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41.
根据2001年7月对南黄海的大面积调查,研究了南黄海夏季pCO2的分布机制,着重讨论下层海水涌升和长江冲淡水对海-气界面CO2通量的贡献,并给出了南黄海海-气界面CO2通量。研究结果表明:夏季南黄海总体上是CO2的1个弱源,大约向大气中释放45.05×104t C。夏季南黄海表层海水pCO2分布表现出了极大的不均性,其汇区主要由长江冲淡水造成,影响区域占汇区吸收CO2的99.9%;而在源区,下层海水涌升虽然面积较小却占源区释放CO2的35.2%。可见陆架边缘海区源/汇格局的地域差异非常之特别。 相似文献
42.
根据1963-1992年嵊山海洋站2月海气感热输送和22a太阳磁周期与降水的关系,提出了一个长江中下游6月降水的综合预报指标,用此指标,对1993年6月长江中下游降水进行回报,结果与实况一致。 相似文献
43.
主要根据台湾海峡的实测海流资料,以夏、冬为代表季节,分析了台湾海峡2—3个纬向断面的海流结构,计算出各断面的海水通量。结果表明:夏季,台湾海峡中、北部海域各层的海流一般偏N向流动,N向的海水净通量为3.32×106m3·s-1;冬季,高温高盐的黑潮水和南海水由南向北经南部断面进入台湾海峡,其海水通量分别为1.69×106m3·s-1和0.59×106m3·s-1;而东海水由北向南通过北部断面进入台湾海峡,其海水通量为1.02×106m3·s-1,其中,有0.40×106m3·s-1的海水沿着福建和广东近岸流进南海,其余0.62×106m3·s-1的海水在台湾海峡北部混合后随同黑潮水和南海水流入东海。总之,流经台湾海峡的N向海水净通量为1.74×106m3·s-1。 相似文献
44.
Chemical fluxes of Asian rivers into oceans bear different regional variations. Three zones are characteristic of distinct dissolved sediment loads and yields and ionic concentration.Rivers into oceans in China play an important role in Asia because of their different chemical fluxes, among which those draining the Loess Plateau have high ionic concentration, low water discharges and dissolved sediment loads and yields.Climate, vegetation, soil and strata lithology, chemical weathering intensity and tectonic activity dominate chemical fluxes of Asian rivers into oceans, and different factors have different effects on the chemical fluxes of separate regional rivers. Rising of the Tibet Plateau also exerts an important influence on chemical compositions of rivers originating from it. 相似文献
45.
In 1998, the Australian Government released Australia's Oceans Policy (AOP), a world first policy initiative focused on providing a framework for integrated ecosystem-based management of Australia's vast marine domain. The South East Regional Marine Plan, the first regional marine plan to be implemented under AOP, was released on 21 May 2004. This paper argues that although full integration across sectors and jurisdictions has not occurred, new AOP initiatives, institutions and governance processes have considerably increased sectoral and jurisdictional coordination in the South East region. 相似文献
46.
1Introduction TheIndianCentralWater (ICW) ,formedandsubductedintheSubtropicalConvergenceintheSouthIndianOcean ,occupiesasignificantportionofthethermoclineintheIndianOcean[1,2 ] (Fig .1 ) .TheSubantarcticModeWater(SAMW)isformedinthe 2 6.5-2 7.1σθrangenorthoftheSub antarcticFront—thesouthernboundaryofthesubtropicalgyres[3] .InthesoutheastIndianO cean ,theSAMWisthethickest,ventilatedasathicklayerofhighoxygenextendingtothetropicalIndianOcean[4 ,5 ] . Watermasstransformation… 相似文献
47.
Intense studies of upper and deep ocean processes were carried out in the Northwestern Indian Ocean (Arabian Sea) within the framework of JGOFS and related projects in order to improve our understanding of the marine carbon cycle and the ocean’s role as a reservoir for atmospheric CO2. The results show a pronounced monsoon-driven seasonality with enhanced organic carbon fluxes into the deep-sea during the SW Monsoon and during the early and late NE Monsoon north of 10°N. The productivity is mainly regulated by inputs of nutrients from subsurface waters into the euphotic zone via upwelling and mixed layer-deepening. Deep mixing introduces light limitation by carrying photoautotrophic organisms below the euphotic zone during the peak of the NE Monsoon. Nevertheless, deep mixing and strong upwelling during the SW Monsoon provide an ecological advantage for diatoms over other photoautotrophic organisms by increasing the silica concentrations in the euphotic zone. When silica concentrations fall below 2 μmol l−1, diatoms lose their dominance in the plankton community. During diatom-dominated blooms, the biological pathway of uptake of CO2 (the biological pump) appears to be more efficient than during blooms of other organisms, as indicated by organic carbon to carbonate carbon (rain) ratios. Due to the seasonal alternation of diatom and non-diatom dominated exports, spatial variations of the annual mean rain ratios are hardly discernible along the main JGOFS transect.Data-based estimates of the annual mean impact of the biological pump on the fCO2 in the surface water suggest that the biological pump reduces the increase of fCO2 in the surface water caused by intrusion of CO2-enriched subsurface water by 50–70%. The remaining 30 to 50% are attributed to CO2 emissions into the atmosphere. Rain ratios up to 60% higher in river-influenced areas off Pakistan and in the Bay of Bengal than in the open Arabian Sea imply that riverine silica inputs can further enhance the impact of the biological pump on the fCO2 in the surface water by supporting diatom blooms. Consequently, it is assumed that reduced river discharges caused by the damming of major rivers increase CO2 emission by lowering silica inputs to the Arabian Sea; this mechanism probably operates in other regions of the world ocean also. 相似文献
48.
利用234Th-238U不平衡研究南海东北部海域3个站位上层水体中的颗粒动力学性质,测定了水往中溶解态及颗粒态234Th的比活度,具体讨论各相中234Th/238U)AR(放射性活度比)比值的垂直分布情况及其与水化学要素间的关系。运用稿态箱式模型计算出各站位不同水层中溶解态234Th相对于清除至颗粒物的平均停留时间和颗粒态234Th相对于迁出作用的停留时间。由模型得出的参数表明3个站位的真光层具有两种不同的层化图像,这一情形与我们在南沙群岛海域得到的结果相一致。结合POC/PTh比值,估算出3个站位从真光层输出的颗粒有机碳(POC)通量分别为4.025.0和5.4mmolC·m-3-d-1。文中进一步讨论了234Th与POC两者停留时间的关系。 相似文献
49.
50.
Frdric Gazeau Stephen V. Smith Bernard Gentili Michel Frankignoulle Jean-Pierre Gattuso 《Estuarine, Coastal and Shelf Science》2004,60(4):673-694
The geomorphic, oceanographic, terrestrial and anthropogenic attributes of the European coastal zone are described and published data on ecosystem function (primary production and respiration) are reviewed. Four regions are considered: the Baltic Sea, Mediterranean Sea, Black Sea and the European Atlantic coast including the North Sea. The metabolic database (194 papers) suffers from a non-homogeneous geographical coverage with no usable data for the Black Sea which was therefore excluded from this part of our study. Pelagic gross primary production in European open shelves is, by far, the most documented parameter with an estimated mean of 41 mmol C m−2 d−1, the lowest value is reported in the Mediterranean Sea (21 mmol C m−2 d−1) and the highest one in the Atlantic/North Sea area (51 mmol C m−2 d−1). Microphytobenthic primary production, mostly measured in shallow areas, is extrapolated to the entire 0–200 m depth range. Its contribution to total primary production is low in all regions (mean: 1.5 mmol C m−2 d−1). Although macrophyte beds are very productive, a regional production estimate is not provided in this study because their geographical distribution along the European coastline remains unknown. Measurements of pelagic community respiration are clearly too sparse, especially below the euphotic zone, to yield an accurate picture of the fate of organic matter produced in the water column. With a mean value of 17 mmol C m−2 d−1, benthic community respiration consumes approximately 40% of the pelagic organic matter production. Estuaries generally exhibit high metabolic rates and a large range of variation in all parameters, except microphytobenthic primary production. Finally, the problem of eutrophication in Europe is discussed and the metabolic data obtained in the framework of the Land–Ocean Interactions in the Coastal Zone (LOICZ) project are compared with available direct measurements of net ecosystem production. 相似文献