• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.37-46
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• 2007

A feasibility test was conducted to evaluate the addition of turbidity substance in a coagulation process to remove natural organic matters (NOM), the precursor of disinfection by-products (DBPs). The experimental water sources were synthetic water containing 5 mg/L of humic acid and 50 mg/L of NaHCO3 and drinking water resource of Ulsan city (S Dam water, D Dam water and Nak-Dong raw water). The examined turbidity substances were kaolin, acid clay, and modified clay (0.38 meq $NH_4{^+}-N/g$ clay). In Jar tests at different concentrations of the turbidity substances (5, 10, 15, 20, 30 mg/L) using the synthetic water, the turbidity substances improved the removal of turbidity, UV-254 absorbance and dissolved organic carbon (DOC) by 23.8-38.1%, 17.0-24.5% and 2.5-44.5%, respectively. The modified clay showed higher removal efficiencies than other substances. In Jar tests using the drinking water, 10 and 20 mg/L of modified clay enhanced the removal efficiencies of turbidity, UV-254 absorbance, DOC, trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) by 3.0~4.3%, 19.1~29.0%, 12~34.9%, 4.9~36.7%, and 1.6~30.2%, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.445-453
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• 2012

An investigation for removal of 1-indanone (1-ID), which were commonly produced from the biological and/or chemical treatment and natural weathering of the PAHs-contaminated soils, via oxidative transformation mediated by birnessite in the presence of various phenolic mediators is described. This study also examines the potential effect of the natural occurring substance humic acid (HA) on the oxidative transformation. The experiment was carried out in aqueous phase as a batch test (10 mg/L 1-ID, 0.3 mM phenolic mediators, $1.0g/L\;{\delta}-MnO_2$, at pH 5). All of the 11 tested phenoilic mediators belong to the group of natural occurring phenols and are widely used as model constituents of humic substances. From the results of HPLC analysis, it is demonstrated that 1-ID was not reactive to birnessite itself, but it can be effectively removed in birnessite-mediated cross coupling reactions in the presence of the phenolic mediators. The percent removals of 1-ID after 2 day incubation were ranged from 9.2 to 71.2% depending on the phenolic mediators applied. The initial rate constant ($K_{int}$, $hr^{-1}$) values for the 1-ID removals obtained from the pseudo-first-order kinetic plots also widely ranged from 0.18 to 15.0. Results of the correlative analysis between the removal efficiencies and structural characteristics of phenolic mediators indicate that the transformation of the 1-ID was considerably enhanced by the addition of electron-donating substituents (e.g., -OH, $-OCH_3$) at the benzne ring, and much less enhanced by the addition of electron-withdrawing substituents (e.g., -COOH, -CHO). The presence of HA showed that removal efficiencies of 1-ID in the birnessite-phenolic mediator systems decreased with increasing HA concentrations. However at low concentration of HA (< 2 mg/L), it caused some enhancement in the removals of 1-ID as compared to the control.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.16-23
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• 2011

BACKGROUND: This study was conducted to investigate the effects of different organic treatments and a chemical fertilizer on the soil chemical, physical, and microbial properties in an organic pear orchard. METHODS AND RESULTS: Control was referred as a NPK chemical fertilizer (15N-9P-10K) and organic treatments included compost containing with oil cake, compost containing with humic acid, and compost containing with chitin substance. All treatments applied at rates equivalent to 200 g N per tree per year under the tree canopy in March 30 of 2008 and 2009. Soil bulk density, solid phase, liquid phase, and penetration resistance were not significantly different among the treatments. Organic treatment plots had greater organic matter, total nitrogen, potassium, and magnesium concentrations compared to control, and the nutrient concentrations were not consistently affected by the organic treatments. Microbial biomass nitrogen and carbon, dehydrogenase, acid-phosphatase, and chitinase activities overall increased from March to August. Organic treatments, especially compost containing with oil cake or chitin aicd, increased the microbial variables compared to control. CONCLUSION(s): All the organic treatments consistently stimulated soil biological activity. The consistent treatment effect, however, did not occur on the soil mineral nutrition as the trees actively taken up the nutrients during a growing season, which would have diminished treatment effects. Long-term study required for evaluating soil physical properties in a pear orchard.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.712-720
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• 2022

In this study, we evaluated the production and photoreactivity of CDOM of two polar phytoplanktons - Phaeocystis antarctica and Phaeocystis pouchetii, in order to find out UV effects on phytoplanktons. In visible region, CDOM in media of both phytoplanktons under UV-R decreased during 48hrs incubation period. However, in UV region CDOM decreased 30 % in the media of P. antarctica, but increased 10% in media of P. pouchetii, compared to CDOM concentrations of control after 48 hr incubation. This result indicates that biota in polar environment would not well protected from UV-R harmful effect when P. antarctica is dominant because of loss of CDOM, but when P. pouchetii is dominant species, production of UV absorbing organic matter could play more efficiently for UV screening for marine biota. Also we confirmed that FDOM of humic substance (C-peak) produced by these phtoplanktons under UV-R stress were well matched with fluorescence characteristics of the UV-protecting compound, MAAs. This finding shows that Phaeocystis pouchetti with low photoreactivity would contribute to DOM pool of polar marine environment under stratification by global warming.

• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.145-152
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• 2000

In order to select an effective antibiotic substance against oral resident bacteria, we were isolated from soil and texonomically analyzed. Seven hundred and eighteen strains were isolated on humic acid- vitamin agar(HV agar) and 220 strains were on methanol medium from three each paddy forest, field and riverside soil samples. So, during the screening of antibiotics from soil, we isolated microorganisms showing powerful antagonistic activity against oral resident bacteria. Microorganism was tested against 25 strains of bacteria, yeast and fungi. Among them, No. 248 strain exhibited the most strongly growth inhibition. So, the taxonomical analysis the isolated strain was found to be unknown Actinomyces sp. and was named No 248. A production of the antibiotics from No. 248 begins at the early exponential phase developed at the 72th hour under the optinum conditions. The property of No. 248 antimicrobial compound was very stable under acid(pH 3.0) and alkali(pH 10.0) treatment, but it was instable in heat treatment at $120^{\circ}C$. For the improvement of antibiotic activity, two mutants were isolated from strain No. 248 by the treatment of mutagenic agents, NTG and hydroxylamine. As a result, the mutant strains excreted the potent antibiotics to inhibit the growth of Candida albicans.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.23-29
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• 1997

The main reason of applying chlorination is to sterilize microbes existing in the drinking water treatment. But chlorination could lead to the formation of disinfection by-products (DBPs) by the reaction of free chlorine with humic substance in the water. Especially the DBPs including trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and haloketones (HKs) exist in the tap water. The US environmental protection agency (US EPA) defines that trihalomethanes, dichloroacetic acid, trichloroacetic acid, and dichloroacetonitrile among DBPs are probable/possible human carcinogens. US EPA suggests maximum contaminant levels (MCLs) for THMs (80$\mu$g/L) and HAAs (60$\mu$g/L) in drinking water. In Korea, THMs in drinking water has been surveyed but DBPs in general has not been studied in drinking water practically. Therefore only THMs have been regulating as criteria compounds since 1990 but neither HAAs nor HANs. Researches on HAAs are yet to be found. HAA formation potentials(HAAFPs) have not been practiced. HAAs depends on the characteristics of water sources by chlorination. In this study, HAAFPs from three distinct sources were investigated by laboratory chlorination experiments. This study was performed to measure the level of HAAs in drinking water in Seoul area. At April 1996, after collecting the raw waters from the three sites with the different properties, the water samples were chlorinated at various conditions(pH 5.5, pH 7.0 and without pH adjustment) in the state of raw water to have 0. 5mg/L of residual chlorine concentration. And the raw water, treated water, and tap water of water treatment were collected to measure the HAAs concentration. The quantitative analysis of HAAs was conducted by US EPA methods.

• Ocean and Polar Research
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• v.29 no.2
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• pp.87-99
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• 2007

This study was conducted to understand the source and behavior of organic matter using the fluorescent technique (excitation-emission matrix) as a part of environmental monitoring program in the Korea manganese nodule mining site in the Northeastern Pacific Ocean. Water samples were collected at $0^{\circ},\;6^{\circ}N$, and $10.5^{\circ}N$ along $131.5^{\circ}W$ in August 2005. The concentration of total organic carbon (TOC) ranged from 58.01 to $171.93\;{\mu}M-C$. The vertical distribution of TOC was characterized as higher in the surface layer and decreased with depth. At $6^{\circ}N$, depth-integrated (from surface to 200 m depth) TOC was $337.1\;gC/m^2$, which was 1.4 times higher value than other stations. The exponential decay curve fit of vertical profile of TOC indicated that 59% of organic carbon produced by primary production in the surface layer could be decomposed by bacteria in the water column. Dissolved organic matter is generally classified into two distinctive groups based on their fluorescence characteristics using three-dimensional excitation/emission (Ex/Em) fluorescence mapping technique. One is known as biomacromolecule (BM; protein-like substance; showing max. at Ex 280/Em 330), mainly originated from biological metabolism. The other is geomacromolecule (GM; humic-like substance; showing max. at Ex 330/Em 430), mainly originated from microbial degradation processes. The concentration of BM and GM was from 0.42 to 7.29 TU (tryptophan unit) and from 0.06 to 1.81 QSU (quinine sulfate unit), respectively. The vertical distribution of BM was similar to that of TOC as high in the surface and decreased with depth. However, the vertical distribution of GM showed the reverse pattern of that of BM. From these results, it appeared that BM occupied a major part of TOC and was rapidly consumed by bacteria in the surface layer. GM was mainly transformed from BM by microbial processes and was a dominant component of TOC in the deep-sea layer.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.484-489
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• 2005

In order to determine the removal rate of non-biodegradable substances and the change of their structural properties, this study was carried out by an ozone-treatment experiment on leachate collected from the landfill area of D City in Chung chung nam-do and examined the change of the chemical properties of non-biodegradable substances. The main elements of non-biodegradable substances in landfill leachate were benzene, toluene, trichloroethane, trichloroethylene, xylene, etc. and the concentration of toluene was 15.7 mg/L on the average, benzene 7.2 mg/L, trichloroethane 1.1 mg/L, trichloroethylene 0.75 mg/L and xylene 0.5 mg/L. When leachate was treated with ozone for 10 min, 30 min and 60 min, UV absorbance was reduced with the increase of reaction time, and the reduction rate was 38.6% at 60 min. TOC was removed by 13.2% at 60 min. The low reduction rate of TOC may be because TOC reacts indirectly with OH radical produced from reaction with ozone while UV absorbance usually relies on direct reaction between organic matters and ozone molecules. Color was removed by up to 97%, which suggests that ozonation is highly effective in removing coloring elements in leachate. Sixteen kinds of non-biodegradable compounds were found in the leachate and most of them had the characteristic of aromatic hydrocarbon. Among them dibutyl phthalate was identical with a substance included in the list of US EPA, which is classified as a mutagen that may cause the mutation of genes and disorders in chromosomes. In addition, 2,5-Cyclohexadiene-1,4-dione, 1,2-Benzenedicarboxylic acid and butyl octyl ester were found to be similar to substances listed by USEPA. According to the result of analyzing structural changes before and after ozonation using GC-MS, cyclic compounds and aromatic compounds were observed in the original water and aliphatic compounds were newly observed after ozonation. In addition, through ozonation, humic substances of high molecular weight were oxidized and decomposed and produced low-molecular compounds such as aldehyde, ketone and carboxyl acid and highly biodegradable aliphatic carbon, which suggests the bio-degradability of non-biodegradable substances.

• 한국해양학회지
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• v.29 no.2
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• pp.171-182
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• 1994

Dissolved free amino acid (DFAA) dissolved hydrolyzable amino acid (DHAA) and D/L amino acid racemic ratio in the dissolved organic compounds were studied to investigate the biogeochemical characteristics of dissolved organic compound in the Yellow Sea. Concentration of total DFAA ranged from 0.06 uM to 0.26 uM in the study area. DFAA composition showed that aspiratae, glutamate, serine, glycine and alanine were predominant. According to characteristics of functional group of amino acid, these belonged to hydroponic group. C-18 short column cartridge (Sep-Pak) activated by methanol was used to extract organic macromolecules in the seawater. In operational scheme, macromolecules were divided into two fractions. Geomacromolecule fraction eluted with 50% methanol was used to extract organic macromolecules in the seawater. In operational scheme, macromolecules were divided into two fractions. Geomacromolecule fraction eluted with 50% methanol was moderately hydrophilic and showed characteristics of humic substance in the seawater. Biomacromolecule fraction eluted with 100% methanol was hydrophobic and most abundant in the surface seawater samples. DHAA was much higher than DFAA in this study area. DHAA ranged from 2.05 uM to 6.19 uM in the B-fraction and from 8.13 uM to 24.46 uM in the G-fraction. DHAA was higher in the surface water than in the bottom water where the vertical stratification developed well. The result of HPLC analysis of D/L amino acid showed that low racemic ratio was found in the B-fraction. It implies that the B-fraction is relatively younger than the G-fraction and freshly derived from biosphere.

• Particle and aerosol research
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• v.15 no.3
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• pp.91-104
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• 2019

In this study, hourly measurements of $PM_{2.5}$ and its major chemical constituents such as organic and elemental carbon (OC and EC), and ionic species were made between January 15 and February 10, 2018 at the air pollution intensive monitering station in Gwangju. In addition, 24-hr integrated $PM_{2.5}$ samples were collected at the same site and analyzed for OC, EC, water-soluble OC (WSOC), humic-like substance (HULIS), and ionic species. Over the whole study period, the organic aerosols (=$1.6{\times}OC$) and $NO_3{^-}$ concentrations contributed 26.6% and 21.0% to $PM_{2.5}$, respectively. OC and EC concentrations were mainly attributed to traffic emissions with some contribution from biomass burning emissions. Moreover, strong correlations of OC with WSOC, HULIS, and $NO_3{^-}$ suggest that some of the organic aerosols were likely formed through atmospheric oxidation processes of hydrocarbon compounds from traffic emissions. For the period between January 18 and 22 when $PM_{2.5}$ pollution episode occurred, concentrations of three secondary ionic species ($=SO{_4}^{2-}+NO_3{^-}+NH_4{^+}$) and organic matter contributed on average 50.8 and 20.1% of $PM_{2.5}$, respectively, with the highest contribution from $NO_3{^-}$. Synoptic charts, air mass backward trajectories, and local meteorological conditions supported that high $PM_{2.5}$ pollution was resulted from long-range transport of haze particles lingering over northeastern China, accumulation of local emissions, and local production of secondary aerosols. During the $PM_{2.5}$ pollution episode, enhanced $SO{_4}^{2-}$ was more due to the long-range transport of aerosol particles from China rather than local secondary production from $SO_2$. Increasing rate in $NO_3{^-}$ was substantially greater than $NO_2$ and $SO{_4}^{2-}$ increasing rates, suggesting that the increased concentration of $NO_3{^-}$ during the pollution episode was attributed to enhanced formation of local $NO_3{^-}$ through heterogenous reactions of $NO_2$, rather than impact by long-range transportation from China.