Evaluation of weir construction on water quality related to algal blooms in the Nakdong River     

Jungsu Park  Dingbao Wang  Woo Hyoung Lee 《Environmental Earth Sciences》2018,77(11):408

Understanding the effect of various environmental factors on algal blooms is essential for proper management of water resources. Eight weirs were constructed on the Nakdong River in South Korea between 2010 and 2011 to manage water resources and deal with possible floods and droughts. In this study, water quality observation data were collected from eight representative monitoring sites in the Nakdong River between 2001 and 2016. Particularly, the effect of the weirs construction on water retention time was statistically analyzed in terms of algal growth and other important water quality parameters. While there was slight increase of water temperature (0.8 °C) over 16 years, the concentrations of total phosphorous (TP) and total nitrogen (TN) decreased by 62.3, and 12.9%, respectively, after the construction of weirs. This TP decrease was noticeable, but still high enough to maintain the eutrophic state of the river. Correlation statistical analysis suggests that the Chl-a concentration is positively affected by the changes of TP, TN and chemical oxygen demand. However, there was no direct correlation between Chl-a concentration and the increased water retention time from the weir construction.  相似文献   

Development of a natural analogue database to support the safety case of the Korean radioactive waste disposal program     

Min Hoon Baik  Tae-Jin Park  In Young Kim  Jongtae Jeong  Kyung Woo Choi 《Swiss Journal of Geoscience》2015,108(1):139-146

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Separation of incident and reflected waves in wave–current flumes     

Kyung Doug Suh  Woo Sun Park  Beom Seok Park 《Coastal Engineering》2001,43(3-4)

A technique is developed to separate the incident and reflected waves propagating on a known current in a laboratory wave–current flume by analyzing wave records measured at two or more locations using a least squares method. It can be applied to both regular and irregular waves. To examine its performance, numerical tests are made for waves propagating on quiescent or flowing water. In some cases, to represent the signal noise and measurement error, white noise is superimposed on the numerically generated wave signal. For all the cases, good agreement is observed between target and estimation.  相似文献   

Pb on groundwater particles,Door County,Wisconsin   总被引：4，自引：0，他引：4  

N. C. Woo 《Environmental Geology》1994,24(2):150-156

Pb was detected on groundwater particles larger than 0.45m. Pb concentration (micrograms per liter) showed positive correlations with particle concentration (milligrams per liter) at five sampled wells, although the slopes of the best-fit lines were different. X-ray fluorescence scans suggested that the particles primarily consist of K-Al silicate minerals, and that Pb is absorbed onto Fe oxyhydroxide coatings on Mg-rich silicates. Particle compositions varied at wells, but remained consistent at each well through the sampling period of a month. The particulate nature of Pb in groundwater could cause the spatial and temporal variations due to: (1) the unique composition of particles at wells, (2) the irregular pathways for groundwater particles, (3) the unpredictable amount of Pb-carrying particles entering the groundwater system during recharge events, and (4) the irregular sampling of groundwater particles subsequently dispersed along the advective flow path.  相似文献   

<Emphasis Type="Italic">In-situ</Emphasis> measured primary productivity of ice algae in Arctic sea ice floes using a new incubation method     

Ho Jung Song  Jae Hyung Lee  Gawn Woo Kim  So Hyun Ahn  Houng-Min Joo  Jin Young Jeong  Eun Jin Yang  Sung-Ho Kang  Sang Heon Lee 《Ocean Science Journal》2016,51(3):387-396

Recent changes in climate and environmental conditions have had great negative effects such as decreasing sea ice thickness and the extent of Arctic sea ice floes that support ice-related organisms. However, limited field observations hinder the understanding of the impacts of the current changes in the previously ice-covered regions on sea ice algae and other ice-related ecosystems. Our main objective in this study was to measure recent primary production of ice algae and their relative contribution to total primary production (ice plus pelagic primary production). In-situ primary productivity experiments with a new incubation system for ice algae were conducted in 3 sea ice cores at 2 different ice camps in the northern Chukchi Sea, 2014, using a ¹³C and ¹⁵N isotope tracer technique. A new incubation system was tested for conducting primary productivity experiments on ice algae that has several advantages over previous incubation methods, enabling stable carbon and nitrogen uptake experiments on ice algae under more natural environmental conditions. The vertical C-shaped distributions of the ice algal chl-a, with elevated concentrations at the top and bottom of the sea ice were observed in all cores, which is unusual for Arctic sea ice. The mean chl-a concentration (0.05 ± 0.03 mg chl-a m^?3) and the daily carbon uptake rates (ranging from 0.55 to 2.23 mg C m^?2 d^?1) for the ice algae were much lower in this study than in previous studies in the Arctic Ocean. This is likely because of the late sampling periods and thus the substantial melting occurring. Ice algae contributed 1.5–5.7% of the total particulate organic carbon (POC) contents of the combined euphotic water columns and sea ice floes. In comparison, ice algae contributed 4.8–8.6% to the total primary production which is greater than previously reported in the Arctic Ocean. If all of the ice-associated productions were included, the contributions of the sea ice floes to the total primary production would be greater in the Arctic Ocean and their importance would be greater in the arctic marine ecosystems.  相似文献   

Emergency planning and mitigation at Vesuvius: A new evidence-based approach     

P.J. Baxter  W.P. Aspinall  A. Neri  G. Zuccaro  R.J.S. Spence  R. Cioni  G. Woo 《Journal of Volcanology and Geothermal Research》2008

Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.  相似文献   

Erratum to “A WIMP detector with two-phase xenon” [Astropart. Phys. 12 (2000) 373–377]     

D. Cline  A. Curioni  A. Lamarina  G. Mannocchi  S. Otwinowski  L. Periale  R. Periale  P. Picchi  F. Pietropaolo  H. Wang  J. Woo 《Astroparticle Physics》2000,13(4):373

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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   

Residual depth and residual geoid anomalies of the South Atlantic ocean     

Woo‐yeol jung  Philip D. Rabinowitz 《Marine Geodesy》2013,36(1):33-52

Abstract

We have obtained the residual depth and residual geoid anomalies of the South Atlantic Ocean and interpreted them in terms of upper mantle processes. Starting from the 5’ X 5’ SYNBAPS data, we computed the 1° X 1° mean water depth. We digitized a recent sediment thickness map of the South Atlantic and corrected for the isostatic sediment loading effects. A plot of the corrected basement depth against crustal ages shows a good match to the depth‐age curve of the plate model. We then subtracted the predicted plate model depths from the corrected basement depths and obtained the 1° X 1° residual depth. The residual depth anomalies have positive values over the topographic highs and relative negative values over the ocean basins. A prominent asymmetry is observed between the residual depth over the Argentine Basin and that over the Cape Basin.

We have obtained the 1° X 1° residual geoid of the South Atlantic by subtracting both the long wavelength features and the geoid variations due to the plate cooling from the 1° X 1° Seasat altimeter derived geoid. The long wavelength features are represented by the degree and order 10 geoid of GEM1OC, and the geoid variations due to the plate cooling effects are predicted by the plate model geoid‐age relationship. The residual geoid anomalies also show an asymmetry although weaker than the case of the residual depth, between the Argentine and Cape basins.

By taking the 5° X 5° averages, we removed possible plate bending effects on the depth and geoid anomalies. We then compared those two data sets with respect to the reported hot spot tracks in the South Atlantic. The residual depth generally shows positive values over the hot spot tracks, whereas the residual geoid does not show any sign of them. A prominent asymmetric feature of depth and geoid anomalies is observed over the Argentine and Cape basins. This asymmetry is probably caused by hotter and less dense materials beneath the Cape Basin. Hot spots or other mantle upwellings may be the heat sources.  相似文献   

Groundwater nitrate contamination and risk assessment in an agricultural area,South Korea   总被引：2，自引：1，他引：1  

Jae-Yeol Cheong  Se-Yeong Hamm  Jeong-Hwan Lee  Kwang-Sik Lee  Nam-Chil Woo 《Environmental Earth Sciences》2012,66(4):1127-1136

The nitrate of groundwater in the Gimpo agricultural area, South Korea, was characterized by means of nitrate concentration, nitrogen-isotope analysis, and the risk assessment of nitrogen. The groundwaters belonging to Ca–(Cl + NO₃) and Na–(Cl + NO₃) types displayed a higher average NO₃ ⁻ concentration (79.4 mg/L), exceeding the Korean drinking water standard (<44.3 mg/L NO₃ ⁻). The relationship between δ¹⁸O–NO₃ ⁻ values and δ¹⁵N–NO₃ ⁻ values revealed that nearly all groundwater samples with δ¹⁵N–NO₃ ⁻ of +7.57 to +13.5‰ were affected by nitrate from manure/sewage as well as microbial nitrification and negligible denitrification. The risk assessment of nitrate for groundwater in the study area was carried out using the risk-based corrective action model since it was recognized that there is a necessity of a quantitative assessment of health hazard, as well as a simple estimation of nitrate concentration. All the groundwaters of higher nitrate concentration than the Korean drinking water standard (<44.3 mg/L NO₃ ⁻) belonged to the domain of the hazard index <1, indicating no health hazard by nitrate in groundwater in the study area. Further, the human exposure to the nitrate-contaminated soil was below the critical limit of non-carcinogenic risk.  相似文献