• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.04a
• /
• pp.42-45
• /
• 2005

Accurate prediction of the fate and transport of contaminants in soils and sediments is very Important to environmental risk assessment and effective remediation of contaminated soils and sediments. The fate and transport of contaminants in subsurface are affected by geosorbents, especially carbonaceous materials including black carbon. Various physical and chemical treatment methods have been developed to separate different kinds of carbonaceous materials from soils and sediments. However, the effects of these separation methods on the properties of remaining carbonaceous materials including sorption capacity and linearity are unclear. The objective of this study is to determine if the chemical and thermal treatment methods previously used to separate different carbonaceous material fractions affect the properties of carbonaceous materials including longer term sorption capacity of hydrophobic organic contaminants. The results indicate that treatments with hydrochloric acid (HCl)/hydrofluoric acid (HF), trifluoroacetic acid (TFA), sodium hydroxide (NaOH) may not affect the sorption capacity of black carbon reference materials such as char and soot, however, treatments with acid dichromate $(K_2Cr_2O_7/H_2SO_4)$ and heat $(375^{\circ}C)$ for 24 hours in sufficient of oxygen) decrease the sorption capacity of them. The results of longer term sorption isotherm indicate that 2 days might be enough for trichloroethene (TCE) to equilibrate apparently with treated black carbon reference materials. The results suggest that acid dichromate and heat treatments may not appropriate method to investigate sorption properties of black carbon in soils and sediments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.434-437
• /
• 2003

The fate and the behavior of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the environment are mainly controlled by their interactions with various components of soils and sediments. Due to their large surface area and abundance in many soils, smectites may greatly influence the fate and transport of the contaminants in the environment. In our experiment, PAH sorption by hexadecyltrimethylammonium (HDTMA)-modified smectite linearly increased in proportion to the amount of HDTMA added on the clay. However, trimethylammonium (TMA)-modified smectite did not show superiority in its sorption of PAH compared with the HDTMA-smectite or dodecyltrimethylammonium (DTMA)-smectite. Meanwhile, the smectites modified with the same cationic surfactants adsorbed Cd$^{2+}$ (heavy metal) significantly from water at low surfactant loading level, but the Cd$^{2+}$ adsorption linearly decreased as the loading of surfactant increased. The result shows that the sorption tendency of organoclays for organic or inorganic contaminants was significantly influenced by the amount and size of the surfactants added on the clay. It means that the stabilization and configuration of cationic surfactant formed on the clay interlayer according to the loading amount of each surfactant of different sizes may be an important factor in effectively sorbing environmental pollutants.nts.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.3
• /
• pp.35-45
• /
• 2021

Digestate or slurry produced from anaerobic digestion is mostly applied to crop lands for its disposal and recovering nutrients. However, minimizing nitrogen losses following field application of the digestate is important for maximizing the plant's nitrogen uptake and reducing environmental concerns. This study was conducted to assess the effects of three different biogas digestate application techniques (sawdust mixed with digestate (SSD), the hole application method (HA), and digestate injected in the soil (SD)) on nitrate leaching potential in the soil. A pot laboratory experiment was conducted at room temperature of 25 ± 2 ℃ for 107 days. The experimental results showed that sawdust application method turned out to be appropriate for quick immobilization of surplus N in the form of microbial biomass N, reflecting its lower total nitrogen and NH₄-N contents and low pH. The NH₄-N and total nitrogen fate in the soil fertilized with manure showed no statistically significant (p > 0.05) differences between the different methods applied during the incubation time under room temperature. In contrast, NO₃-N concentration indicates significant reduction in sawdust treatment (p < 0.05) compared to the control and other application methods. However, the soil sawdust mixed with digestate was more effective than the other methods, because of the cumulative labile carbon contents of the amendment, which implies soil net N immobilization.

• Environmental Analysis Health and Toxicology
• /
• v.28
• /
• pp.6.1-6.7
• /
• 2013

Objectives In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs). Methods Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively. Results The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory. Conclusions This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

• Journal of Environmental Health Sciences
• /
• v.25 no.3
• /
• pp.7-12
• /
• 1999

Bioremediation is the technology to harness nature's biodegradative capabilities to remove or detoxify pollutions that threaten public health as environmental contaminants. Composting may become one of major bioremediation technologies for treating soils contaminated with petroleum if the fate of contaminants during composting is better understood Most composting research of petroleum was primarily focused on removing contaminant by optimizing composting conditions. Accordingly, laboratory feasibility studies may be useful to establish a realistic basis in co-composting complex substrate such as petroleum hydrocarbons. The purpose of this study was to assess the optimal conditions of kerosene biodegradation following supplementation with nutrient amendments under simulated composting conditions. Although it increased the growth of bacterial consortium, addition of co-substrates 0.5%(w/v) such as acetic acid, citric acid, glucose, and malic acid was not beneficial. Combination of nitrogen and phosphorous source enhanced kerosene biodegradation and reduced VOC evolution. These results showed that kerosene was able to utilize in bioremediation technology.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.318-322
• /
• 2004

Arsenic is a toxic and carcinogenic metalloid, whose sources in nature include mineral dissolution and volcanic eruption. Abandoned mines and hazardous waste disposal sites are another major source of arsenic contamination of soil and aquatic systems. To predict concentrations of the toxic inorganic arsenic in aqueous phase. the biogeochemical redox processes and transport behavior need to be studied together and be coupled in a reactive transport model. A new reaction module describing the fate and transport of inorganic arsenic species (As(II)), dissolved oxygen, nitrate, ferrous iron, sulfate, and dissolved organic carbon are developed and incorporated into the RT3D code.

• Journal of Environmental Science International
• /
• v.17 no.3
• /
• pp.343-350
• /
• 2008

The fate of two cyclic ethers, THF(Tetrahydrofuran) and 1,4-Dioxane, in conventional biological wastewater treatment plants was investigated using sequential activated sludge process. Removal efficiency of THF were about 86% in average, which was greater than that of 1,4-Dioxane, 30%. However, it was not clear whether the removal of cyclic ethers in biological system was caused by microbial activity or not. Thus treatability tests were conducted by batch experiments. The effects of mixing, aeration and the addition of activated sludge on the removal of cyclic ethers were investigated in batch experiments. THF was totally removed by mixing and aeration in 24 hours while removal ratio of 1,4-Dioxane was at most 30% for the same period. This results could be ascribed to the differences in Henry's law constants between the two chemicals. In addition, biological degradation including biosorption was not obviously observed in these batch tests.

• Economic and Environmental Geology
• /
• v.38 no.5 s.174
• /
• pp.587-597
• /
• 2005

This review deals with arsenic chemistry and its occurrence in groundwater. Specifically, the paper gives an overview regarding chemical and physical properties of arsenic species, oxidation of As(III), geochemical processes related to the fate and transport of arsenic, arsenic leaching from soil, and mechanism of arsenic leaching from arsenic-containing minerals.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.10
• /
• pp.1311-1323
• /
• 2012

In the present work, current knowledge on the potential fate, microbial degradation, and toxicity of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was thoroughly reviewed, focusing on the toxicological assessment of a variety of potential RDX degradation pathways in bacteria and fungi. The present review on microbial degradation pathways and toxicities of degradation intermediates suggests that, among aerobic RDX degradation pathways, the one via denitration may be preferred in a toxicological perspective, and that among anaerobic pathways, those forming 4-nitro-2,4-diazabutanal (NDAB) via ring cleavage of 1-nitroso-3,5-dinitro-1,3,5-triazinane (MNX) may be toxicologically advantageous owing to its potential mineralization under partial or complete anoxic conditions. These findings provide important information on RDX-degrading microbial pathways, toxicologically most suitable to be stimulated in contaminated fields.

• Environmental Analysis Health and Toxicology
• /
• v.20 no.2 s.49
• /
• pp.109-121
• /
• 2005

A chemical ranking and scoring (CRS-Korea) system was developed and proposed to use as the first step to prioritize the toxic chemicals for the purpose of monitoring and detailed risk assessment that might follow as necessary. The CRS-Korea system takes a basic concept of risk assessment (both human health risk and ecological risk) in that risk score is determined by the product of toxicity score and exposure score. Included in the toxicity category are acute toxicity, chronic/sub -chronic toxicity, carcinogenicity, and other toxicity. The exposure category consists of quantity released to the environment, bioconcentration, and persistence. A consistent scheme and a comprehensive chemical data base are offered in the CRS-Korea system to calculate a score for the each component in the two categories by using specific physicochemical, fate, and toxic properties and the quantity of the chemical used. The toxicity score is obtained by adding up all the individual scores for the components in the toxicity category. The exposure score is determined by multiplication of the score of the quantity released with the sum of persistent score and bioconcentration score. Equal weight is given to the toxicity score and the exposure score. As the CRS-Korea system was applied to identify 50 national priority chemicals, it was found that significant data gap exists on toxicity and fate properties and that the uncertainty associated with estimating the quantify released to the environment is notably high. The proposed CRS system is only a screening tool in the first step toward the priority setting and should be used with expert judgement and other considerations necessary.