• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.86-92
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• 2008

This study was conducted to determine removal effect on phytoplankton (chlorophyll-${\alpha}$ as whole algae) and cyanobacteria by a fish Pseudorasbora parva and macroinvertebrate Palaemon paucidens in September 2006. Three treatments with 25 (T1), 50 (T2) and 100 (T3) individuals along with control (C1, no input fish), and two treatments with 25 (T4) and 50 (T5) individuals along with control (C1) were made for fish and macroinvertebrate, respectively. The initial concentrations of chlorophyll-${\alpha}$ $(Chl_i)$ in each 10L test tank were set up for the levels of $95{\sim}100{\mu}g\;L^{-1}$ and the daily values were monitored in the test tank during 7 days. In the lab tests, P. parva did not show Chl-${alpha}$ removal effect; the removal rate of Chl-${alpha}$ for P. parva was -58% in T1, -56% in T2, and 61% in T3 during the test period. In contrast, P. paucidens. in the treatments of T4 and T5 removed the phytoplankton effectively and the removal effect were appeared to be 33% and 22%, respectively. Also, P. paucidens showed high feeding efficiency in the removal of cyanobacteria. The levels of cyanobacteria were greatly lowed from 6,048 to 927 cells $mL^{-1}$ in T4 and from 6,539 to 1,053 cells $mL^{-1}$ in T5, resulting in 85% and 84% in the removal effect, respectively. Our results for biomanipulation tests suggest that P. paucidens may be used as a potential candidate organism for algae control in spite of the preliminary results by laboratory tests.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.203-213
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• 2011

Agriculture modern environments can vary due to factors such as land consolidation and ditch enhancement projects. But, these improvements projects can include cover-ing-up of irrigation ditches with concrete, increasing the drop between paddy field and drainage ditches, which might decrease the abundance and diversity of fish fauna around paddy fields. In this study, for the management of agrobiodiversity on fish in paddy fields, we installed a small-scale fishways between paddy fields and drainage ditches, and evaluated the effects on the eco-connection of the paddy fields, ditches and stream. Five fish species were recovered at the drainage ditches. The species exhibited characteristics spawning and growth based on the paddy field. The results indicate that the five fish species could ascend the paddy fields through the small-scale fishways. There are no difference of species numbers at ditches of environment-friendly agriculture paddy fields (A) and good agricultural practices (B) region, but individual numbers were higher at the B region. This result could be interpreted as indicating that ditch diversity was affected by positional properties rather than farming practices because the water flow and connection to adjacent stream of B region were better than A region. After ascertaining the fish species capable of ascending in a pre-survey of the drainage ditches, we set up small-scale fishways at the drop between paddy fields and drainage ditches. Three species of fish (Aphyocypris chinensis, Misgurnus anguillicaudatus, M. mizolepis) arrived at the paddy fields via small-scale fishways. The main movement time was from 18:00~24:00 and 00:00~06:00, indicating a preference for the night time period rather than the day period for migration. Concentrating the operation time from night to dawn seems prudent for effective management of small-scale fishways.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.295-303
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• 1997

To investigate the transformation characteristics of nitrogen and carbon from cow manure compost amended in soil under different moisture conditions, dynamics of nitrogen and carbon were determined periodically for 15 weeks of aerobic incubation at room temperature during July${\sim}$November, 1996. Cow manure compost matured with mixing saw dust was amended with the 4 ratios (0, 2, 4, 6%(wt/wt)) in Ap horizon soil, which collected from green house in Yesan, Chungnam. Moisture was controlled with 0.2, 0.3, 0.4, and 0.5 of mass water conte nt (${\theta}$m) to air dried soil, and water loss was compensated at every sampling. During incubation, soil pH was decreased continuously, that was caused by hydrogen generated from nitrification of ammonium nitrogen. And pH became higher with inclining cow manure compost amendment and water treatment, that meaned the increase of mineralization of organic-N to $NH_4\;^+-N$. Total nitrogen was reduced with increasing water content, but total carbon showed the contrast tendency with that of nitrogen. Therefore, C/N ratio slightly decreased in the low water condition (${\theta}$m 0.2) during incubation, but increased continuously in high water condition over ${\theta}$m 0.4. As a result, it was assumed that soil fertility is able to be reduced in the high water content over available water content. Nitrate transformation rate increased lasting in the low water content less than ${\theta}$m 0.3. Itdropped significantly in the first $2{\sim}3$ weeks of incubation over ${\theta}$m 0.4. In particular, nitrate was not detected in ${\theta}$m 0.5 of water content after the first $2{\sim}3$ weeks. In contrast, ammonium transformation was inclined with increasing water treatment. Nitrogen mineralization rate, which calculated with percentage ratio of (the sum of ex.$NH_4\;^+-N$ and $NO_3\;^--N$)/total nitrogen, was continuously increased in the low water content of ${\theta}$m 0.2 and 0.3. But it saw the different patterns in high water content over ${\theta}$m 0.4 that was drastically declined in the initial stage and then gradually inclined . From the above results, nitrogen transformation patterns differentiated decisively in water content between ${\theta}$m 0.3 and 0.4 in soil. Thus, it is very important for the maintain of suitable soil water content to enhance fertility of soil amended with manure compost. However, excess treatment of manure compost might enhance the possibility of contamination of small watershed and ground water around agricultural area.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.147-152
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• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Korean Journal of Heritage: History & Science
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• v.44 no.3
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• pp.18-43
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• 2011

The results of study on planting and cultivate of Hong Man-Seon(1643~1715)'s 'Salimkyungjae(The Economy of Forest)' the first summative textbook of agricultural skill of South Korea, are as follows. First, 'Salimkyungjae' suggests that one can enrich oneself, eat fruits in fall, enjoy the shade of trees in summer, and enjoy flowers in spring if one plants tree with 10 year plan with knowledge of ecology. Second, the number of plants had increased continuously from the early Chosun Dynasty to the mid Chosun Dynasty. The 52 plants in the book are classified into 31 trees, 8 shrubs, 3 others, and 10 herbs, and 28 of them are fruit trees. Hence, we can see that the book is for the promotion of welfare. Third, planting(transplantation) is the best on January of the lunar calendar, and the second on February, and fertile soil should be added much. Trees must be planted as deep as once it was planted, and buttressed. It will sprout well if it is planted at the depth of one inch, and planting a cutting should be carried out at the early March with 5 inch and finger-thick branches. Grafting is the best when it begins to sprout. Fruit trees will bear many fruits if they are grafted at the direction of South, and fruits will be greater if the trees' branches are cutting off on January. Especially, January was selected for the best season of planting traditionally. Fourth, flower trees are planted or sowed with manure around January and February of the lunar calendar, and it is recommended to replant them into flowerpots with manure when having flower buds around March and April of the lunar calendar. It would bloom earlier when using water mixed with stable manure, and sulfur smoke can be used in order to change the flower color from red to white. Flowerpots would be placed at half shaded lot with being supported by bricks. Pomegranate, gardenia, camellia and four-season flower should be planted after flowers fallen. When flower trees are beside walls, they need to be rotated frequently since their branches all point toward house. Seeds need to be preserved in a sunny hut, where its entrance and ventilating openings would be at south because it is convenient to manage pots. Fifth, insects hidden at fruit trees would be destroyed by torch smoke when roosters cry on New year's day of the lunar calendar. Insects would be decoyed into straw hanged at dawn of Cheongmyeongday(淸明日). Insects on fruit trees would be controlled using sulfur powder to close up holes or sulfur smoke to fumigate. Particularly, it suggests that utilization of fertile soil would be the best solution for growing health plants and preventing pest.

• Journal of Life Science
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• v.29 no.1
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• pp.112-117
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• 2019

Herbal medicines are widely used as therapeutic products in many countries. Corni fructus (CF), the dried ripe sarcocarp of Cornus officinalis Sieb. et Zucc (Cornaceae), has been used for thousands of years in traditional medicine and has been reported to be effective for the prevention and treatment of various diseases, such as kidney diseases and diabetes. Recent research on CF has documented a wide spectrum of therapeutic properties, which include anti-inflammatory, ant-oxidative, immunomodulatory, and anti-cancer effects. However, there is no information on its safety. Therefore, in this study, the toxicity of water extract of CF to ICR mice was investigated. The mice received a single dose of water extract of CF (1,000, 2,000, and 5,000 mg/kg of body weight) via the oral route. Mortality, clinical signs, body weight changes, gross findings, and weights of the principal organs after 14 d were then assessed. The results revealed no adverse effects of CF as determined by clinical signs, body weights, or organ weights and no gross pathological findings in any of the treatment groups. These results suggest that the 50% lethal dose and approximated lethal dose of CF extract is over 5,000 mg/kg. The findings provide scientific evidence for the safety of CFs.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.281-302
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• 2023

Carbon is not only an essential element for life but also a key player in climate change. The radiocarbon (¹⁴C) analysis using accelerator mass spectrometry (AMS) is a powerful tool not only to understand the carbon cycle but also to track pollutants derived from fossil carbon, which have a distinct radiocarbon isotope ratio (Δ¹⁴C). Many studies have reported Δ¹⁴C of carbon compounds in streams, rivers, rain, snow, throughfall, fine particulate matter (PM_2.5), and wastewater treatment plant effluents in South Korea, which are reviewed in this manuscript. In summary, (1) stream and river carbon in South Korea are largely derived from the chemical weathering of soils and rocks, and organic compounds in plants and soils, strongly influenced by precipitation, wastewater treatment effluents, agricultural land use, soil water, and groundwater. (2) Unprecedentedly high Δ¹⁴C of precipitation during winter has been reported, which can directly and indirectly influence stream and river carbon. Although we cannot exclude the possibility of local contamination sources of high Δ¹⁴C, the results suggest that stream dissolved organic carbon could be older than previously thought, warranting future studies. (3) The ¹⁴C analysis has also been applied to quantify the sources of forest throughfall and PM_2.5, providing new insights. The ¹⁴C data on a variety of ecosystems will be valuable not only to track the pollutants derived from fossil carbon but also to improve our understanding of climate change and provide solutions.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.187-195
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• 2023

Almost all of the water from agricultural dams located to the upper of the Yeongsan river is supplied as irrigation water for farmland and thus is not discharged to the main stream of the river. Also, most of the irrigation water does not return to the river after use, adding to the lack of flow in the main stream. As a result, the water quality and aquatic health of the river have become the poorest among the four major rivers in Korea. Therefore, in this study, several strategies for water quality improvement of the river were developed considering pollution reduction and flow rate increase, and their effect analysis was performed using a water quality model. The results of this study showed that the target water quality of the Yeongsan river could be achieved if flow increase strategies (FISs) are intensively pursued in parallel with pollution reduction. The reason is because the water quality of the river has been steadily improved through pollution reduction but this method is now nearing the limit. In addition, rainfall-related FISs such as dam construction and water distribution adjustment may be less effective or lost if a megadrought continues due to climate change and then rainfall does not occur for a long time. Therefore, in the future, if the application conditions for the FISs are similar, the seawater desalination facility, which is independent of rainfall, should be considered as the priority installation target among the FISs. The reason is that seawater desalination facilities can replace the water supply function of dams, which are difficult to newly build in Korea, and can be useful as a climate change adaptation facility by preventing water-related disasters in the event of a long-term megadrought.