• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.263-271
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• 2004

To collect the basic ecological information about the microbial food webs in eutrophic water system with different residence time, the monthly variation of bacterioplankon (bacteria and small-sized cyanobacteria) and nanoplankton (phytoplankton and protists) were examined from December 2000 to September 2001. Kyungan stream is shorter in resident time (ca.5.4 d) than Seokchon reservoir (ca.72 d), even though they showed the same pattern in precipitation. With the basic environments, we examined the biomass (standing crops and its carbon content) of each plankton collected from the surface water. Large-sized planktons flourished in the time of low temperature, while small planktons were in the time of the high temperature period. Especially, in the Kyungan stream with much disturbance by rainfall and outflow, high diversity showed in term of species and cell morphology, compared to that of Seokchon lake. The time-lag relationship remarkably showed between phytoplankton and bacteria in Seokchon reservoir, and between protists and bacteria in Kyungan stream, respectively.

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

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.733-743
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• 2020

We estimated the carbon storage of coal mines reclaimed using Betula platyphylla (BP), Pinus koraiensis (PK), and Pinus spp. (PS, Pinus densiflora, Pinus rigida, and Pinus thunbergii). The carbon storage of tree biomass (TB), forest floor(FF), mineral soil (MS), and the total forest were quantified. Reclaimed sites were located in Gangwon-do, Gyeongsangbuk-do, and Jeollanam-do; reclamation was conducted at various times in each region. The carbon storage (ton C ha^-1) in FF (BP: 3.31±0.59, PK: 3.60±0.93, PS: 4.65±0.92), MS (BP: 28.62±2.86, PK: 22.26±5.72, PS: 19.95±3.90), and the total forest(BP: 54.81±7.22, PK: 47.29±8.97, PS: 45.50±6.31) were lower than that of natural forests (NF). The carbon storage in TB was lower in BP (22.57±6.18) compared to NF, while those in PK(21.17±8.76) and PS (20.80±6.40) were higher than in NF. While there were no significant differences in the carbon storage of TB, FF, and the total forest among tree species, results from MS showed a significant difference among species. TB and the total forest carbon storages in all sites increased after reclamation. Soil pH and cation exchange capacity values in BP and PS were lower than in NF. Amounts of labile carbon, available phosphate, and microbial biomass carbon in reclaimed sites were less than half of NF. There are a number of methods that could increase the reclamation efficiency. Applications of lime or organic fertilizers, as well as tillage operations, may improve soil properties in reclaimed coal mines. Additionally, pruning and thinning would increase tree growth thereby increasing carbon storage.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.499-504
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• 2015

The composite anodes of expanded graphite (EG) and multiwall carbon nanotube (MWCNT) for microbial fuel cells were fabricated by using coal tar pitch (CTP) binder containing nickel (Ni), and the effect of the anodes with the binders on the performance of the MFCs were examined in a batch reactor. During the start-up of the MFCs, quick increase in voltage was observed after a short lag phase time, indicating that the CTP binder is biocompatible. The biomass attatched on the anode surface was more at higher Ni content in the binder, as well as at smaller amount of CTP binder for the fabrication of the anode. The internal resistance of the MFC was smaller for the anode with more biomass. Based on the results, the ideal combination of CTP and Ni for the CTP binder for anode was 2 g and 0.2 g, respectively. The maximum power density was $731.8mW/m^2$, which was higher 23.7% than the anode with Nafion binder as control. The CTP binder containing Ni for the fabrication of anode is a good alternative in terms of performance and economics of MFCs.

• 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.

• Asian Journal of Atmospheric Environment
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• v.5 no.3
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• pp.157-163
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• 2011

Atmospheric aerosol deposition caused by Asian dust (KOSA) events provide nutrients, trace metals, and organic compounds over the Pacific Ocean that enhance ocean productivity and carbon sequestration and, thus, influence the atmospheric carbon dioxide concentrations and climate. Using dust particles obtained from the snow layers on Mt. Tateyama and the surface sand of Loess Plateau in incubation experiments with natural seawater samples on a shipboard, we demonstrate that dust-particle additions enhanced the bacterial growth on the first day of incubation. Gram-positive bacterial group and alpha-proteobacteria were specifically detected form seawater samples including the mineral particles. Although the remarkable dynamics of trace elements and nutrients depend on dust-particle additions, it is possible that organic compounds present in the mineral particles or transported microbial cells could also contribute to an increase in the quantities of bacteria. The chlorophyll concentrations at fractions of every size indicated a similar pattern of change between the seawater samples with and without the dust-particle additions. In contrast, the chlorophyll measurement using submersible fluorometer revealed that the dynamics of phytoplankton composition were influenced by the dust-particles treatments. We conclude that the phytoplankton that uses the bacterial products would increase their biomass. We show that KOSA deposition can potentially alter the structures of bacterial communities and indirectly influence the patterns of marine primary production in the Pacific Ocean.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.144-153
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• 2014

Both docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) have attracted increasing attention since the first epidemiological report on the importance of n-3 essential fatty acids. Lipids in microbial cells play various biological roles and, consequently, much research has been carried out on their role in cell physiology. The lipid composition of microorganisms can exhibit considerable variations depending on environment. The effects of culture conditions, temperature (15, 20, 24, 28, 32 and $36^{\circ}C$), salinity (10, 20, 30, 40 and 50 psu), pH (pH5, 6, 7, 8 and 9), rotation speeds (50, 100, 150 and 200 rpm), carbon sources, nitrogen sources and C/N ratio on the production of docosahexaenoic acid, fatty-acid profiles, and acids secreted to the broth culture by the oleaginous microorganism, Schizochytrium mangrovei (KCTC 11117BP), were studied. Temperature (initially $28^{\circ}C$), salinity (20 psu), pH (pH7), rotation speeds (100 rpm), organism fatty acids, and secreted acids in the broth were varied during cultivation of S. mangrovei. At pH 7.0, S. mangrovei was able to accumulate lipids up to 40% of its biomass, with 13% (w/w) DHA content. The monosaccharides glucose and fructose, and yeast extract were suitable carbon and nitrogen sources, respectively. The primary omega-3 polyunsaturated fatty acid produced was docosahexaenoic acid.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.601-608
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• 2008

The objective of this study was to evaluate the effect of ozonation as pretreatment on the removal of dissolved or biodegradable organic matter(DOM or BOM), the variance of DOM fractionation, and microbial regrowth by pilot-scale granular activated carbon processes in which adsorption and biodegradability was proceeding due to long time operation. Regardless of point of ozonation applied, GAC processes with ozonation(i.e., Ozonation combined with GAC Filter-adsorber; Pre O$_3$ + F/A, Ozonation combined with GAC adsorber; Post O$_3$ + GAC) compared with GAC processes without ozonation(i.e., GAC Filter-adsorber; F/A, GAC adsorber; GAC) removed approximately 10 to 20% more of DOC, hydrophilic DOM(HPI), BDOC and AOC after long period of operation that biological activity was assumed to happen. Ozonation was not found to have a significant effect on the removal of DOC, but caused the decrease of AOC by approximately 20%. It was found that the fixed bacterial biomass on GAC media did not show a significant difference between the GAC with ozonation and GAC without ozonation as pre-treatment, whereas the HPC of column effluent was more biostable at Post O$_3$ + GAC compared with F/A or GAC.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.59-69
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• 2003

As part of study on the microbial food web in the southern Jeju Island of Korea, Planktonic tintinnids and aloricate oligotrichs were investigated from July 1998 to June 2000 to understand seasonal variation and water mass indication with environmental factors. 39 species of tintinnids were identified representing 1 order, 11 families, 20 genera. Tintinnid abundance ranged from 100 to 5,400 cells.1$^{-1}$ (mean 314 cells.1$^{-1}$ ), and oceanic species were mainly dominant in fall and winter season, while neritic species were a little pre- dominant in spring and summer season. 15 species of aloricate oligotrichs were identified representing 1 order, 5 families, 7 genera, and many belonged to genus Strombidium which was most abundant and most frequently occurred in many months. Abundance of aloricate oligotrichs ranged from 140 to 21,000 cells.1$^{-1}$ (mean 2,356 cells.1$^{-1}$ ). Species diversity and standing crops of tintinnids were quite different according to seasons, but few seasonal variations were detected in aloricate oligotrichs. In terms of water mass indication tintinnids represented obvious characteristics which were affected by marine environmental factors, but alor- icate oligotrichs had no such apparent indication as tintinnids. Ciliates were more abundant and more diverse in inshore than in offshore station. Total carbon biomass of ciliates ranged from 0.01 to 136.06 $\mu\textrm{g}$C.1$^{-1}$ (mean 5.01 $\mu\textrm{g}$C.1$^{-1}$ ). The carbon biomass, however, did not coincided with seasonal variations of abun- dance Vertical profiles of mean abundance of both tintinnids and aloricate oligotrichs were similar, and had same trend as those of mean chlorophyll o concentration. It suggests that phytoplankton and ciliates reflected the prey-predator relationship in the study area.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.261-266
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• 2001

Effects of elevated carbon dioxide ($CO_2$) on soil microbial processes were studied in a northern peatland. Intact peat cores with surface vegetation were collected from a northern Welsh fen, and incubated either under elevated carbon dioxide (700 ppm) or ambient carbon dioxide (350 ppm) conditions for 4 months. Higher algal biomass was found under the elevated $CO_2$ condition, suggesting $CO_2$ fertilization effect on primary production, At the end of the incubation, trace gas production and consumption were analyzed using chemical inhibitors. For methane ($CH_4$ ), methyl fluoride ($CH_3F$) was applied to determine methane oxidation rates, while acetylene ($C_2H_2$) blocking method were applied to determine nitrification and denitrification rates. First, we have adopted those methods to optimize the reaction conditions for the wetland samples. Secondly, the methods were applied to the samples incubated under two levels of $CO_2$. The results exhibited that elevated carbon dioxide increased both methane production (210 vs. $100\;ng\;CH_4 g^{-1}\;hr^{-1}$) and oxidation (128 vs. $15\;ng\;CH_4 g^{-1}\;hr^{-1}$), resulting in no net increase in methane flux. For nitrous oxide ($N_2O$) , elevated carbon dioxide enhanced nitrous oxide emission probably from activation of nitrification process rather than denitrification rates. All of these changes seemed to be substantially influenced by higher oxygen diffusion from enhanced algal productivity under elevated $CO_2$.