Kwangyang Bay Research Articles

The Change of Tide and Tidal Current Due to the Development of the Kwangyang Bay, Korea

The Change of Tide and Tidal Current Due to the Development of the Kwangyang Bay, Korea

광양만에서 소형 저인망으로 어획된 어류의 종조성 및 양적 변동

Species composition and seasonal variation in Kwangyang bay were investigated 6 times from October, 1999 to August, 2000. The fishes caught by a small otter trawl were identified into 10,017 individuals, 72 species, 61 Genus, 38 families and 9 orders. Perciformes were dominant identified into 31 species, 28 Genus and 17 families. Followed by Scorpaeniformes (12 species, 8 genus and 6 families) and Pleuronectiformes (9 species, 8 genus and 4 families) and Clupeiformes (7 species, 6 genus and 3 families) were caught in the study period. During the study, most dominant species was Leiognathus nuchalis by 6,257 individuals (62.46%) of the total, followed by Konosirus punctatus by 937 individuals (9.35%), Engraulis japonicus by 612 individuals (6.11%). The diversity was the highest in February (H’=1.931), while the lowest in April (H’= 1.001). The evenness was the highest in February (E=0.645), while the lowest in April (E=0.268). The dominance was the highest in April (d=0.858), while the lowest in February (d= 0.521). The richness was the highest in April (E=4.860), while the lowest in February (E=2.834). The similarity of community structure was 64.36% between June and August, which was the most similar in monthly similarity.

Photosynthetic functions of Synechococcus in the ocean microbiomes of diverse salinity and seasons.

Synechococcus is an important photosynthetic picoplankton in the temperate to tropical oceans. As a photosynthetic bacterium, Synechococcus has an efficient mechanism to adapt to the changes in salinity and light intensity. The analysis of the distributions and functions of such microorganisms in the ever changing river mouth environment, where freshwater and seawater mix, should help better understand their roles in the ecosystem. Toward this objective, we have collected and sequenced the ocean microbiome in the river mouth of Kwangyang Bay, Korea, as a function of salinity and temperature. In conjunction with comparative genomics approaches using the sequenced genomes of a wide phylogeny of Synechococcus, the ocean microbiome was analyzed in terms of their composition and clade-specific functions. The results showed significant differences in the compositions of Synechococcus sampled in different seasons. The photosynthetic functions in such enhanced Synechococcus strains were also observed in the microbiomes in summer, which is significantly different from those in other seasons.

광양만권 일자리 미스매치 완화를 위한 구직자와 재직자의 요구 분석

이 연구는 중소기업과 구직자간의 생각의 접점을 찾을 수 있는 정책적 대안을 모색하고자 광양 산업단지 중소기업 재직자와 인근 지역 구직자들을 대상으로 보상, 숙련, 정보의 측면에서 미스매치 수준을 논의하였다. 구체적으로 첫째, 구직자와 재직자를 대상으로 기대 수준 및 현재 수준의 차이를 분석하고, 둘째, 항목별 불일치 수준을 비교함으로써 미스매치 개선방안을 도출하였다. 광양을 포함한 인근 지역의 구직자와 중소기업 재직자를 유의표집하여 최종 113명의 구직자와 80명의 재직자가 분석에 포함되었다. 일자리 미스매치 영역에 따른 정책적 시사점을 제시하기 위해서 Mink의 “The Locus for Focus Model”을 활용하였다. 연구결과는 다음과 같다. 첫째, 구직자 기대수준이 높은 급여수준, 근무환경, 직원복지수준, 근로시간, 기업의 미래비전, 개인발전가능성에서 기대수준과 현재 수준의 차이가 큰 영역으로 나타나 미스매치의 문제가 심각함을 알 수 있었다. 둘째, 숙련의 미스매치에 있어서는 자격증, 정보기술 활용능력, 업무 관련 경험, 직업에 대한 흥미, 커뮤니케이션 능력에 대해 높은 수준의 재직자 기대수준에 비해 구직자가 현재 갖추고 있는 정도가 충분하지 않은 것으로 나타났다. 셋째, 정보의 미스매치에 있어서는 구직자 기대수준이 높은 급여수준, 근무환경, 기업의 미래비전, 개인발전가능성 관련 정보에 대한 적극적인 공개가 중요한 것으로 나타났다. 본 연구는 신규 구직자들과 기존 근로자들의 노동시장, 근로조건에 대한 인식의 차이가 크다는 것을 확인할 수 있었다. 이에 따라 무조건 청년들에게 눈높이를 낮춰 중소기업으로 유도하기 보다는 미스매치 수준을 완화하고자 하는 노력과 함께 중소기업들이 채용 대상을 다양하게 찾는 것이 중요할 것으로 생각한다.

An Analysis of Job Mismatch in Kwangyang Bay Area by an Approach of Job-seekers Decomposition

An Analysis of Job Mismatch in Kwangyang Bay Area by an Approach of Job-seekers Decomposition

Human and riverine impacts on the dynamics of biogeochemical parameters in Kwangyang Bay, South Korea revealed by time-series data and multivariate statistics

The successful management of sustainable coastal environments that are beneficial to both humans and marine ecosystems requires knowledge about factors that are harmful to such environments. Here, we investigated seawater nutrient and carbon parameters between 2010 and 2012 in Kwangyang Bay, Korea, a coastal environment that has been exposed to intensive anthropogenic activities. The data were analyzed using cluster and factor analysis. We found that the biogeochemical cycles of nutrients and carbon were determined by river discharge into the bay and biological activity. However, the impacts of these factors varied both spatially and seasonally. During the past 10years, nutrient loads from the river and industrial complexes to the bay have decreased. The impacts of this decrease are visible in the phosphate concentration, which has fallen to a third of its initial value. We also examined the potential role of atmospheric nitrogen deposition in nitrogen cycling in the study area.

A Statistical Evaluation of Consolidation Properties of Marine Clay in South Korea

In this study consolidation properties of marine clay in south Korea were investigated through standard consolidation tests (SCT) and constant rates of strain (CRS) tests, and Rowe Cell tests. This examination was conducted based on the field data collected in Kwangyang Bay area, which is one of the representative harbor regions in the southern coast of Korea. Consolidation parameters, including preconsolidation pressure (P c ), compression index (C c ), swelling index (C s ), overconsolidation ratio (OCR), vertical and horizontal consolidation coefficient (C v , C h ), vertical and horizontal coefficients of permeability (K v , K h ), were obtained through the statistical analysis. A correlation between these parameters was evaluated by the regression analysis after removing outliers of the collected data. As a result, it was shown that the relationship between swelling index and compression index was C s = 0.0969C c and between modified compression index and compression index was C c ′ = 1.1411C c(lab). Furthermore, the mean consolidation coefficient ratio (C h /C v ) and permeability coefficient ratio (K h /K v ) were found to be 2.34 and 2.21, respectively.

준 폐만 점착성 퇴적물의 퇴적매개변수 산정에 관한 실험적 연구

In this study, a series of deposition tests have been performed using an annular flume and depositional parameters of natural cohesive sediments have been estimated domestically for the first time. The natural cohesive sediments for deposition tests have been collected from Kwangyang Bay and total 18 deposition tests have been carried out on different bed shear stress respectively but with the same initial concentration. Test results for natural cohesive sediments of Kwangyang bay show that minimum bed shear stress , standard deviation , and time scale parameter are , 0.68 and 0.85, respectively. Through the comparison with results of previous studies for other sediments, the results of this study are shown to be good enough to verify.

대기질 모사를 통한 인접지역 배출량이 광양만 오존농도에 미치는 영향분석 - 2010년 6월 사례를 중심으로

Simulations of CMAQ with the High-order Decoupled Direct Method (HDDM) for a 2010 June episode are applied to estimate the influence of local and neighborhood emissions on ozone concentrations in the Kwang-Yang Bay (KYB) area. In order to examine ozone response to reductions in and VOC emissions from KYB and Gyeongsang, ozone isopleths are generated with the first and second-order sensitivity coefficients from HDDM simulations at three sites; Taein, Samil, and Gwangmoo. Simulations show that reduction in KYB may increase ozone over the sites. On the contrary, reduction from Gyeongsang may decrease ozone at the sites when transport of ozone and its precursors from upwind Gyeongsang is potentially high. However, VOC reductions from KYB and Gyeongsang are favorable to lower ozone over KYB. The study implies that emission reductions for both local and neighboring areas are likely more effective to bring KYB to ozone attainment.

Role of iron colloids in copper speciation during neutralization in a coastal acid mine drainage, South Korea: Insight from voltammetric analyses and surface complexation modeling

A coastal acid mine drainage (AMD) of ~ 800 m length, Chonam-ri Creek flows through a neutralizing pond mid-stream before discharging to the Kwangyang Bay of South Korea. The creek water displays a low dissolved organic carbon (DOC) concentration of ~ 1 mg/L, with a wide range of pH from ~ 3 to ~ 7 and Fe concentration from 0.005 to 106 mg/L. Our previous field study showed that the fraction of labile Cu and Pb in the creek water, determined by anodic stripping voltammetry (ASV), decreases rapidly with increasing pH, but no such pH dependence was observed for Cd or Zn. To further understand geochemical processes governing metal speciation during neutralization in AMD, we conducted two sets of laboratory experiments using Chonam-ri Creek water samples and model solutions, as well as Visual MINTEQ modeling. When the natural pH of the creek water samples was adjusted to a range between 2 and 8 by adding acid or base, the pH dependence of metal speciation or lack thereof was reproduced. A model solution simulating the water of Chonam-ri Creek also demonstrated the pH dependence of Cu speciation, determined by competitive ligand exchange-cathodic stripping voltammetry (CLE-CSV) in the presence of Fe and strong organic ligand. Based on VMINTEQ modeling indicating that 0.45 μm filterable Fe in the downstream sites of Chonam-ri Creek is most likely in the form of Fe colloid, surface complexation modeling of Cu adsorption onto Fe colloid using 1-pK Three Plane Model (TPM) was successful (RMSE = 0.185) in predicting the labile Cu concentrations. VMINTEQ modeling suggests that Cu speciation is dominated by interaction with Fe colloids over dissolved organic matter (DOM) during neutralization in a typical AMD with high Fe and low DOM, and that Cu is discharged to the bay in the form of colloids. The coupled application of voltammetric technique and geochemical modeling provides useful information on metal speciation in AMD.

광양만과 진주만 해역에서 담수 유입으로 인한 밀도성층 변화

본 연구에서는 EFDC 모델을 이용하여 광양만과 진주만 해역에 대한 조석과 수온, 염분을 고려한 3차원 해수순환 양상을 재현하였다. 수치모델 결과는 관측 자료를 이용하여 검증하였고 그 결과 모델은 관측결과를 잘 재현하였다. 실험 결과, 연구해역의 해수순환은 노량수도와 대방수도 중간 해역에서 해수가 수렴 및 발산되는 양상을 보이고 잔차류는 전형적인 2층 순환구조를 보인다. 모델을 통해 광양만과 진주만 일대의 밀도성층 변화를 분석한 결과, 연구해역은 담수의 영향이 지배적인 해역으로 진주만의 경우 남강댐 방류의 영향을 지배적으로 받는 해역이지만 남강댐에서 방류를 하지 않는 경우에는 섬진강의 영향도 받는 것으로 나타났다. 한편 남강댐 방류시에는 광양만의 성층이 상대적으로 강화되는 결과를 볼 수 있었다. This study simulate three-dimensional ocean circulation patterns using the EFDC model in the Kwangyang Bay and Jinju Bay, considering tide, water temperature and salinity. The numerical model results were verified using observed data. The model results well reproduced the observed data. As a result, ocean circulation patterns in the study area show convergence and divergence in the middle area of Noryang waterway and Daebang waterway, the residual flow patterns show typical two-layer circulation. According to the change of the density stratification in the Kwangyang Bay and Jinju Bay, the effect of fresh water is dominant in study area. In the case of Jinju Bay, although it is strongly influenced by the Namgang fresh water, also it is affected by Seomjin River when there is no discharge by Namgang Dam. On the other hand, the stratification of the Kwangyang Bay is relatively enhanced by the discharge of Namgang Dam.

Characteristics of Benthic Chlorophyll a and Sediment Properties in the Tidal Flats of Kwangyang Bay, Korea

Characteristics of benthic microalgae and sediment properties were investigated for the intertidal flats of Kwangyang Bay, Korea. Sampling stations were selected every 100 m in the intertidal flats from land-side to open ocean at two different sampling sites. Samples were collected in June 2004, July, September, November, February and May 2005. Sediments properties were measured including temperature, water contents, sediment bulk density, nutrient concentrations in porewater. Chlorophyll a concentrations in surface sediment (0.5 cm) were measured and relationships between the chlorophyll a and various sediment properties were analyzed to identify major mechanisms regulating biomass of benthic microalgae in the intertidal flats using simple linear regression analysis. Sediment chlorophyll a concentrations were maximum during winter and minimum during warm seasons ranging from 4.4 mg m –2 to 81.2 mg m –2 . No clear spatial variations were observed for the sediment chlorophyll a in the study sites. Results from regression analysis suggested that benthic microalgae biomass was affected by sediment temperature and nutrients especially ammonium and silicate. Grazing effect was estimated using chlorophyll: pheopigments ratio, indirect indicator of grazing activity, and the positive correlation of the ratio and chlorophyll a implied that microalgae biomass is affected by grazing of zoobenthos although direct measurement of grazing activity is required to determine the importance of top-down controls in the benthic microalgae dynamics.

Sulfur hexafluoride as a complementary method for measuring the extent of point-source thermal effluents

The transport and dilution dynamics of power-plant thermal effluent were measured for 10 consecutive days, between 25 June and 4 July 2006, by concurrently mapping the daily distributions of seawater temperature and concentrations of deliberately released sulfur hexafluoride (SF6) within the tidal Kwangyang Bay on the southern coast of Korea. Estimates of the daily extent of the thermal plume based on temperature and SF6 data showed distinct differences. These differences were particularly pronounced on sunny days during which solar radiation significantly heated river or bay waters moving across the tidal flats; in these cases, the estimates based on seawater temperature data were consistently greater than those based on SF6 data, indicating considerable overestimates of the extent of the thermal plume when temperature data were used. The present results indicate that the concurrent use of seawater temperature and SF6 data is a powerful method in determining the extent of thermal plumes, particularly for shallow areas in which the effects of solar heating lead to large uncertainties in temperature-based estimates.

디지털 음향측심기를 이용한 광양만 잘피(Zostera marina L.)의 피도와 생물량 추정

Eelgrass beds are very productive and provide nursery functions for a variety of fish and shellfish species. Management for the conservation of eelgrass beds along the Korean coasts is critical, and requires comprehensive strategies such as vegetation mapping. We suggest a mapping method to spatial distribution and quantify of eelgrass beds using a digital echosounder. Echosounding data were collected from the northeast part of Kwangyang Bay, on the south of Korea, in March, 2007. A transducer was attached to a boat equipped with a DGPS. The boat completed a transect survey scanning whole eelgrass beds of 11.7 km2 with a speed of 1.5-2 m s-1 (3-4 knot). The acoustic reflectivity of eelgrass allowed for detection and explicit measurements of canopy cover and height. The results showed that eelgrass bed was distributed in depth from 1.19 to 3.6 m (below MSL) and total dry weight biomass of 4.1 ton with a vegetation area of 4.05 km2. This technique was found to be an effective way to undertake the patch size and biomass of eelgrass over large areas as nondestructive sampling.

Microphytobenthos seasonality determines growth and reproduction in intertidal bivalves

The annual cycles of phytoplanktonic and microphytobenthic biomasses as food sources for intertidal bivalves were investigated in a temperate estuarine muddy sandflat of Kwangyang Bay (Korea) from January to December 2002. Seasonal patterns in growth and reproductive activity of a suspension-feeder Laternula marilina and a deposit-feeder Moerella rutila were examined in order to assess their relationship with the annual cycles of pelagic and benthic microalgae, and were com- bined with analyses of δ 13 C and δ 15 N of bivalve tissues and their potential food resources. Biomasses of phytoplankton and microphytobenthos peaked in late spring-summer, and demonstrated a uni- modal pattern of seasonal variation. Photosynthetic pigment composition showed a predominance of diatom marker pigment, fucoxanthin, in the water and the sediments throughout the year. Similar patterns of annual cycles in pelagic and benthic microalgal biomasses and similarities in taxonomic composition indicated that resuspended microphytobenthos is an important contributor to the bay's phytoplankton component. This was supported by the δ 13 C values of suspended particulate organic matter (POM) and physical characteristics of the bay. Synchrony in growth and reproductive activity was observed for both bivalves: their shell and tissue growth and gonadal development were achieved together during late spring and summer when chlorophyll a (chl a) concentrations were highest. This temporal coupling of macrofaunal and microalgal processes indicated that the activities of intertidal bivalves might depend largely on microphytobenthos seasonality. The isotopic signa- tures of the bivalve tissues demonstrated their dependence on organic matter of microphytobenthic source irrespective of season, despite a comparable contribution of phytoplankton to the diet of the suspension-feeding bivalve. These results highlight the importance of seasonal development of microphytobenthos as an available food source during the critical period of gamete production and growth for both suspension- and deposit-feeding bivalves.

광양만 해수 중 유기인 잔류 농약성분의 GC-MS 분석

Sea water samples collected in August, 1994 from 20 stations in the Kwangyang Bay were analyzed by gas chromatography/mass spectrometry-selected ion monitoring (GC/MS-SIM) to investigate persistence and distribution pattern of four organophosphorus pesticides (DDVP, Diazinon, IBP, EDDP). Except for IBP, the contamination by DDVP, Diazinon, and EDDP in marine aquatic environment in Korea has not been reported previously. In this study, however, all these four pesticides were detected in all stations (except DDVP) and their concentrations were in ng/L level. The concentrations ranged from detection limit to 15.3ng/L for DDVP, 1.8-27.7ng/L for Diazinon, 7.3-63.5ng/L for IBP, and 22.2-1100.1ng/L for EDDP. It is noteworthy that the measured concentrations of IBP and EDDP in this study would be much lower than usual, since the use of IBP and EDDP was less than 50% of average annual consumption due to unusually dry and hot weather condition in the summer of 1994. It was very surprising to find that the highest concentrations of organophosphorus pesticides were observed at stations near Daesa Streamlet instead of Seomjin River, which has more point source of the pesticides. This result suggests that the small river discharge during heavy ram period in summer can give harmful effect on marine biota (both wild and aqua-cultured) with its organophosphorus pesticide residue, despite of their short residence time in aquatic environment. In order to protect the marine life properly from acute toxicity of the organophosphorus pesticides, it needs to be emphasized that monitoring the level of agricultural pesticides in river run-off should be done during active consumption period rather at regular intervals.

서남해 연안해역의 유기오염물질 분포특성에 관한 연구

In this study, we try to determine the distributive property in southwest coastal waters, such as K wang-yang bay, Ka-mak bay, Yeo-ja bay, Wan-do, Hea-nam, Young-gwang, and Mok-po, using simultaneous analytical method of 310 chemicals. The results were detected tens of the organic pollutants in sampling sites, and the major chemicals detected were CH type chemicals such as aliphatic, polycyclic compounds and were CHN(O) type chemicals such as aromatic amines, nitro compounds, In particular, pesticides were mainly detected in summer, phenols and phthalate esters were not seasonal effect. Also, a number of aromatic chemicals were detected in Kwang-yang bay, From the results of this study, we confirmed that it is mainly contaminated in summer and the pesticide chemicals are the major pollutants in southwest coastal waters.

Instrumental and bioanalytical measures of dioxin-like and estrogenic compounds and activities associated with sediment from the Korean coast

Sediments from inland areas and open bays along the Korean coast were analyzed to examine the distribution of dioxin-like and estrogenic compounds. Concentrations of target chemicals varied considerably among locations (Lake Shihwa, Masan Bay, and Kwangyang Bay) and between inland and coastal areas. Principal component analysis (PCA) of contaminants measured in sediments showed that all of the inland locations from Lake Shihwa were highly contaminated, and the variations among locations were explained predominantly by the distribution of alkylphenols and polycyclic aromatic hydrocarbons (PAHs). PCA of PAH congener profiles among locations indicated that automobiles were a major source of PAH contamination. Dioxin-like and estrogenic activities associated with sediment from inland sites were approximately three- and six-fold, respectively, greater than those associated with open bay locations. The target dioxin-like and estrogenic compounds measured in raw extracts of sediments accounted for approximately 20% and 40% of the activities measured in the sediment extracts. The results suggest that a combination of instrumental and bioanalytical measurements of dioxin-like and estrogenic compounds is a valuable approach to screen, identify, and prioritize the risks posed by contaminants in complex environmental matrices.

Description of two new species of Neotachidius Shen & Tai, 1963 (Copepoda, Harpacticoida, Tachidiidae) from Korean brackish waters and proposal of a new genus for Tachidius (Tachidius) vicinospinalis Shen & Tai, 1964

Two new sympatric species of Neotachidius Shen & Tai, 1963, N. coreanus sp. nov. and N. parvus sp. nov., are described from plankton samples collected from brackish waters in Kwangyang Bay, South Korea. Morphological differences with the type species N. triangularis (Shen & Tai, 1963) comb. nov. are discussed in detail. Korean material from Chindo Island, previously identified as N. triangularis by Song and Chang in 1995 is at least partly based on N. parvus sp. nov. The occurrence of N. triangularis in estuaries in British Columbia and Washington is attributed to transoceanic transport by ballast water from cargo ships entering the Columbia River or neighbouring estuaries. The subgeneric division of the genus Tachidius proposed by Shen and Tai in 1963 is rejected and instead full generic rank is assigned to both Tachidius and Neotachidius. The taxonomic position and original description of Tachidius (Tachidius) vicinospinalis Shen & Tai, 1964 are reviewed and the species is designated as the type species of a new genus Sinotachidius gen. nov. The latter and Neotachidius form a clade which stands in apposition to Tachidius. Tachidius discipes Giesbrecht, 1881 sensu Song & Chang is considered species inquirenda in Sinotachidius gen. nov. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 143, 133–159.

Ecological modeling for water quality management of Kwangyang Bay, Korea

This study estimated the appropriate pollutant load reduction from point sources in Kwangyang Bay, Korea, using an eco-hydrodynamic model. The total chemical oxygen demand (COD), nitrogen (TN), and phosphorus (TP) loads from rivers and ditches that provide input to the bay were approximately 2.8×10 4, 2.5×10 4, and 5.9×10 2 kg day −1, respectively. Wastewater discharge from industrial complexes was the greatest contributor to pollutant loads in the inner part of the bay. COD values in the inner part of the bay were greater than 3.0 mg l −1, and exceeded Korean seawater quality grade III limits. A residual current was simulated, using a hydrodynamic model, to have a slightly complicated pattern in the inner part of the bay, ranging from 0.001 to 8 cm s −1. In the outer part of the bay, the simulated current flowed out to the South Sea with a southward flow at a maximum of 15 cm s −1. The results of the ecological model simulation of COD levels showed high concentrations, exceeding 4 mg l −1, in the southwest of the Myodo, an area of wastewater discharge, and lower levels, approaching less than 1 mg l −1, closer to the outer part of the bay. Engineering countermeasures to reduce the organic and inorganic material loads from point sources by more than 45% were required to keep the COD levels below 2 mg l −1.