Spatial phase structure of low-latitude Pc3–4 pulsations     

O. Saka  J.S. Kim 《Planetary and Space Science》1985,33(9):1073-1079

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Effects of Laboratory Consolidation on Petrophysical Properties of Fine-Grained Marine Sediments: Electron Microscopic Observations     

Jin-Wook Kim  Yir-Der E. Lee  Thomas T. Tieh  William R. Bryant 《Marine Georesources & Geotechnology》2000,18(4):347-360

Pliocene-Recent marine sediments, recovered at site 1125 by ODP Leg 181 on the eastern New Zealand margin, were subjected to laboratory consolidation tests and analyzed by scanning electron microscopy (SEM) before and after consolidation test. The primary objective of this study is to document the effects of consolidation on microfabric and petrophysical properties. X-ray diffraction and grain-size distribution data indicate that the samples are mineralogically and texturally similar and thus are ideal for the present study on the role of consolidation solely on petrophysical properties. Porosity was measured before and after each consolidation test, and permeability was estimated indirectly based on the theoretical method. SEM photomicrographs show details of changes of pore geometry and distribution after the consolidation test that account for the porosity loss.  相似文献   

Non-parametric simulations-based conditional stochastic predictions of geologic heterogeneities and leakage potentials for hypothetical CO2 sequestration sites     

Weon Shik Han  Kue-Young Kim  Sungwook Choung  Jina Jeong  Na-Hyun Jung  Eungyu Park 《Environmental Earth Sciences》2014,71(6):2739-2752

The present study focuses on understanding the leakage potentials of the stored supercritical CO₂ plume through caprocks generated in geostatistically created heterogeneous media. For this purpose, two hypothetical cases with different geostatistical features were developed, and two conditional geostatistical simulation models (i.e., sequential indicator simulation or SISIM and generalized coupled Markov chain or GCMC) were applied for the stochastic characterizations of the heterogeneities. Then, predictive CO₂ plume migration simulations based on stochastic realizations were performed and summarized. In the geostatistical simulations, the results from the GCMC model showed better performance than those of the SISIM model for the strongly non-stationary case, while SISIM models showed reasonable performance for the weakly non-stationary case in terms of low-permeability lenses characterization. In the subsequent predictive simulations of CO₂ plume migration, the observations in the geostatistical simulations were confirmed and the GCMC-based predictions showed underestimations in CO₂ leakage in the stationary case, while the SISIM-based predictions showed considerable overestimations in the non-stationary case. The overall results suggest that: (1) proper characterization of low-permeability layering is significantly important in the prediction of CO₂ plume behavior, especially for the leakage potential of CO₂ and (2) appropriate geostatistical techniques must be selectively employed considering the degree of stationarity of the targeting fields to minimize the uncertainties in the predictions.  相似文献   

Application of electrical resistivity tomography (ERT) technique to detect underground cavities in a karst area of South Korea   总被引：1，自引：1，他引：0  

Mi Kyung Park  Samgyu Park  Myeong-Jong Yi  Changryol Kim  Jung-Sul Son  Jung-Ho Kim  Adepelumi Adekunle Abraham 《Environmental Earth Sciences》2014,71(6):2797-2806

Recently, the electrical resistivity tomography (ERT) technique has been increasingly applied to underground cavity detection filled with groundwater and/or clay. In this study, an ERT survey was conducted to examine the spatial distribution and shape of underground cavities in a karst area in Korea. Numerical ERT modeling and inversion were carried out to select appropriate field survey parameters. Two geological structures, similar to those that exist in the field survey area, were modeled: a sinkhole model and a vein-type structure. Electrode configurations using pole–pole, pole–dipole, dipole–pole, and dipole–dipole arrays were tested with the two geologic models and compared. The numerical modeling showed that the resistivity distribution of the ERT tomogram using the pole–dipole array produced the best representation of the two models. The pole–dipole and pole–pole array configurations were applied in an ERT field survey using six boreholes. The field ERT results show that cavity areas filled with clay or groundwater appeared as low-resistivity anomalies in the limestone formation. This was particularly evident in the inclined vein-type structures attributed to fracture zones, where the field data were similar to the modeling results. Therefore, the ERT technique could be effectively used for detecting underground limestone cavities under similar geological conditions as those at our study area.  相似文献   

The occurrence of cyanobacteria and microcystins in the Hoan Kiem Lake and the Nui Coc reservoir (North Vietnam)     

Thi Thuy Duong  Sabine Jähnichen  Thi Phuong Quynh Le  Cuong Tu Ho  Trung Kien Hoang  Trung Kien Nguyen  Thi Nguyet Vu  Dinh Kim Dang 《Environmental Earth Sciences》2014,71(5):2419-2427

The occurrence of increasing blooms of toxic cyanobacteria in freshwaters has received much attention due to the ability of many cyanobacteria to produce potent cyanotoxins. In this paper, the occurrence of dominant cyanobacteria and the concentration of microcystins (MCs) analysis were investigated monthly from July 2008 to April 2009 in the Hoan Kiem Lake and from February to April 2009 in the Nui Coc reservoir. Concentrations of intracellular MCs from water, bloom samples, and isolated strains were quantified by using high performance liquid chromatography (HPLC). During the study period, the microscopic examination of the phytoplankton samples showed the dominance of the genus Microcystis in the water environment of the Hoan Kiem Lake and the Nui Coc reservoir. The toxin analysis by HPLC demonstrated the presence of two MC variants: MC-LR and MC-RR in water samples. Total concentrations of the toxins in filtered samples from surface water ranged from non-detected to 0.91 μg L^?1 at Nui Coc reservoir and they ranged from 2.1 to 46.0 μg L^?1 at Hoan Kiem Lake. The results of the HPLC analysis confirmed the production of MCs in bloom samples (ranged from 115.9 to 184.6 μg L^?1 in the Hoan Kiem Lake and from 726.5 to 1116 μg L^?1 in the Nui Coc reservoir) and isolated strains of Anabaena sp. and Microcystis with the concentration of MC ranging from 152 to 396.2 μg g^?1 dry mass, respectively.  相似文献   

Runoff characteristics of non-point pollutants caused by different land uses and a spatial overlay analysis with spatial distribution of industrial cluster: a case study of the Lake Sihwa watershed     

Sea-Won Kim  Joon-Seok Park  Daeik Kim  Jong-Min Oh 《Environmental Earth Sciences》2014,71(1):483-496

To characterize a runoff pattern of non-point pollutants in relation with different land uses in a watershed, a monitoring activity and field measurements were carried out and data points were recorded during the rainfall events for 2 years. The study area includes industrial, urban, and rural sectors, which can represent a model case for the runoff study. Each sector was monitored with methodology and parameters including partial event mean concentration, first flush effect, mass first flush ratios, and correlation analysis. The Banwol Industrial Outfall No. 4 (4TG), an industrial area, showed a strong first flush effect, indicating that pollutants such as suspended solids, chemical oxygen demand, total nitrogen, and total phosphorus, were discharged at the early stage of a storm. An MFF₃₀ analysis of the runoff revealed a mean pollutant load was over 50 %. In the Ansan Stream, an urban area, a strong first flush effect did not appear; however, the concentrations of pollutants reached a peak some time later during a storm event. Then, the concentrations of pollutants quickly reduced. On the other hand, Jangjunbo and Munsan Stream, rural areas, did not exhibit the first flush effects, and when considering the value of MFF₃₀, 30 % or fewer pollutants on average were discharged at the initial stage of a storm. This means most of pollutants were streamed out at the later time of a storm event. The monitoring results found that the runoff characteristics of non-point pollutants in industrial, urban, and rural areas were distinctly different and site-specific. Therefore, each watershed management plan should be prepared to meet its own characteristics. Also, this kind of data can be an important base in designing and sizing a regional wastewater treatment facility to treat pollutants from a contaminated watershed.  相似文献   

Development of a CO2 emission factor in Korea from sub-bituminous coal by the classification method     

Seungjin Kim  Jeongwoo Lee  Seehyung Lee  Chang-Sang Cho  Jae-Hwan Sa  Eui-Chan Jeon 《Environmental Earth Sciences》2014,72(7):2325-2332

While the Intergovernmental Panel on Climate Change classifies coal as anthracite, bituminous coal, and sub-bituminous coal, Korea only distinguishes coal as anthracite and bituminous coal while sub-bituminous coal is considered bituminous coal. As a result, Korea conducted research in the CO₂ emission factors of anthracite and bituminous coal, but largely ignored sub-bituminous coal. Therefore, the purpose of this research is to develop the CO₂ emission factor of sub-bituminous coal by classifying sub-bituminous coal from resources of bituminous coal activities collected in Korea between 2007 and 2011. The 2007–2011 average carbon content of sub-bituminous coal was analyzed to be 69.63 ± 3.11 %, the average hydrogen content 4.97 ± 0.37 %, the inherent moisture 12.60 ± 4.33 %, the total moisture 21.91 ± 5.45 %, and the dry-based gross calorific value was analyzed to be 5,914 ± 391 kcal/kg; using these analyzed values, the as-received net calorific value was found to be 20.75 ± 7.59 TJ/Gg and the CO₂ emission factor was found to be 96,241 ± 4,064 kg/TJ. In addition, the 62.7 million ton amount for the 2009 greenhouse gas emission from sub-bituminous coal as estimated with the analyzed value of this study is an amount that is equivalent to 11.1 % of the 2009 total greenhouse gas emission amount of 564.7 million tons, and this amount is larger than the 9.3 % for the industrial processes sector, 3.3 % for the agricultural sector and 2.5 % for the waste sector. Therefore, it is important to reflect the realities of Korea when estimating the greenhouse gas emission from such sub-bituminous coals.  相似文献   

Evaluation of drought and flood risks in a multipurpose dam under climate change: a case study of Chungju Dam in Korea     

Soojun Kim  Jaewon Kwak  Hui Seong Noh  Hung Soo Kim 《Natural Hazards》2014,73(3):1663-1678

The purpose of this study was to evaluate the effects of climate change on the drought and flood risks of a multipurpose dam. To achieve this, A2 climate change scenarios of RegCM3 were collected about Chungju Dam in Korea. To analyze drought risks, weather data obtained by the statistical downscaling method were entered to produce runoff series by runoff modeling and water balance was analyzed based on water use scenarios to review changes in the storage volume under climate change. To analyze flood risks, changes in water levels of the dam in future flood seasons were reviewed based on the current dam operation method. The results of the review indicated that both the drought and the flood risks of the dam would increase in the future. The reason was considered to be the movement of the flood season’s runoff characteristics from July and August to August and September because of climate change. Therefore, for climate change adaptation planning, not only quantitative changes in hydrologic values but also changes in temporal characteristics should be considered and given importance.  相似文献   

Northern landscapes in transition: Evidence,approach and ways forward using the Krycklan Catchment Study     

Hjalmar Laudon  Eliza Maher Hasselquist  Matthias Peichl  Kim Lindgren  Ryan Sponseller  Fredrik Lidman  Lenka Kuglerová  Niles J. Hasselquist  Kevin Bishop  Mats B. Nilsson  Anneli M. Ågren 《水文研究》2021,35(4):e14170

Improving our ability to detect changes in terrestrial and aquatic systems is a grand challenge in the environmental sciences. In a world experiencing increasingly rapid rates of climate change and ecosystem transformation, our ability to understand and predict how, when, where, and why changes occur is essential for adapting and mitigating human behaviours. In this context, long-term field research infrastructures have a fundamentally important role to play. For northern boreal landscapes, the Krycklan Catchment Study (KCS) has supported monitoring and research aimed at revealing these changes since it was initiated in 1980. Early studies focused on forest regeneration and microclimatic conditions, nutrient balances and forest hydrology, which included monitoring climate variables, water balance components, and stream water chemistry. The research infrastructure has expanded over the years to encompass a 6790 ha catchment, which currently includes 11 gauged streams, ca. 1000 soil lysimeters, 150 groundwater wells, >500 permanent forest inventory plots, and a 150 m tall tower (a combined ecosystem-atmosphere station of the ICOS, Integrated Carbon Observation System) for measurements of atmospheric gas concentrations and biosphere-atmosphere exchanges of carbon, water, and energy. In addition, the KCS has also been the focus of numerous high resolution multi-spectral LiDAR measurements and large scale experiments. This large collection of equipment and data generation supports a range of disciplinary studies, but more importantly fosters multi-, trans-, and interdisciplinary research opportunities. The KCS attracts a broad collection of scientists, including biogeochemists, ecologists, foresters, geologists, hydrologists, limnologists, soil scientists, and social scientists, all of whom bring their knowledge and experience to the site. The combination of long-term monitoring, shorter-term research projects, and large-scale experiments, including manipulations of climate and various forest management practices, has contributed much to our understanding of boreal landscape functioning, while also supporting the development of models and guidelines for research, policy, and management.  相似文献   

Rainfall frequency analysis using a mixed GEV distribution: a case study for annual maximum rainfalls in South Korea     

Philyong Yoon  Tae-Woong Kim  Chulsang Yoo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2013,27(5):1143-1153

Extreme rainfalls in South Korea result mainly from convective storms and typhoon storms during the summer. A proper way for dealing with the extreme rainfalls in hydrologic design is to consider the statistical characteristics of the annual maximum rainfall from two different storms when determining design rainfalls. Therefore, this study introduced a mixed generalized extreme value (GEV) distribution to estimate the rainfall quantile for 57 gauge stations across South Korea and compared the rainfall quantiles with those from conventional rainfall frequency analysis using a single GEV distribution. Overall, these results show that the mixed GEV distribution allows probability behavior to be taken into account during rainfall frequency analysis through the process of parameter estimation. The resulting rainfall quantile estimates were found to be significantly smaller than those determined using a single GEV distribution. The difference of rainfall quantiles was found to be closely correlated with the occurrence probability of typhoon and the distribution parameters.  相似文献