissolved organic iodine concentration keeps constant generally either in horizontal or in vertical. Discussions on the relationships of iodine with chemical, biological and hydrological factors reveal that iodine has a transitional behavior between conservative and biodepleting elements; I/S ratio is of a certain stability on a vast scale, however, it may be largely affected by organism activity in some zones. Besides, evidence shows that iodine is adsorbed by     

Distributions of particulate and dissolved organic and inorganic phosphorus in North Pacific surface waters

Several operationally defined fractions of phosphorus (P) were measured along a surface water transect in the North Pacific. The P content in all fractions was found to increase northward from the edge of the subtropical to the subarctic region. Particulate organic P (POP) concentrations increased from 9 to 110 nmol L^− 1, whereas the particulate inorganic P (PIP) concentrations increased from 1 to 13 nmol L^− 1. A significant correlation between POP, PIP and chlorophyll a suggested that these P pools are associated directly or indirectly with phytoplankton cells. PIP comprised 10–20% of the total particulate P pool across the transect, indicating it is an important component of the marine P cycle in this region. Dissolved non-reactive P (assumed to consist predominantly of non-reactive organic P compounds, thus referred to as DOP) concentration increased from 0.10 to 0.22 μmol L^− 1, whereas soluble reactive P (SRP) concentration increased from 0.01 to 1.42 μmol L^− 1 along the transect. The proportion of DOP and SRP varied widely, with a large proportion of DOP in areas with low total dissolved P concentrations in lower latitudes and a large proportion of SRP in areas with high total dissolved P concentrations in higher latitudes. High demand for DOP in the lower latitudinal region would diminish the concentration of this pool relative to higher latitudinal regions where SRP is more abundant and would be preferentially utilized. The availability of SRP could have a significant impact on the concentration and probably on the composition of DOP. We show that P fractionation provides an important insight for discussing the marine P cycle.     

Light scattering and size distribution of particles in the surface waters of the North Pacific Ocean

The volume scattering function and size distribution of suspended particles in the surface water were determined in the North Pacific. The relationship between the scattering coefficient estimated from observed volume scattering function and cross-section concentration of the particles greater than 2.4m in diameter was found to be linear in both northern and southern regions of central North Pacific. Difference in the constant of proportionality between two regions, however, was very great. Moreover the constant in the southern region was too large compared with the values obtained by the Mie theory. This is considered to be due to the fact that particles smaller than 2.4m which were not measureable by the Coulter Counter, were neglected in the calculation of cross-section concentration. If small particles are taken into consideration, total cross-section concentration and scattering coefficient in the two regions tend to follow a linear relation. From the correlation between the scattering coefficient computed from size distribution and the volume scattering function, the refractive index of particles was estimated to be 1.03–1.05. By the same procedure, the refractive index of particles in Tateyama Harbour where the water was very turbid, was estimated to be also 1.03–1.05. This is in contrast to the result for the refractive index of particles originating from the river which flows into the harbour. This index was found to be 1.10–1.20.     

Reconstruction of sea surface dimethylsulfide in the North Pacific during 1970s to 2000s

We proposed an empirical equation of sea surface dimethylsulfide (DMS, nM) using sea surface temperature (SST, K), sea surface nitrate (SSN, μM) and latitude (L, °N) to reconstruct the sea surface flux of DMS over the North Pacific between 25°N and 55°N: ln DMS = 0.06346 · SST − 0.1210 · SSN − 14.11 · cos(L) − 6.278 (R² = 0.63, p < 0.0001). Applying our algorithm to climatological hydrographic data in the North Pacific, we reconstructed the climatological distributions of DMS and its flux between 25 °N and 55 °N. DMS generally increased eastward and northward, and DMS in the northeastern region became to 2–5 times as large as that in the southwestern region. DMS in the later half of the year was 2–4 times as large as that in the first half of the year. Moreover, applying our algorithm to hydrographic time series datasets in the western North Pacific from 1971 to 2000, we found that DMS in the last three decades has shown linear increasing trends of 0.03 ± 0.01 nM year^− 1 in the subpolar region, and 0.01 ± 0.001 nM year^− 1 in the subtropical region, indicating that the annual flux of DMS from sea to air has increased by 1.9–4.8 μmol m^− 2 year^− 1. The linear increase was consistent with the annual rate of increase of 1% of the climatological averaged flux in the western North Pacific in the last three decades.     

Numerical experiment for strontium-90 and cesium-137 in the Japan Sea

A numerical experiment is carried out to reproduce distribution of concentration of ⁹⁰Sr and ¹³⁷Cs, estimate their total amount and verify their source in the Japan Sea. Model results are in good agreement with observational findings in the Japan Sea expeditions between 1997 and 2002 by the Japan Atomic Energy Agency. Vertical profiles of the concentration of ⁹⁰Sr and ¹³⁷Cs show exponential decreases with depth from the sea surface to the sea bottom. From the model and observational results, it is suggested that the concentration of ⁹⁰Sr and ¹³⁷Cs in the surface layer is approximately in the range of 1.0–1.5 Bq/m³ and 2.0–2.5 Bq/m3, respectively. On the other hand, it is found that the concentration in the intermediate and deep layer is higher than that observed in the northwestern Pacific Ocean, suggesting active winter convection in the Japan Sea. The total amount of ⁹⁰Sr and ¹³⁷Cs in the seawater is evaluated to be 1.34 × 10¹⁵ Bq and 2.02 × 10¹⁵ Bq, respectively, in the numerical experiment, which demonstrates an estimation by observational data obtained in the Japan Sea expeditions. The total amount of ⁹⁰Sr and ¹³⁷Cs changed during the second half of 20th century corresponding to deposition at the sea surface with the maximums of 4.86 × 10¹⁵ Bq for ⁹⁰Sr and 7.33 × 10¹⁵ Bq for ¹³⁷Cs, respectively, in the mid-1960s. The numerical experiment suggests that the main source of ⁹⁰Sr and ¹³⁷Cs has been global fallout, although there have been some potential sources in the Japan Sea.     

黑潮及相邻海域表层砂壳纤毛虫分布模式:以夏季黄海、东海至西太平洋断面为例

2019年夏季对沿黄、东海至西太平洋跨越黑潮一个断面(122°E～145°E)的表层砂壳纤毛虫群落进行调查,研究了黑潮中砂壳纤毛虫与相邻水体的差异.根据水文环境及各站位所处的空间位置,我们将研究区域划分为大洋边缘区域、黑潮区域和大洋区域.各站位砂壳纤毛虫的丰度范围为3.95～31.94 ind·L–1,种丰富度范围为6...     

Influence of the White Sea on tides in adjacent marginal seas of the North European Basin

An investigation into the interaction of surface M ₂ tides in the system of marginal seas of the North European Basin is carried out using the three-dimensional finite-element hydrostatic model QUODDY-4. Three numerical experiments are performed for this purpose. In the first (control), the model equations are solved in the system of the Norwegian, Greenland, Barents, and White seas; thereby the interaction of the tides in these seas is explicitly taken into account. In the second experiment, the White Sea is excluded from consideration and the no-flux condition is posed at the entrance to the sea. The third experiment uses an approach in which the observed tidal elevations that determine the existence of a finite horizontal transport of barotropic energy to the White Sea are specified at the open boundary of the White Sea. It is shown that changes in tidal dynamics represented by changes in the amplitudes and phases of tidal elevations and in the barotropic tidal velocity ellipse parameters are within the model noise in experiments 2 and 3 when compared with the control experiment. On the contrary, changes in energy characteristics (the horizontal wave transport, density, and dissipation rate of barotropic tidal energy) are equal to or greater (in order of magnitude) than the energy characteristics themselves.     

Mesopelagic fishes of the Bering Sea and adjacent northern North Pacific Ocean

Fourteen midwater trawl collections to depths of 450 m to 1,400 m were taken at eleven stations in the Bering Sea and adjoining regions of the northern North Pacific by the R/V Hakuho Maru during the summer of 1975. A total of 29 kinds of fishes were identified. Mesopelagic fishes of the families Myctophidae, Gonostomatidae and Bathylagidae predominated in the catches, contributing 14 species (94%) of the fishes caught.Seventeen species of fishes were caught in the Bering Sea, and all of these are known from nearby areas. The mesopelagic fish fauna of the Bering Sea is similar to that in adjoining regions of the northern North Pacific Ocean: endemic species are rare or absent. Stenobrachius nannochir was usually the most common mesopelagic fish in our catches.Stenobrachius leucopsarus is a diel vertical migrant that is usually the dominant mesopelagic fish in modified Subarctic waters of the northeastern Pacific. The change in dominance fromS. nannochir in the western Bering Sea toS. leucopsarus in the eastern Bering Sea is related to differences in oceanographic conditions.     

夏季珠江口邻近海域表层浮游植物的碳叶绿素比值及其碳含量

Chlorophyll a(Chl a),particulate organic carbon(POC)and biogenic silica(BSi)were determined in coastal waters adjacent to the Zhujiang(Pearl)River Estuary(ZRE)during summer,in order to examine the C:Chl a ratio of phytoplankton and phytoplankton carbon in the plume-impacted coastal waters during summer,as well as to assess the relative contribution of diatoms to the phytoplankton biomass,by the regression between Chl a,POC and BSi.Our results showed that the C:Chl a ratio(g/g)of phytoplankton was high(up to 142),likely due to high light intensity and nutrient limitation.The river plume input stimulated phytoplankton growth,especially diatoms,resulting in higher relative contribution of phytoplankton carbon(55%)and diatoms(34%)to POC in the plume-impacted region than those(33%and 13%)in high salinity area,respectively.Phytoplankton carbon(up to 538μg/L)in the plume-impacted region was much higher than that(<166μg/L)in high salinity area.Our findings were helpful to improve the biogeochemical model in coastal waters adjacent to the ZRE.