• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.92-102
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• 2002

This study was conducted to compare filtering abilities of three species of freshwater mussels (Cobicula fluminea, Corbicula leana and Unio douglasiae) and to evaluate their filter feeding effects on water quality change in experimental enclosure systems. Mussel feeding in both laboratory and enclosure resulted in decrease of particulate material, such as chlorophyll, total P, SS. In the treatment with 600 individuals of mussels, chllorophyll concentration and net primary productivity decreased from $87.3{\pm}4.5\;{\mu}g/L$ and $106.3{\pm}8.8\;{\mu}gC\;L^{-1}\;hr^{-1}$ to nearly the same level as the mussel-free enclosure ($25.0{\pm}0.5\;{\mu}g/L$ and $15.6{\pm}13.3\;{\mu}gC\;L^{-1}\;hr^{-1}$, respectively)(P< 0.05, n = 6, ANOVA). In concert with the decrease of chlorophyll concentration, not only was the transparency enhanced from 0.48 m to 1.2m but also the suspended solids and total phosphorus decreased from $22.0{\pm}1.0\;mg/L$ to $7.5{\pm}0.5\;mg/L$ and $133{\pm}0.8\;{\mu}g/L$ to $70{\pm}0.0\;{\mu}g/L$, respectively (P<0.001, $r^2$>0.71, n = 11). Although slight decrease of SRP concentration and the increase of inorganic nitrogen ($NH_3-N$ and $NO_2-N$) were observed in the mussel addition enclosure, there was no statistical difference between two enclosures. Based on the filtering rate on phytoplankton and nutrient release rate in forms of feces and pseudofeces, Corbicula leana appeared to be the most efficient filter-feeder among three mussel species. These results inidicate that Cobicula play an important role in controlling particulate sestons and thus it could be applied as a biocontroler for the water quality management in lakes and reservoirs with algal blooms.

• Environmental and Resource Economics Review
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• v.27 no.1
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• pp.105-138
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• 2018

This paper reports novel empirical results of a choice experiment that elicited the economic values that residents in the Seoul metropolitan area place on the amenity services realized from the landscape views and accessibilities to urban green spaces (i.e., mountains, rivers and urban parks). The 1,000 respondents in the sample were divided into two residential of housing types (apartments vs. houses) and occupancy types (owners vs. tenants). Residents living in apartments are willing to pay an average of 28% (5.0 million KRW per year) above the current housing prices per household for a mountain view, compared to an apartment view from their living room. Their willingness to pay values are about 22% (4.0 million KRW per year) and 10% (1.8 million KRW per year) respectively for a river view and a urban park view. Economic benefits of having access (i.e., a 10 minutes working distance) to mountains, rivers and urban parks are estimated to be an average of 16% (2.9 million KRW per year), 20% (3.6 million KRW per year) and 18% (3.2 million KRW per year), respectively, above the current housing prices per household. On the other hand, access benefits for those residing in houses are 18% (4.7 million KRW per year), 16% (4.1 million KRW per year) and 22% (5.6 million KRW per year) per household, respectively. They are also willing to pay an average of 35% (8.9 million KRW per year) above the current housing prices for keeping or having a garden or vegetation bed. Furthermore, a strong "greenspace premium" is centered around the three Gangnam districts for house-dwellers, whereas it is areas of "new real estate boom" for apartment dwellers.

• Korean Journal of Ecology and Environment
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• v.48 no.2
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• pp.129-138
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• 2015

Forest vegetation of Geumsusan (1,016.0 m) and Doraksan (964.4 m) in Woraksan National Park is classified into mountain forest vegetation. Mountain forest vegetation is subdivided into deciduous broad-leaved forest, mountain valley forest, coniferous forest, riparian forest, afforestation and other vegetation. Including 77 communities of mountain forest vegetation and 5 communities of other vegetation, the total of 82 communities were researched; mountain forest vegetation classified by physiognomy classification are 37 communities deciduous broad-leaved forest, 16 communities of mountain valley forest, 8 communities of coniferous forests, 1 community of riparian forest, 15 afforestation and 5 other vegetation. As for the distribution rate for surveyed main communities, Quercus variabilis and Quercus mongolica communities account for 33.031 percent of deciduous broadleaved forest, Cornus controversa community takes up 29.142 percent of mountain valley forest, Pinus densiflora community holds 64.477 percent of mountain coniferous forest holds. In conclusion, minority species consisting of Quercus variabilis, Quercus mongolica, Pinus densiflora, Quercus serrata and Cornus controversa are distributed as dominant species of the uppermost part in a forest vegetation region in Woraksan National Park. In addition, because of vegetation succession and climate factors, numerous colonies formed by the two species are expected to be replaced by Quercus variabilis, Quercus mongolica, Cornus controversa and Fraxinus mandshurica which are climax species in the 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.