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1.
Total dissolvable metals (Co, Ni, Cu, Cd, and Pb) in both surface waters and the water columns were acquired in the southern East/Japan Sea during a cruise around the Ulleung Basin in June 2001 to understand the spatial distributions of the metals. Concentrations in offshore surface waters were found to be Co 60 ± 12 pM, Ni 2.16 ± 0.25 nM, Cu 1.85 ± 0.55 nM, Cd 0.134 ± 0.018 nM, and Pb 155 ± 40 pM. Spatial distributions in surface waters showed that metal levels were generally enhanced at coastal sites in both Korea and Japan, where the metal distributions indicated complex patterns due to inputs, biogeochemical processes, and physical factors including upwelling. The Co distributions in the water columns seemed to be influenced predominantly by surface and bottom inputs, scavenged rather than regenerated at depth. For Cd, there was generally good agreement between the Cd and PO4 depth distributions, in agreement with the literature. The Cd/PO4 ratio from the water columns was found to be 0.133–0.203, lower than that in other marginal seas (e.g. the East/South China Seas and the Philippine Sea) of the western Pacific Ocean; this might be a result of the fast ventilation rate in this sea. The vertical Pb profile showed typical scavenged-type behavior with a surface maximum and deep minimum. From a comparison of inputs from the atmosphere and the Tsushima Warm Current, atmospheric deposition is substantial enough that it cannot be ignored, and its role in metal cycling is more significant in the offshore zone.  相似文献   

2.
In order to identify the major sources of trace metals (TM) in the Portuguese coastal waters, 58 surface water samples were collected during September 1988. The area sampled extended from the Tagus Estuary (down to a salinity of 25) to cape Ste Marie on the southern coast of Portugal. Dissolved metal concentrations in the fully marine waters ranged from 30 to 250 pM for Cd, 0.7–15 nM for Cu, 0.9–20 nM for Zn and 1.8–4.5 nM for Ni. Within the Tagus Estuary (salinity 25), concentrations increased to 3400 pM for Cd, 26 nM for Cu, 14 nM for Ni and 230 nM for Zn.The large-scale distribution of these metals is dominated by two strong continental sources, both probably linked to the exploitation of pyrite ores. In the Tagus Estuary, TM enrichments can be mostly attributed to a pyrite roasting plant located on the shore in front of Lisbon. Concerning the south Portuguese shelf waters, several hypotheses are proposed to explain their elevated metal concentrations. We particularly discussed the likely influence of the Tinto/Odiel rivers located 100 km eastward, an influence well known in the shelf waters of the Gulf of Cadiz. These rivers are extremely metal-rich because of acid mine tailings originating from their catchment. Between these two regions, upwelling of relatively metal-poor water largely contributes to the dilution of the continental inputs. Indeed, water exchanges on the shelf linked to the upwelling involve water fluxes 500 times higher than the Tagus River flow, and renew the coastal waters that are thus cleaned from terrestrial contamination. Contrary to many other upwelling systems in non-contaminated areas, the Portuguese upwelling does not act as a source of trace-metal enrichment of the continental margin waters.  相似文献   

3.
南海表层水中的溶解态Cu,Pb, Zn,Cd   总被引：9，自引：0，他引：9  
于1998年“南海海洋环境调查”外业工作期间在南海的各个站位,按照严格的防沾污措施采集了106个表层海水样品.采用溶剂萃取-石墨炉原子吸收法对样品中的痕量重金属Cu,Pb,Zn,Cd含量进行了分析测试.测得各重金属的平均值如下:Cu 0.100 μg/dm3,Pb 0.060μg/dm3,Zn 0.086 μg/dm3,Cd 0.007μg/dm3,接近世界大洋水的浓度水平.各重金属的空间分布呈现出海区周边含量高于中央,浓度有自近岸向远海逐渐减小的趋势.相关分析的结果表明各重金属夏季相关性优于冬季,Cu与Cd存在良好的正相关关系,并且首次在南海表层水发现Cu,Cd与营养盐的相关关系.将重金属浓度值作数理统计分析,得到它们在南海的基线值.  相似文献   

4.
The understanding of the distribution of trace heavy metals in the world ocean has greatlyimProved in the past decades. But most of the data are of vertical profiles of certain stations(Bruland, l980; Paul et al., l992; RObert et al., l990) and large--scale study of temporaland spatial variability of trace heaVy metals in the ocean is rather few. In fact, affected by ver-tical mixing by upwelling or convection, biogenic removal, atmospheric fallout and continentalinput frorn rivers, the dist…  相似文献   

5.
- In this paper, the depth of the summer thermocline of the South Huanghai Sea and the East China Sea is calculated with two kinds of one-dimentional models, and the formation reasons are explained for the summer thermocline depth distribution characteristics in the study area. It is proved that in the shelf area of the East China Sea, tidal mixing has an important impact on the thermocline depth. And a new explanation for certain phenomena of the so-called coastal upwelling in the East China Sea is proposed.  相似文献   

6.
近些年来，夏季黄海浒苔大规模暴发，并在青岛近岸海域大面积聚集，引起了广泛的关注。本文基于在夏季和冬季所获得的多学科调查资料，重点研究了青岛近海的水文-生物地球化学过程及其生态影响，阐明了该海域物理-化学-生物等多参数之间的耦合响应。研究显示，夏季黄海冷水团的边界可扩展至青岛近岸海域，并在局部涌升至上层水体，形成沿岸上升流；该上升流可对上层营养盐产生一定的补充，进而促进浮游植物的繁殖，并于底层海域对应形成溶解氧（DO）和pH的低值。夏季青岛近海的上升流可能还有利于随南风漂移至此的浒苔的生长，并在一定程度上引起浒苔的局地旺发；同时，夏季该海域特定的锋面系统对浒苔聚集的影响也不容忽视。冬季黄海暖流在苏北浅滩外侧向山东半岛南部海域延伸，扩展至青岛近海的暖水舌与近岸低温水之间的锋面特征明显，而且在向岸暖水与近岸冷水间还对应形成了明显的营养盐和叶绿素（Chl-a）锋面。该项研究从多学科交叉的视角，增进了对青岛近海物理、化学和生物过程之间耦合关系的认识。  相似文献   

7.
The variability of the upwelling along the western coast of the Kamchatka Peninsula (northeastern part of the Sea of Okhotsk) has been studied based on an analysis of the multisensor satellite data. The intensity of upwelling is estimated on the basis of wind-forced offshore Ekman transport (upwelling index). The wind data for studying the seasonal variation of upwelling were collected in 1999–2009 using a Quik-SCAT/SeaWinds scatterometer. The upwelling events along the western Kamchatka coast were observed in December at the beginning of the winter monsoon period. During the period of strong winter monsoon northern winds from January to the middle of March, the drifting ice prevents the upwelling of the deep water at the western Kamchatka shelf edge under the mean conditions. The oceanographic data show that upwelling in the western coastal zone of Kamchatka was also observed during the transitional periods from winter to the summer monsoon (April). In summer, upwelling events are rarely observed in this region. The main cause of the summer upwelling is the propagation of the atmospheric cyclones over the Kamchatka Peninsula.  相似文献   

8.
On the basis of the data obtained from the comprehensive Kuroshio surveys in 1987-1988,this paper analyses the oceanographic characteristics in the area (125°-130° E,27°-31° N) of the continental shelf edge of the East China Sea (E. C. S. ) and its adjacent waters and discusses the effects of the Kuroshio front,thermocline and upwelling of the Kuroshio subsurface water on the distribution of standing stock of phytoplankton (chlorophyll-a). The distribution of high content of chlorophylly-a has been detected at 20-50 in depth in the water body on the left side of the Kuroshio front in the continental shelf edge waters of the E. C. S. The high content of chlorophyll-a spreads from the shelf area to the Kuroshio area in the form of a tongue and connects with the maximum layer of subsurface chlorophyll-a of the Kuroshio and pelagic sea. The author considers that the formation of the distribution of high content chlorophyll-a in this area results from the bottom topography and oceanic environment and the  相似文献   

9.
Trace element concentrations (Pb, Cd, Mn, Fe, and Zn) were measured along four surface water transects across the continental shelf off Baja California, to evaluate the magnitude of heavy metal contamination in the coastal waters along the US-Mexican boundary. These initial measurements of trace elements in Mexican neritic waters revealed offshore concentration gradients, with the highest levels in coastal waters with high salinities and nutrient concentrations. There were also longshore gradients, with lower concentrations in the southern locations. Although the relative enrichment of metals detected at nearshore stations along the US-Mexican border appeared to correspond to wastewater discharges in that area, these trace metal enhancements were found to be primarily associated with physical oceanographic processes (upwelling and advection), rather than anthropogenic inputs. This was demonstrated both by metal-nutrient correlations and multivariate statistical analyses. Mass balance calculations also indicated that about 1% of Cd, 9% of Zn, and 29% of Pb were from urban discharges within the area.  相似文献   

10.
Shelf break systems are highly dynamic environments. However little is known about the influence that benthic interactions and water mass mixing may have on vertical distributions of iron in these systems. Dissolved Fe (< 0.4 μm) concentrations were measured in samples from nine vertical profiles across the upper slope (150–2950 m water depth) at the Atlantic Ocean–Celtic Sea shelf break. Dissolved iron concentrations varied between less than 0.2 and 5.4 nM, and the resulting detailed section showed evidence of a range of processes influencing the Fe distributions. The near sea floor data were interpreted in terms of release and removal processes. The concentrations of dissolved Fe present in near seabed waters were consistent with release of Fe from in situ remineralisation of particulate organic matter at two upper slope stations, and possibly release from pore water upon resuspension on shelf. Lateral transport of dissolved iron was evident from elevated Fe concentrations in an intermediate nepheloid layer and its advection along isopycnals. Surface waters at the shelf break also showed evidence of vertical mixing of deeper iron-rich waters. These waters contained macronutrients that sustained primary productivity in these otherwise nutrient-depleted surface waters. The data also suggest some degree of stabilisation of relatively high concentrations of iron, presumably through ligand association or as colloids. This study supports the view that lateral export of dissolved iron to the interior of the ocean from shelf and coastal zones and may have important implications for the global budget of oceanic iron.  相似文献   

11.
We studied the behavior of chemical substances in the upper 300 m of the water column across the continental shelf–slope interface in the East China Sea off the Okinawa Trough. The behaviors of iron, inorganic nutrients, and humic-like fluorescent dissolved organic matter were strongly influenced by the extensive water exchange between the East China Sea and the Kuroshio Current across the shelf break and slope via upwelling and frontal processes. We attributed the high humic-like fluorescent intensity at the subsurface of the shelf break and slope regions to the lateral supply of humic-like fluorescent dissolved organic matter from the shelf sediments to the outer shelf region due to the intrusion of shelf water into Kuroshio subsurface water. We found that the behavior of iron at the continental shelf–slope was remarkably different from the conservative mixing of inorganic nutrients and humic-like fluorescent dissolved organic matter. In deep and bottom waters at the shelf–slope, high total iron concentrations, which were closely related to water transmittance, possibly resulted from the swept transport of iron-rich resuspended sediments over the shelf floor from the slope by the invading Kuroshio Intermediate Water close to the bottom.  相似文献   

12.
Dissolved and particulate trace metal concentrations (dissolved Fe, Zn, Cd, Co, Cu and Ni; particulate Fe, Mn and Al) were measured along two transects in the Ross Sea during austral summer of 1990. Total Fe concentrations in southern Ross Sea and inshore waters were elevated >3.5 times that of northern waters. Dissolved Zn, Cd and Co concentrations were lower by factors of 4.5, 3.5 and 1.6 in southern surface waters relative to northern waters. Dissolved Cu and Ni concentrations were similar in both areas. Elevated Fe concentrations coincided with areas of increased productivity, phytoplankton biomass and nutrient drawdown, indicating that Fe is an important factor controlling the location of phytoplankton blooms in the Ross Sea. Particulate concentrations of Fe, Mn and Al indicate two possible sources of iron to the Ross Sea, resuspension of continental shelf sediments and iron incorporated in annual sea ice and released with meltwaters.  相似文献   

13.
This study describes the main seasonal stages in oceanographic conditions and phytoplankton off La Coruña (Galicia, NW Spain), during 1991 and 1992, based mainly on monthly cruises near the coast. Upwelling conditions were studied using an upwelling index calculated from local winds. The Galician coast is affected by a long upwelling season for most of the year. The upwelling pulses interact with the thermal stratification-mixing cycle of surface waters, primarily affecting the dynamics of phytoplankton. In addition, the presence of water masses of different salinity in the subsurface layers changes the stratification of the water column. The less-saline North Atlantic Central Water (NACW) was normally associated with upwelling events during summer. However, on several occasions during the study, the presence of Eastern North Atlantic Water (ENAW) of subtropical origin was observed with salinities up to 36·22 and temperatures between 13 and 14 °C.Observations were grouped into five main stages related to the degree of surface stratification and characteristics of phytoplankton communities. These stages were recognized in both annual cycles, and were termed: winter mixing, spring and autumn blooms, summer upwelling, thermal stratification and special events (red tides and downwelling). A homogeneous water column was the main characteristic of the winter stage, with high nutrient concentrations and low phytoplankton biomass. Eastern North Atlantic Water appeared at the end of this stage, which lasted from November to February. The spring and autumn blooms occurred along with weak thermohaline gradients at the surface, producing high phytoplankton concentrations. Favourable upwelling conditions and the presence of ENAW in a subsurface layer were the factors that most likely induced earlier blooms, while thermal gradients developed at the surface could have been more important for later blooms. Upwelling events during summer were related to a reduction in the depth of the surface mixed layer as the pycnocline moved upwards, and can produce significant phytoplankton accumulations. These summer blooms interrupted the thermal stratification stage, characterized by low nutrient and phytoplankton concentrations at the surface. The dominant phytoplankton in the study was composed mainly of diatoms, especially during blooms. However, a proliferation of red-tide dinoflagellates was observed along with weak upwelling conditions in late summer. Also in late summer, strong downwelling conditions caused the accumulation of warmer shelf waters inshore, inducing the sinking of particulate matter produced at the surface.  相似文献   

14.
Freshwater concentrations confirm the pristine character of the Lena River environment as already pointed-out in a previous study with a limited set of data (Martin et al., 1993). Total dissolved concentrations of the freshwater are 13.8 ± 1.6 nM, Cu, 4.4 ± 0.1 nM, Ni, 0.054 ± 0.047 nM, Cd, 642 ± 208 nM, Fe, 0.2–0.3 nM Pb and 1.2 ± 1.0 nM, Zn. For Zn and Pb, a simple mixing of the Lena River waters with the Arctic waters is observed. Relationships with salinity suggest that for Cu, Ni and Cd, there is a mobilization of the dissolved fraction from the suspended matter, with an increase of the dissolved concentration of 1.5, 3 and 6 times, respectively. For Fe, the total dissolved concentrations follow an exponential decrease in the mixing zone and 80% of the total “dissolved” Fe is removed from the solution. For Cu, Ni, Cd and Fe, the riverine end-members are 20 nM, 12 nM, 0.3 nM and 47 nM, respectively. When considering the input of total dissolved metals to the Arctic Ocean, the fraction attributed to the freshwaters from the Arctic rivers appears to be small (4% of the input of dissolved metal to the Arctic Ocean for Cd, 27% for Cu, 11 % for Ni and 2% for Zn). Metal concentrations in the Laptev Sea and Arctic Ocean are very similar, indicating a generally homogeneous distribution in the areas sampled.  相似文献   

15.
The question of whether the Irish Sea is eutrophic is addressed by reviewing the evidence for anthropogenic nutrient enrichment, elevated phytoplankton production and biomass and undesirable disturbance in the context of the EU and OSPAR definitions of eutrophication. Winter concentrations of dissolved available inorganic phosphate (DAIP), nitrogen (DAIN as nitrate and nitrite) and silicate (Si) in coastal waters and concentrations of DAIP and Si in offshore waters of the Irish Sea are elevated relative to winter Celtic Sea shelf break concentrations (0.5 μM DAIP, 7.7 μM DAIN and 2.7 μM Si). Significant, negative nutrient salinity relationships and analysis of the Isle of Man nutrient time-series indicate that the elevated Irish Sea levels of DAIP and DAIN are the result of anthropogenic enrichment with highest concentrations (≈2.0 μM DAIP, 30 μM DAIN and 17 μM Si) measured in near shore eastern Irish Sea waters.  相似文献   

16.
Dissolved copper concentrations in surface waters of the Bering Sea ranged from 106 to 882 ngl–1. Higher concentrations were found in continental shelf waters. In the northwestern North Pacific dissolved copper ranged from 54 to 140 ngl–1. Particulate copper concentrations varied regionally and seasonally from 6 to 79 ngl–1. Regionally averaged particulate copper concentrations decreased from 175 to 33g g–1 against an increase in suspended materials because of the dilution effects of biological fractions. Apparent sporadic increases in copper concentrations were found in the mixing area of the Kuroshio and the Oyashio waters. The feature is attributed to the lateral distribution of different water types rather than to the upwelling of deeper waters by eddies. In the same area west of 160E, waters with high concentrations of dissolved copper (96±9 ngl–1) were found. Their origin appears to be the continental shelf of the Bering Sea. In spite of intensive biological activity, a considerable fraction of copper added to shelf waters was transported to the area off Japan via the circulation in the Bering Sea and the Oyashio current.  相似文献   

17.
A synoptic oceanographic study was conducted in August 1978 at the Middle Atlantic shelfbreak along the shelf-slope front and over the Wilmington Canyon. Four masses (surface, cold pool, shelf, and slope waters) were identified from nutrients and hydrographic variables. Also identified were two pycnocline mixing regimes; one between cold pool and slope waters across the inverted thermocline at the bottom of the cold bool protruding off the shelf, and the other directly across the summer thermocline between slope and shelf waters seaward of the cold pool. These two distinct mixing regimes appear to provide some of the common means for water exchange across the shelf-slope front. The associated mixing may be promoted by the circulation and mixing anomalies induced over canyon topographies. Physical data suggested a cyclonic flow pattern over the Wilmington Canyon, with warm slope water moving up its axis and cold pool water moving off its southwest flank. The above water masses were best identified chemically on the basis of oxygen saturation due to the high apparent photosynthesis at the shelf-slope front. This high primary productivity at the front seems linked to the cold pool and its nutrient supplies.  相似文献   

18.
海浪混合参数化的渤海、黄海、东海水动力环境数值模拟   总被引：9，自引：2，他引：9  
在浪-流耦合的概念下,对Princeton Ocean Model(POM)模式进行改进,增加特征波参数下的海浪混合作用,并把潮流和环流同时模拟,得到了渤海、黄海、东海典型的环流和水文特征,特别是夏季黄海的温跃层现象,夏季长江冲淡水扩展路径以及我国东部海域冬季和夏季典型环流等.研究表明,海浪的作用使海洋上层混合得更均匀,潮流的作用使海洋底层混合得更均匀,二者是温跃层形成的重要原因;考虑潮效应模拟流场,由于潮扩散和潮余流的作用,长江冲淡水路径与实际观测更为符合.  相似文献   

19.
Concentrations of dissolved Ni, Cu, Zn, Cd and Pb were measured in water samples collected during a cruise with R.V Pelagia (29-6/14-7-1993) in the northern North Sea and N.E. Atlantic Ocean. At least six depths (0–90 m) were sampled with modified Go-Flo samplers from a rubber zodiac. In the study area, the first 25 m were well mixed and stratification occurred below this depth. The local bloom of Emiliania huxleyi hardly affected the trace metals concentration, except for some removal of Cd as seen from its correlation with nitrate. The mean dissolved concentrations were for Ni (3.66 nM), Cu (1.61 nM), Zn (4.5 nM), Cd (48 pM) and Pb (108 pM). These concentrations are among the lowest reported for the North Sea and are of similar magnitude to those found in the eastern North Atlantic at the same latitude. Zn was the only exception with values 10 times higher compared to those in the Atlantic Ocean, suggesting external inputs, mainly atmospheric and possibly from surrounding land masses. The observed ratio Zn:Cd in the North Sea and estuaries is in between the high ratio 600–900 for continental sources and the low ratio 5–10 for oceanic waters. Latter low ratio is consistent with the 21-fold stronger inorganic complexation of Cd in seawater which, in combination with the preferential biological uptake of Zn, may lead to the observed about hundredfold fractionation of Zn versus Cd in the marine system. Other processes may play a role but would need further investigation. The dissolved Pb values tend to be lower than found before in the North Sea, indicating decreasing inventories due to reduced anthropogenic emissions.  相似文献   

20.
2009年2月(冬季)和8月(夏季)在南海北部海域(nSCS)采用流式细胞术对聚球藻、原绿球藻、超微型光合真核生物3类超微型光合浮游生物和异养浮游细菌的丰度和碳生物量的时空分布特征进行了研究,并分析了其与环境因子之间的关系。结果表明,夏季聚球藻和原绿球藻的平均丰度高于冬季,超微型光合真核生物和异养浮游细菌的丰度反之,为冬季高于夏季。聚球藻、超微型光合真核生物和异养浮游细菌在富营养的近岸陆架海域丰度较高,而原绿球藻高丰度则出现在陆坡开阔海域。在垂直分布上,聚球藻主要分布在跃层以上,跃层以下丰度迅速降低;原绿球藻高丰度主要出现在真光层底部;超微型光合真核生物在水层中的高值同样出现在真光层底部,且与Pico级份叶绿素a浓度分布一致;异养浮游细菌在水体中的分布与聚球藻类似。这些分布格局的差异,取决于环境条件的变化和4类超微型浮游生物生态生理适应性的差异。在超微型光合浮游生物群落中,各类群碳生物量的贡献因季节和海域类型的不同而发生变化:聚球藻在夏季近岸陆架区占超微型光合浮游生物总碳生物量的41%,原绿球藻在陆坡开阔海成为主要贡献者(50%),超微型光合真核生物碳生物量以冬季为高(在近岸陆架区占比68%)。冬、夏季异养浮游细菌碳生物量均高于超微型光合浮游生物碳生物量。  相似文献   

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