• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.463-466
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• 2003

This study was conducted to introduce the characteristics of the freshwater environment of Mulkol, considering that it is less known area about the ecosystem of the Tok Island. The salinity of freshwater in the Mulkol was less than 2.0 psu, while its periphytic algal biomass was thriving with 25.9 ${\mu}g\;chl-a/cm^2$. As for the nutrients in water, the content of $NH_4$ was higher than the rest of inorganic nitrogen components, and SRP and SRSi were much higher as 117.3 ${\mu}$g P/l and 4,104.6 ${\mu}$g Si/l respectively, than nitrogen components. Also, the ratio of N/P was found less than 1.0, revealing the condition that N was greatly limited. The high level of nutrient concentration and periphytic algal biomass at the Mulkol ecosystem could be explained as a result of natural pollution, but no full explanation was made in this study. It is a question that needs additional research in the future.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.2
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• pp.124-134
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• 2021

Water in the Mulgol pond on Dokdo (island), Korea, was historically used for drinking water, but now it has been no longer used for this purpose due to regionally low water quality. Since 2007, this pond has been covered with a metal lid to protect from pollutants of seabirds, indicating limited light penetration into the Mulgol pond. Here, we investigated water quality in the pond and potential relationships of nitrogen components and microbes in May, June, August, and November 2020. The source salinity ranged from 1.39 to 1.57 psu. Suspended solids (0.8~5.1 mg L^-1) and chlorophyll-a (<0.01~0.49 ㎍ L^-1) remained low. The concentration of dissolved inorganic nitrogen (DIN) was between 35.9 and 47.2 mg L^-1. Thus, water in the Mulgol pond proves to be brackish water with low chlorophyll-a and high nutrients. This unique environment may be established by limited light intensity, sea fog (or seawater), and fecal pellets from many seabirds. Although the light source (800~8000 lux) was exposed to the four subsamples, chlorophyll-a concentrations were below <0.5 ㎍ L^-1 during the incubation periods. This result suggests that the biomass of phytoplankton does not increase along with an increase in light intensity. Furthermore, the content of nitrate constituted more than 90% of DIN, and a significant negative correlation between nitrate concentration and bacterial abundance was shown in May and June 2020 during the light exposure experiments (R=-0.762, p<0.05). Thus, it is possible that bacteria may be a significant agent to reduce nitrate concentration in the Mulgol pond, the relationship between nitrate concentration and bacterial abundance may vary seasonally.

• Journal of Bio-Environment Control
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• v.14 no.2
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• pp.128-136
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• 2005

The objective of this study was to determine the effect of calcium concentrations in fertilizer solution on growth and cut flower quality of chrysanthemum 'Biarritz' To achieve this, deficiency symptom and growth characteristics as influenced by controlled Ca concentrations in fertilizer solution were investigated. The analysis of plant tissue and soil solution of root media were also conducted to secure optimum concentration for plant growth. Calcium deficiency developed on the very youngest leaves and the young leaves developed 'cupped' shape as they expand. The cut flower length of 0, 3.0 and 6.0 mM treatments were 105.8, 106.5, and 107.3cm, respectively. Elevated Ca concentration within the range from 0 to 6.0mM in fertilizer solution increased cut flower weight. The cut flower weight of control and 6.0mM treatment were 51.6 and 59.4 g, respectively. The tissue Ca content of 6.0mM treatment in which crops showed the highest growth among treatments was $3.09\%$ based on the dry weight of the youngest fully expanded leaves. From the results, it seems necessary to maintaining tissue Ca content higher than $2.8\%$. Soil Ca concentrations increased as K concentrations in fertilizer solution were elevated. Ca concentration in 0.0, 1.5, 3.0, 4.5 and 6.0mM treatments were 5.0, 7.4, 12.1, 16.5 and $28.2mg{\cdot}L^{-1}$, respectively, at harvesting stage. It is suggested that Ca concentration higher than $25.4mg{\cdot}L^{-1}$ in soil solution of root media is required to maintain normal growth.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.36-46
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• 2004

We evaluated the effect of limiting nutrients and N/P ratio on the growth of phytoplankton in a small eutrophic reservoir from November 2002 to December 2003. Nutrient limitation was investigated seasonally using nutrient enrichment bioassay (NEB). DIN/DTP and TN/TP ratio (by weight) of the reservoir during the study period ranged 17${\sim}$187 and 13${\sim}$60, respectively. Most of nitrogen in the reservoir account for $NO_3$-N, but sharp increase of ammonia was evident during the spring season. Seasonal variation of dissolved inorganic phosphorus concentration was relatively small. DTP ranged 26.5${\sim}$10.1 ${\mu}g\;P\;L^{-1}$, and the highest and lowest concentration was observed in August and December, respectively. Chlorophyll a concentration ranged 28.8${\sim}$109.7 ${\mu}g\;L^{-1}$, and its temporal variation was similar to that of cell density of phytoplankton. Dominant phytoplankton species were Bacillariphyceae (Melosira varians) and Chlorophyceae (Dictyosphaerium puchellum) in Spring (March${\sim}$April). Cyanophyceae, such as Osillatoria spp., Microcystis spp., Aphanizomenon sp. dominated from May to the freezing time. TN/TP ratio ranged from 46 to 13 (Avg. 27${\pm}$6) from June to December when cyanobacteria (Microcystis spp.) dominated. p limitation for algal growth measured in all NEB experiments (17cases), while N limitation occurred in 8 out of 17 cases. The growth rates of phytoplankton slightly increased with decreasing of DIN/DTP ratio. Evident increase was observed in the N/P ratio of > 30, and it was sustained with DTP increase until 50 ${\mu}g\;P\;L^{-1}$. Under the same N/P mass ratio with the different N concentrations (0.07, 0.7and 3.5 mg N $L^{-1}$), Microcystis spp. showed the highest growth rate in the N/P ratio of< 1 with nitrogen concentration of 3.5 mg N $L^{-1}$). The responses of phytoplankton growth to phosphate addition were clearly greater with increase of N concentration. These results indicate that the higher nitrogen concentration in the water likely induce the stronger P-limitation on the phytoplankton growth, while nitrogen deficiency is not likely the case of nutrient limitation.

• Korean Journal of Medicinal Crop Science
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• v.9 no.1
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• pp.15-20
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• 2001

Adventitious shoot buds, without an intervening callus phase, were induced from stem explants of Trichosanthes kirilowii on MS medium supplemented with 2 mg/L BA. The culture medium, carbon source as well as plant growth regulators were found to influence further shoot multiplication and eventual shoot growth. A maximum number of shoots was obtained on a MS medium containing 0.5 mg/L BA and 3% sucrose. Shoot produced in vitro were rooted on half-strength phytagelled 1/2MS medium prior to transfer to green house condition.

• Korean Journal of Medicinal Crop Science
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• v.10 no.2
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• pp.116-119
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• 2002

A protocol has been developed for differentiation of adventitious shoots directly from leaf segments of Tetragonia tetragonoides O. Kuntze. Murashige and Skoog (MS) medium supplemented with 2 mg/L $N^6-benzyladenine$ (BA) and 0.5 mg/L ${\alpha}-naphthaleneacetic$ acid (NAA) supported the induction of adventitious shoots from leaf explants. Adventitious shoots were multiplied by subculturing on the double strength MS (2MS) medium supplemented with 0.5 mg/L NAA and 2 mg/L BA. Shoots were rooted on MS basal medium without any growth regulators.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.369-376
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• 2006

This research was conducted to evaluate the effect of root medium formulations on growth and nutrient uptake of hot pepper 'Knockgwang' in 72-cell plug trays. To achieve this, the nine root media were formulated by adjusting blending rate of perlite (PL) to coir (CO), peatmoss (PM) or coir+peatmoss (5:5, v/v, COPM). Then, the growth characteristics and tissue nutrient contents were determined at 35 and 70 days after sowing. The elevated blending rate of PL to CO increased fresh and dry weight of hot pepper at 35 days after sowing. The treatments of 20% in blending rate of PL to PM or that of 0% to COPM produced the highest fresh and dry weight among perlite treatments of PM or COPM. The results of crop growth at 70 days after sowing also showed similar trends to those of 35 days after sowing. The elevated blending rate of PL to CO or PM decreased tissue $P_2O_5$ and K contents and increased Ca and Mg contents at 35 days after sowing, With the equal blending rate of perlite, the plant tissue grown in CO had higher K contents and lower N, Ca and Mg contents than those in PM and COPM. The elevated blending rate of perlite in three organic matter also decreased tissue $P_2O_5$ and K contents at 70 days after sowing, but Ca and Mg contents were the highest in the treatment of 20% PL in CO, 40% PL in PM and 40% PL in COPM among perlite treatments in each organic matter.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.478-484
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• 2012

This study was carried out to investigate the plant growth and ion absorbance balance of various native plants affected by the NaCl concentration (0, 100, 200, 300 mM). Carex blepharicarpa, Carex lenta, Carex matsumarae, Carex sendaica, Iris pseudacorus L., Sedum oryzifolium Makino, Sedum polytrichoides Hemsl., and Typha angustifolia L. were used in this experiment. Carex blepharicarpa, Carex lenta, Carex matsumarae, and Iris pseudacorus L. were tolerant of salinity at the NaCl concentration of 200 mM. The root growth of Carex sendaica and Typha angustifolia L. was suppressed at the NaCl concentration of 100 mM, expecially the root growth responded more sensitively than the upper growth to salinity. The K absorbance of Carex sendaica decreased according to the NaCl application, and the Na/K rate value was 3 at the NaCl concentration of 300 mM. The K, Ca, and Mg absorbance of Typha angustifolia L. decreased at the NaCl concentration of 200~300 mM, and the Na/K rate value was 0.8 at the NaCl concentration of 300 mM. The plant growth of Sedum oryzifolium Makino and Sedum polytrichoides Hemsl. was suppressed at the NaCl concentration of 100~200 mM. The K, Ca, and Mg absorbance of Sedum oryzifolium Makino decreased at the NaCl concentration of 200~300 mM, and Sedum polytrichoides Hemsl. was unaffected by the NaCl application. The Na/K value was 1 in both plants. Therefore, Carex blepharicarpa, Carex lenta, Carex matsumarae, and Iris pseudacorus L. were tolerant plants of salinity at the NaCl concentration of 200 mM considering the plant growth and ion absorbance balance. Especially, the Carex plants were expected to expanding use by the proven tolerance of salinity. The root growth of Carex sendaica, Sedum oryzifolium Makino, Sedum polytrichoides Hemsl., and Typha angustifolia L., was suppressed at the NaCl concentration of 100 mM, but there was no distinct tendency of ion absorbance in leaves according to the NaCl application.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.4
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• pp.23-36
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• 2000

Bottom sea waters in eight stations including from inner bay to outer bay to understand the importance of the submarine groundwater discharge for the environmental assessment of Chinhae Bay was collected in August 1999 and January 2000. Generally, /sup 222/Rn is very useful tracer to assess the submarine groundwater discharge because it is 2-4 orders of magnitude more concentrated in groundwater compared to surface water. The /sup 222/Rn activities ranged between about 33 to 182 dpm/100kg within the bay. Higher activities more than 100 dpm/100kg were found at the inner bay. The /sup 226/Ra activities, its parent, however, were little different between stations. /sup 222/Rn activities at the same station varied with season. It suggests that the major source of /sup 222/Rn is not from the bottom sediment, but from the change of submarine groundwater discharge by precipitation. The contents of Cl/sup -/ and SO/sub 4//sup 2-/ in the groundwater of Wonjeon-ri were very high as 1,312 and 369 ppm, respectively, indicating that this groundwater along the Chinhae coast was affected by seawater. Therefore, the submarine groundwater in the inner Bay may discharge to the overlying water. It indicates that these submarine groundwater discharges may play an important role as another important source of nutrients in the Chinhae Bay, because groundwater around the Chinhae Bay showed high concentration of dissolved inorganic nutrients (average , nitrate>174 μM, silicate>262 μM). Therefore, further studies are required to assess the contribution by the submarine groundwater discharge in the biogeochemical processes of the Chinhae Bay.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.136-142
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• 2007

Recent publications have paid attention on the utilization of solid reagents for the removal of substances causing eutrophication, in particular $PO_4^{3-}$ ions. The adsorption of dissolved inorganic phosphate on slag produced by the refining process of iron ore was fundamentally studied for suppressing the liberation of phosphate from wastewater. This study has been conducted in order to find a possibility to improve the phosphate removal and to evaluate the phosphate removal variation to form hydroxyapatite, when the converter slag is used for phosphate removal. The result shows that the converter slag can be applied to remove phosphate using Freundlich isotherm. The size of converter slag, $2{\sim}0.425 mm$ was more efficient than $2{\sim}4.75mm$ to remove phosphate. In particular, 1 mg/L of phosphate can be removed up to 80% of the initial concentration for the continuous column experiment.