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81.
台湾海峡北部冬季水文特性对叶绿素a分布变化的作用 总被引：3，自引：0，他引：3
营养盐是限制浮游植物生长的主要因素之一 ,但在冬季 ,温度也是浮游植物生长繁殖的控制因素。台湾海峡北部的水文情况复杂 ,低温低盐高营养盐的沿岸水与来自台湾海峡南部的高温高盐低营养盐水相互消长［１］,必定影响海区内营养物质及温度的分布及变化 ,这势必对海区浮游植物的生长及叶绿素ａ的分布和变化起到重要的控制作用。本文根据１９９８年２月在台湾海峡北部的调查资料 ,研究了海区内重要水文特征对于叶绿素ａ分布变化的作用。１材料与方法１９９８年２月 ,福建海洋研究所与厦门大学联合在台湾海峡北部进行了综合性海洋调查。观测站… 相似文献
82.
基于STIRPAT模型,运用情景分析法对西北地区2017—2030年能源消费碳排放进行预测,在高、中、低三种环境规制强度下设定出9种发展模式,以分析环境规制与FDI对能源碳排放峰值的影响。研究表明：（1） 在初始发展情境下,西北地区2030年碳排放总量为70 273.07×104 t,无法实现碳排放达峰目标。（2） 低环境规制背景下,高、高中、高低三种发展模式2030年能源消费碳排放额为73 550.53×104 t、64 881.98×104 t、56 296.96×104 t。（3） 中、高环境规制下,中低、低两种发展模式分别于2025年、2020年达到碳排放峰值,峰值额度为53 447.15×104 t、51 022.68×104 t。能源碳排放强度为0.86 t·（104元）-1、0.68 t·（104元）-1,相比较2005年碳排放强度下降48.38%、60.14%。9种发展模式中,仅中低、低两种发展模式能够如期实现碳排放峰值任务,表明严格的环境规制政策能够有效减缓西北地区能源消费碳排放,为促进西北地区碳排放峰值目标如期实现,针对西北地区碳减排工作提出了相应对策建议。 相似文献
83.
84.
The variation of the fine-structure constant α = e
2 / ħc can be probed by comparing the wavelength of atomic transitions from the redshift of quasars in the Universe and laboratory
over cosmological time scales t ~ 1010 yr. After a careful selection of pairs of lines, the Thong method with a derived analytical expression for the error analysis
was applied to compute the α variation. We report a new constraint on the variation of the fine-structure constant based on the analysis of the CIV, NV, MgII, AlIII, and SiIV doublet absorption lines. The weighted mean value of the variation in α derived from our analysis over the redshift range 0.4939 ≤ z ≤ 3.7 is = ( 0.09 ± 0.07)×10−5. This result is three orders of magnitude better than the results obtained by earlier analysis of the same data on the constraint
on Δα/α . 相似文献
85.
Interactions between the Indonesian Throughflow and circulations in the Indian and Pacific Oceans 总被引：2，自引：0，他引：2
Circulations associated with the Indonesian Throughflow (IT), particularly concerning subsurface currents in the Pacific Ocean, are studied using three types of models: a linear, continuously stratified (LCS) model and a nonlinear, -layer model (LOM), both confined to the Indo-Pacific basin; and a global, ocean general circulation model (COCO). Solutions are wind forced, and obtained with both open and closed Indonesian passages. Layers 1-4 of LOM correspond to near-surface, thermocline, subthermocline (thermostad), and upper-intermediate (AAIW) water, respectively, and analogous layers are defined for COCO.The three models share a common dynamics. When the Indonesian passages are abruptly opened, barotropic and baroclinic waves radiate into the interiors of both oceans. The steady-state, barotropic flow field from the difference (open − closed) solution is an anticlockwise circulation around the perimeter of the southern Indian Ocean, with its meridional branches confined to the western boundaries of both oceans. In contrast, steady-state, baroclinic flows extend into the interiors of both basins, a consequence of damping of baroclinic waves by diapycnal processes (internal diffusion, upwelling and subduction, and convective overturning). Deep IT-associated currents are the subsurface parts of these baroclinic flows. In the Pacific, they tend to be directed eastward and poleward, extend throughout the basin, and are closed by upwelling in the eastern ocean and Subpolar Gyre. Smaller-scale aspects of their structure vary significantly among the models, depending on the nature of their diapycnal mixing.At the exit to the Indonesian Seas, the IT is highly surface trapped in all the models, with a prominent, deep core in the LCS model and in LOM. The separation into two cores is due to near-equatorial, eastward-flowing, subsurface currents in the Pacific Ocean, which drain layer 2 and layer 3 waters from the western ocean to supply water for the upwelling regions in the eastern ocean; indeed, depending on the strength and parameterization of vertical diffusion in the Pacific interior, the draining can be strong enough that layer 3 water flows from the Indian to Pacific Ocean. The IT in COCO lacks a significant deep core, likely because the model’s coarse bottom topography has no throughflow passage below 1000 m. Consistent with observations, water in the near-surface (deep) core comes mostly from the northern (southern) hemisphere, a consequence of the wind-driven circulation in the tropical North Pacific being mostly confined to the upper ocean; as a result, it causes the near-surface current along the New Guinea coast to retroflect eastward, but has little impact on the deeper New Guinea undercurrent.In the South Pacific, the IT-associated flow into the basin is spread roughly uniformly throughout all four layers, a consequence of downwelling processes in the Indian Ocean. The inflow first circulates around the Subtropical Gyre, and then bends northward at the Australian coast to flow to the equator within the western boundary currents. To allow for this additional, northward transport, the bifurcation latitude of the South Equatorial Current shifts southward when the Indonesian passages are open. The shift is greater at depth (layers 3 and 4), changing from about 14°S when the passages are closed to 19°S when they are open and, hence, accounting for the northward-flowing Great Barrier Reef Undercurrent in that latitude range.After flowing along the New Guinea coast, most waters in layers 1-3 bend offshore to join the North Equatorial Countercurrent, Equatorial Undercurrent, and southern Tsuchiya Jet, respectively, thereby ensuring that northern hemisphere waters contribute significantly to the IT. In contrast, much of the layer 4 water directly exits the basin via the IT, but some also flows into the subpolar North Pacific. Except for the direct layer 4 outflow, all other IT-associated waters circulate about the North Pacific before they finally enter the Indonesian Seas via the Mindanao Current. 相似文献
86.
Whereas the US President signed the Kyoto Protocol, the failure of the US Congress to ratify it seriously hampered subsequent international climate cooperation. This recent US trend, of signing environmental treaties but failing to ratify them, could thwart attempts to come to a future climate agreement. Two complementary explanations of this trend are proposed. First, the political system of the US has distinct institutional features that make it difficult for presidents to predict whether the Senate will give its advice and consent to multilateral environmental agreements (MEAs) and whether Congress will pass the required enabling legislation. Second, elected for a fixed term, US presidents might benefit politically from supporting MEAs even when knowing that legislative support is not forthcoming. Four policy implications are explored, concerning the scope for unilateral presidential action, the potential for bipartisan congressional support, the effectiveness of a treaty without the US, and the prospects for a deep, new climate treaty. Policy relevance Why does the failure of US ratification of multilateral environmental treaties occur? This article analyses the domestic political mechanisms involved in cases of failed US ratification. US non-participation in global environmental institutions often has serious ramifications. For example, it sharply limited Kyoto's effectiveness and seriously hampered international climate negotiations for years. Although at COP 17 in Durban the parties agreed to negotiate a new agreement by 2015, a new global climate treaty may well trigger a situation resembling the one President Clinton faced in 1997 when he signed Kyoto but never obtained support for it in the Senate. US failure to ratify could thwart future climate agreements. 相似文献
87.
Spatial and temporal trends of organic contaminants in sediments along the Korean coast were estimated through a nationwide environmental monitoring program from 2001 to 2007. The concentrations of organic contaminants in sediments along the Korean coast were relatively low or moderate compared with foreign studies. The mean detection frequencies of organic contaminants during the seven years were highest for PAHs and PCDD/Fs, followed by PCBs, DDTs, TBT and HCHs in decreasing order. Based on published sediment quality guidelines, the ecological risks of persistent organic pollutants in sediments along the Korean coast were low, despite exceedances of the ERL at 2-6 sites for DDTs, and the TEL at 9-18 sites for PCDD/Fs. Nonparametric tests to assess temporal trends revealed significant decreasing trends for PCBs and PCDD/Fs at four and three sites, respectively (p < 0.05). These results reflect the effects of regulations on the use of those contaminants. 相似文献
88.
Composition of the organic matter of the water,suspended matter,and bottom sediments in Nha Trang Bay in Vietnam in the South China Sea 总被引：1，自引：0，他引：1
V. I. Peresypkin A. V. Smurov N. A. Shulga E. S. Safonova T. G. Smurova Ch. V. Bang 《Oceanology》2011,51(6):959-968
Research has been conducted in Nha Trang Bay (Southern Vietnam, the South China Sea) at the section from the estuary of the
Cai River to the marine part of the bay, as well as in the area of coral reefs. The objects of the studies are the river and
sea waters, the suspended matter, and the bottom sediments. Data on the dissolved organic carbon and the total nitrogen in
the water are obtained. The organic carbon content is estimated in the suspended matter; the organic carbon and the molecular
and group composition of the n-alkanes are determined in the bottom sediments. The molecular and group composition of the n-alkanes in the bottom sediments of the landfill have made it possible to identify three types of organic matter (OM): marine,
mixed, and of mainly terrigenous origin. All the types of OM are closely related to the specificity of the sedimentation and
the hydrodynamics of the waters in this water area. 相似文献
89.
We consider n bodies (with equal mass m) disposed at the vertices of a regular n-gon and rotating rigidly around an additional mass m
0(at its center) with a constant angular velocity (relative equilibrium). In the present paper, we prove results on the existence
and on the linear stability of equilibrium positions for a zero-mass particle submitted to the gravitational field generated
by the previous system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
90.