Vibrio vulnificus, a normal inhabitant in estuaries, is of great concern because it is a potent human pathogen causing septicemia, wound infection and gastrointestinal disease in susceptible hosts. To elucidate the distribution and environmental factors of V. vulnificus in Kum river, sampling was undertaken in five station from March, 26, 1993 to February, 22, 1994. Samples of 54 and 49 were collected from seawater and bottom deposit. The total detection rate of V. vulnificus was 11.7%. The detection rates of V. vulniftcus in the seawater and the bottom deposit were 9.3% and 14.3% respectively. V. vulnificus was mainly detected in estuary water when temperature was above 23℃ and salinity was below 15‰. We suppose that water temperature, salinity, pH and COD affect growth of V. vulnificus.

This study was conducted to understand the variation characteristics of suspended solid in the Keum River Estuary. Water sampling was carried out regularly with response to the tidal cycle from September, 1986 to August, 1987. Analyzed or observed items were sea water temperature, salinity, TS, TDS, TSS, VSS, FSS. and also the relationships between wind velocity, precipitation, tidal cycle and TSS were investigated. It is found that the sea water temperature is the lowest in January(2.5℃)and the highest in August(24.4℃), and increases toward upstream in summer and vice versa in winter. Salinity is the lowest in August (13.6‰) and the highest in December(20.3‰), and the annual mean value shows 13.6‰. TS and TDS are firmly related with the variation of salinity, thus, high in spring and low in summer. The annual mean values of TSS in 199.8(65.3∼454.5)㎎/ℓ, highest in March 308.2(67.5∼792. 3)㎎/ℓ and lowest in June 36.8(10.9∼200.0)㎎/ℓ. The annual mean values of VSS is 22.0㎎/ℓ, its variation tendency is similar to that of TSS. The annual mean value of VSS /TSS ratio is 13.9(6.8∼20.2)%, which are not high level compared with those of polluted sea areas. This ratio is high in summer(24.1%) and low in autumn(13.3%), and increases toward the downstream direction. It is also revealed that TSS shows a positive correlation with the wind velocity(r=0.59), and a negative with the precipitation in the Keum River basin(r=-0.64). TSS concentration is primarily subjected to the tidal range and the freshwater discharge and also related to the resuspension of bottom sediments by the action of wind force or wind waves. The dilution rate is strongly subjected to the seasonal variation of the freshwater discharge, therefore, TSS concentration shows low in summer and high in winter. Under low discharge condition in spring, autumn and winter, TSS, VSS are high level in spring tide compared with those in neap tide : under high discharge condition in summer, these values are reversed that is, TSS is higher in neap tide than in spring tide.

Physical, chemical and biological surveys on Nakdong River estuary were made from October, 1985 to September, 1986. 1. For all the seasons except summer, the sea surface temperature in northwest area of the line which linked from Seo Island to Jisim Island was I-2˚C lower than in southeast area, but in summer the sea surface temperature in northwest area was I-2˚C higher than in southeast area. On the contrary, bottom temperature of coastal area was 1˚C higher than that of oceanic area except winter. 2. Surface salinity in summer and fall has minimum value of 1. 9%0 and maximum value of 32.9%0. This large variation was caused by the runoff of the Nakdong River. Effect of less saline Nakdong River water in northwest area of the line which linked from Seo Island to Jisim Island was greater than in southeast area. A strong current rip always formed near this line. 3. The yellowish-green colored zone was observed in the Nakdong River estuary throughout the year by influence of river discharge. The characteristics of the water quality in the zone have shown that the water color was grade 7 by the Forel water-color meter, transparency was less than 4 m, and concentration of suspended solids was more than 5 mg/1. This water body was in the state of eutrophication in terms of chlorophyll-a and inorganic nitrogen concentration during summer season. 4. During the study period, total 276 taxa were identified. Most of them were diatoms and dinoflagellates which consisted of 97.5%. The component ratio of the above two groups was 84.4% and 13.1 % respectively. Diatoms were plentiful in December and dinoflagellates in July. Dominant species were Nitzschia seriata in October, Thalassiosira rotula in December, Skeletoncma costatum in April, and Nitzschia longissima in July. 5. A total of 47 zooplankton taxa was identified from the samples collected. Copepods were numerically the most important components of zooplankton communities in the study area. The domir:ant copepod species were Paracalanus parvus, Acartia clausi and Temora turbinata. Noctiluca scintillans was the next important component. The other zooplankton with minor abundance were Cladocera. Sagitta spp., Cnidaria, Mysidacea, Lucifer spp. and Amphipoda. 6. During the study period, fishes from 47 families and 87 species were sampled in th~ study area. The four most abundant fish species were Rep~mucen//'s valencicnnei, Leiognathus n~cha!is, Amblychaeturicllthys hexanema and Sardirel/a zun:zsi. The fish species of the secondary importance in abundance were Cynoglossus joyneri, Sillago sihama, Engra~lis japonicus, Encdrias nebulos'l, Acanthogobius flavimanus, Trichiurus lepturus, LiParis tanai/ai, Cynagloss//'s interruptus, Aj)ogon line:z!us, Thrissz la 1l.'1la!ensis, and Limanda yokohamac.

This paper describes that air noise and underwater noise in the Somjin Estuary are measured and analysed to get the basic data to find out the influence of environment on the underwater. The results obtained are summerized as follows: 1. The spectrum level of air noise in the Somjin Estuary increases until 500Hz, and decreases a little over 2KHz. 2. The spectrum level of underwater noise in the Somjin Estuary increases from 50 Hz to 1 KHz, but it decreases over 1 KHz as the depth is deeper. 3. When the influence of other factors is scarce but the influence of flowing speed is significant, the noise level seems to be higher at speedy layer than at slower layer. 4. The underwater sound level seems to be wider at speedy layer than at slower layer.

In this study, the bathymetric data acquired from 2018 to 2020 and the precipitation and suspended sediment data were analyzed for changes in bathymetry owing to the discharge from the Nakdong River barrier and environmental factors, especially the torrential rain in 2020. Sediment erosion and deposition processes are repeated because of complex environmental factors such as discharge from the Nakdong River barrier and the influence of waves generated from the external sea. In the first half of the year after the dry season, bathymetric data showed relative erosion trends, whereas in the second half after the flood season, deposition trends were identified owing to the increase in sediment transport. However, the data from the second half of 2020 showed a large amount of erosion, resulting in tendencies different to those of erosion in the first half and deposition in the second half of the year. This result is judged to be influenced by the weather in the summer of 2020. The torrential rain in the summer of 2020 resulted in a higher force of erosion than that of deposition. In summary, the tendency for erosion is more significant than that of sedimentation, especially in the main channel area of the Nakdong River.

To evaluate the geochemical characteristics and assess the pollution in surface sediments of the Nakdong River estuary, two sites adjacent to the estuary bank (Hh1 and Hh2) and one site at the upper part of the estuary bank (Hh3) were investigated. The surface sediments were analyzed for their contents of metals (Cu, Pb, Ni, Cr, Zn, and Al), organic matter (IL, COD, TOC, and TN), and grain size from 2018 to 2020. As a result of the pollution assessment, there was little anthropogenic contamination by most of the metals. The surface sediments in Hh2 had comparatively abundant silt and clay, whereas the other sites were mainly composed of sand. The organic index and contents of organic matter were highest at Hh2. Multivariate statistical analyses (cluster analysis and Pearson correlation analysis) showed that the contents of organic matter and pollution were associated with fine sediment. These results suggest that the geochemical characteristics were changed by the estuary bank built in the research area and that the increase in fine sediment attributable to the low-energy environment resulted in an increase in organic matter pollution.

In order to provide fundamental information about the floristic composition of the area along with an assessment of the environmental impact, a floristic study of the vascular plants in the Tamjin River estuary in Gangjin-gun was conducted for a total of nine days, in the period from June 2014 to September 2014. We found that the vascular plants in this region comprised 424 taxa belong to 102 families, 281 genera, 390 species, 5 subspecies, 26 varieties, and 3 forma. Five taxa of Korean endemic plants including Weigela subsessilis (Nakai) L.H.Bailey, Lespedeza maximowiczii var. tricolor (Nakai) Nakai, and Clematis trichotoma Nakai were collected. Two least concern (LC) taxa of rare plants (as designated by the Korea Forest Service) were collected: Hydrocharis dubia (Blume) Backer and Platycladus orientalis (L.) Franco. Ten the floristic regional indicator taxa from the third to the fifth grade were identified: two taxa belonged to grade IV, and eight taxa belonged to grade III. Twenty-four taxa of salt-tolerant plants, including Artemisia fukudo Makino, Carex rugulosa Kuk., and Suaeda glauca (Bunge) Bunge, as well as 44 taxa of aquatic plants, including Najas marina L., Nuphar oguraensis Miki, and Nymphoides indica (L.) Kuntze, were investigated in this region. Fifty-nine taxa of naturalized plants were recorded, among which the following six taxa were plants that caused ecosystem disturbance: Ambrosia artemisiifolia L., Humulus scandens (Lour.) Merr., Lactuca scariola L., Rumex acetosella L., Solidago altissima L., and Symphyotrichum pilosum (Willd.) G.L.Nesom.

낙동강 하구의 지형변화 메커니즘을 파악하는 것은 하구의 관리방안과 처리방법 연구에 매우 중요하다. 본 연구에서는 낙동강 하구의 지형변화에 관여하는 강우, 하천유량, 유사량과 같은 육역으로부터 영향과 조석, 조류, 파랑, 표층퇴적물 등과 같은 해역으로부터의 영향을 조사·분석하였다. 분석된 자료에 근거하여 지형변화 실험을 수행하고, 지형변화와 외력조건별 기여도를 분석하였다. 수치실험 결과 지형변화는 하굿둑 방류 영향을 직접적으로 받는 수로부를 중심으로 침식이, 간접 영향권인 간석지를 중심으로 퇴적이 우세하게 나타났다. 수로부를 따라 이동되는 퇴적물이 파랑에 의해 분급, 배분되면서 울타리선 전면부에는 퇴적이 우세하였다. 지형변화 실험결과인 퇴적 우세현상과 비교 하여, 외력조건별로 침식의 기여도가 크게 나타나고 있으나 각 외력조건의 복합적인 영향은 퇴적이 우세하게 나타나고 있다. 따라서, 낙동강 하구의 지형변화는 여러 복합적인 외력인자의 결과로 판단된다. 또한, 각 외력조건별 영향은 구역별로 상이한 기여도를 보이므로 하구관리방안 수립시 이러한 결과를 고려해야 하고, 반드시 복합적인 상호작용의 결과로 이해하고 있어야 할 것으로 사료된다.

본 연구에서는 조석의 영향을 주기적으로 받는 임진강 하류부의 계획홍수위를 보다 합리적으로 산정하는 방안을 검토해 보았다. 우선 감조하천의 특성을 감안할 수 있는 부정류모의를 수행하여 홍수위의 변동을 살펴보았고, 수위 계산에 민감한 매개변수인 조도계수를 해당지역의 특성에 맞게 현실화하여 홍수위 변화를 분석하였다. 그 결과를 2011년 임진강하천기본계획보고서에서 고시한 임진강 하구 계획홍수위와 비교하고, 감조구간에서 홍수위 산정시 유의해야 할 점들을 정리하였다. 참고로 2011년에 고시된 계획홍수위는 대규모 하상 준설 단면을 입력자료로 하여 부등류모의를 통해 산정된 바 있다. 본 연구의 결과, 임진강 하구의 경우 홍수위 산정에 있어서 조도계수를 한강하구와 동일한 값으로 할당하고, 하구 조위를 감안할 수 있는 부정류 모의를 수행하면 하상 준설을 하지 않더라도 홍수위가 제방 여유고를 만족함을 알 수 있었다.

To understand the changes in physical parameters and phytoplankton size structure caused by tides, a fixed station in the Youngsan River estuary was monitored at 2-h intervals, on April 28, 2012 and August 12, 2012. No clear relationship was observed between the temperature and salinity changes and tidal levels in April. However, in August, temperature decreased during the ebb tide and increased during the flood tide, while salinity showed the opposite trend. In addition, there was no specific change in the phytoplankton biomass corresponding to tidal levels in April. In August, the total chlorophyll a and the biomass of net phytoplankton (>20μm ) increased almost 20 times during the ebb tide and decreased during the flood tide. The biomass of nanophytoplankton (<20μm ) showed a similar variation in response to tidal level changes. In April, the relationship between percent contributions of phytoplankton size structure and tidal levels was not clear. In August, the net phytoplankton was dominant in the early stage and nanophytoplankton was dominant in the later stage, while contribution of nanophytoplankton and net phytoplankton increased at high tide and low tide, respectively. Therefore, in April, other factors such as freshwater discharge were more important than the tide, whereas in August, when no freshwater discharge was recorded, the changes in semidiurnal tides influenced the physical parameters and phytoplankton dynamics. These results could contribute to the understanding of phytoplankton dynamics in the Youngsan River estuary.

Bird species (BS) of the Nakdong River estuary (NRE) were selected to suggest conservation and management strategies, taking habitats and major threats into consideration. Five BS (Cygnus spp., Calidris alpina, Sterna albifrons, Fulica atra, and Anser fabalis) were selected following analysis of their dominance, national importance, seasonality, taxonomic group, and distribution within the NRE. The BS comprise two winter birds, one summer, one passage bird, and one resident bird. They can also be classified into four taxonomic groups: two under ducks and geese (Anatidae), and one each under gulls (Laridae), shorebirds (Scolopacidae), and diving birds (Rallidae). The results show that BS could be a useful tool in guiding estuary management because their habitats are clearly distinct, and include important areas of the NRE. A reduction of feeding and resting places—such as tidal flats, Scirpus planiculmis habitat, and agricultural farmland—and climate change are major threats to BS, therefore countermeasures to such threats should be considered in future estuary management plans.

하구둑과 같은 구조물이 설치된 하구역에서는 상류로부터 내려온 하천수와 외해의 조석, 수문의 운영에 따라 복잡한 유출특성을 가지게 되며, 하나의 하구역에 2개 이상의 유역출구가 존재하는 경우 더욱 복잡한 형태의 홍수유출특성을 나타낸다. 이러한 사례로 현재 개발계획이 수립중인 새만금 지역을 들 수 있다. 새만금 지역의 경우 만경강과 동진강 유역에서 하천수가 유입되고 방조제에서는 배수갑문을 통해 하천수를 방류하고 해수유입을 차단한다. 두 하천이 만나는 새만금호 내에는 분리하는 용지가 들어서게 되며, 두 수계의 유출량을 연결수로를 통해 교환할 수 있도록 계획되고 있다. 이러한 연결수로는 평소에는 주운의 역할을 하지만 홍수시에는 두 수계간의 홍수를 소통시켜 홍수를 분담하는 기능을 하게 된다. 따라서 하구역 내의 치수적 안전성 확보를 위해서는 연결수로에 대한 홍수분담능력을 파악하는 것이 중요하다. 본 연구에서는 연결수로의 통수능에 따른 홍수위 저감효과를 수치해석을 통해 분석하였 다. 해석에는 Delft3D를 활용하였으며 해석기간은 배수갑문의 방류가 어려워 최대홍수위가 발생되는 소조기로 설정하였다. 새만금종합개발계획상의 토지이 용계획에서는 3개의 연결수로가 계획되어 있으나 연결수로에 의한 홍수위저감효과를 검토하기 위해 해석을 단순화하여 가장 폭이 넓은 수로 1개만 운영되도 록 설정하였다. 연결수로의 폭은 동일하게 하고 하상고를 EL.-15 m～EL.-3 m까지 2 m 단위로 변화시켜 다양한 통수능 조건에서의 홍수저감효과를 검토하 였다. 수치해석 결과 연결수로의 통수능이 감소하면 두 수계간의 수위차가 증가하면서 배수갑문지점에서의 최대수위도 증가하며, 동일한 수위차라 하더라도 통수단면적에 따라 유속의 영향으로 홍수위 저감효과도 변화한다는 것을 확인하였다. 또한, 통수단면적이 증가하더라도 홍수위 저감효과가 발생하지 않게 되는 통수단면적도 분석하여 제시하였다. 본 연구결과는 향후 연결수로 설계시 기초자료로 활용될 수 있으며, 준설로 인한 공사비를 최소화하면서 홍수위 저감효과는 극대화할 수 있는 최적 연결수로를 설계할 수 있을 것으로 기대된다.

본 연구는 경관생태학적 분석방법과 생태네트워크 개념을 도입하여 금강하구 광역 생태축을 구상을 그 목적으로 하고 있다. 연구의 대상지는 전라북도 군산시 성산면, 나포면 일대 금강 군산권역 전체이며, 그 중에서도 제방을 중심으로 제내지 1km 이내 권역을 설정하였다. 본 연구의 결과를 정리하면 다음과 같다. 첫째, 금강하구의 자연생태·인문환경에 대한 종합분석을 기반으로 가창오리를 목표종으로 선정하였다. 금강 일대의 우수한 기존 서식환경을 적극 보전하고, 신규 서식처의 조성·복원을 목표로 수변지역 일대를 관리하고자 하며, 가창오리와 수금류가 직접적으로 머무르는 서식처의 보전 뿐만 아니라, 이들 생물종을 부양하는 하위 생태피라미드 및 서식기반환경에 대한 포괄적인 관리를 수행하도록 한다. 둘째, 생태권역의 설정과 관련하여, 유네스코 MAB모형을 기반으로 대상지를 핵심지역, 완충지역, 연결지역, 복원지역 및 지속가능지역으로 세분화 한 후, 최종적으로 보전권역, 복원권역 및 체험·이용권역으로 생태관리권역을 분석 및 구분하였다. 보전권역은 경관생태학적 분석의 핵심지역을 중심으로 인간의 이용 및 간섭을 최소화하며, 지역의 생물다양성을 증진시킬 수 있는 야생동식물의 서식처로 관리하기 위해 설정된 공간으로, 핵심지역의 배후부지로 완충지역 일부가 포함한다. 복원권역은 생물서식공간의 확대와 생태계의 건전성 회복을 목표로, 기존 생태공간에 대한 기능향상 및 단절·훼손지역에 대한 생태복원 등 지속적인 관리가 요구되는 공간으로, 완충지역, 연결지역, 복원지역 등을 포함한다. 마지막으로 체험·이용권역은 기개발지 및 접근성 우수지역을 중심으로 체계적이고 효율적으로 금강의 생태자원을 이용·활용할 수 있는 공간으로, 주변지역과의 연계를 통한 생태관광 활성화를 도모하는 지역으로 정의한다. 본 연구는 최종적으로 각 권역별로 관리방향, 8대 추진전략 및 26개의 주요 사업과 프로그램을 제시하였다. 보전권역은 생물다양성 관리계약의 확대, 무논습지 조성, 녹지 및 습지총량제 등의 관리제도 도입을 제안하였으며, 복원권역의 경우 조류 및 생물서식공간 조성, 단절지역 소규모 비오톱 조성 및 수질정화습지의 조성 등을 제안하였다. 마지막으로 체험·이용권역의 경우 생태체험마을 조성, 습지생태공원 조성 및 생태해설사 양성 및 활성화 프로그램을 제안하였다. 이러한 프로젝트 및 프로그램은 본 대상지의 지속가능한 발전을 위한 가이드라인을 제시해줄 것으로 판단된다. 반면에 생태관리권역의 설정 및 권역별 주요 사업 및 프로그램의 선정이 일부 주관적인 판단에 의해 진행된 부분이 있으며, 향후 보다 객관적이고 과학적인 접근방법이 담보되어 진다면, 향후 국가 광역 핵심생태축 조성사업 등과 연계하여 보다 체계적인 생태자원의 보전 및 활용의 가이드라인을 제공해줄 것으로 기대된다.

동해안과 접하고 있는 하천의 대부분은 경사가 급하고 유로연장이 짧아 하천의 유황과 흐름에 따라 다양한 지형 변화가 발생하고 있다. 특히 강원도 동해안의 하구는 산지에서 발생한 토사가 하천을 따라 이동하여 침식과 퇴적을 반복하며 하구부에 도달시 퇴적토사가 점차 증가하는 하구폐색현상이 빈번히 발생하고 있다. 하구폐색현상은 홍수시 하천 수위상승에 따른 범람의 위험을 증가시키는 것과 동시에, 갈수기에는 주항에 지장을 초래하는 등 우리 사회생활에 중대한 영향을 미치는 재해를 가져오고 있다. 본 연구의 대상지역인 강원도 삼척시 가곡천 하구부 지형 또한 계절적 영향 및 자연적 요인과 인위적인 요인으로 인해 하구부의 개폐현상이 지속적으로 이루어지고 있다. 따라서 본 연구에서는 하구부의 개폐와 수리특성을 연관 지어 분석하기 위해 가곡천 하구부에 CCTV를 설치하고 모니터링을 실시하였으며 그 결과를 토대로, 홍수기 전·후 및 계절별 지형변화 특성을 분석하였다.

Characteristics of the developmental stages of spermatids during spermiogenesis and phylogenetic classicfication of the species using sperm ultrastructures in male Crassostrea ariakensis were investigated by transmission electron microscope observations. The morphology of the spermatozoon of this species has a primitive type and is similar to those of Ostreidae. Ultrastructures of mature sperms are composed of broad, modified cap-shaped acrosomal vesicle and an axial rod in subacrosomal materials on an oval nucleus, four spherical mitochondria in the sperm midpiece, and satellite fibres which appear near the distal centriole. The axoneme of the sperm tail shows a 9+2 structure. Accordingly, the ultrastructural characteristics of mature sperm of C. ariakensis resemble to those of other investigated ostreids in Ostreidae in the subclass Pteriomorphia. In this study, particularly, two transverse bands (stripes) appear at the anterior region of the acrosomal vesicle of this species, unlike two or three transverse bands (stripes) in C. gigas. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm ultrastructures and morphologies in the resolution of taxonomic relationships within the Ostreidae in the subclass Pteriomorphia. These spermatozoa, which contain several ultrastructures such as acrosomal vesicle, an axial rod in the sperm head part and four mitochondria and satellite fibres in the sperm midpiece, belong to the family Ostreidae in the subclass Pteriomorphia.

Restoration is the process of reducing or reversing damage to an ecosystem so that it can function in its original manner. However, many restoration programs do not achieve this. In the Nakdong Estuary, the largest migratory nesting site in the center of the East Asian–Australasian flyway, an estuarine barrage was constructed in the 1980s that required site restoration following its completion in 1987 and the expansion of several large industrial complexes(Noksan and Jangrim) and a residential development(Myeongji). The goal of the restoration was to restore the function of the wetland to its pre-disturbance state. To achieve this, a restoration program was designed consisting of three stages. The first stage(1993– 1995), saw the construction of three artificial wetlands(Shinhori, Daemadeung, and Eulsuk), the second(2003–2005) involved the dredging and returning of farmed lands to their natural state, and the third(2008–2012) focused on the rehabilitation and vegetation development of the wetlands. However, the project has not achieved all of the desired goals, and it is an example of the lapses in ecological restoration following anthropogenic disturbance. Issues that resulted in an incomplete restoration included the timing of the stages, noncompliance with the restoration plan, not directly monitoring the restoration or continuing the monitoring following completion of the development project, and the political subversion of the restoration plan. For the success of the restoration plan, it is necessary to avoid mistakes such as inconsistent monitoring, unequal levels of stakeholder involvement, and political interference.

Total organic carbon(TOC), Total nitrogen(TN), and carbon and nitrogen stable isotopes were measured in the sediment and suspended parties in fresh lake water and saline estuarine water to determine the sources of Particulate organic matter(POM) in the sediments of the Youngsan river estuary. POM in the freshwater discharge water was mostly phytoplankton origin with little trace of terrestrial plants. POM from phytoplankton blooms formed in estuarine water in response to the nutrient enriched freshwater discharges was the most important sources of POM in the sediment near the dike, comprising more than 40% of the total organic matter. POM from freshwater phytoplankton and oceanic phytoplankton were also important sources of the sediment POM, and their contributions varied with the distances from the dike. Contribution of freshwater phytoplankton to sediment POM decreased from the dike to the outside of the estuary.