The Development of Anoxia in the Artificial Lake Shihwa, Korea, as a Consequence of Intertidal Reclamation     

Myung Woo Han  Yong Chul Park 《Marine pollution bulletin》1999,38(12):187-1199

The reclamation of an intertidal flat recently created Lake Shihwa, in Kyunggi province, on the western coast of Korea. The artificial, saline lake was expected to transform into a freshwater one. However, the drainage structure of the lake does not allow entrapped Yellow Sea water to be fully replaced by freshwater from its hinterland. The lake water is strongly stratified with polluted freshwater at the surface and entrapped, saline water on the bottom. The pycnocline, lying at a depth range of 6–8 m, prevents mixing between the two water bodies, and thus generates anoxic conditions in the deeper waters. The pycnocline matches the oxic/anoxic interface between the oxygenated surface water and the hydrogen sulphide rich deep water. Stratification, the inflow of polluted water, and anoxia all contribute to the disastrous pollution of the lake.  相似文献   

Developing an Event Tree for probabilistic hazard and risk assessment at Vesuvius     

A. Neri  W.P. Aspinall  R. Cioni  A. Bertagnini  P.J. Baxter  G. Zuccaro  D. Andronico  S. Barsotti  P.D. Cole  T. Esposti Ongaro  T.K. Hincks  G. Macedonio  P. Papale  M. Rosi  R. Santacroce  G. Woo 《Journal of Volcanology and Geothermal Research》2008

Probabilistic characterizations of possible future eruptive scenarios at Vesuvius volcano are elaborated and organized within a risk-based framework. In the EXPLORIS project, a wide variety of topics relating to this basic problem have been pursued: updates of historical data, reinterpretation of previous geological field data and the collection of new fieldwork results, the development of novel numerical modelling codes and of risk assessment techniques have all been completed. To achieve coherence, many diverse strands of evidence had to be unified within a formalised structure, and linked together by expert knowledge. For this purpose, a Vesuvius ‘Event Tree’ (ET) was created to summarise in a numerical-graphical form, at different levels of detail, all the relative likelihoods relating to the genesis and style of eruption, development and nature of volcanic hazards, and the probabilities of occurrence of different volcanic risks in the next eruption crisis. The Event Tree formulation provides a logical pathway connecting generic probabilistic hazard assessment to quantitative risk evaluation. In order to achieve a complete parameterization for this all-inclusive approach, exhaustive hazard and risk models were needed, quantified with comprehensive uncertainty distributions for all factors involved, rather than simple ‘best-estimate’ or nominal values. Thus, a structured expert elicitation procedure was implemented to complement more traditional data analysis and interpretative approaches. The structure of the Vesuvius Event Tree is presented, and some of the data analysis findings and elicitation outcomes that have provided initial indicative probability distributions to be associated with each of its branches are summarized. The Event Tree extends from initiating volcanic eruption events and hazards right through to human impact and infrastructure consequences, with the complete tree and its parameterisation forming a quantitative synoptic framework for comprehensive hazard evaluation and mapping of risk impacts. The organization of the Event Tree allows easy updating, as and when new information becomes available.  相似文献   

Seismic reliability assessment of lifeline networks using clustering‐based multi‐scale approach          下载免费PDF全文

Hyun‐Woo Lim  Junho Song  Nolan Kurtz 《地震工程与结构动力学》2015,44(3):355-369

Seismic reliability assessment of lifeline networks gives rise to various technical challenges, which are mostly caused by a large number of network components, complex network topology, and statistical dependence between component failures. For effective risk assessment and probabilistic inference based on post‐hazard observations, various non‐simulation‐based algorithms have been developed, including the selective recursive decomposition algorithm (S‐RDA). To facilitate the application of such an algorithm to large networks, a new multi‐scale approach is developed in this paper. Using spectral clustering algorithms, a network is first divided into an adequate number of clusters such that the number of inter‐cluster links is minimized while the number of the nodes in each cluster remains reasonably large. The connectivity around the identified clusters is represented by super‐links. The reduced size of the simplified network enables the S‐RDA algorithm to perform the network risk assessment efficiently. When the simplified network is still large even after a clustering, additional levels of clustering can be introduced to have a hierarchical modeling structure. The efficiency and effectiveness of the proposed multi‐scale approach are demonstrated successfully by numerical examples of a hypothetical network, a gas transmission pipeline network, and a water transmission network. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Spatiotemporal Distribution of Dissolved Heavy Metals in Gyeonggi Bay,Korea     

Sojung Park  Mansik Choi  Dongjun Jang  Dongjin Joe  Kyunggue Park  Hyojin Lee  Junsik Woo  Taeha Kim  Jongkyu Park 《Ocean Science Journal》2020,55(1):69-84

In this study, we investigated the spatial and temporal distribution of heavy metals and nutrients in Gyeonggi Bay, Korea, to determine their present statu  相似文献   

Harmful Dinoflagellate Prorocentrum donghaiense Lu is Widely Distributed Along the East China Sea and Korean Coastal Area     

Shin  Hyeon Ho  Li  Zhun  Seo  Min Ho  Soh  Ho Young  Lim  Weol Ae  Park  Jong Woo 《Ocean Science Journal》2019,54(4):685-691

Ocean Science Journal - There have been controversies regarding the taxonomy of Prorocentrum donghaiense, however Zhang et al. (2016) recently developed a probe with a quantitative real-time PCR...  相似文献   

Spatial scales of mesoscale eddies from GOCI Chlorophyll-a concentration images in the East/Japan Sea   总被引：2，自引：0，他引：2  

Kyung-Ae Park  Hye-Jin Woo  Joo-Hyung Ryu 《Ocean Science Journal》2012,47(3):347-358

The spatial scales of mesoscale eddies are of importance to understand physio-biogeochemical processes in the East/Japan Sea. Chlorophyll-a concentration images from the Geostationary Ocean Color Imager (GOCI) revealed numerous eddies during the phytoplankton bloom in spring. These eddies were manually digitized to obtain geolocation information at the peripheries from GOCI images and then least-square fitted to each ellipse. The elliptic elements were the geolocation position of the eddy center, the rotation angle from due east, the eccentricity, the lengths of the semi-major and semi-minor axes, and the mean radius of the ellipse. The spatial scales of eddies had a mean radii ranging from 10 km to 75 km and tended to be smaller in the northern region. The scales revealed a linear trend of about ?7.26 km/°N as a function of the latitude. This tendency depended on the latitudinal variation of the internal Rossby radius of deformation, which originates from the substantial difference in the density structure of the water column. The scales from the sea surface temperature image were larger by 1.30 times compared to those from ocean color image. This implies that physical processes along the periphery of the eddy affect the nutrient dynamics.  相似文献   

Bioremediation of contaminated coastal sediment: Optimization of slow release biostimulant ball using response surface methodology (RSM) and stabilization of metals from contaminated sediment     

Bakthavachallam Subha  Young Chae Song  Jung Hui Woo 《Marine pollution bulletin》2017,114(1):285-295

The aim of the present study is to optimize the slow release biostimulant ball (BSB) for bioremediation of contaminated coastal sediment using response surface methodology (RSM). Metals contamination and stabilization of metals in coastal sediments using BSB were investigated. The effects of BSB size (1–5 cm), distance (1–10 cm), and time (1–4 months) on the stabilization of metals including Fe, Cd, Cu, and Pb were determined. The maximum stabilization percentages of Fe, Cd, Cu, and Pb, of 64.5%, 54.9%, 63.8%, and 47.6%, respectively, were observed at a 3 cm ball size, 5.5 cm distance, and a period of 4 months; these values are the optimum conditions for effective treatment of contaminated coastal sediment. The determination coefficient of the R² value suggests that > 91.55%, 89.97%, 96.10%, and 86.40% of the variance is attributable to the variables of Fe, Cd, Cu, and Pb, respectively.  相似文献   

Evaluation of ICA and CEM algorithms with Landsat-8/ASTER data for geological mapping in inaccessible regions     

Amin Beiranvand Pour  Yongcheol Park  Tae-Yoon S. Park  Jong Kuk Hong  Mazlan Hashim  Jusun Woo 《国际地球制图》2019,34(7):785-816

Many regions remain poorly studied in terms of geological mapping and mineral exploration in inaccessible regions especially in the Arctic and Antarctica due to harsh conditions and logistic difficulties. Application of specialized image processing techniques is capable of revealing the hidden linear mixing spectra in multispectral and hyperspectral satellite images. In this study, the applications of Independent component analysis (ICA) and Constrained Energy Minimization (CEM) algorithms were evaluated for Landsat-8 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data for geological mapping in Morozumi Range and Helliwell Hills areas, Northern Victoria Land (NVL), Antarctica. The results of this investigation demonstrate the capability of the two algorithms in distinguishing pixel and subpixel targets in the multispectral satellite data. The application of the methods for identifying poorly exposed geologic materials and subpixel exposures of alteration minerals has invaluable implications for geological mapping and mineral exploration in inaccessible regions.  相似文献   

Connection between weak stratospheric vortex events and the Pacific Decadal Oscillation     

Sung-Ho Woo  Mi-Kyung Sung  Seok-Woo Son  Jong-Seong Kug 《Climate Dynamics》2015,44(11-12):3481-3491

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Does sea-level rise have an impact on saltwater intrusion?     

Sun Woo ChangT. Prabhakar Clement  Matthew J. SimpsonKang-Kun Lee 《Advances in water resources》2011,34(10):1283-1291

Climate change effects are expected to substantially raise the average sea level. It is widely assumed that this raise will have a severe adverse impact on saltwater intrusion processes in coastal aquifers. In this study we hypothesize that a natural mechanism, identified here as the “lifting process,” has the potential to mitigate, or in some cases completely reverse, the adverse intrusion effects induced by sea-level rise. A detailed numerical study using the MODFLOW-family computer code SEAWAT was completed to test this hypothesis and to understand the effects of this lifting process in both confined and unconfined systems. Our conceptual simulation results show that if the ambient recharge remains constant, the sea-level rise will have no long-term impact (i.e., it will not affect the steady-state salt wedge) on confined aquifers. Our transient confined-flow simulations show a self-reversal mechanism where the wedge which will initially intrude into the formation due to the sea-level rise would be naturally driven back to the original position. In unconfined systems, the lifting process would have a lesser influence due to changes in the value of effective transmissivity. A detailed sensitivity analysis was also completed to understand the sensitivity of this self-reversal effect to various aquifer parameters.  相似文献