It is essential that continual assessments of the impact of mine-derived water as a long-lasting burden on freshwater environments. Abundance-based evaluations of benthic macroinvertebrates have been conducted to evaluate anthropogenic disturbances and devise policies to reduce their impact. In this study, the status of a stream habitat was evaluated based on the body length and biomass weight of benthic macroinvertebrates of the family Baetidae. Following the renewal of the mining water treatment plant, the abundance of Baetidae assemblages recovered to a level comparable to that of a reference site. However, relatively low values were found for both body length and biomass weight in Baetidae species inhabiting the reddened streambed area, suggesting that the habitat has not yet been completely recovered despite the recovery of the abundance of the Baetidae assemblages. Therefore, continuous investigation and evaluation of this disturbed stream are necessary until their growth conditions of the habitat have functionally recovered

Recently, environmental DNA (eDNA)-based metabarcoding approaches have been proposed to evaluate the status of freshwater ecosystems owing to various advantages, including fast and easy sampling and minimal habitat disruption from sampling. Therefore, as a case study, we applied eDNA metabarcoding techniques to evaluate the effects of an abandoned mine land located near a headwater stream of Nakdonggang River, South Korea, by examining benthic macroinvertebrate diversity and compared the results with those obtained using the traditional Surber-net sampling method. The number of genera was higher in Surbernet sampling (29) than in the eDNA analysis (20). The genus richness tended to decrease from headwater to downstream in eDNA analysis, whereas richness tended to decrease at sites with acid-sulfated sediment areas using Surber-net sampling. Through cluster analysis and non-metric multidimensional scaling, the sampling sites were differentiated into two parts: acid-sulfated and other sites using Surber-net sampling, whereas they were grouped into the two lowest downstream and other sites using eDNA sampling. To evaluate freshwater ecosystems using eDNA analysis in practical applications, it is necessary to constantly upgrade the methodologies and compare the data with field survey methods.

In this study, we investigated the relationships between benthic macroinvertebrate assemblages and various environmental factors in Iancheon (NIA) and Bukcheon (NBC) streams, Korea. We collected benthic macroinvertebrates and 33 environmental factors in April 2017 at 9 sites (5 sites in NIA and 4 sites in NBC). We identified 93 species (5 phyla, 9 classes, 16 orders, and 53 families) and 69 species (5 phyla, 9 classes, 17 orders, and 47 families) in NIA and NBC streams, respectively. Considering benthic macroinvertebrate index (BMI), NIA (88.2) and NBC (80.2) streams were in “very good” status. Upstream areas showed the highest scores, 95.5 (NIA1) and 94.2 (NBC1), whereas BMI score was the lowest in downstream areas of both streams, especially in NBC4 (51.0 “bad” status). Cluster analysis and non-metric multidimensional scaling analysis represented the differences of benthic macroinvertebrate assemblages according to spatial and anthropogenic gradients. Our findings provide reference data and highlight the need for the continued monitoring to maintain the good status and manage macroinvertebrate diversity in these two streams, in Sangju-si, Korea.

Headwater streams are the main sources of water sediment and organic material for downstream reaches and their small catchments coupled terrestrial-aquatic linkages. Because headwater streams provide valuable habitats for unique and diverse assemblages of aquatic fauna, they are also essential for sustaining the structure and function of the watersheds. Therefore, it has been recently supported that headwaters are important areas for maintaining biodiversity. In this study, we surveyed four different headwater streams in different watersheds to characterize differences of benthic macroinvertebrate assemblages among study streams. Benthic macroinvertebrates were collected seasonally with a Surber net at four different streams. In addition, hydrological and physicochemical environmental factors including temperature, discharge, width, conductivity, dissolved oxygen and pH were also measured at each sampling site. Community indices were used to differentiate spatiotemporal changes of macrointertebrate communities. Multivariate analysis were used to characterize the relationships between communities and environmental factors. Differences of their environmental condition such as meteorological factors and stream hydromorphological factors were reflected in the ordination with macroinvertebrate communities.

Benthic macroinvertebrates are sedentary and have an intermediate life span ranging from months to a few years. They play a key role as consumers in the food trophic structure by linking producers, top carnivores, and decomposers in aquatic communities. Therefore, they have been widely used for ecological assessment of aquatic ecosystem health in an integrative and continuous manner. In this study, we characterized benthic macroinvertebrate communities at reference sites, which are not disturbed. Benthic macroinvertebrates were collected seasonally with a Surber net at three different streams (Pocheon, Hongcheon, and Namhae). In addition, hydrological and physicochemical environmental factors including temperature, discharge, width, conductivity, dissolved oxygen and pH were also measured at each sampling site. Spatial and temporal differences of benthic macrointertebrate communities were analyzed based on community indices, functional guilds, etc. relating to their environmental factors. Multivariate analysis were used to characterize the relationships between communities and environmental factors. Benthic macroinvertebrates were significantly different among sampling sites reflecting differences of their environmental condition such as hydromorphological factors, meteorological factors, etc.

Distribution of aquatic organisms is governed by various environmental factors Hydromorphological characteristics which are heavily affected by heavy rains in stream are one of the fundamental factors to influence the distribution of aquatic organisms. In this study we evaluated the difference response of two aquatic species Chironomus yoshimatisui and Limnodrilus hoffmesteri habiting to changes of discharge due to heavy rains. We compared the differences in their resilience and recover to disturbances. Our results showed that after a heavy rain during the sampling periods, the proportion of macrosubstrate highly increased and was not recovered into the previous states. Nonmetric Multi-dimensional scaling based on Chironomidae and Oligochaeta biota well represented annual and seasonal differences with heavy rain effects. Random forest model showed that the abundance of C. yoshimatisui were mainly influenced by microsubstrate, precipitation and Reynolds number, whereas stream roughness, mesosubstrate and macrosubstrate much more influenced the abundance of L. hoffmesteri.

This study was carried out to investigate the changes of guilds in benthic macroinvertebrate community in a undisturbed headwater stream. Samples were collected seasonally with a Surber sampler (30×30cm) at three different sampling sites (five replicates in each sampling sites) at Bongsunsa stream in Korean National Arboretum in Gyeonggi-do for 7 years from 2006 to 2012. Physicochemical environmental factors including discharge, water width, substrate composition, dissolved oxygen, pH and conductivity were also measured at each sampling sites. Changes of community indices and functional guilds such as functional feeding groups and trophic groups were evaluated in each sampling sites during study periods. In the samples, 84 species (9 order, 36 family) were identified, and Gammarus sobuegensis, Chironomidae spp, Ephemera strigata and Ecdyonurus kibunensis were dominant taxa. Considering the changes of functional feeding groups, shredder tended to decrease from upstream to downstream, whereas collector-gatherer and collector-filterer became higher. In addition, shredder was higher during autumn seasons. Self-Organizing Map was also applied to find out the temporal changes of benthic macroinvertebrate community composition, displaying the effects of seasonal variations in reference stream ecosystems.

This study was conducted to evaluate the seasonal changes of benthic macroinvertebrate communities in a reference stream as well as the effects of physicochemical environmental factors on benthic macroinvertebrate communities in a study stream. Benthic macroinvertebrates were sampled seasonally at five different sampling sites with five replicates at Changjeon stream in Mountain Gariwang from spring to winter in 2011. Physicochemical environmental factors (e.g., discharge, width, substrate, conductivity, dissolved oxygen, pH and water temperature) were measured at each sampling sites. Water quality factors such as conductivity, dissolved oxygen and pH were similar among the sampling sites, whereas hydrological factors including discharge and width tended to be higher from upstream to downstream. In substrate composition, the relative ratio of large substrate such as cobbles was higher in summer season. In macroinvertebrate samples, 79 species with 2 phylum, 5 order and 9 family were identified during the sampling periods. Gammarus sp. was higher in upstream (sites 1 and 2), whereas Chironomidae spp. tended to be higher in downstream. In functional feeding groups, shredder was higher in upstream, whereas predator and collector-gatherer were higher in downstream. The ratios of Gammarus sp. and Plecopetera were higher in summer. Nonmetric multidimensional scaling was applied to figure out the differences of macroinvertebrate communities during the survey periods, representing the seasonal changes as well as hydrological gradients.

Pomacea canaliculata (golden apple snail) as an invasive species in Asia has become a serious agricultural pest, especially in young rice, and makes significant environmental changes resulting from the depletion of macrophytes in natural wetlands. Even though various environmental factors influence to growth rate, reproduction, survival and behavior in apple snail, water temperature is one of the overwhelming effect on freshwater snails in general. In this sense, the objective of this study was to examine the changes of individual behavior in the apple snail according to the temperature changes. The snails were acclimated at 25℃, and 9 behavior categories were examined in each temperature regime (25℃ to 30℃, 2 5℃ to 20℃, and 25℃ to 15℃) for three days. Autocorrelation function (ACF) was applied to characterize the presence or absence of periodic behaviors in apple snails. The snails’ behavior in the treatment of elevated temperature were irregularly fluctuated or decayed in most behavior categories. On the other hands, in decreasing temperature from 25℃ to 15℃, the snails were nonstationary, especially in clinging behavior. The snails showed periodicity and some of them were decayed in clinging behavior in temperature changing from 25℃ to 20℃.

Ni-doped was prepared by the encapsulated induction melting and hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping.

The encapsulated induction melting and hot pressing were employed to prepare Fe-doped skutterudites and their thermoelectric properties were investigated. Single phase was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Iron atoms acted as electron acceptors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping. was found as an optimum composition for best thermoelectric properties in this work.

Sobolev approximation can be adopted to a macroscopic supersonic motion comparatively larger than a random (thermal) one. It has recently been applied not only to the winds of hot early type stars, but also to envelopes of late type giants and/or supergiants. However, since the ratio of wind velocity to stochastic one is comparatively small in the winds of these stars, the condition for applying the Sobolev approximation is not fulfilled any more. Therefore the validity of the Sobolev approximation must be checked. We have calculated exact P Cygni profiles with various velocity ratios, V∞/Vsto, using the accelerated lambda iteration method, comparing with those obtained by the Sobolev approximation. While the velocity ratio decrease, serious deviations have been occured over the whole line profile. When the gradual increase in the velocity structure happens near the surface of star, the amount of deviations become more serious even at the high velocity ratios. The investigations have been applied to observed UV line profile of CIV in the Copernicus spectrums of ʃ Puppis and NV of τ Sco. In case of τ Sco which has an expanding envelope with the gradual velocity increase in the inner region, The Sobolev approximation has given the serious deviations in the line profiles.

In Korea, 18 soybean cultivars have been recommended for food source that cooked with rice, however, the appropriate selection criteria are still unestablished in soybean breeding program. Since consumers prefer higher quality products, it is need to establish selection criteria of palatability. This study was investigated the relationship between palatability and physicochemical properties of black soybean. We conducted sensory evaluation and analyzed physicochemical properties with 4 cultivars and 12 germplasms. In the results, the crude fat content varied from 13.1 to 18.6%. The content of crude fiber was 4.0～5.0%. The saturated and unsaturated fatty acid contents were 12.09～16.47% and 83.53～87.91%. Beany flavor(0.76***), nutty flavor(0.89***), sweetness(0.83***) and chewiness(0.72**) were highly positively correlated with overall preference. The crude fiber contents had negative correlation with nutty flavor(-0.61*) and overall preference(-0.62*). The highest palatability was observed in Cheongjakong which had low fiber content and good appearance, chewiness and taste. The result suggest that fiber content is good selection factor in breeding program of soybean for cooking with rice.

The purple and blue grain of barley have anthocyanins that is good sources of antioxidant. Thus we investigated the malt and wort characteristic of purple and blue barley for brewing. During steeping period, anthocyanins content reduced both materials. However the lost content was different from 80% and 20% in purple and blue barley, respectively. Also the anyhocyanin content was different both malt comparing to raw grain from 0.4~4.2% in purple but 50% in blue grain. The wort and beer color(EBC unit) and content of polyphenol and soluble nitrogen from malt of purple and blue were higher than control malt(Hopum). There was no anthocyanins in wort and beer of malt in purple and blue. In these results, it was identified that the anthocyanins from raw grain lost during malting and brewing processing with conventional method.