• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.943-953
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• 2021

The purpose of this study is to investigate sediment recovery after the relocation of fish cage farms, by examining the changes in sediments and the benthic polychaete community. A preliminary survey was carried out in October 2017, before the relocation of the farms, and monthly surveys were conducted from November 2017 to October 2018 after the farms were moved. Subsequently, it was conducted every 2-3 months until October 2020. The survey was carried out at three stations (Farm1-3) at the location of the removed fish farms and at three control stations (Con1-3) without farms. The overall organic carbon content of the farm stations was higher than the control stations, but it gradually decreased after the farm was demolished, and there was no statistically significant difference about one year after the relocation of the farms (p<0.05). In the benthic polychaete community, abiotic community appeared at the farm stations in the summer, and consequently, the community transitioned to a low-diversity region with the predominant species Capitella capitata, which is an indicator of pollution. Until the abiotic period in the summer of the next year, the species diversity increased and the proportion of indicator species decreased, showing a tendency of recovering the benthic polychaete community, and these changes were repeated every year. In this study, the abiotic community appeared every year owing to the topographical characteristics, but as the survey progressed, the period of abiotic occurrence became shorter and the process of community recovery progressed expeditiously. Biological recovery of sediments after the relocation of the fish farms is still in progress, and it is imperative to study recovery trends through continuous monitoring.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.306-314
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• 2023

Stream sediments are an important component of water quality management because they are receptors of various pollutants such as heavy metals and organic matters emitted from upland sources and can be secondary pollution sources, adversely affecting water environment. To effectively manage the stream sediments, identification of primary sources of sediment contamination and source-associated control strategies will be required. We evaluated the performance of machine learning models in identifying primary sources of sediment contamination based on the physico-chemical properties of stream sediments. A total of 356 stream sediment data sets of 18 quality parameters including 10 heavy metal species(Cd, Cu, Pb, Ni, As, Zn, Cr, Hg, Li, and Al), 3 soil parameters(clay, silt, and sand fractions), and 5 water quality parameters(water content, loss on ignition, total organic carbon, total nitrogen, and total phosphorous) were collected near abandoned metal mines and industrial complexes across the four major river basins in Korea. Two machine learning algorithms, linear discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the sediments into four cases of different combinations of the sampling period and locations (i.e., mine in dry season, mine in wet season, industrial complex in dry season, and　industrial complex in wet season). Both models showed good performance in the classification, with SVM outperformed LDA; the accuracy values of LDA and SVM were 79.5% and 88.1%, respectively. An SVM ensemble model was used for multi-label classification of the multiple contamination sources inlcuding landuses in the upland areas within 1 km radius from the sampling sites. The results showed that the multi-label classifier was comparable performance with sinlgle-label SVM in classifying mines and industrial complexes, but was less accurate in classifying dominant land uses (50~60%). The poor performance of the multi-label SVM is likely due to the overfitting caused by small data sets compared to the complexity of the model. A larger data set might increase the performance of the machine learning models in identifying contamination sources.

• Korean Journal of Poultry Science
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• v.50 no.3
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• pp.143-159
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• 2023

The study aimed to evaluate the antioxidative effects of rosemary (Rosmarinus officinalis L.) and clove (Syzgyium aromaticum L.) essential oils on fried Korean native thigh meat, including their impact on processed characteristics and flavor compounds. Clove essential oil showed higher DPPH scavenging activity, FRAP and total phenol content compared to rosemary essential oil (P<0.05). The treatments with the addition of 0.005% and 0.01% rosemary (0.005RB and 0.01RB) and clove (0.005CB and 0.01CB) essential oils to the batter weight compared to control that did not include essential oils in batter. The addition of rosemary and clove essential oils to fried Korean native chicken thigh meat did not significant affect proximate composition, pH, TBARS, sensory characteristics. Except for 0.005CB, treatments adding essential oils decreased cooking loss (P<0.05) and 0.005CB showed significantly higher pick-up value than control. Addition of clove essential oil in fried Korean native chicken thigh meat resulted in higher levels of arachidonic acid compared to control (P<0.05). Volatile organic compounds (VOCs) analysis showed that addition of rosemary essential oil might mask its own VOCs, while clove essential oil addition reduced some pyrazine compounds. Although addition of rosemary and clove essential oil did not have significant sensory characteristics on fried Korean native chicken thigh meat, instrumental analysis revealed changes in the compounds that influenced flavor. Further studies are required to evaluate the stability of flavor and sensory characteristics of fried Korean native chicken thigh meat with added essential oils during storage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.134-144
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• 2009

Paleoproductivity changes in the central part of the Bering Sea since the last glacial period were reconstructed by analyzing opal and total organic carbon (TOC) content and their mass accumulation rate (MAR) in sediment core PC23A. Ages of the sediment were determined by both AMS $^{14}C$ dates using planktonic foraminifera and Last Appearance Datum of radiolaria (L. nipponica sakaii). The core-bottom age was calculated to reach back to 61,000 yr BP. and some of core-top was missing. Opal and TOC contents during the last glacial period varied in a range of 1-10% and 0.2-1.0%, and their average values are 5% and 0.7%, respectively. In contrast, during the last deglaciation, opal and TOC contents varied from 5 to 22% and from 0.8 to 1.2%, respectively, with increasing average values of 8% and 1.0%. Opal and TOC MAR were low ($1gcm^{-2}kyr^{-1}$, $0.2gcm^{-2}kyr^{-1}$) during the last glacial period, but they increased (>5 and >$1gcm^{-2}kyr^{-1}$) during the last deglaciation. High diatom productivity during the last deglaciation was most likely attributed to the elevated nutrient supply to the sea surface resulting from increased melt water input from the nearby land and enhanced Alaskan Stream injection from the south under the restricted sea-ice and warm condition during the rising sea level. On the contrary, low productivity during the last glacial period was mainly due to decreased Alaskan Stream injection during the low sea-level condition as well as to extensive development of sea ice under low-temperature seawater and cold environment.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.13-28
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• 2023

This study assessed the biochemical methane potential (B_u-P) of three grass species-Poa pratensis (PP), Zoysia japonica (ZJ), and Agrostis stolonifera (AS). B_u-P values were determined as 0.330 Nm³/kg-VS_added for PP, 0.297 Nm³/kg-VS_added for ZJ, and 0.261 Nm³/kg-VS_added for AS. Notably, PP exhibited superior suitability for methane production. The investigation also examined the impact of silage storage duration on PP grass clippings, revealing a 19% decline in B_u-P from an initial value of 0.269 Nm³/kg-VS_added on day 0 to 0.217 Nm³/kg-VS_added on day 180. Throughout the storage period, there were significant increases in neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude protein (CP) contents, rising from 67.59%, 39.68%, and 3.02% on day 0 to 77.12%, 54.65%, and 6.24% on day 180, respectively. These findings highlight the influence of storage duration on the anaerobic digestibility of PP grass clippings. To effectively utilize grass clippings as a renewable resource for methane production, further studies considering factors such as initial moisture content, pretreatment methods, and potential effects of residual pesticides are necessary to optimize anaerobic digestion efficiency for herbaceous biomass.

• Journal of Wetlands Research
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• v.26 no.2
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• pp.168-181
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• 2024

Constructed wetlands (CWs) deliver a range of ecosystem services, including the removal of contaminants, sequestration and storage of carbon, and enhancement of biodiversity. These services are facilitated through hydrological and ecological processes such as infiltration, adsorption, water retention, and evapotranspiration by plants and microorganisms. This study investigated the correlations between microbial populations, soil physicochemical properties, and treatment efficiency in a horizontal subsurface flow constructed wetland (HSSF CW) treating runoff from roads and parking lots. The methods employed included storm event monitoring, water quality analysis, soil sampling, soil quality parameter analysis, and microbial analysis. The facility achieved its highest pollutant removal efficiencies during the warm season (>15℃), with rates ranging from 33% to 74% for TSS, COD, TN, TP, and specific heavy metals including Fe, Zn, and Cd. Meanwhile, the highest removal efficiency was 35% for TOC during the cold season (≤15℃). These high removal rates can be attributed to sedimentation, adsorption, precipitation, plant uptake, and microbial transformations within the CW. Soil analysis revealed that the soil from HSSF CW had a soil organic carbon content 3.3 times higher than that of soil collected from a nearby landscape. Stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P) in the inflow and outflow were recorded as C:N:P of 120:1.5:1 and 135.2:0.4:1, respectively, indicating an extremely low proportion of N and P compared to C, which may challenge microbial remediation efficiency. Additionally, microbial analyses indicated that the warm season was more conducive to microorganism growth, with higher abundance, richness, diversity, homogeneity, and evenness of the microbial community, as manifested in the biodiversity indices, compared to the cold season. Pollutants in stormwater runoff entering the HSSF CW fostered microbial growth, particularly for dominant phyla such as Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes, which have shown moderate to strong correlations with specific soil properties and changes in influent-effluent concentrations of water quality parameters.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.4
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• pp.31-37
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• 2010

Livestock manures have a potential to be a valuable resource with an efficient treatment. In Korea, 42 million tons of livestock manure were generated in 2008, and 84 % of them were used for compost and liquid fertilizer production. Recently recycling of livestock manure for biogas production through anaerobic digestion is increasing, but its utilization in agriculture is still uncertified. In this study, there was applied co-digestate to the paddy for rice cultivation based on N supplement. Co-digestate was fertilizer fermented with pig slurry and food waste combined with the ratio of 70:30(v:v) in its volumetric basis. For assessing the safety of co-digestate, it was monitored the contents of co-digestate for seasonal variation, resulted in no potential harm to the soil and plant by heavy metals. The results showed that soil applied with co-digestate was increased in exchangeable potassium, copper and zinc mainly due to the high rate of pig slurry in co-digestate applied. Considering high salt content due to the combination with food waste, strict quality assurances are needed for safe application to arable land though it has valuable fertilizer nutrient. Leachate after treatment showed that the concentration of nitrate nitrogen washed out within two weeks. Considering the salt accumulation results in soil, it is highly recommended that the application rate of co-digestate should not exceed the crop fertilization rate based on N supplement. With these results, it was concluded that co-digestate could be used as an alternative fertilizer for chemical fertilizer. More study is needed for the long-term effects of co-digestate application on the soil and water environment.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.E
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• pp.1-17
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• 2000

In this study, the concentrations of particulate organic constituents of environmental tobacco smoke(ETS) were determined using an environmental smog chamber, where ETS is the sole source of target compounds. ETS was generated in a 30 ㎥ environmental chamber by a number of different cigarettes, including the Kentucky 1R4F reference cigarette and eight commercial brands. A total of 12 experimental runs was conducted, and target analytes included a group of ETS markers both in vapor and particulate phase and a class of polycylic aromatic hydrocarbos(PAHs) associated with ETS particles. The mass concentrations of PAH in ETS particles were also determined. The average contents of benzo(a) pyrene and benzo(a) anthracene in ETS particles for the commercial brands were 12.8 and 21.5$\mu\textrm{g}$/g, respectively, There values are all somewhat higher than those determined previously by other studies. Results form the chamber study are further used to estimate the average and variability of cigarette yields for target compounds associated with ETS. Finally, ratios of RSP to the surrogate standards of UVPM, FPM and solanesol were calculated for each sample. The average conversion factors factors for the eight commercial brands were 7.3, 38, and 41 for UVPM, EPM, and solanesol, respectively. The UVPM and FPM factors are in good agreement with the recently published values. Whereas there might be a substantial difference in the solanesol content among cigarettes produced in different countries, the variability is somewhat greater than those of UVPM and FPM, Unfortunately, comparison of the PAH yield data from this study with literature values was complicated by a lack of consistency in cigarette smoke generating methodology. Validation of the PAH yields was also difficult due to a lack of information on the ETS related PAH in the literature. From and engineering viewpoint , however, these data on the cigarette yields of ETS components may still provide useful information to studies on the mathematical modeling of indoor air quality management regarding tobacco smoke as a source of interest, or to studies on the assessment of human exposure to ETS.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.115-121
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• 1986

This experiment was conducted to examined the effects of the physico-chemical and mineral-logical properties of paddy soil on the desorption of $Cs^{137}$ from radionuclide, $Cs^{137}$ absorbed soils. 1. Adsorption of $Cs^{137}$ by paddy soil was very much and exchangeable fraction of $Cs^{137}$ extracted by ammonium acetate was very high compared to the water soluble fraction. Exchangeable fraction of $Cs^{137}$ in paddy soil decreased with the increase of potassium application and increased proportionally with the increase of $Cs^{137}$ treatment. 2. The distribution of several forms of $Cs^{137}$ in soils depend on the soil type. Average-distribution rates of water soluble, exchangeable and non-exchangeable fractions of $Cs^{137}$ in soils were 5.9%, 17.1% and 77.0%, respectively. 3. The desorption of $Cs^{137}$ from adsorbed soils decreased with increase of pH and exchangeable cations of the soils, but it increased as organic matter and clay content increase in soil. 4. Non-exchangeable adsorption of $Cs^{137}$ was high in the soils of which both Illite and Vermiculite were dominant.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.132-137
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• 1993

This study was conducted to establish a safe cultivation technique of rice in the area irrigated with polluted water. The changes of water and grain quality were investigated in the two paddy soils which are located in the adjacent of Geumho river in 1991. The results obtained in this study are as follows : 1. The qualities of irrigation water were shown to be in the range of 6.7~7.4 in pH, 21.3~52.8ppm in COD. 3.2~5.3ppm in $NH_4-N$ and 1.6~6.0ppm in $PO_4$, respectively. Concentration of COD and $NH_4-N$ were over the standard levels. Therefore, the water pollution was mainly caused by organic waste matters. 2. Ranges of the Soil pH of Gyeongsan and Gyuam series were 5.6~6.0, 6.1~6.3 respectively. The contents of avaiable $P_2O_5$ and $SiO_2$ were high in the silicate treatment plots among other plots. 3. Degree of irrigation water pollution of Geumho river showed the highest peak in June. 4. Plant height, number of panicle and yield of rice grain were not decreased by the diminution of nitrogen fertilizer application. 5. The $Mg/(K{\times}N)$ ratio and Gel consistency of milled rice were increased in the nitrogen decreasing plot, but the alkali digestability value and protein content were decreased. Therefore, it was desirable to decrease the amount of nitrogen fertilizer application.