• Journal of Korean Society of Forest Science
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• v.85 no.4
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• pp.656-666
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• 1996

Aspen demand has increased recently in the Great Lakes region in the United States. Since aspen has moved into the region in late 1800's, its growing stock has increased so as to change forestry industry of the Lake States. Intensive timber harvesting and biomass removal may cause nutrient depletion, especially on nutrient-poor sites. Forest nutrients and nutrient cycling were investigated in aspen stands of 7-10, 27-33, and 41-42 year-old growing on sandy soils in Minnesota. Nutrients added to the aspen stands by atmospheric deposition and soil weathering were efficiently absorbed and stored in the tree biomass. Aboveground biomass increased from $24.4t{\cdot}ha^{-1}$ at young stands to $139.2t{\cdot}ha^{-1}$ at mature stands. Nutrients accumulated in the tree biomass showed same magnitude of difference. Nutrients added to the site through atmospheric deposition were in the order of Ca, N, K, Mg, and P. Annual litterfall was greater in older stands. However, the amount of nutrients returned by litterfall was not significantly different among stand ages due to the greater nutrient contents in the litterfall of young stands. Litter decomposition and nutrient release rates were greater at young stands than at older stands. Likewise, nutrient availability was higher in young aspen stands and became lower as the stands grew older. Nutrient leaching loss was minimal at all stand ages. Soil N mineralization was greater at young stands than at older stands. Nutrient cycling process was facilitated in young aspen stands with an increased level of available nutrients, Based on the estimations of nutrient balance and nutrient removal by harvesting, Ca was the most critical element which was likely to be depleted if aspen stands are intensively harvested with short rotations.

• Korean Journal of Ecology and Environment
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• v.51 no.3
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• pp.205-211
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• 2018

In this study, we estimated the applicability of length-weight relationship-based biomass calculations by comparison of body length of genus Polyarthra collected from different habitats. Through the comparison, we also tested availability of representative species-specific biomass value of Polyarthra which is often used without length measurement. Polyarthra samples were collected from rivers (Han River and Nakdong River) and reservoir (Paldang Reservoir), and the body length was measured for statistical comparison among habitats and biomass calculations using different equations suggested previously. According to the results, the body length of Polyarthra spp. was significantly different among sampling sites, and the necessity of body length measurement for rotifer species in each situation has been suggested rather than using the representative biomass values which is fixed without considering time and space. Comparison of suggested biomass calculations based on our measured Polyarthra body length, the equation suggested by McCauley showed more reasonable range of biomass values than that suggested by EPA. In addition, in order to calculate more accurate biomass, it is necessary to measure the body length of rotifers, at least more than 44 individuals to reduce error probability to less than 5% with 99% probability. However, since direct measurement of rotifers biomass is limited, it is considered that further analyses are required for more precise application of rotifer biomass of which has high variability due to complex morphologies and species-specific cyclomorphosis often induced by biotic and abiotic factors in the habitats.

• The Korean Journal of Ecology
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• v.8 no.1
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• pp.21-29
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• 1985

The physico-chemical properties of sediment, the species composition and biomass of benthic diatoms were investigated in the intertidal zone of Kum river estuary, from July 1983 to May 1984. Sandflat sediment was more oligotrophic than mudflat one. The diatom composition was primarily associated with sediment grain size. The dominant epipelic diatoms belonged to the centric diatoms such as Paralia sulcata and Thalassiosira spp., while the epipsammic diatoms consisted mainly of Achnanthes haukiana and Amphora sabyii. Diatom flora of sandflat was more significantly diverse than that of mudflat. Mean yearly crop of sandflat diatoms was 2.8 times greater than that of mudflat diatoms and peaked at March reflecting the greater availability of ammonia.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.393-402
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• 2017

In this study, greenhouse gas (GHG) reductions from bioenergy (biogas, biomass) have been estimated in Korea, 2015. This study for construction of reduction inventories as direct and indirect reduction sources was derived from IPCC 2006 guidelines for national greenhouse gas inventories, guidelines for local government greenhouse inventories published in 2016, also purchased electricity and steam indirect emission factors obtained from KPX, GIR respectively. As a result, the annual GHG reductions were estimated as $1,860,000tonCO_{2eq}$ accounting for 76.8% of direct reduction (scope 1) and 23.2% of indirect reduction (scope 2). Estimation of individual greenhouse gases (GHGs) from biogas appeared that $CO_2$, $CH_4$, $N_2O$ were $90,000tonCO_2$ (5.5%), $55,000tonCH_4$ (94.5%), $0.3tonN_2O$ (0.004%), respectively. In addition, biomass was $250,000tonCO_2$ (107%), $-300tonCH_4$ (-3.2%), $-33tonN_2O$ (-3.9%). For understanding the values of estimation method levels, field data (this study) appeared to be approximately 85.47% compared to installed capacity. In details, biogas and biomass resulting from field data showed to be 76%, 74% compared to installed capacity, respectively. In the comparison of this study and CDM project with GHG reduction unit per year installed capacity, this study showed as 42% level versus CDM project. Scenario analysis of GHG reductions potential from bioenergy was analyzed that generation efficiency, availability and cumulative distribution were significantly effective on reducing GHG.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1566-1573
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• 2014

Although most algae cultivation systems are operated in suspended culture, an attached growth system can offer several advantages over suspended systems. Algal cultivation becomes light-limited as the microalgal concentration increases in the suspended system; on the other hand, sunlight penetrates deeper and stronger in attached systems owing to the more transparent water. Such higher availability of sunlight makes it possible to operate a raceway pond deeper than usual, resulting in a higher areal productivity. The attached system achieved 2.8-times higher biomass productivity and total lipid productivity of $9.1g\;m^{-2}day^{-1}$ and $1.9g\;m^{-2}day^{-1}$, respectively, than the suspended system. Biomass productivity can be further increased by optimization of the culture conditions. Moreover, algal biomass harvesting and dewatering were made simpler and cheaper in attached systems, because mesh-type substrates with attached microalgae were easily removed from the culture and the remaining treated wastewater could be discharged directly. When the algal biomass was dewatered using natural sunlight, the palmitic acid (C16:0) content increased by 16% compared with the freeze-drying method. There was no great difference in other fatty acid composition. Therefore, the attached system for algal cultivation is a promising cultivation system for mass biodiesel production.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.12-12
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• 2023

Plant biomass, or lignocellulose, is one of the most abundant natural resources on earth. Lignocellulosic biomass, such as agricultural and forestry residue, serves as a renewable feedstock for microbial cell factories due to its low price and abundant availability. However, the recalcitrance of lignocellulosic biomass requires a pretreatment process prior to microbial fermentation, from which fermentable sugars including xylose and glucose are generated along with various inhibitory compounds. The presence of furan derivatives, such as 5-hydroxymethyl-2-furaldehyde and 2-furaldehyde (furfural), hampers the microbial conversion of lignocellulosic biomass into value-added commodities. In this study, furfural tolerance was improved by investigating the detoxification mechanism in non-model yeast. The genes encoding aldehyde dehydrogenases were overexpressed to enhance furfural tolerance and resulted in improving cell growth and lipid production that can be converted into biofuel. Taken together, this approach contributes to the understanding of the reducing toxicity mechanism of furfural by the aldehyde dehydrogenases and provides a promising strategy that the use of microorganism as an industrial workhorse to treat efficiently lignocellulosic biomass as sustainable plant derivatives.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.181-189
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• 1996

Several phosphate-solubilizing microorganisms were isolated in order to enhance the availability of insoluble phosphates accumulated in soils. Among the microorganisms, Aspergillus niger was selected and identified for this study. The phosphate-solubilizing activity. the phosphorus uptake by plants and the changes in soil microbial biomass by inoculation of Aspergillus niger were investigated. The uptake amounts of phosphorus by lettuce and pimiento were increased by inoculation of Aspergillus niger in all experimental treatments. There was negative correlation between the soil microbial biomass P and the soil phosphorus content. However the soil available phosphorus ($Y=-0.0007X^2+0.7126X^2-29.46$, $R=0.8283^{**}$) and the phosphorus absorption of plants ($Y=0.0049X^2-2.2352X+326.34$, $R=0.6350^*$) were significantly correlated to soil microbial biomass C on the positive section of quadric curve.

• Fisheries and Aquatic Sciences
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• v.26 no.7
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• pp.423-436
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• 2023

The objectives of this review were to synthesize the community structure of phytoplankton and the role of atelomix in the phytoplankton dynamics in Ethiopian highland lakes. Changes in a lake's physical structure, light dynamics, and availability of nutrients are closely associated with phytoplankton ecology, and phytoplankton assemblages provide insight into phytoplank- ton responses to these environmental changes. Based on the available information, a total of 173 species of phytoplankton are grouped under seven classes, Chlorophyceae (80 taxa), Bacillariophyceae (55 taxa), Cyanophyceae (24 taxa), Dinophyceae (6 taxa), Eugleonophyceae (6 taxa), Xanthophyceae (1 taxon), and Cryptophyceae (1 taxon) were recorded in five different tropical Ethiopian highland lakes. Chlorophyceae and Bacillariophyceae dominated in terms of species composition. Partial atelomixis, seasonality, and low nutrient concentrations seem to be the main drivers in structuring phytoplankton composition and abun-dances in Ethiopian highland lakes, characterized by a high diversity of atelomix-dependent benthic diatoms and desmids. Thus, this review will help understand the role of atelomix and nutrient availability in the phytoplankton composition and biomass of tropical highland lakes of Ethiopia.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.455-461
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• 2004

Effects of the different strengths and intervals of the periodic outer water intrusions (kyuchos and bottom intrusions) on the dynamics of phytoplankton biomass in a small embayment were examined with a simple numerical model. Environmental conditions of Kitanada Bay in the Bungo Channel were applied to the model. As the interval of the intrusion became longer and the amplitude became smaller, phytoplankton biomass In the bay became higher. On the other hand, as the interval became shorter and the amplitude became larger, the growth rate of the phytoplankton became higher. It suggested that when the intrusion was weaker, water exchange of the bay decreased and the phytoplankton in the bay accumulated at a high density, When water exchange was improved by active intrusions, availability of light would become more efficient and the growth rate of the phytoplankton was enhanced.

• ALGAE
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• v.28 no.2
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• pp.193-202
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• 2013

Nitrogen availability and cell density each affects growth and cellular astaxanthin content of Haematococcus pluvialis, but possible combined effects of these two factors on the content and productivity of astaxanthin, especially under outdoor culture conditions, is less understood. In this study, the effects of the initial biomass densities IBDs of 0.1, 0.5, 0.8, 1.5, 2.7, 3.5, and 5.0 g $L^{-1}$ DW and initial nitrogen concentrations of 0, 4.4, 8.8, and 17.6 mM nitrate on growth and cellular astaxanthin content of H. pluvialis Flotow K-0084 were investigated in outdoor glass column photobioreactors in a batch culture mode. A low IBD of 0.1 g $L^{-1}$ DW led to photo-bleaching of the culture within 1-2 days. When the IBD was 0.5 g $L^{-1}$ and above, the rate at which the increase in biomass density and the astaxanthin content on a per cell basis was higher at lower IBD. When the IBD was optimal (i.e., 0.8 g $L^{-1}$), the maximum astaxanthin content of 3.8% of DW was obtained in the absence of nitrogen, whereas the maximum astaxanthin productivity of 16.0 mg $L^{-1}\;d^{-1}$ was obtained in the same IBD culture containing 4.4 mM nitrogen. The strategies for achieving maximum Haematococcus biomass productivity and for maximum cellular astaxanthin content are discussed.