• The Journal of Engineering Geology
• /
• 제28권3호
• /
• pp.501-512
• /
• 2018

The acid leachate derived from the sulfide mineral such as pyrite can cause problems such as aging of infrastructure and environment contamination around the civil construction site. The purpose of this study is to assess the environmental effect of an acid leachate derived from pyrite in the Miryang area under road construction. In this study, 13 samples of situ core were used for the net acid generation (NAG) experiment. The chemical composition including pH, oxidation and reduction potential (ORP) and electrical conductance of water samples produced from the NAG test was analyzed. In additional, five polished thin sections of rock cores were made for electro microprobe analyses. In the results of the NAG tests, 7 samples showed lower values than pH 3.5. It strongly indicated that these areas are under the environmental and infrastructure damage by the acid leachate. The chemical type of the 7 samples was classified as the $Fe(Ca)-SO_4$ type, which is totally a different type compared to general groundwater. The concentration of total sulfur ranges from 0.004% to 12.5%. 6 rock samples are plotted on a potentially acid forming zone in the relation diagram between the total sulfide and NAG-pH. In conclusion, it is suggested that a protection method against an environmental demage and an infrastructure corrosions by the acid leachate should be prepared in all of areas under a road construction.

• Journal of Soil and Groundwater Environment
• /
• 제11권6호
• /
• pp.69-75
• /
• 2006

Improper disposal of petroleum and spills from underground storage tanks have created large areas with highly toxic contamination of the soil and groundwater. Methyl tert-butyl ether (MTBE) is widely used as a fuel additive because of its advantageous properties of increasing the octane value and reducing carbon monoxide and hydrocarbon exhausts. However, MTBE is categorized as a possible human carcinogen. This research investigated the Modified Photo-Fenton system which is based on the Modified Fenton reaction and UV light irradiation. The Modified Fenton reaction is effective for MTBE degradation near a neutral pH, using the ferric ion complex composed of a ferric ion and environmentally friendly organic chelating agents. This research was intended to treat high concentrations of MTBE; thus, 1,000 mg/L MTBE was chosen. The objectives of this research are to find the optimal reaction conditions and to elucidate the kinetic and mechanism of MTBE degradation by the Modified Photo-Fenton reaction. Based on the results of experiments, citrate was chosen among eight chelating agents as the candidate for the Modified Photo-Fenton reaction because it has a relatively higher final pH and MTBE removal efficiency than the others, and it has a relatively low toxicity and is rapidly biodegradable. MTBE degradation was found to follow pseudo-first-order kinetics. Under the optimum conditions, [$Fe^{3+}$] : [Citrate] = 1 mM: 4 mM, 3% $H_2O_2$, 17.4 kWh/L UV dose, and initial pH 6.0, the 1000 ppm MTBE was degraded by 86.75% within 6 hours and 99.99% within 16 hours. The final pH value was 6.02. The degradation mechanism of MTBE by the Modified Photo-Fenton Reaction included two diverse pathways and tert-butyl formate (TBF) was identified to be the major degradation intermediate. Attributed to the high solubility, stability, and reactivity of the ferric-citrate complexes in the near neutral condition, this Modified Photo-Fenton reaction is a promising treatment process for high concentrations of MTBE under or near a neutral pH.

• Journal of Korea Soil Environment Society
• /
• 제1권1호
• /
• pp.67-79
• /
• 1996

Clay soils typically have low hydraulic conductivities in the presence of high polarity pore fluid, such as water. Low polarity fluids, such as hydrocarbon fuels and halogenated organic solvents, typically cannot migrate into clay pores because they cannot displace the pore water. Oxygenated additives in gasoline, such as alcohols and methyl-tert-butyl ether, are increasingly used to control air pollution emissions. These relatively polar and highly water-soluble compounds may facilitate displacement of pore water and enhance migration of fuels and solvents through clay-rich soil strata. In the reported research, the migration of gasoline-alcohol fuel mixtures (gasohol) through consolidated clay was examined. Prepared kaolinite clay samples were consolidated from slurry, and various combinations of gasoline, alcohol, and water were applied to the clays under 152 Pa gauge pressure. Movement of the fluids into the clay samples was monitored by measur ing displaced pore fluid and by magnetic resonance imaging of the samples. The structures of selected samples were examined using environmental scanning electron microscopy. Results of the research suggest that alcohol added to hydrocarbon fuels can enhance migration through some clays significantly. Gasoline did not migrate appreciably into water saturated clay, even after 14 days under pressure. The gasohol mixture migrated readily into the clay in only 20 minutes. Increased hydraulic conductivity of the clay in the presence of gasohol is hypothesized to be due to the collapse of the clays pore structure when ethanol is present, creating larger pores. Increasing pore diameter decreases the capillary pressure needed for the gasohol to replace water and allows gasohol to migrate through the clay.

• Journal of Korean Society of Environmental Engineers
• /
• 제22권1호
• /
• pp.33-42
• /
• 2000

Adsorption onto the surfaces of solid particles is a well known phenomenon that causes the retardation effect of heavy metals in soils. For adequate remediation of soil and groundwater contamination, it is important to investigate the mobility of heavy metals that largely depends on pH conditions in the soil water since adsorption of heavy metals is pH-dependent. In this study, we investigated the transport of Zn ion under various pH conditions in a sandy soil by conducting batch and column tests. The batch test was performed using the standard procedure of equilibrating fine fractions collected from the soil with eleven different initial $ZnCl_2$ concentrations, and analysis of Zn ion in the equilibrated solutions using ICP-AES. The column test consisted of monitoring the concentrations of soil solutions exiting the soil column with time known as a breakthrough curve (BTC). We injected respectively $ZnCl_2$ and KCl solutions with the concentration of 10 g/L as a tracer in a square pulse type under three different pH conditions (7.7, 5.8, 4.1) and monitored the flux concentration at the exit boundary using an EC meter and ICP-AES. The resident concentration was also monitored at the 10cm-depth by Time Domain Reflectometry (TDR). The results of batch test showed that ion exchange process between Zn and other cations (Ca, Mg) was predominant. The retardation coefficients obtained from adsorption isotherms (Linear, Freundlich, Langmuir) resulted in the various values ranging from 1.2 to 614.1. No retardation effect but ion exchange was found for the BTCs under all pH conditions. This can be explained by the absence of other cations to desorb Zn ion from soil exchange sites under the conditions of ETC experiment imposing blank water as leachate in steady-state flow. As pH decreased, the peak concentration of Zn increased due to the competition of Zn with hydrogen ions ($H^+$) and the concentrations of other cations decreased. The peak concentration of Zn was increased by 12.7 times as pH decreased from 7.7 to 4.1.

• Korean Journal of Environmental Agriculture
• /
• 제24권3호
• /
• pp.253-260
• /
• 2005

Salt accumulation in the plastic film house soils under continuous cultivation condition causes problems such as salt damages to plants, nitrate accumulation in vegetables, groundwater contamination, etc. due to excess application of fertilizers. Objective of this research was to find an optimum adsorbent to reduce salt concentration in the soil solution of plastic film house soils, where crop injuries have been observed due to the salt accumulation. The soils were significantly high in available P $(1,431{\sim}6,516mg\;kg^{-1}),\;NO_3-N\;(117.60{\sim}395.73mg\;kg^{-1})$, exchangeable Ca $(4.06{\sim}11.07\;cmol_c\;kg^{-1})$ and Mg $(2.59{\sim}18.76\;cmol_c\;kg^{-1})$, as compared to those of the average upland soils in Korea. Soils were treated with each of adsorbent such as ion-exchange resin, zeolite, rice bran, etc. at 2% level and prepared into saturated-paste samples. After equilibrium, soil solution was vacuum-extracted from the soil and measured for changes of the pH, EC, and concentrations of $Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+,\;{NH_4}^+,\;{PO_4}^{3-}\;and\;{NO_3}^-$. Rice bran effectively removed ${PO_4}^{3-}\;and\;{NO_3}^-$ in the soil solution up to 100%. Efficiency was decreased in the orders of rice bran > ion-exchange resin > zeolite. Removal efficiencies of zeolite and ion-exchange resin for $Ca^{2+}$ were ranged from 1 to 65% and from 7 to 61%, respectively. Ion-exchange resin was also effective for removing $Mg^{2+},\;K^+,\;Na^+,\;and\;{NH_4}^+$. Overall results demonstrated that rice bran and ion-exchange resin could be applicable for salt accumulated soil to remove the respective anion and cation.

• Economic and Environmental Geology
• /
• 제56권6호
• /
• pp.715-728
• /
• 2023

Tracksite of pterosaurs, birds, and dinosaurs in Chungmugong-dong in Jinju was designated as a natural monument in 2011 and is known as the world's largest in terms of the number and density of pterosaur footprints. This site has been managed by installing protection buildings to conserve in 2018. About 17% of the footprints of pterosaur, theropod, and ornithopod in this site under management in the 2nd protection building are of great academic value, but observation of footprints has difficulties due to continuous physical and chemical damage. In particular, the accumulation of milk-white contaminants is formed by the gypsum and air pollutant complex. Gypsum remains evaporated with a plate or columnar shape in the process of water circulation around the 2nd protection building, and the dust is from through the inflow of the gallery windows. The aqueous solution of gypsum, consisting of calcium from the lower bed and sulfur from grass growth, is catchmented into the groundwater from the area behind the protection building. Pollen and a few minerals other constituents of contaminants, go through the gallery window, which makes it difficult to expel dust. To conserve the fossil-bearing beds from two contaminants of different origins, controlling the water and atmospheric circulation of the 2nd protection building and removing the contaminants continuously is necessary. When cleaning contaminants, the steam cleaning method is sufficiently effective for powder-shaped milk-white contaminants. The fossil-bearing bed consists of dark gray shale with high laser absorption power; the laser cleaning method accompanies physical loss to fossils and sedimentary structures; therefore, avoiding it as much as possible is desirable.

• Economic and Environmental Geology
• /
• 제53권5호
• /
• pp.529-542
• /
• 2020

The cesium (Cs) sorption characteristics of a bead-type polysulfone carrier contained HNO₃-treated bamboo charcoal (3 - 5 mm in diameter) in water system were investigated and its Cs removal efficiency as an adsorbent from water was also identified by various laboratory experiments. From the results of batch sorption experiments, the bead-type polysulfone carrier with only 5% HNO₃-treated bamboo charcoal (P-5NBC) represented the high Cs removal efficiency of 57.8% for 1 hour sorption time. The Cs removal efficiency of P-5NBC in water after 24 hours reaction maintained > 69% at a wide range of pH and temperature conditions, attesting to its applicability under various water systems. Batch sorption experiments were repeated for P-5NBC coated with two cultivated microorganisms (Pseudomonas fluorescens and Bacillus drentensis), which were typical indigenous species inhabited in soil and groundwater. The Cs removal efficiency for two microorganisms coated polysulfone carrier (BP-5NBC) additionally increased by 19% and 18%, respectively, compared to that of only P-5NBC without microorganisms coated. The average Cs desorption rate of P-5NBC for 24 h was lower than 16%, showing the Cs was stably attached on HNO₃-treated bamboo charcoal in so much as its long-term use. The maximum Cs sorption capacity (q_m) of P-5NBC calculated from the Langmuir isotherm model study was 60.9 mg/g, which was much higher than those of other adsorbents from previous studies for 1 h sorption time. The results of continuous column experiments showed that the P-5NBC coated with microorganisms packed in the column maintained > 80% of the Cs removal efficiency during 100 pore volumes flushing. It suggested that only 14.7 g of P-5NBC (only 0.75 g of HNO₃ treated bamboo charcoal included) can successfully clean-up 7.2 L of Cs contaminated water (the initial Cs concentration: 1 mg/L; the effluent concentration: < 0.2 mg/L). The present results suggested that the Cs contaminated water can be successfully cleaned up by using a small amount of the polysulfone carrier with HNO₃-treated bamboo charcoal.