• Korean Journal of Weed Science
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• v.4 no.2
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• pp.135-142
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• 1984

To obtain the basic information for weed management in polder land, a colligated assessment on weed distribution and it`s plant sociological indices on Gyewha polder land were arranged. At the situation of assessment, the Gyewha polder land was reclaimed with aim with paddy-rice production. As a result of reclamation, the salinity of most soil samples were below 0.3%, and acidity ranged from pH 5.5 to 6.5. Total weed species were counted as much as 17 species (3 gramineae, 7 cyperucese, and 8 broad-leaved species), and a most dominant species, Scirpus maritimus, were succeeded with Monochoria v., Eleocharis a., and Cyperus d., etc. by reclamation. Declining of soil salinity and soil pH, the number of weed species, individuals, biomass, species diversity, evenness, sociability index were increased, but the population particularity was weaken in tendencies. By developing of reclamation, the weed species which is summer annual broad leaf, wind and water disseminating, and tussock formed species are increased instead of salt-resistant, perennial cyperus, and rhizomatous extending species.

• Ocean and Polar Research
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• v.29 no.4
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• pp.283-295
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• 2007

We investigated the longitudinal variations in zooplankton abundances and their related physicochemical properties at nine stations located between $136^{\circ}W$ and $128^{\circ}W$ at $10.5^{\circ}N$ in the northeastern Pacific in summer 2004. Temperature, salinity, inorganic nutrients, chlorophyll-a (hereafter chl-a) and zooplankton ($>200\;{\mu}m$) were sampled within the depth from the surface to 200 m depth at $1^{\circ}$ longitude intervals. Zooplankton($>200\;{\mu}m$) samples were vertically collected at two depth intervals from surface to 200 m, consisting of surface mixed and lower layers (thermocline$\sim$200 m). Longitudinal distributional pattern of hydrological parameters (especially salinity) was physically influenced by the intensity of westward geostrophic current passage relating to the NEC (North Equatorial Current). Data from the longitudinal survey showed clear zonal distributions in the hydrological parameters(temperature, salinity and nutrients). However, spatial patterns of the chl-a concentrations and zooplankton abundances were mostly independent of the zonal distributions of hydrological parameters. The two peaks of zooplankton abundance in the surface mixed layer were characterized by different controlling factors such as bottom-up control from nutrients to zooplankton ($129^{\circ}W$) and accumulation by increment of friction force and taxonomic interrelationship ($133^{\circ}$ and $134^{\circ}W$). Divergence-related upwelling caused introduction of nutrients into surface waters leading to the increment of chl-a concentration and zooplankton abundances ($129^{\circ}W$). Increased friction force in relation to reduced flow rates of geostrophic currents caused accumulation of zooplankton drifting from eastern stations of study area($133^{\circ}$ and $134^{\circ}W$). Besides, high correlation between immature copepods and carnivorous groups such as chaetognaths and cyclopoids also possibly contributed to the enhanced total abundance of zooplankton in the surface mixed layer (p<0.05). Zooplankton community was divided into three groups (A, B, C) which consecutively included the eastern peak of zooplankton($129^{\circ}W$), the western peak($133^{\circ}$ and $134^{\circ}W$) and high nutrient but low chl-a concentration and zooplankton abundance ($136^{\circ}W$). Moreover, Group B corresponded to the westward movement of low saline waters(<33.6 psu) from 128 to $132^{\circ}W$. In summary, longitudinal distributions of zooplankton community was characterized by three different controlling factors: bottom-up control ($129^{\circ}W$), accumulation by increased friction force and relationships among zooplankton groups ($133^{\circ}$ and $134^{\circ}W$), and mismatch between hydrological parameters and zooplankton in the high nutrient low chlorophyll area ($136^{\circ}W$) during the study period.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.78-85
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• 2005

This study, combining geophysical and environmental approaches, was undertaken to investigate the causes of secondary salinity in the Goondoola basin, in southwestern Queensland. Airborne radiometric, electromagnetic and ground electromagnetic datasets were acquired, along with data on soils and subsurface materials and groundwater. Relationships established between radiometric, elevation data, and measured material properties allowed us to generate predictive maps of surface materials and recharge potential. Greatest recharge to the groundwater is predicted to occur on the weathered bedrock rises surrounding the basin. Electromagnetic data (airborne, ground, and downhote), used in conjunction with soil and drillhole measurements, were used to quantify regolith salt store and to define the subsurface architecture. Conductivity measurements reflect soil salt distribution. However, deeper in the regolith, where the salt content is relatively constant, the AEM signal is influenced by changes in porosity or material type. This allowed the lateral distribution of bedrock weathering zones to be mapped. Salinisation in this area occurs because of local-andintermediate-scale processes, controlled strongly by regolith architecture. The present surface outbreak is the result of evaporative concentration above shallow saline groundwater, discharging at break of slope. The integration of surficial and subsurface datasets allowed the identification of similar landscape settings that are most at risk of developing salinity with groundwater rise. This information is now being used by local land managers to refine management choices that prevent excess recharge and further salt mobilisation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.4
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• pp.121-132
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• 2023

Marine heatwaves (MHWs), referring to anomalously high sea surface temperatures, have drawn significant attention from marine scientists due to their broad impacts on the surface marine ecosystem, fisheries, weather patterns, and various human activities. In this study, we examined the impact of the distribution of Changjiang diluted water (CDW), a significant factor causing oceanic property changes in the East China Sea (ECS) during the summer, on MHWs. The surface salinity distribution in the ECS indicates that from June to August, the eastern extension of the CDW influences areas as far as Jeju Island and the Korea Strait. In September, however, the CDW tends to reside in the Changjiang estuary. Through the Empirical Orthogonal Function analysis of the cumulative intensity of MHWs during the summer, we extracted the loading vector of the first mode and its principal component time series to conduct a correlation analysis with the distribution of the CDW. The results revealed a strong negative spatial correlation between areas of the CDW and regions with high cumulative intensity of MHWs, indicating that the reinforcement of stratification due to low-salinity water can increase the intensity and duration of MHWs. This study suggests that the CDW may still influence the spatial distribution of MHWs in the region, highlighting the importance of oceanic environmental factors in the occurrence of MHWs in the waters surrounding the Korean Peninsula.

• Journal of Environmental Health Sciences
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• v.50 no.1
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• pp.66-72
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• 2024

Background: Vibrio vulnificus is a serious opportunistic human pathogen that has a worldwide distribution in a variety of marine and estuarine environments. Objectives: For this reason, we investigated the distribution of Vibrio vulnificus in coastal areas of Gyeonggido Province from 2018 to 2022. Also, we analyzed the correlation between V. vulnificus leading to infection and two marine environmental factors (water temperature and salinity). Methods: We collected a total of 266 samples from six coastal area points (i.e., seawater, mudflats). Specimens were isolated using selective plating media and isolated strains were identified by a VITEK 2 system. To find the relevance of the isolation rates of V. vulnificus and number of cases of V. vulnificus infection, we summarized the data on 48 cases of V. vulnificus infection from the open data of the Korea Disease Control and Prevention Agency. Results: Among the 266 samples taken during the investigation period, 47 strains were isolated, and the separation rates of V. vulnificus were 17.7%. The monthly isolation rates of V. vulnificus were ranked in the order of August (53.8%), September (33.3%), June (28.6%), and July (21.1%). There was a positive correlation with the temperature of seawater, but salinity was not significant. The number of cases of V. vulnificus infection reported in Gyeonggi-do Province were 18 (37.5%) in September, 14 (29.2%) in August, and eight (16.7%) in October. The proportion was 83.3%. It was relevant to the isolation rates of V. vulnificus in the marine environmental sources. Conclusions: Our data showed that the number of V. vulnificus infection cases could be affected by changes in the distribution of V. vulnificus due to rise the temperature of seawater in the marine environment.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.98-104
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• 2008

In April, July, October and December, 2003, we investigated the effects of water temperature, salinity and extinction coefficient on the distribution of phytoplankton communities at 22 stations in Jinju Bay of Korea. Water temperature and salinity showed a wide range of $10.4^{\circ}C-21.8^{\circ}C$ and 4.34-33.21 psu. Extinction coefficients showed a range of 0.09-3.08, above 1 from almost all the areas except in some central areas, especially, showed highest value (>2) in the estuary area. In phytoplankton, a total of 95 species belonging to 51 genera were identified. The predominant species were mainly diatoms throughout the year. Dominant species was Thalassionema nitzschioides, Skeletonema costatum, Thalassiosira sp. in April, S. costatum, Leptocylindrus danicus in July, C. debilis, S. costatum, C. curvisetus, Pseudonitzshia pungens in October, S. costatum, Asterionellopsis glacialis and C. debilis in December. S. costatum was a major dominant species for all the seasons. Considering the results of literature which is about physiological study, S. costatum seems to be euryhaline and eurythermal, and high affinity on the irradiance. Thus, the species might have been spread population in Jinju Bay where is characteristic of wide range of water temperature, salinity and high extinction coefficients.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.3-18
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• 2002

This study has been carried out to find the water Quality in coastal sea of fungmun area, southern Jeju Island. In-situ observations and water sampling had been made every month from July 1997 to June 2000. The distributions of water temperature and salinity over the study area have been 13.8~27.0℃ and 30.0~34.7‰, respectively. Salinity is showed low salinity from June to September (rainy season) because of rain. Tsushima Warm Waters (TWW) as ≥15℃ and ≥34‰ influence the adjacent sea around Jeju Island all year round. Yangtse Coastal Waters (YCW) influence the surface layer around Jeju from June to September and so strong stratification (termocline, halocline) resulted at the depth of between 20~30m at outer-sea. However the stratification does not happen even in summer at inner-sea, which seem to be caused due to vertical mixing by wind, waves and tides. A water mass of high value of water temperature and salinity (respectively 14.1~17.7℃, 33.9~34.1‰) stayed at the lower layer in outer-sea all the year round. It is probably formed by mixing between TWW and YSBCW(Yellow Sea Bottom Cold Water). The mean value of DO was the lowest in summer and the highest in winter. COD and TH were the highest in summer and the lowest in winter. However, TP showed the lowest value in summer season, because the mean value of N/P ratio was over 16. The mean of N/P ratio was under 16 in other seasons. The phosphate would be a limiting factor in the growth of phytoplanHon in summer. Nitrate would be a limiting factor in other seasons. Distribution of chlorophyll a did not show any seasonal change in the study period, but especially increased during April and May in the first year(1998) and the second year(1999) all over the study area, which suggested that phytoplankton inhabitation distributed widely in the study area. The space averaged values were the highest for TIN in rainy season and lower for TP in rainy season than in other seasons. It suggests that river runoff influences the inner-sea.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.265-271
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• 1991

This study was crried out in order to changes of soil salinity in the Kyehwa saline paddy soil from 1978 find out the to 1988. Surveyed soil was Munpo, Gwanghwal, Yeompo, Hasa series and distribution ratio of those area was 51.2%, 16.6 %, 30.2 %, 1.0 % respectively on the 2,500ha. In the cultivated field, the ratio of desalinization was increased in accordance with rice cultivating years but desalization was not conduct after six years in the uncultivated field. Soil salinity of Summer(during cultivation) and Fall(after cultivation) were 52.3 %, 62.5 % respectively as compare with Spring(before cultivating) and about changes of soil salinity according to different soil depth, underground layer 20-40cm and 40-60cm were raised the rate 28.4 % and 66.2 % in accordance with top soil.

• Journal of the korean society of oceanography
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• v.39 no.2
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• pp.119-135
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• 2004

A three-dimensional numerical model using POM (the Princeton Ocean Model) is established in order to understand the dispersion processes of the Yangtze River water in the Yellow and East China Seas. The circulation experiments for the seas are conducted first, and then on the bases of the results the dispersion experiments for the river water are executed. For the experiments, we focus on the tide effects and wind effects on the processes. Four cases of systematic experiments are conducted. They comprise the followings: a reference case with no tide and no wind, of tide only, of wind only, and of both tide and wind. Throughout this study, monthly mean values are used for the Kuroshio Current input in the southern boundary of the model domain, for the transport through the Korea Strait, for the river discharge, for the sea surface wind, and for the heat exchange rate across the air-sea interface. From the experiments, we obtained the following results. The circulation of the seas in winter is dependent on the very strong monsoon wind as several previous studies reported. The wintertime dispersion of the Yangtze River water follows the circulation pattern flowing southward along the east coast of China due to the strong monsoon wind. Some observed salinity distributions support these calculation results. In summertime, generally, low-salinity water from the river tends to spread southward and eastward as a result of energetic vertical mixing processes due to the strong tidal current, and to spread more eastward due to the southerly wind. The tide effect for the circulation and dispersion of the river water near the river mouth is a dominant factor, but the southerly wind is still also a considerable factor. Due to both effects, two major flow directions appear near the river mouth. One of them is a northern branch flow in the northeast area of the river mouth moving eastward mainly due to the weakened southerly wind. The other is a southern branch flow directed toward the southeastern area off the river mouth mostly caused by tide and wind effects. In this case, however, the tide effect is more dominant than the wind effect. The distribution of the low salinity water follows the circulation pattern fairly well.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.207-215
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• 2002

Changes in salinity, hydraulic conductivity and penetration resistance in a reclaimed tidal land reclaimed in 1986 were studied. The salinity monitoring based on electrical conductivity of saturated extract, ECe, was conducted from 1994, when the land use for experimental crop production started after tile drainage. The site was abandoned since 1999. The hydraulic conductivity was measured by a sand fill auger hole method, and the resistance was measured with a dynamic penetrometer in situ. The averaged ECe in 1994 was $33.7dS\;m^{-1}$ ranging from 25.5 to $44.8dS\;m^{-1}$, and was decreased to $25.7dS\;m^{-1}$ with large range from 0.8 to $70.3dS\;m^{-1}$ before experiment was $1.89{\times}10^{-7}m\;s^{-1}$. It increased to $1.32{\times}10^6m\;s^{-1}$ in the top 20-cm soil with large variability, while it showed $3.44{\times}10^7m\;s^{-1}$ beneath the 20-cm soil depth with less variability. The penetration resistance of the soil ranged from 0.05 to 9.99MPa. The vertical distribution of penetration resistance indicated the hardened layer was developed at the depth of 20~40 cm where the hydraulic conductivity was sharply decreased.