The irreversible adsorption capacity of radioactive cesium in soil of granite origin was assessed via a desorption experiment. The results demonstrated that the cesium desorption only occurred when it reached 0.035% of the cation exchange capacity, despite the presence of the competing ion (K + ). The fixation of cesium on frayed edge sites, primarily ascribed to weathered mica and interpretable via the dual-site Langmuir model, may contribute to this irreversible binding. Consequently, the extraction of these minerals from granite-origin soil possesses the potential to diminish the concentration and volume of radioactive soil waste contamination.

Extended Abstract Treatment of As(III) can be a challenging task due to its high mobility and small affinity to mineral surfaces and that pre-oxidation step to As(V) is necessary for enhancing removal efficiency[1]. In this study, Fe-Mn oxide was synthesized through chemical precipitation in solutions with varying concentrations of FeCl 3 • 4H 2 O and MnO 2 • 4H 2 O for oxidative adsorption of As(III) in aqueous solution. The synthesized Fe-Mn oxide mineral possessed oxidation property rendered from manganese dioxide phases and adsorption capacity from the iron oxide phases. The Fe-Mn oxide was characterized for surface area, morphology, composition, and magnetic property and bench scale laboratory experiments were carried out to investigate potential utility of the mineral in treating As(III) under the mineral dose of 1 g/L and 1mg/L As(III). The results of kinetic experiments revealed the oxidation of As(III) occurred in very short period time (less than 30 min.), followed by adsorption to iron oxide phase, with its removal efficiency being the highest for the mineral synthesized under 1:0.25 Fe:Mn condition. The maximum adsorption capacity determined from isotherm experiments was found to be 200 mg/g. The removal of As(V) remained relatively constant in the pH 3-6 at around 60% removal but dramatically decreased when pH was raise to 10. The ionic strength in the range of 0.001-0.1 M NaNO 3 and the presence of competing anion (0.1-1 mM PO 43) had little effect on the As(III) removal. The overall results of this study demonstrated the potential utility of the Fe-Mn oxide for treatment on the As(III) in field applications for high removal

The purpose of this study is to present the possibility a utilization of the tertiary mudstone in Pohang as road subsoil material through pilot experiments on the road embankment structure. This mudstone is an unconsolidated rock that is distributed in the soft rock sedimentary layer, the tertiary layer of the Cenozoic, and causes physical problems such as slaking, swelling, and reduced shear strength and chemical problem like acid drainage. In order to solve various complex problems, an laboratory mixing test was conducted, and the optimal mixing conditions of the tertiary mudstone (90%), composite slag (steel making 70%, blast furnace 30%), and neutralization and coating agent treatment were derived. In order to prove its utilization, a real-scale road embankment structure was constructed and tests were conducted for each section. The pre-processing section is stable due to the design of optimal mixing conditions, while in post-processing section, natural weathering proceeded rapidly, and structural problems were concerned. Since the effect of neutralizing and coating agents was confirmed in temporary-staking section, the neutralizing and coating agents can be applied during the temporary storage period.

This study investigated mercury contamination with respect to the sediment characteristics in Gumu Creek near the Pohang Industrial Complex, South Korea. The contaminated sediment had high levels of Hg, exceeding 250 mg Hg/kg sediment at the sampling position, and high concentrations of iron, sulfur, and organic carbon under extreme anaerobic conditions. The anoxic condition of the sediment produced large amounts of FeS. Hg L-3-edge EXAFS analysis revealed that FeS controlled the Hg species in the sediment mainly as beta-HgS like precipitation or Hg-S complexation. We also speculated that the presence of FeS induced the abiotic reduction of Hg(II) to Hg(0) and consequently suppressed the formation of highly toxic methylated mercury species. The results obtained in this study are mostly consistent with those reported in previous studies of geochemical reactions of FeS in controlling Hg(II) under pure FeS mineral systems under laboratory scenarios. This study demonstrates that the laboratory controlled reaction scenarios can explain the field behavior of Hg in the contaminated anoxic sediment of the Gumu Creek site.

A large amount of cyanide has been produced and used in a variety of industrial processes such as metal plating, gas production, mining and pigment production.Cyanide in environment has attracted a concern due to its high toxicity.Toxicity and mobility of cyanide in soil are strongly depending on its form [1]. Chemical oxidation and biological degradation are commonly adopted for the remediation of cyanide contaminated soil [2].The chemical oxidation with the direct injection of oxidants revealed a limited remedial efficiency due to the degradation of oxidants by organic matter, manganese oxide and sulphide and to the low oxidation rate of adsorbed metal cyanide complex and solid metal cyanide.We tried to develop the washing method with a phosphate solution for the remediation of cyanide contaminated soil.The cyanide contaminated soil was collected at a gold mine site in Korea and was air-dried.The air-dried soil sample (< 2 mm in diameter) contained 85 mg kg -1 of cyanide and used in the experiment for the technology development.The kinetic study and the washing efficiency test were conducted with the reaction of 1 soil and 5 washing solution.The washing solutions contained 0 -100 mM Na-orthophosphate, Na-hexametaphosphate or Na-pyrophosphate and the pH of solutions was adjusted to 10 -12 with 1N NaOH.After the reaction, the pH and the concentrations of cyanide species (free, weak acid dissociable and strong acid dissociable) and heavy metals of the solutions were determined.The extracted amount of cyanide from the soil sharply increased with increasing reaction time until 100 minutes and then the extraction rate slowly increased.The cyanide extraction rate was gradually increased with increasing the solution pH.The cyanide extraction rate sharply increased with increasing phosphate concentration of the washing solution until 30 mM and then the extraction rate slowly increased.The cyanide extraction efficiency of the phosphate species at the same pH and the same concentration revealed as following: pyrophosphate > hexametaphosphate > orthophosphate.The optimum washing solution for cyanide extraction among the tested solutions was the pH 12 30mM Na-hexametaphosphate solution.Ninety seven percent of the soil cyanide were extracted by reacting with the optimum washing solution for 30 minutes.The As concentration of the solution after the reaction increased with increasing the pH and the phosphate concentration of the washing solutions.The experimental data indicate that the soil washing with alkali phosphate solution can be successfully applied for the remediation of cyanide contaminated soil with an attention on As desorption during washing.

The main purpose of our work lies in a new methodology of fabricating sorptive materials possessing bi-functionality to adsorb both cationic and anionic contaminants. As noted in the manuscript, many contaminated soils tend to contain multiple contaminants, and therefore, single-phase adsorbents cannot adequately address those mixed contaminants in a water body. In this respect, bi- or multi-functional adsorbents capable of removing multiple contaminants have great merits and practical advantages.

Mono-potassium phosphate (MKP), natural phosphate fertilizer, and red mud (RM) were tested individually and as mixed agents for stabilizing Cd, Pb, and Zn in mine tailings. The mixed stabilizer containing MKP/RM was the most effective among the tested stabilizers. This is based on the efficiency of conversion from the plant-available metal fractions to the non-plant-available metal fractions and on the performances of toxicity characteristic leaching procedure tests. MKP/RM converted Cd and Zn mainly to carbonate and Fe/Mn oxide fractions, and Pb mainly to the residual fraction. When the mine tailings were treated with MKP/RM, the pH value of the stabilized soil increased from 3.4 to 6.4 after 28 days, which is advantageous for plant growth. The X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy, and the sequential extraction results imply that the major stabilization mechanism for Cd and Zn by MKP and RM involves the formation of surface complexes with Fe (hydr)oxides or Fe phosphates. The major stabilization mechanism of Pb by MKP is believed to involve the formation of Pb-phosphate precipitates, and that by RM is proposed to involve the formation of inner sphere complexes with Fe/Al (hydr) oxides or incorporation within the grids of Fe/Al (hydr) oxides or silicate minerals.

The present study investigated fluorene biodegradation by Sphingobacterium sp. KM-02 in the presence of heavy metals. A fluorene-degrading strain of Sphingobacterium was isolated from polycyclic aromatic hydrocarbon-contaminated soil near a mine-impacted area in Korea. When Sphingobacterium sp. KM-02 was grown in a medium with fluorene as the sole carbon source, it removed 78.4% of this compound within 120h. Identification of the metabolic intermediates (9-fluorenone, 4-hydroxy-9-fluorenone, and 8-hydroxy-3,4-benzocoumarin) were also performed. Composting experiments under laboratory conditions indicated that this microbe also removed fluorene from contaminated soil. In particular, treatment of microcosm soil with strain KM-02 for 20 days resulted in a 65.6% reduction of fluorene concentration. Experiments of effects of heavy metals on fluorene removal by strain KM-02 showed that 10mg/L cadmium, copper, zinc, and lead, reduced growth and fluorene degradation by this microbe. Cadmium and copper had strong effects at 10mg/L, although zinc and lead had relatively slight inhibitory effect at concentrations of 10 and 100mg/L. Arsenic had no effect on the growth or fluorene degradation, even at 100mg/L.

To determine the characteristics of metal pollution sources in Ulsan Bay, East Sea, 39 surface and nine core sediments were collected within the bay and offshore area, and analyzed for metals and stable lead (Pb) isotopes. Most surface sediments (>95% from 48 sites) had high copper (Cu), zinc (Zn), cadmium (Cd), and Pb concentrations that were as much as 1.3 times higher than background values. The primary source of metal contamination came from activities related to nonferrous metal refineries near Onsan Harbor, and the next largest source was from shipbuilding companies located at the mouth of the Taehwa River. Three different anthropogenic sources and background sediments could be identified as end-members using Pb isotopes. Isotopic ratios for the anthropogenic Pb revealed that the sources were imported ores from Australia, Peru, and the United States. In addition, Pb isotopes of anthropogenic Pb discharged from Ulsan Bay toward offshore could be determined.