Analysis of Cryptosporidium parvum oocyst transport in porous media     

Song‐Bae Kim  M. Yavuz Corapcioglu 《水文研究》2004,18(11):1999-2009

Cryptosporidium parvum is a protozoan parasite, transmitted through aqueous environments in the form of an oocyst. In this study, a transport model into which sorption, filtration and inactivation mechanisms are incorporated is applied to simulate laboratory column data, and the suitability of a kinetic model to describe the C. parvum oocyst transport and removal in porous media is compared with an equilibrium model. The kinetic model is applied to simulate previous column experimental data and successfully simulates the concentration peak; the late time tailing effect appeared in the breakthrough curves, indicating that the kinetic model is more suitable than the equilibrium one at simulating the fate and transport of the oocysts in porous media. Simulation illustrates that sorption causes retardation along with a tailing in the breakthrough curve. Additionally, filtration acts as a major mechanism of removing the oocysts from the aqueous phase, whereas the role of inactivation in reducing the viable oocyst concentration is minimal. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Quaternary glacial history of the Central Karakoram   总被引：3，自引：0，他引：3  

Yeong Bae Seong  Lewis A. Owen  Michael P. Bishop  Andrew Bush  Penny Clendon  Luke Copland  Robert Finkel  Ulrich Kamp  John F. Shroder Jr. 《Quaternary Science Reviews》2007,26(25-28):3384-3405

The Quaternary glacial history of the world's highest mountains, the Central Karakoram, is examined for the first time using geomorphic mapping of landforms and sediments, and ¹⁰Be terrestrial cosmogenic nuclide surface exposure dating of boulders on the moraines and glacially eroded surfaces. Four glacial stages are defined: the Bunthang glacial stage (>0.7 Ma); the Skardu glacial stage (marine Oxygen Isotope Stage [MIS] 6 or older); the Mungo glacial stage (MIS 2); and the Askole glacial stage (Holocene). Glaciers advanced several times during each glacial stage. These advances are not well defined for the oldest glacial stages, but during the Mungo and Askole glacial stages glacial advances likely occurred at 16, 11–13, 5 and 0.8 ka. The extent of glaciation in this region became increasingly more restricted over time. In the Braldu and Shigar valleys, glaciers advanced >150 km during the Bunthang and Skardu glacial stages, while glaciers advanced >80 km beyond their present positions during the Mungo glacial stage. In contrast, glaciers advanced a few kilometers from present ice margins during the Askole glacial stage. Glacier in this region likely respond in a complex fashion to the same forcing that causes changes in Northern Hemisphere oceans and ice sheets, teleconnected via the mid-latitude westerlies, and also to changes in monsoonal intensity.  相似文献   

The comparison of two severe Hwangsa (Asian dust) cases of spring and winter in Seoul, Korea     

Haeyoung Lee  Jeong Eun Kim  Youngsin Chun 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(1):49-56

This study investigated meteorological, physical, and chemical characteristics of 2 severe Hwangsa (Asian dust, maximum average of PM₁₀ above 1000 μg m^?3) observed in Seoul, the capital city of Korea, during 30～31^st May, 2008 (DSS2008) and 25～26^th December, 2009 (DSS2009). DSS2008 and DSS2009 had a same source region and route. However, they have different meteorological conditions. DSS2009 had a shorter travel time from the source region to Korea and shorter duration time in Korea than DSS2008 due to a strong winter Siberian anticyclone. One of DSS2008 sample was affected by not only Asian dust but also a long-range transported haze due to consecutive influx after low pressure passed while DSS2009 sample collected only dust aerosol. For both cases, the mass concentration of coarse particles (PM_10-1) increased by 3～14 times compared to that during non Asian dust period, however, that of fine particles (PM₁) increased only in DSS2008. For DSS2008 water-soluble ion balance between anions and cations in fine mode was close to 1:1 while cations were higher than anions in coarse mode. NH₄ ⁺ and Ca²⁺ were found to be the main contributing factors for the neutralization. Cl^? loss was observed about 60% indicating an active interaction of Na⁺ with pollutants. Reconstruction of chemical compositions showed relatively high concentrations of secondary pollutants (NH₄NO₃ and (NH₄)₂SO₄), CaCO₃, and Ca(NO₃)₂ compared to that during non Asian dust period. DSS2009 exhibited the typical characteristics of Asian dust having a high concentration of Ca²⁺ with higher equivalent concentration of cations than anions in all size bins. Cl^? loss was hardly observed. The secondary pollutants were lower than that of non Asian dust cases. The result of reconstruction of ionic components indicated the CaCO₃ derived from soil particle, CaSO₄, and Ca (NO₃)₂ were dominant in DSS2009.  相似文献   

Changes in future precipitation over South Korea using a global high-resolution climate model     

Sanghun Lee  Deg-Hyo Bae  Chun-Ho Cho 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(5):619-624

We used daily precipitation data from a global high-resolution climate scenario to analyze the features of future precipitation including extreme and heavy rainfall. The scenario shows that the model reproduces the daily precipitation over South Korea well. The projections show an increase in annual precipitation of approximately 18% in the late 21st century, with the highest increase (38%) occurring in winter. The number of days with daily precipitation of less than 5 mm decreases, but that of daily precipitation of more than 5 mm increases slightly in the latter part of the 21st century. The peak of precipitation days shifted from July to August. The number of days with relatively small amounts of precipitation (10 and 30 mm d^?1) increases most substantially in the winter season, but that for large amounts of precipitation (50, 80, 100, and 130 mm d^?1) increases most in the summer season. Events with heavy precipitation rates of 100 and 130 mm d^?1 are expected to occur in the winter season in the late 21st century, although no such events occurred during the winter season in the reference period.  相似文献   

Laplace–Fourier-Domain Waveform Inversion for Fluid–Solid Media     

Seung-Goo Kang  Ho Seuk Bae  Changsoo Shin 《Pure and Applied Geophysics》2012,169(12):2165-2179

Full waveform inversion algorithms are widely used in the construction of subsurface velocity models. In the following study, we propose a Laplace–Fourier-domain waveform inversion algorithm that uses both Laplace-domain and Fourier-domain wavefields to achieve the reconstruction of subsurface velocity models. Although research on the Laplace–Fourier-domain waveform inversion has been published recently that study is limited to fluid media. Because the geophysical targets of marine seismic exploration are usually located within solid media, waveform inversion that is approximated to acoustic media is limited to the treatment of properly identified submarine geophysical features. In this study, we propose a full waveform inversion algorithm for isotropic fluid–solid media with irregular submarine topography comparable to a real marine environment. From the fluid–solid system, we obtained P and S wave velocity models from the pressure data alone. We also suggested strategies for choosing complex frequency bands constructed of frequencies and Laplace coefficients to improve the resolution of the restored velocity structures. For verification, we applied our Laplace–Fourier-domain waveform inversion for fluid–solid media to synthetic data that were reconstructed for fluid–solid media. Through this inversion test, we successfully restored reasonable velocity structures. Furthermore, we successfully extended our algorithm to a field data set.  相似文献   

Rates of fluvial bedrock incision within an actively uplifting orogen: Central Karakoram Mountains, northern Pakistan     

Yeong Bae Seong  Lewis A. Owen  Michael P. Bishop  Andrew Bush  Penny Clendon  Luke Copland  Robert C. Finkel  Ulrich Kamp  John F. Shroder Jr. 《Geomorphology》2008,97(3-4):274-286

Terrestrial cosmogenic nuclide (TCN) ¹⁰Be surface exposure ages for strath terraces along the Braldu River in the Central Karakoram Mountains range from 0.8 to 11 ka. This indicates that strath terrace formation began to occur rapidly upon deglaciation of the Braldu valley at  11 ka. Fluvial incision rates for the Braldu River based on the TCN ages for strath terraces range from 2 to 29 mm/a. The fluvial incision rates for the central gorged section of the Braldu River are an order of magnitude greater than those for the upper and lower reaches. This difference is reflected in the modern stream gradient and valley morphology. The higher incision rates in the gorged central reach of the Braldu River likely reflect differential uplift above the Main Karakoram Thrust that has resulted in the presence of a knickpoint and more rapid fluvial incision. The postglacial fluvial incision rate (2–3 mm/a) for the upper and lower reaches are of the same order of magnitude as the exhumation rates estimated from previously published thermochronological data for the Baltoro granite in the upper catchment region and for the adjacent Himalayan regions.  相似文献   

Coastal Pollution Mitigation with Lime and Zero Valent Iron     

John L. Daniels  Gautham P. Das  Maria Teresa Serrano Hernandez  Sunyoung Bae 《Marine Georesources & Geotechnology》2013,31(3):183-191

The Taiwan Strait region has many miles of coastline, and the Taiwan Straits Tunnel (TST) project faces many potential pollution problems as construction proceeds through sensitive areas. Conventional approaches for pollution mitigation require further examination. The recent development of nanoscale particle technology has shown distinct advantages for contaminant attenuation and ground improvement. This paper is focused on trace metals and is part of the overall effort to develop the nanoscale particle technology. Trace metals in ground and surface waters represent a continued threat to human and ecological health. One of the difficulties in removing toxic concentrations of trace metals from solution is the variable oxidation state and amphoteric nature of multiple constituents. In particular, while cationic metals (e.g., Pb²⁺, Cd²⁺, Ni²⁺) may be rendered less mobile under high pH conditions, anionic metals (e.g., AsO₄ ^3?, CrO₄ ^2?, SeO₄ ^2?)may become more mobile. The objective of this research was to evaluate the sorption of both cationic and anionic trace elements, including arsenic (As), cadmium (Cd), chromium (Cr) and selenium (Se) under batch conditions. Mixtures of a local residual soil were tested alone and in combination with lime and zero valent iron. It was hypothesized that lime would raise the pH and precipitate positively charged metals while zero valent iron would create reducing conditions favorable to the immobilization of negatively charged metals. Results indicate that the use of lime and/or zero valent iron can increase the sorption capacity of soil. Compared to the baseline soil, sorption capacity increased with addition of lime for arsenic and cadmium while it decreased for chromium and selenium. In the case of zero valent iron addition, sorption capacity increased for cadmium, chromium and selenium, while showing no change for arsenic. When both lime and zero valent iron were used, the sorption capacity increased for all metals tested. These results suggest that the combined use of lime and zero valent iron may serve as an alternative treatment technology for removing trace metals from contaminated water systems.  相似文献   

An experimental transplantation to select the optimal site for restoration of the eelgrass Zostera marina in the Taehwa River estuary     

Jung-Im Park  Jeong Bae Kim  Kun-Seop Lee  Min Ho Son 《Ocean Science Journal》2013,48(4):311-318

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Gap size effect on the tribological characteristics of the roller for deep-sea mining robot     

Jae-Won Oh  Hyung-Woo Kim  Sup Hong  Ki-Young Sung  Dae-Sung Bae 《Marine Georesources & Geotechnology》2017,35(1):120-126

To design the deep-sea mining robot, it is essential to analyze the tribological characteristics of its roller. In this study, we introduced the dynamic simulation model to analyze the tribological characteristics of the roller for deep-sea mining robot, considering the temperature, viscosity, viscous damping force, and gap size between the inner and outer rib seals. Effective viscosity changes with gap size in micro/nanoscale while the effective viscosity is equal to the kinematic viscosity in macroscale. For the stable operation of the roller, the effective viscosity must be less than the critical viscosity. As the gap size decreases, the effective viscosity increases while the critical viscosity decreases. This study shows that the gap size between the inner and outer rib seals of roller is the most dominant factor in designing the roller for deep-sea mining robot to use at relatively low temperatures that are found in the deep-sea environments.  相似文献   

Growth and reproduction of the Japanese mantis shrimp, <Emphasis Type="Italic">Oratosquilla oratoria</Emphasis> (De Haan 1844) in the coastal area of Tongyeong,Korea     

SeongEun Kim  HanJu Kim  HoJin Bae  Hyeong-Gi Kim  Chul-Woong Oh 《Ocean Science Journal》2017,52(2):257-265

Growth and reproduction of the Japanese mantis shrimp, Oratosquilla oratoria, were investigated in the Tongyeong, Korea from July 2014 to August 2015. A total of 2,621 samples (1,380 females and 1,241 males) were collected during the study period. Females were observed more frequently than males. The mean body length (BL) was 128.5 ± 0.38 mm in females and 126.9 ± 0.42 mm in males. The mean body weight (BW) was 31.2 ± 0.28 g in females and 31.1 ± 0.32 g in males. There was a significant difference in the length-frequency distribution between females and males. The relationship between BL and BW was lnBW = 2.85 × lnBL - 10.43 for females and lnBW = 2.87 × lnBL -10.52 for males. The gonadosomatic index (GSI) varied on a monthly basis. The GSI reached a maximum in May and a minimum in November. The highest values of the GSI coincided with the spawning period of O. oratoria. Larger individuals of O. oratoria have their spawning season earlier than smaller ones. The size at sexual maturity of females was estimated as 96.5 mm. The Von Bertalanffy growth function parameters were BL_∞ = 184.5 mm, K = 0.72 year^?1, C = 0.36 and WP = 0.45 for females and BL_∞ = 183.75 mm, K = 0.82 year^?1, C = 0.38 and WP = 0.22 for males. The growth of males was slightly faster than females. The present study will help with the fisheries management of O. oratoria based on ecological parameters.  相似文献