• Journal of Wetlands Research
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• v.21 no.2
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• pp.102-113
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• 2019

Slack-tide sampling was carried out at 6 stations at high and low tide for a tidal cycle during spring tide of the early summer (June) and summer (July, August) of 2016 to determine the difference of water quality according to tide in Masan Bay, Korea. The mixing regime of all the water quality components investigated was well explained through the correlation with SAL. In the early summer and summer, TURB, DSi and NNN which mainly flow into the bay from the streams and SS, COD, AMN and $H_2S$ which mainly indicate the internal sink and source materials have a property of conservative mixing and non-conservative mixing, respectively. The conservative mixing showed a good linear relationship of the water quality between high and low tide, and the non-conservative mixing showed a variation of different pattern each other. Factor analysis performed on the concentration difference data sets between high and low tide helped in identifying the principal latent variables for them. In early summer, multiple effects (tidal action, natural influx and internal sinks and sources etc.) acted in combination for the differences to be distributed evenly in four factors (VF1~4), since there were few allochthonous inputs as a low-water season. On the contrary, in summer, the parameters showing large concentration difference at ST-1 affected by stream water were concentrated in one factor (VF1) and clearly distinguished from the parameters affected by the internal sinks and sources. In fact, there is no estuary (bay) that always maintains steady state flow conditions. The mixing regime of an estuary might be changed at any time due to the change of flushing time, and furthermore the change of end-member conditions due to the internal sinks and sources makes the occurrence of concentration difference inevitable. Therefore, when investigating the water quality of the estuary, it is necessary to take a sampling method considering the tide to obtain average water quality data.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.4
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• pp.282-293
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• 2018

The heading response of rice varieties is determined by the combined effects of their basic vegetative phase (BVP), photoperiod-sensitivity (PS), and thermo-sensitivity (TS). This study was performed to analyze the effect of differences among heading ecotypes of rice on their heading response in the field. To do this, we investigated the heading response of 15 varieties grown under different day-length and temperature conditions in a phytotron. The characteristics of heading ecotypes were compared to the heading responses in the field-grown rice varieties that were used in the phytotron experiments. The ranges of these characteristics across the 15 varieties were 18 - 35 days for BVP, 12 - 61 days for PS, and 12 - 35 days for TS. In comparisons of coupled varieties that differed only in a single trait among BVP, PS, and TS, the variety with the longer BVP and that with the higher PS had a longer period from sowing to heading (DTH), while the variety with the higher TS had a shorter DTH. The comparative magnitude of DTH in the coupled varieties followed the PS trait when BVP and PS were involved, the BVP trait when BVP and TS were involved, and the PS trait when PS and TS were involved in the heading response of field-grown rice. When comparing the coupled varieties with different traits of the three examined factors, the heading response was consistent with the PS trait. The DTH in all 15 varieties was significantly correlated with the PS, and the DTH in 9 selected varieties with a relatively small PS was correlated with BVP. The reduced DTH of rice in the July 10 seeding treatment compared to those in the June 25 and May 11 seeding treatments was positively associated with PS, but not with TS. We concluded that the heading response of rice varieties under natural conditions in Korea is mainly governed by the PS trait and is also greatly affected by the BVP trait when the PS is small.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.1
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• pp.106-127
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• 2019

This study aims to understand spatio-temporal variations of macrozoobenthos community in Han River (HRE), Geum River (GRE), and Nakdong River estuaries (NRE) of Korea, sampled by National Survey of Marine Ecosystem. The survey was seasonally performed at a total of 20 stations for three years (2015-2017). Sediment samples were taken three times with van Veen grab of $0.1m^2$) areal size and sieved through a 1 mm pore size mesh on site. A total of 1,008 species were identified with 602 species in HRE, 612 in GRE, and 619 in NRE, showing similar number of species between estuaries. Mean density was $1,357ind./m^2$, showing the high in NRE ($1,357ind./m^2$), mid in GRE ($1,357ind./m^2$), and low in HRE ($1,127ind./m^2$). Mean biomass was $116.8g/m^2$, showing similar variations to density ($174.2g/m^2$ in NRE, $129.0g/m^2$ in GRE, $49.0g/m^2$ in HRE). Polychaeta dominated in number of species and density in three estuaries. Biomass-dominated taxon was Mollusca in HRE and GRE, and Echinodermata in NRE. Polychaetous species dominated all three estuaries over 4% of density, such as Dispio oculata, Heteromastus filiformis and Aonides oxycephala in HRE, Heteromastus filiformis and Scoletoma longifolia in GRE, and Pseudopolydora sp. and Aphelochaeta sp. in NRE, showing various density between estuaries. Community structure was determined by various environmental variables among estuaries such as mean grain size and sorting (HRE), salinity and mean grain size (GRE), and salinity, dissolved oxygen, loss on ignition and mud content (NRE). Our study demonstrates the application of different measures to manage ecosystems in three estuaries. HRE needs to alleviate sedimentary stressors such as sand mining, land-filling, dike construction. Management of GRE should be focused on fresh water control and sedimentary stressors. In NRE, monitoring of dominant benthos and process study on hypoxia occurrence in inner Masan Bay are necessary.

• The Korean Journal of Mycology
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• v.49 no.3
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• pp.337-349
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• 2021

This study aimed to isolate wild yeasts from water and soil sample of the Nonsan stream and Sapgyoho (lake) in Chungcheonnam-do, Korea, and to further characterize previously unrecorded wild yeast strains. In total, 102 strains, representing 55 different species of wild yeast were isolated from 95 samples collected from the Jangseoncheon and Ipchoncheon of Nonsan stream in Jellabuk-do and Chungcheonnam-do. Among these, 33 strains were isolated from alkalophilic yeast extract-peptone-dextrose (YPD) medium (pH 9.0), and 9 strains were isolated concurrently on general YPD medium (pH 6.5) and alkalophilic medium. Seventeen strains of Cryptococcus laurentii were predominantly isolated. Additionally, 65 strains, representing 27 different species of wild yeast were isolated from 58 samples obtained from Sapgyoho (lake). Among the 82 isolated wild yeast strains, 8 strains, including Candida fructus JSC 72-1(JSL-GGU 015), had not previously been recorded. All 8 previously unrecorded yeasts were oval in shape except C. fructus JSC72-1(JSL-GGU-015), and only the Filobasidium chernovii JSC39-1(JSL-GGU-013) strain formed spores. All strains except Pseudosydowia eucalypti JSC23-6(JSL-GGU-012) grew well in yeast extract-peptone-dextrose (YPD) and yeast extract-malt extract media and grew in vitamin-free medium. Four strains, including P.eucalypti JSC23-6(JSL-GGU-012) grew well in 15% NaCl-containing YPD medium. F.chernovii JSC39-1(JSL-GGU-013) and Sirobasidium intermedium JSC7-3(JSL-GGU-014) assimilated lactose, and five strains, including F. chernovii JSC39-1(JSL-GGU-013) also assimilated starch. All strains were resistant to 800 ppm of Ca, Cu, Li, and Mg ions.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.9-10
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• 2019

순천만은 순천시의 남쪽에 위치하여 여수반도와 고흥반도의 사이에 있는 만 지형 형태로 만 전체를 순천만이라고도 하나, 보통 고흥군반도와 여수반도 사이의 만을 여자만이라 하고 만내부에 위치한 여자도라는 섬의 위쪽으로 순천시의 해안하구에 형성된 지역을 순천만이라 일컫는다. 순천만은 순천시에서 유입되는 동천과 이사천 및 해룡천의 하류에 형성되어 있어서 육지부에서 유입되는 퇴적물과 유기물로 인하여 갯벌과 갈대등이 잘 형성된 습지로서 2003년 12월 31일 해양수산부 갯벌 습지보존지역으로 지정되어 관리되고 있으며, 2004년에는 동북아 두루미 보호 국제네트워크에 가입하였고, 2006년 1월 국내 연안습지로는 최초로 람사르협약에 "Suncheon Bay"로 등록되었으며, 2016년 6월에는 람사르습지로 지정된 국내외적으로 중요한 습지이다. 순천만습지에 형성되어 있는 갯벌($28.0km^2$)은 세계 5대 연안습지 중 하나로서, 넓은 사니질 갯벌과 갈대군락이 잘 발달되어 있는 생태계의 보고(寶庫)이자 소중한 생태자원으로서, 순천시에서는 순천만을 자연생태공원으로 지정하여 보호 관리하고 있으며, 각종 자연학습자료들과 영상물들을 갖춘 생태전시관과 갈대숲 탐방로, 용산전망대, 야생화 정원, 담수습지, 갈대정자, 갯벌관찰대 등 사계절 생태체험을 위한 각종 시설들을 잘 갖춰놓고 많은 관광객의 이용할 수 있도록 하고 있다. 갯벌은 바닷가의 넓은 벌판이란 뜻으로서 삼면이 바다인 우리나라는 갯벌의 전체 면적이 약 $2,500km^2$에 달하는데 여기에는 많은 종류의 다양한 생물들이 살아가고 있으며 어민들의 생계에 지대한 영향을 주고있다. 이러한 갯벌은 퇴적된 입자의 구성에 따라 펄갯벌, 모래갯벌, 혼합갯벌 등으로 구별되는데 이에 따라 갯벌 생태계를 구성하고 있는 생물들의 종류도 바뀌게 된다. 순천만갯벌과 여기에 조성되어 있는 습지환경에 따라 확인되고 있는 수산자원으로는 새꼬막, 꼬막, 눈알고둥, 갯고둥, 비툴이고둥, 돌조개, 접시조개, 새알조개, 가무락조개, 바지락, 우럭, 가재붙이, 방게, 칠게, 농게 등의 저서 생물들과 짱뚱어, 문절망둑 등의 어류가 있으며, 해조류로 우뭇가사리 등이 있고, 인근의 어민들의 어업형태는 꼬막 등 패류의 채취나 종패를 뿌려 일정기간 양성하여 수확하는 양식업, 육상부에서 폐염전 등을 활용한 전어나 새우 등을 양식하는 양식업, 수산물을 직접 손이나 간단한 도구를 이용하여 잡는 맨손 어업 형태가 주를 이루고 있는 것으로 나타나고 있다. 이와 같이 국내외적으로 중요할 뿐만 아니라 인근의 어민들의 생계에도 지대한 영향을 미치고 있는 순천만의 습지는 뻘층이 깊고, 분해성 미생물이 다양하게 서식하여 유기물 분해능력이 뛰어나며, 유기영양분이 풍부하여 우리나라에서 가장 질이 좋은 습지로 평가되고 있으나, 순천시 등 순천만 인근에 거주하고 있는 인간의 활동에 따른 간섭에 많은 영향을 받고 있으며, 이에 따라 끊임없는 생태환경이 변화하고 있어서 순천만의 효율적인 보전 및 지속가능한 이용을 위해서는 생태계에서 가장 기본적인 요소인 수 저질 환경의 지속적이고 체계적인 조사 및 관리가 필요하다. 한편, 오염물질의 70% 이상은 하천이나 강을 통해서 해역으로 유입된다고 알려져 있기 때문에 생태계의 보고(寶庫)라고 알려진 순천만의 지속적인 보존 및 관리를 위해서는 유입수계 하천의 수질현황 및 오염물질의 주요 배출원을 파악하고, 이에 대한 저감대책을 수립할 필요가 있다. 따라서 본 연구는 순천만의 수저질 특성과 여기에 유입되는 하천의 수질환경 현황 및 오염원을 파악함으로써 순천만의 보전을 위한 효율적 관리방안을 제시하는 것을 목적으로 수행되었다. 연구의 결과에 따르면, 순천만의 수질평가지수에 의한 등급(WQI)은 III등급으로 나타나고 있으며, 득량만, 광양만 등에 비해 비교적 높은 유기물 및 T-N, T-P의 농도 분포를 보이고 있는 것으로 조사되었다. 이는 순천만에 유입되는 하수종말처리장의 방류수와 도시하수가 유입되어 그대로 방류되고 있는 해룡천 및 연안에 위치한 어촌으로부터 직접 방류되고 있는 일부 정화조 유출수 등, 다양한 원인에 의한 것으로 판단되며 이들의 관리가 부실할 경우 순천만의 갯벌과 습지의 지속가능한 생태환경유지는 쉽지 않다. 따라서 이를 효율적으로 관리하기 위해서는 순천만 연안의 오염물질 방류를 총량관리로 전환하여 철저히 관리하는 것이 필요할 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.431-438
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• 2021

To prepare more stringent regulations for USCG Phase II ballast water management, this study investigated the staining efficiency of SYBR Green I(SGI) and SYBR Gold(SG) on the virus-like particle (VLP). A dye with high staining efficiency was applied to the treated water that was passed through the ballast water treatment system (BWTS). VLP staining was observed most clearly under the 100-fold and 200-fold dilution of the stock solution when the volume of filtered samples was 0.5 mL to 2 mL. The staining efficiency of SGI and SG did not show a significant difference. On the other hand, the green fluorescence of viruses in the sample stained with SGI was more pronounced than in the samples stained with SG (expressed yellow fluorescence), making it easier to observe. The abundance of VLP in the test water and control water treatments that did not pass through the two types of BWTS (electrolysis type, UV + electrolysis type) was approximately 109 - 1010 VLP 100 mL-1. In contrast, no stained VLP was observed in the treated water treatments. Moreover, SGI was confirmed to be effectively stained under various salinity conditions, including seawater, brackish water, and freshwater. Further verification tests and development of staining methods under various BWTS are required, but the SGI staining method is believed to be a good alternative to the VLP live/dead determination of the USCG Phase II type approval test.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.195-206
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• 2021

In 2020, South Korea initiated research and development of a longitudinal connectivity evaluation between upstream and downstream based on stream ecosystem health. This study analyzed the migration of upstream and downstream migratory fish species, fish distribution characteristics, trophic guilds, tolerance guilds, and species composition changes from 2015 to 2020 at Songrim weir in Yeongok stream, where the cross-structure of an ice harbor-type fishway for fish movement was recently improved. A total of 5,136 fish, including 36 species, were collected and three major migratory fishes were identified, namely, Tribolodon hakonensis, Plecoglossus altivelis altivelis, and Oncorhynchus keta. According to the comparative analysis before (Pre-I) and after (Post-I) improvement of the fishway, the relative abundance of primary freshwater fish increased in the upstream section, while the number of migratory fishes decreased. The fish species that used the fishway in the Songrim weir were Tribolodon hakonensis (58.4%) and Plecoglossus altivelis altivelis(11.8%). According to the Wilcoxon Signed-Rank Test migratory fish showed a statistically significant difference (p<0.05) in the upstream and downstream, showing a biological improvement effect of the crossstructure. On the other hand, the annual change of migratory fish based on the MannKendall trend test did not significantly increase or decrease (p>0.05). Therefore, in the fish passage improvement project, it is necessary not only for physical, hydrological, and structural tests, but also for pre- and post-biological tests on the use and improvement effect of fishway.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.650-657
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• 2020

We conducted a phylogeographic analysis of Korean endemic Zacco koreanus populations inhabiting the East-flowing river (Gangneung Yeongokcheon; GY, Yangyang Namdaecheon; YN), the Han River (Seomgang; SG, Soksacheon; SS), and the Nakdong River(Gilancheon; GA) using the mitochondrial DNA cytochrome oxidase I (COI) gene (619 bp). Population genetic analysis was further performed to assess the population connectivity for the GY river where there is a large number of human-made artificial weirs with several fishways. The phylogeographic analysis revealed that while the populations of the East-flowing river and those of the Han River formed a monophyletic lineage, the Nakdong River individuals represented a distinct lineage with 3.7-4.2% (mean=4.0%) genetic distance from the other lineages. The population genetic analysis of the GY showed that a mid-stream population harbored relatively higher mitochondrial diversity relative to up- and down-stream populations, and there was no genetic differentiation between these three populations. The latter findings might suggest high genetic connectivity between the populations via genetic flow along the fishways. However, an analysis using faster-evolving genetic markers, such as microsatellites, is needed to confirm the findings of high population connectivity. Our study suggests the possibility of the presence of cryptic species in Z. koreanus in the Nakdong River basin. However, further study with more individual samples as well as additional markers or even more advanced genomic tools is required to test our hypothesis. Ecological or phenotypic analyses should be conducted to test whether the observed Nakdong River lineage represents a different or cryptic species, or simply hidden, but excessive, intraspecific diversity.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.257-270
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• 2022

This study evaluated the hydraulic factors contributing to the decreasing groundwater levels across Jeju island. Time-series data for groundwater level, precipitation, and groundwater usage and information on land use were acquired, and the correlations among them were analyzed to evaluate the causes of the decreasing groundwater. The effects of precipitation and groundwater usage on the fluctuations of groundwater level were quantified using response surface analysis and sensitivity analysis, and methods for groundwater quantity management by region were proposed. The results showed that the rate of groundwater decrease in the western region was larger than that in the eastern region. For the eastern region, the influence of precipitation was large and the rate of decrease in the groundwater level was relatively small. The geological formation of this part of the island and continuous seawater intrusion suggest that although the absolute amount of groundwater extracted for use was large, the decrease in the groundwater level was not seen to be great due to an increase in pressure by seawater intrusion. Overall, precipitation and groundwater usage had the greatest effect on the amount of groundwater in the western region, and thus their data would be most useful for informing groundwater management, whereas other factors (e.g., sea level and the location of the freshwater-seawater transition zone) must be considered when understanding Jeju's eastern region. As the characteristics of groundwater level fluctuations in the eastern and western regions are distinct, an optimal management plan for each region should be proposed to ensure the efficient management of groundwater quantity.

• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.240-249
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• 2022

Measuring chlorophyll fluorescence (CF) is a useful tool for assessing a plant's ability to tolerate abiotic stresses such as drought, waterlogging and high temperature. Korean ginseng is highly sensitive to water stress in paddy fields. To evaluate the possibility of non-destructively diagnosing waterlogging stress using chlorophyll fluorescence (CF) imaging techniques, we screened 57 ginseng accessions for waterlogging tolerance. To evaluate waterlogging tolerance among the 2-year-old Korean ginseng accessions, we treated ginseng plants with water stress for 25 days. The physiological disorder rate was characterized through visual assessment (an assigned score of 0-5). The physiological disorder rates of Geumjin, Geumsun and GS00-58 were lower than that of other accessions. In contrast, lines GS97-62, GS97-69 and GS98-1-5 were deemed susceptible. Root traits, chlorophyll content and the reduction rates decreased in most ginseng accessions. Further, these metrics were significantly lower in susceptible genotypes compared to resistant ones. All CF parameters showed a positive or negative response to waterlogging stress, and this response continuously increased over the treatment time among the genotypes. The CF parameter Fv/Fm was used to screen the 57 accessions, and the results showed clear differences in Fv/Fm between the susceptible and resistant genotypes. Susceptible genotypes had an especially low Fv/Fm value of less than 0.8, reflecting damage to the reaction center of photosystem II. It is concluded that Fv/Fm can be used as a CF parameter index for screening waterlogging stress tolerance in ginseng genotypes.