Analysis of benzene transport in a two‐dimensional aquifer model

In this study, the fate and transport of aqueous benzene was investigated in a laboratory‐scale homogeneous aquifer by conducting a two‐dimensional plume test. Benzene solution was introduced as a pulse type along the width of the aquifer model through a recharge zone situated at the upper‐left part of the model and followed by a steady state flow. Solution samples were collected at various locations on the front side of the model to capture two‐dimensional plumes at discrete time intervals. The benzene plumes showed a moderate retardation relative to chloride plumes observed from the previous study conducted for the same aquifer model. The retardation factor was obtained from the ratio of travel distances of benzene peaks to chloride peaks from the injection point, computed using a line integral method. Mass recovery of aqueous benzene revealed that there was a significant reduction of benzene mass, indicating the occurrence of volatilization and/or irreversible sorption during transport. Thus, retardation along with volatilization and/or irreversible sorption may be important processes affecting the fate and transport of aqueous benzene in the aquifer model. Copyright © 2005 John Wiley & Sons, Ltd.     

Quantification of irreversible benzene sorption in sandy materials

Based on a previous study of the irreversible sorption of benzene in sandy aquifer materials, we further investigated a method to quantify an irreversible sorption coefficient of aqueous benzene. Assuming that the rate of irreversible loss from the solution to the sorption sites followed first‐order kinetics, the irreversible sorption coefficient was derived from a kinetic batch sorption test conducted for an appropriate soil‐to‐solution ratio to reflect the flow conditions imposed on a column test. Simulation results revealed that the irreversible sorption coefficient estimated from the kinetic batch test provided a good agreement with the measured data obtained from the column test, indicating that the method proposed in this study can be used to quantify the irreversible sorption coefficient. Copyright © 2004 John Wiley & Sons, Ltd.     

Rotation and cometary activity of KBO (29981) 1999 TD10

We describe observations of the scattered Kuiper Belt object (29981) 1999 TD₁₀ performed during five observing runs at two observatories, over 370 days from 2000 September to 2001 September. They show significant brightness variations that fit a double-peaked lightcurve with period 15.448±0.012 h in V and R bands. The phase effect in V band, 0.09±0.01 mag deg⁻¹, is smaller than that of Pluto but larger than that of several KBOs, while in R band it is 0.030±0.005 mag deg⁻¹. We find color variation between the two bands, which implies a non-homogeneous albedo distribution on the surface. Evidence of surface activity near perihelion in the form of a coma/tail is presented using radial image profiles and a 2D contour map.     

Crustal Structure of the Korean Peninsula Using Surface Wave Dispersion and Numerical Modeling

Surface wave dispersion is studied to obtain the 1-D average velocity structure of the crust in the Korean Peninsula by inverting group- and phase-velocities jointly. Group velocities of short-period Rayleigh and Love waves are obtained from cross-correlations of seismic noise. Multiple-filter analysis is used to extract the group velocities at periods between 0.5 and 20 s. Phase velocities of Rayleigh waves in 10- and 50-s periods are obtained by applying the two-station method to teleseismic data. Dispersion curves of all group and phase velocities are jointly inverted for the 1-D average model of the Korean Peninsula. The resultant model from surface wave analysis can be used as an initial model for numerical modeling of observations of North Korean events for a velocity model appropriated to the Korean Peninsula. The iterative process is focused especially on the surface sedimentary layer in the numerical modeling. The final model, modified by numerical modeling from the initial model, indicates that the crust shear wave velocity increases with depth from 2.16 km/s for a 2-km-thick surface sedimentary layer to 3.79 km/s at a Moho depth of 33 km, and the upper mantle has a velocity of 4.70 km/s.     

The Effect of Specimen Size on Strength and Other Properties in Laboratory Testing of Rock and Rock-Like Cementitious Brittle Materials

The effect of specimen size on the measured unconfined compressive strength and other mechanical properties has been studied by numerous researchers in the past, although much of this work has been based on specimens of non-standard dimensions and shapes, and over a limited size range. A review of the published literature was completed concentrating on the presentation of research pertaining to right cylindrical specimens with height:diameter ratios of 2:1. Additionally, new data has been presented considering high strength (70 MPa) cement mortar specimens of various diameters ranging from 63 to 300 mm which were tested to failure. Currently, several models exist in the published literature that seek to predict the strength–size relationship in rock or cementitious materials. Modelling the reviewed datasets, statistical analysis was used to help establish which of these models best represents the empirical evidence. The findings presented here suggest that over the range of specimen sizes explored, the MFSL (Carpinteri et al. in Mater Struct 28:311–317, 1995) model most closely predicts the strength–size relationship in rock and cementitious materials, and that a majority of the empirical evidence supports an asymptotic value in strength at large specimen diameters. Furthermore, the MFSL relationship is not only able to model monotonically decreasing strength–size relationships but is also equally applicable to monotonically increasing relationships, which although shown to be rare do for example exist in rocks with fractal distributions of hard particles.     

Forest fire risk mapping of Kolli Hills, India, considering subjectivity and inconsistency issues

Forest fires have adverse ecological, economic, and social impacts. In this light, the present research aimed, first, to construct a fire risk model using a GIS-based multi-criteria analysis and second, to derive a forest fire risk modeling strategy that alleviates the problem of inconsistency in the assigning of scores and weights to forest fire categories and layers. Third, the local-orientation effects and causes, which are relevant to the subjectivity problem, were investigated by comparing the risk scoring and weighting outcomes from Indian and Korean expert groups (IEG and KEG). Fourth, forest fire factors that can be considered regional and global also were investigated. Kolli Hills, India, was selected as the study area in this research. In the interests of alleviating the inconsistency problem, a weighting and scoring scheme based on the analytic hierarchy process was applied. The experiences from the existence of prevailing westerly winds, the most common forest types (i.e., in Korea: pine trees), and the different anthropogenic pressures between Korea and India resulted in the different scoring and weighting decisions of the two expert groups. Among the five fire risk factors, slope, road, and settlement can be considered to be global factors. On the other hand, forest cover and aspect are regional factors that can be more influenced by local environmental conditions. When considering the producer’s accuracy, the approach of the IEG together with the natural breaks thresholding method provided the best fire risk mapping result. On the other hand, the model from the IEG with equal interval provided the best result from the viewpoint of user’s accuracy and overall accuracy. Overall, this paper proposes a forest fire risk mapping procedure as basis for developing a global forest fire risk modeling in the future, where a series of standardized modeling steps and variables should be defined.     

Adsorptive attenuation of ferrocyanide from seepage water in landfill clay liners

The spent potliner (SPL) landfill liner system provides the primary attenuation mechanism that blocks the leaching of ferrocyanide. If the seepage occurs, however, the off-site leaching potential of ferrocyanide will be enhanced, resulting in contaminant dispersion. In this study, the adsorptive attenuation of ferrocyanide by two common lining materials (kaolinite and montmorillonite) was investigated under various seepage settings, such as influent concentration, liner thickness, and seepage velocity. The attenuation of ferrocyanide through both lining materials was obvious by lowering the maximum concentration and retarding the peak arrival time and was greater than that expected from batch data, likely due to the high mass-volume ratio under seepage condition. In comparison, seepage of ferrocyanide through lining material layer was retarded when (1) influent concentration was halved, (2) liner thickness was 1.5-fold, and (3) seepage velocity was halved. These experimental results strongly support the concentration-specific and rate-limited adsorptive attenuation of ferrocyanide by lining materials during the seepage process. An extended desorption front was observed for all seepage conditions; it was particularly more apparent for montmorillonite with a slow seepage velocity, further supporting that the release of adsorbed ferrocyanide from adsorbent is energetically hysteretic. Among the factors investigated in this study, the greatest retardation of ferrocyanide movement from seepage water was achieved upon doubling liner thickness. Therefore, for the design of a SPL landfill liner to minimize the leaching potential and thus the environmental risk of ferrocyanide, optimization of the liner thickness should be considered foremost.     

A study on measurement and analysis of radon-222 (uranium series) emitted to the atmosphere from construction materials (cement block, kaolin brick, and gypsum board) in living environment

The purpose of this study was to measure, compare, and analyze the air concentration of radon that was emitted to the atmosphere from construction materials such as cement brick, tile, red clay tile, and gypsum tile. The study method was to use continuous radon monitoring equipment (RTM 1688-2) to measure concentrations of radon and thoron contained in brick, tile, red clay tile, and gypsum tile. According to the measurement results, the cement brick among the four samples showed the highest measurement value for radon, while the red clay tile showed the highest measurement value for thoron. When the radon emission concentration was estimated based on materials required for construction per unit area (3.3 m²) in an actual construction, the cement brick had the highest measurement values for radon and thoron. This study confirmed the degree of radon emission from construction materials. The purpose of this study was also to suggest a method to examine the effects of radon and reduce the dose of personal radiation exposure. It is believed that the government should be active in publicizing and managing use of construction materials that have lower levels of radon emission.     

The results of measurements of heavy metals in atmospheric aerosols in the open areas of the Arctic Seas in 2009–2010

By experimental data on the concentration of toxic microelements (Pb, Cd, Cu, Zn, Ni, Co, and Cr) in atmospheric aerosols over the White and Norwegian Seas in winter-spring period of 2009–2010, the contamination of air environment over two sea basins, significantly different by geographical conditions but being heavily impacted by North-European industrial centres, including the impact of the largest in the European Arctic Kola industrial centre, has been analyzed. It has been indicated and described that the air basin over the White Sea water area, when compared to the Norwegian Sea, is under a significantly greater impact of the emission sources of heavy metals, located on the Kola Peninsula.