Stabilization of arsenic-contaminated mine tailings using natural and calcined oyster shells

Natural oyster shells (NOS) and calcined oyster shells (COS) were used to immobilize arsenic (As) from contaminated mine tailings. In addition, a blend of Portland cement (PC)/cement kiln dust (CKD) was used as a stabilizing agent. The Korean Standard Test (KST) method (1 N HCl extraction) was used to evaluate the effectiveness of the treatment. The experimental results showed that COS effectively immobilized As in treated mine tailings. Specifically, an As concentration less than 1 mg L⁻¹ was obtained following COS treatment at 25 and 30 wt%. However, all the samples subjected to NOS treatments failed the Korean warning standard of 1.2 mg L⁻¹ after 28 days of curing. All of the COS-PC treatments were successful meeting the Korean warning standard after 7 days of curing. However, the PC-only treatment failed to meet the Korean warning standard. Similarly, the CKD-only treatment was failed to meet the Korean warning standard after 7 days of curing. However, the COS-CKD treatment showed that when the COS content was greater than 20 wt%, less than 1 mg L⁻¹ of As leachability was obtained. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) showed needle-like and torpedo-like Ca–As phases in the COS-treated samples suggesting that As was strongly associated with Ca and O. X-ray absorption near edge structure (XANES) analyses confirmed that As(V) was prevalent in the tailings and that there were no changes in As speciation following NOS or COS treatment.     

Spectral analysis method for a limited area using the eigenmodes of the spherical Laplacian operator

We propose a spectral analysis method using the eigenmodes of the spherical Laplacian operator on the limited area domain. Two numerical methods are considered for the horizontal discretization: One uses the half-ranged Fourier series for both longitudinal and latitudinal directions, and the other uses the Fourier finite-element method with piecewise linear basis functions for the latitudinal direction. The field variable for the two numerical algorithms is represented as linear combinations of the eigenvectors of the Laplacian operator on the limited area domain; we define the one-dimensional spectrum with the eigenvector coefficients as a function of the indices equivalent to the total wavenumbers of the Laplacian operator on the global domain. The spatial robustness of this method was verified through the self-consistency test comparing the spectra of isotropic Gaussian bells on the sphere. We used the method in the kinetic energy spectral analysis for a limited area with global atmospheric data, and compared the results for different seasons. The kinetic energy spectra represented the well-known characteristics with scale and different powers with season.     

Synmetamorphic granitoids (~ 490 Ma) as accretion indicators in the evolution of the Ol’khon terrane (western Cisbaikalia)

We present geological, structural, and geochemical data on synmetamorphic granitoids from the Tutai and South Ol’khon plutons of the Ol’khon terrane (Central Asian Fold Belt) with an estimation of the U–Pb zircon age of the Tutai granites. The structural and petrological data suggest the synfolding and synmetamorphic origin of the granitoids. The U–Pb zircon age of the Tutai granites (488.6 ± 8.0 Ma) almost coincides with the previously estimated age of quartz syenites from the South Ol’khon pluton (495 ± 6 Ma). The plutons occupy the same position in the regional structure. The granitoids underwent final deformations and metamorphism at 464 ± 11 Ma. The Tutai pluton consists of moderately potassic granites, whereas the South Ol’khon pluton is made up of quartz syenites and granites. The geochemical characteristics of the granites from both plutons (low Y and Yb contents, fractionated REE patterns) indicate their formation under conditions of garnet crystallization in deep crustal restite. The higher Y and Yb contents of the South Ol’khon quartz syenites as compared with those of the granites suggest the lack of equilibrium between the quartz syenite magmas and garnet parageneses during their formation or evolution. The Tutai and South Ol’khon granites were derived from quartz-feldspar crustal rocks, whereas the South Ol’khon quartz syenites might have originated from a mixed (crust-mantle) source. It is presumed that the granitoids formed within accretion-thickened crust. Early accretion, which has been first identified in the region, affected not only the Pribrezhnaya zone (the zone of the Tutai and South Ol’khon plutons) but also the entire Anga–Satyurty megazone of the Ol’khon terrane. The accretion ended with the convergence and oblique collision of the Ol’khon terrane and Siberian continent, when strike-slip tectonics became ubiquitous.     

Uranium isotopes as a tracer of sources of dissolved solutes in the Han River,South Korea

The uranium (U) content and ²³⁴U/²³⁸U activity ratio were determined for water samples collected from Korea's Han River in spring, summer, and winter 2006 to provide data that might constrain the origin of U isotope fractionation in river water and the link between U isotope systematics in river waters and the lithological nature of the corresponding bedrock. The large difference in the major dissolved loads between the two major branches of the Han River, the North Han River (NHR) and South Han River (SHR), is reflected in the contrasting U content and ²³⁴U/²³⁸U activity ratio between the tributaries: low U content (0.08–0.75 nM; average, 0.34 nM) and small ²³⁴U/²³⁸U activity ratio (1.03–1.22; average, 1.09) in the NHR; and high U content (0.65–1.98 nM; average, 1.44 nM) and large ²³⁴U/²³⁸U activity ratio (1.05–1.45; average, 1.24) in the SHR. The large spatial differences in U content and ²³⁴U/²³⁸U activity ratio are closely related to both lithological differences between the two tributaries and groundwater input. The low U content and small ²³⁴U/²³⁸U activity ratio in the NHR arise mainly from a combination of surface and meteoric weathering of the dominant silicate rocks in this branch and congruent dissolution of already weathered (secular equilibrium) materials. In contrast, the high U content and large ²³⁴U/²³⁸U activity ratio in the SHR are ascribed to the dissolution of carbonates and black shales along with significant inputs of deep groundwater.     

Sr, Nd and Pb Isotopic Systematics of the Cenozoic Basalts of the Korean Peninsula and Their Implications for the Permo-Triassic Continental Collision Boundary

Sr, Nd and Pb isotopic compositions of the Cenozoic basalts were analyzed from Baengnyeongdo Island, Jeongok, Ganseong, and Jejudo Island of Korea. They reveal relatively enriched Sr and Nd isotopic compositions (⁸⁷Sr/⁸⁶Sr = 0.703300.70555, ¹⁴³Nd/¹⁴⁴Nd = 0.512980.51256) compared with MORB.²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb values of all the analyzed Korean basalts lie above the Northern Hemisphere Reference Line (NHRL) defined by Hart (1984). Pb isotopic compositions of basalts from Jejudo Islands (²⁰⁶Pb/²⁰⁴Pb = 18.6119.12, ²⁰⁷Pb/²⁰⁴Pb = 15.5415.69, ²⁰⁸Pb/²⁰⁴Pb = 38.9839.72) are significantly more radiogenic than the rest (²⁰⁶Pb/²⁰⁴Pb = 17.7218.03, ²⁰⁷Pb/²⁰⁴Pb = 15.4415.58, ²⁰⁸Pb/²⁰⁴Pb = 37.7738.64). The Cenozoic Korean basalts thus can be divided into two groups based on their Sr, Nd and Pb isotopic compositions. The north group reveals mixing between DMM and EM1 while the south group displays DMM-EM2 mixing. Such a distribution is the same as Chinese Cenozoic basalts and it can be interpreted that the subcontinental lithospheric mantle under Korea represents simple lateral continuation of the South and North China Blocks. We suggest that Korean continental collision zone cross the Korean Peninsula through the region between the north and south basalt groups of Korea.     

Two- and three-dimensional oil spill model for coastal waters

This paper presents the development and application of two-dimensional and three-dimensional oil trajectory and fate models for coastal waters. In the two-dimensional model, the oil slick is divided into a number of small grids and the properties of each grid due to spreading, advection, turbulent diffusion, evaporation and dissolution are studied. This model can predict the movement of the oil slick on the water surface. In order to simulate the distribution of oil particles in the water column, a three-dimensional oil fate model is developed based on the mass transport equation and the concentration distribution of oil particles can be solved. A comparison of numerical results with the observed data shows good conformity.     

Estimation of incident and reflected waves in regular wave experiments

This paper presents a laboratory technique for measurement of reflected waves by a submerged horizontal plate. A simple method is proposed to decompose the composite wave record obtained from the wave reflection experiments in the wave flume. The data collected were used to compute the reflected wave height by means of two and three probe methods proposed by other investigators and compared with the directly computed reflected wave using the measured incident wave. The experiment was carried out for a horizontal plate of 1 m length spanning the full width of the flume with wave periods ranging from 0.8 to 1.8 sec with 0.1 sec increments and wave heights of 5, 10 and 15 cm. The methods using two and three probes with phase measurement yield better results than the three probe method without phase measurement, and in general they have a wider range of application. The method using three probes without the phase measurement generally fails due to numerical instability of the scheme. The results obtained by the proposed method are compared with the two and three probe methods and a comparative analysis of the four methods is presented and discussed.     

Lithospheric mantle signatures as revealed by zircon Hf isotopes of Late Triassic post‐collisional plutons from the central Korean peninsula,and their tectonic implications

The Mesozoic tectonic architecture of the Korean peninsula is largely governed by the continental collision between the North and South China blocks. Zircon Hf isotopic compositions presented in this study and whole‐rock geochemical and Sr‐Nd isotope data in the literature collectively suggest that the lithophile‐elements‐enriched signature of the Late Triassic post‐collisional plutons from the Gyeonggi massif in central Korea is a primary feature inherited from the metasomatized mantle lithosphere. Highly negative zircon ε_Hf (t) values (?23 to ?19) of plutons from the middle and eastern parts of the massif indicate an ancient metasomatism of their mantle source. Distinctly higher zircon ε_Hf (t) values (?15 to ?12) from the southwestern plutons are ascribed to a contribution from an accreted component of the South China‐like block. The involvement of asthenospheric mantle is not recognized in zircons from either group. The implications of these isotopic features are discussed in the context of Mesozoic collisional tectonics.     

Multivariate statistical analysis to identify the major factors governing groundwater quality in the coastal area of Kimje,South Korea

The main purpose of this study is to identify the major factors affecting groundwater quality by means of multivariate statistical analysis of the physico‐chemical compositions. Cluster analysis results show that the groundwater in the study area is classified into four groups (A, B, C and D), and factor analysis indicates that groundwater composition, 81·9% of the total variance of 17 variables, is mainly affected by three factors: seawater intrusion, microbial activity and chemical fertilizers. These results might be related to the geographical characteristics of the study area. The main influence on groundwater in groups B, C and D, which are close to the Yellow Sea and contain reclaimed areas, is the seawater intrusion by the present seawater, the trapped seawater, and microbial activity. Group A, however, has been used for agriculture for a long time, and thus groundwater in this group has been largely affected by chemical fertilizers. As groundwater flows from group A to group D according to its path, the governing factor of the groundwater quality gradually changes from chemical fertilizers to microbial activity and seawater intrusion. Copyright © 2004 John Wiley & Sons, Ltd.     

A social assessment of the Hebei-Spirit oil spill

This paper examines the early social consequences of the largest oil spill in Korea from December 2007 up to May 2008. The focus is on the social impact of the oil spill and its social implications in three major areas of oil spill response: (1) clean-up operations, (2) compensation, and (3) ecological impact. The paper highlights both the positive and negative consequences of the spill and the significance of the early social assessment to understand subsequent responses and adaptation in the long run.