排序方式： 共有34条查询结果，搜索用时 15 毫秒
1.
通过全球定位系统已经观测到了东亚和西太平洋的瞬时构造运动。为了这个目的，已经在这个区域建立了一个连续跟踪网络，即西太平洋GPS整体网络(WING)。从各个观测点观测到的速度来看，像太平洋和菲律宾海板块一样的大洋板块总体上作为一个刚性板块运动，而大陆板块变形强烈。通过在冲鸟岛和其他岛屿的GPS观测速度估算出菲律宾海板块的欧拉矢量。为了得出更详细的东亚速度场，许多出版的速度场数据被利用，为了使它们与普通观测点的数据一致而使用最少二乘指向。结果很清楚的表明印度大陆向欧亚大陆发生碰撞。而且证明在西藏北部速度场发生强烈的弯曲说明侵入的岩石圈向东挤出。这个碰撞的效应甚至更向东影响到韩国和日本。日本地理调查所近来建立了一个由大约1000个GPS永久观测点组成的全国性高密度观测网络。从这个网络获得的速度场清楚地描述了周围板块的运动方向。 相似文献
2.
The aim of this study is to apply a parsimonious hydrologic model to the Itxina karstic aquifer that can predict changes in discharge resulting from variable inputs (recharge). The Itxina Aquifer was divided into four cells corresponding to different recharge areas. Each cell was treated as a tank to characterize the conditions within the cell. In the model, when the reservoir boundaries coincide with the position of the siphons, the signal simulated is sensitive to input pulses of the recharge. This supports the hypothesis that the siphons are the controlling mechanism in the flow system of the aquifer. The good agreement between predicted and measured discharges demonstrates the ability of the model to simulate the flow in the Itxina Aquifer. These results demonstrated that the hydraulic conductivity increases downstream within the aquifer. The hydraulic conductivities obtained by calibration varied between 4.2 x 10(-3) m/s upstream of the aquifer, 6.0 x 10(-2) m/s in the central region, and 9.5 x 10(-1) m/s in the lower region of the aquifer. These values seem reasonable because the underground features in the principal caves show that the density of caves increases downstream in the Itxina Aquifer. The simple representation of the system produced results comparable to traditional ground water models with fewer data requirements and calibration parameters. 相似文献
3.
The effect of size and tissue parts as well as site locations on a suite of six anti-oxidative biochemical markers, viz. the enzyme degrading neural transmitters acetylcholinesterase (AChE), the Phase II transforming enzyme glutathione-S-transferase (GST), the anti-oxidative enzymes superoxide dismutase (SOD) and catalase (CAT), the lipid metabolite malondialdehyde (MDA) and the ratio of CAT/MDA, in the bivalve mollusc, Perna viridis, was studied. Field mussels were collected from the piers of University of Science and Technology (UST), Pak Sha Wan or Hebe Haven (PS) and Sai Kung (SK) in Port Shelter, Hong Kong. Statistically, ANOVA showed that the activity of all six biochemical markers were generally tissue dependent, size independent and location dependent. Tukey multi comparison test indicated that the biochemical activities fell into two groups, with SK the highest activity group in most cases. The significance of these findings in relation to long-term coastal water biomonitoring is discussed. 相似文献
4.
5.
6.
A trophic model for the Danshuei River Estuary, a hypoxic estuary in northern Taiwan 总被引：1，自引：0，他引：1
Lin HJ Shao KT Jan RQ Hsieh HL Chen CP Hsieh LY Hsiao YT 《Marine pollution bulletin》2007,54(11):1789-1800
The estuary of the Danshuei River, a hypoxic subtropical estuary, receives a high rate of untreated sewage effluent. The Ecopath with Ecosim software system was used to construct a mass-balanced trophic model for the estuary, and network analysis was used to characterize the structure and matter flow in the food web. The estuary model was comprised of 16 compartments, and the trophic levels varied from 1.0 for primary producers and detritus to 3.0 for carnivorous and piscivorous fishes. The large organic nutrient loading from the upper reaches has resulted in detritivory being more important than herbivory in the food web. The food-chain length of the estuary was relatively short when compared with other tropical/subtropical coastal systems. The shortness of food-chain length in the estuary could be attributed to the low biomass of the top predators. Consequently, the trophic efficiencies declined sharply for higher trophic levels due to low fractions of flows to the top predators and then high fractions to detritus. The low biomass of the top predators in the estuary was likely subject to over-exploitation and/or hypoxic water. Summation of individual rate measurements for primary production and respiration yielded an estimate of −1791 g WW m−2 year−1, or −95 g C m−2 year−1, suggesting a heterotrophic ecosystem, which implies that more organic matter was consumed than was produced in the estuary. 相似文献
7.
Studies at the intersection of cognitive science and linguistics have revealed the crucial role that metaphors play in shaping our thoughts about phenomena we cannot see. According to the domains interaction theory of cognition, a metaphoric expression sets up mappings between a target domain that we wish to understand and a familiar source domain. The source domain contains elements ("commonplaces") that we manipulate mentally, like parts of an analogue model, to illuminate the target domain. This paper applies the structure of domains interaction theory to analyze the dynamics of a metaphor in hydrogeology: the so-called bubble formed by water injected into an aquifer during aquifer storage and recovery (ASR). Of the four commonplaces of bubbles--(1) they are discrete; (2) they are geometrically simple; (3) they rise; and (4) they burst--we focus on the first two using both displacement and dispersion (tracer) models for both homogeneous and heterogeneous storage zones patterned from geological studies of the Suwannee Limestone of Sarasota County, Florida. The displacement model easily shows that "bottle brush" better represents the geometric complexity predicted from the known and inferred heterogeneity. There is virtually no difference, however, in the prediction of recovery efficiency using the dispersion model for a bubble (homogeneous flow zone) vs. bottle brush (heterogeneous flow zone). On the other hand, only the bottle brush reveals that unrecovered tracer is located preferentially in the low-permeability layers that lie adjacent to high-permeability channels in the flow zones. 相似文献
8.
本文所描述的是关于顶底均被低渗透岩石包围的高渗透性岩石以达西流动方式来散失异常压力的一种改进的分析解。该分析解延续了前人所提出的分析解中的两个端元：（1）厚的箱体和薄的遮挡层，（2）厚的遮挡层和薄的箱体。文中还论述了分析油气藏时考虑流体可压缩性的重要性。在该领域中，以前的研究者们均只考虑了岩石可压缩性的影响，而忽略了流体的可压缩性。
在一般的油气藏规模上的异常压力箱以及盆地规模上的异常高压区中，我们均使用了该分析解。结果显示，一个典型的油气藏压力箱的压力梯度能够在几小时或几天的时间内恢复到流体的静态压力梯度，而异常压力却可能需要超过几万年至几十万年的时间才能够散失掉。因此，任何具有与相邻油气藏不同压力的储集箱在开发时都可以被看作是一个独立的单元。然而，盆地级别的异常压力则需要几千万年或几亿年才能够散失掉。所以，在解释地质时期中所存在的异常压力时，并没有必要引入零渗透率封隔层或毛细管压力封隔层等概念。 相似文献
9.
The coral reef at Kahekili, Maui is located ~300 m south of the Lahaina Wastewater Reclamation Facility which uses four Class V injection wells to dispose of 3-5 million gallons of wastewater effluent daily. Prior research documented that the wastewater effluent percolates into the nearshore region of Kahekili. To determine if the wastewater effluent was detectable in the surface waters offshore, we used algal bioassays from the nearshore region to 100 m offshore and throughout the water column from the surface to the benthos. These algal bioassays documented that significantly more wastewater effluent was detected in the surface rather than the benthic waters and allowed us to generate a three-dimensional model of the wastewater plume in the Kahekili coastal region. Samples located over freshwater seeps had the highest δ(15)N values (~30-35‰) and the effluent was detected in surface samples 500 m south and 100 m offshore of the freshwater seeps (~8-11‰). 相似文献
10.