The Heuksan mud belt on the tide-dominated shelf of Korea: a supply-driven depositional system?     

Tae Soo Chang  Hun Jun Ha 《Geo-Marine Letters》2015,35(6):447-460

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Observed changes of global and western Pacific precipitation associated with global warming SST mode and mega-ENSO SST mode     

Byeong-Hee Kim  Kyung-Ja Ha 《Climate Dynamics》2015,44(11-12):3067-3076

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Groundwater responses to the 2011 Tohoku Earthquake on Jeju Island,Korea     

Soo‐Hyoung Lee  Kyoochul Ha  Se‐Yeong Hamm  Kyung‐Seok Ko 《水文研究》2013,27(8):1147-1157

Groundwater responses at 15 monitoring wells on Jeju Island were observed in relation to the magnitude 9.0 Tohoku Earthquake off the Pacific coast of Honshu, Japan, on 11 March 2011, at 14:46:23 h local time (05:46:24 h UTC time). In coastal areas, the groundwater level responses to the earthquake were oscillatory at 12 wells, and the range of the maximum groundwater level changes was 3–192.4 cm. The response durations were approximately 1–62 min. The relationship between the maximum groundwater level changes and the response durations displayed a high correlation coefficient (r = 0.81). Groundwater temperature changes were also observed at 7 of 12 wells 3–10 min after the seismic wave arrived, and the range was from 0.01 °C to 1.20 °C. In mid‐elevation areas, the groundwater level changes appeared in three different forms: oscillatory, spiky and persistent. The groundwater temperature changes were also observed at two wells. One indicated decreasing and recovering temperatures, and the other exhibited rising and persistent temperatures. The primary temperature changes occurred 5–6 min after the earthquake and 2–3 min after the seismic wave arrived. In addition, the electrical conductivities at the depth of the transition zone were monitored, and the responses to the earthquake appeared at all three wells. Although the electrical conductivity and temperature changes were not well understood, groundwater inflow and mixing were likely caused by the earthquake, and the responses were various and site specific. The responses to the earthquake were closely related to the hydrogeological characteristics at each monitoring well, and a more detailed hydrogeological characterization is needed to understand the mechanisms related to earthquakes in general. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Impact of seasonal variations in hydrological stresses and spatial variations in geologic conditions on a TCE plume at an industrial complex in Wonju,Korea     

Jae‐Ha Yang  Kang‐Kun Lee  T. Prabhakar Clement 《水文研究》2012,26(3):317-325

Spatial and temporal variations in a trichloroethylene (TCE) plume at an industrial complex in Wonju, Korea, were examined based on hydrogeological data and seven rounds of groundwater quality data collected over a year. The site has considerable vertical heterogeneities; the top layer of soil is covered by impermeable paving material at several locations, followed by a series of reclaimed or residual soil layers, and with weathered rocks to the crystalline biotite granite at the bottom. Areal heterogeneity in the surface conditions plays an important role in controlling groundwater recharge. The heterogeneity structure is influenced by complex surface conditions paved with asphalt and concrete. Owing to the presence of limited recharge area and concentrated summer precipitation events, the effects of seasonal variations on groundwater hydraulics tend to diminish with distance from the recharge area. This result was established by analysing the influence of the contrasting surface recharge conditions between the near‐source zone and the far zone, and the seasonally concentrated precipitation on the transport patterns of a TCE plume. In addition, variations in the plume's downstream contaminant flux levels were also analysed along a transect line near the source zone. The results show that the general tendency of the TCE plume contaminant concentration and mass discharges were reproducible if we account for seasonal recharge variations and the associated changes in the groundwater level. During recharge events, the TCE concentration variations appear to be influenced by leaching of the residual dense non‐aqueous‐phase liquid (DNAPL) TCE trapped in the unsaturated zone. This result shows that seasonal variations in contaminant plume near the source zone is inevitable at this site, and that these variations indicate the presence of residual DNAPL at or above the water table, at least in some isolated locations. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Acoustic density measurements of consolidating cohesive sediment beds by means of a non-intrusive “Micro-Chirp” acoustic system     

Ho Kyung Ha  Jerome P.-Y. Maa  Charles W. Holland 《Geo-Marine Letters》2010,30(6):585-593

A non-intrusive “Micro-Chirp” acoustic system and a signal-processing protocol have been developed to estimate the bulk density of consolidating cohesive sediment beds. Using high-frequency (300–700 kHz) Chirp acoustic waves, laboratory measurements were conducted with clay–water mixtures. Because acoustic echo strength is proportional to variations in acoustic impedance, and the speed of sound in the clay bed hardly changed during consolidation, the bulk density could be successfully estimated without disturbing the sediment bed. Based on acoustic signal analysis, this study demonstrates that the reflection coefficient and bulk density at the water–sediment interface increase with consolidation time, and that a single speed of sound value can be used for practical bulk density estimation in muddy environments.  相似文献   

Role of extracellular polymeric substances in metal ion complexation on Shewanella oneidensis: Batch uptake, thermodynamic modeling, ATR-FTIR, and EXAFS study     

Juyoung Ha  Alexandre Gélabert  Alfred M. Spormann 《Geochimica et cosmochimica acta》2010,74(1):1-117

The effect of cell wall-associated extracellular polymeric substances (EPS) of the Gram-negative bacterium Shewanella oneidensis strain MR-1 on proton, Zn(II), and Pb(II) adsorption was investigated using a combination of titration/batch uptake studies, surface complexation modeling, attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, and Zn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. Both unmodified (wild-type (WT) strain) and genetically modified cells with inhibited production of EPS (ΔEPS strain) were used. Three major types of functional groups (carboxyl, phosphoryl, and amide groups) were identified in both strains using ATR-FITR spectroscopy. Potentiometric titration data were fit using a constant capacitance model (FITEQL) that included these three functional groups. The fit results indicate less interaction of Zn(II) and Pb(II) with carboxyl and amide groups and a greater interaction with phosphoryl groups in the ΔEPS strain than in the WT strain. Results from Zn(II) and Pb(II) batch adsorption studies and surface complexation modeling, assuming carboxyl and phosphoryl functional groups, also indicate significantly lower Zn(II) and Pb(II) uptake and binding affinities for the ΔEPS strain. Results from Zn K-edge EXAFS spectroscopy show that Zn(II) bonds to phosphoryl and carboxyl ligands in both strains. Based on batch uptake and modeling results and EXAFS spectral analysis, we conclude that the greater amount of EPS in the WT strain enhances Zn(II) and Pb(II) uptake and hinders diffusion of Zn(II) to the cell walls relative to the ΔEPS strain.  相似文献   

2006年青海玉树5.0、5.6、5.4级地震灾害损失及震害特点   总被引：3，自引：1，他引：2  

都昌庭  李文巧  卢宁  哈辉  才扎西  达杰 《震灾防御技术》2006,1(4):371-377

2006年7月18、19日在青海玉树发生了5．0、5．6、5．4级地震,地震造成了玉树县上拉秀乡、杂多县萨呼腾镇的房屋破坏,震后青海省地震局会同玉树州地震局、玉树地震台对玉树地震的灾害损失进行了现场评估,并对玉树地震的震害特点进行了总结,最后提出了相关建议。  相似文献   

Regional eco-efficiency evaluation and spatial pattern analysis of the Yangtze River Economic Zone   总被引：1，自引：0，他引：1  

Ha  Lin  Tu  Jianjun  Yang  Jianping  Xu  Chunhai  Pang  Jiaxing  Lu  Debin  Yao  Zuolin  Zhao  Wenyu 《地理学报(英文版)》2020,30(7):1117-1139

The environmental ecology of the Yangtze River Economic Zone(YREZ) faces ecological function decline, deterioration and degradation under intense human activities, long-term development and utilization and its economy has developed rapidly over recent decades. Eco-efficiency is considered as a measure of coordinated development of economy, resources, environment and ecology, and is currently considered a very important issue. In this paper, based on the slack-based measure and data envelope analysis model, we take 129 prefecture-level cities of the YREZ as the study unit and measure the eco-efficiency of the YREZ in 2000, 2005, 2010 and 2015, which considers undesired output. The evaluation of the status quo of the regional eco-efficiency development was carried out at provincial, prefectural and city scales. The spatial autocorrelation test model and standard deviation ellipse were used to analyze the spatially distributed characteristics and the evolutionary regularity of eco-efficiency. Our study suggested that the eco-efficiency value varied significantly at different spatiotemporal scales and the overall distribution presented an "N-shaped" pattern, the value is the largest downstream and the smallest upstream. Regional eco-efficiency presented certain volatility in growth and a clear spatial positive agglomeration trend from 2000 to 2015. The spatial distribution of each agglomeration area was also significantly different, forming some high-high agglomeration areas at the center of the shaft with Shanghai and surrounding cities, and some low-low agglomeration areas at the center with middle reaches and upstream cities. The low-high over-aggregation and high-low polarization clusters were fewer. At the same time, with the change of the research period, the degree of positive agglomeration became increasingly pronounced and the eco-efficiency gap of the neighborhoodunit reduced. The regional eco-efficiency value of the YREZ presented a spatial distribution pattern in the northeast-southwest axis and the evolutionary pattern of the regional eco-efficiency similarly showed a northeast-southwest orientation.  相似文献   

Influence of flow rate and organic carbon content on benzene transport in a sandy soil     

Song‐Bae Kim  Heon‐Cheol Ha  Nag‐Choul Choi  Dong‐Ju Kim 《水文研究》2006,20(20):4307-4316

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Seasonal prediction and predictability of the Asian winter temperature variability     

June-Yi Lee  Sun-Seon Lee  Bin Wang  Kyung-Ja Ha  Jong-Ghap Jhun 《Climate Dynamics》2013,41(3-4):573-587

Efforts have been made to appreciate the extent to which we can predict the dominant modes of December–January–February (DJF) 2 m air temperature (TS) variability over the Asian winter monsoon region with dynamical models and a physically based statistical model. Dynamical prediction was made on the basis of multi-model ensemble (MME) of 13 coupled models with the November 1 initial condition for 21 boreal winters of 1981/1982–2001/2002. Statistical prediction was performed for 21 winters of 1981/1982–2001/2002 in a cross-validated way and for 11 winters of 1999/2000–2009/2010 in an independent verification. The first four observed modes of empirical orthogonal function analysis of DJF TS variability explain 69 % of the total variability and are statistically separated from other higher modes. We identify these as predictable modes, because they have clear physical meaning and the MME reproduces them with acceptable criteria. The MME skill basically originates from the models’ ability to capture the predictable modes. The MME shows better skill for the first mode, represented by a basin-wide warming trend, and for second mode related to the Arctic Oscillation. However, the statistical model better captures the third and fourth modes, which are strongly related to El Niño and Southern Oscillation (ENSO) variability on interannual and interdecadal timescales, respectively. Independent statistical forecasting for the recent 11-year period further reveals that the first and fourth modes are highly predictable. The second and third modes are less predictable due to lower persistence of boundary forcing and reduced potential predictability during the recent years. In particular, the notable decadal change in the monsoon–ENSO relationship makes the statistical forecast difficult.  相似文献