• Journal of Wetlands Research
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• v.19 no.4
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• pp.383-392
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• 2017

In 2013, August and September(early) as summer and October and November as Fall the probe of eutrophication has been done at 22 sampling points from the entrance of Danghang Bay (Jinhae Bay) to Geosan reservoir. In Danghang Bay, total chlorophyll(TChl) concentration of summer was 3.7 times higher than that of fall, and sampling points closer to the center showed 1.8 times higher concentrations than sampling points near the fringe where fresh water encountered. Eutrophication Index(EI) exceeded 1 at all sampling points in Danghang Bay during summer and fall, and if other conditions for algae growth met there was a possibility red tide to bloom at any place. There was a tendency of EI to gradually increase moving up from the entrance of bay to the inner side during summer and fall. Especially there was a sudden increase by 2.3 times higher at sampling points of 13~22 (planned region as Madong reservoir) than at other points during fall. Nitrogen was a limiting nutrient for growth of algae during summer and fall in Danghang Bay, but phosphorus was a limiting nutrient during summer rainy season. During summer and fall, multiple linear regression analysis between EI and COD, DIN, and DIP showed a significant positive relationship and that DIP was the most effective variable. Whereas multiple linear regression analysis between TChl and COD, DIN, DIP, and DSi showed a significant positive relationship and that DIP was also the most effective variable during summer. There was no significant correlation between TChl and the other parameters during fall.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.1-10
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• 2016

In this paper, an analysis of the inflowing pollution load of the rivers in Hampyeong bay showed the average organic matter pollution loads of BOD, COD, and TOC to be 79.7 kg-BOD/day, 144.06 kg-COD/day, and 93.0 kg-TOC/day, respectively. The inflowing organic matter pollution load was the heaviest in Sonbul dike, followed by Jupo bridge and Yangman complex. With regard to season, the load characteristics were outstanding in July, the rainy period in the summer. The average inflowing pollution loads of nutrients were 20.9 kg-DIN/day, 17.1 kg-DIP/day, 148 kg-TN/day, and 37.4 kg-TP/day A comparison of the inflowing nutrients loads for each river showed the load to be the heaviest in Yangman complex, followed by Baegok bridge and Jupo bridge. In the experiment on the material budgets of Hampyeong bridge conducted using a box model, the detention time of fresh water was found to be 52.4 days, with the bay displaying the characteristics of a so dissolved inorganic nitrogen (DIN) in the nutrients material budgets, ${\Delta}DIN$ values were found to be negative, indicating the tendency of consumption and open sea leak by photosynthesis to be higher than the nitrogen that flowed in. As for dissolved inorganic phosphorus (DIP), ${\Delta}DIP$ showed positive values, indicating a tendency for accumulation as the supply through organic matter decomposition, elution load of sediments, and inflowing load of the river turned out to be higher than the consumption by phytoplankton and outflow to open sea.

• Korean Journal of Environmental Biology
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• v.31 no.1
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• pp.19-36
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• 2013

Physiochemical characters of sea waters during summer flood- and winter dry-seasons and their spatial variations were investigated along the coastal area off the eastern South Sea, Korea. Using the hierarchical clustering method, in this study, we present comprehensive analyses of coastal waters masses and their seasonal variations. The results revealed that the coastal water of the study area was classified into six water masses (A to F). During summer season, the surface water was mainly occupied by the coastal pseudo-estuarine water (water mass B) with low salinity and high nutrients and the river-dominated coastal water (water mass C) with low nutrients, respectively. The bottom water was dominated by cold water (water mass D) with very low temperature, high salinity and high nutrients, compared to masses of surface water. Notably, the water mass B, with high concentrations of nutrients (silicate and nitrogen) and low salinity, which is strongly controlled by the water quality of river freshwater, seems to play an important role in controlling the water quality and further regulating physical processes on ecosystem in the eastern coastal area of South Sea. The water mass D (bottom cold water) coupled with a strong thermocline, which exists in near-bottom layer along the western margin of Korea Strait, has a low temperature, pH and DO, but abundant nutrients. This water mass disappears in winter owing to strong vertical mixing, and subsequently may act as a pool for nutrients during winter dry-season. On the other hand, vertically well-mixed water column during the winter season was typically occupied by the Tsushima (water mass E) and the coastal water (water mass F) with a development of coastal front formed in a transition zone between them. These winter water masses were characterized by low nutrient concentration and balance in N/P ratio, compared with summer season with high nutrient concentrations and strong N-limitation. Accordingly, the analysis of water masses will help one to better chemical and biological processes in coastal area. In most of the study area, characteristically, the growth of phytoplankton community is limited by nitrogen, which is clearly different with coastal environment of West Sea of Korea, with a relative lack of phosphorus. It showed the western and the southern coasts in Korea are substantially different from each other in environmental and ecological characteristics.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.297-305
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• 2014

In order to understand the contribution of seaweed aquaculture to nutrients and carbon cycles in coastal environments, we measured the nutrients & carbon uptake rates of Porphyra yezoensis Ueda sampled at Nakdong-River Estuary using a chamber incubation method from November 2011 to April 2012. It was observed that the production rate of dissolved oxygen by P. yezoensis (n=30~40) was about $68.8{\pm}46.0{\mu}mol\;{g_{FW}}^{-1}h^{-1}$ and uptake rate of nitrate, phosphate and dissolved inorganic carbon (DIC) was found to be $2.5{\pm}1.8{\mu}mol\;{g_{FW}}^{-1}h^{-1}$, $0.18{\pm}0.11{\mu}mol\;{g_{FW}}^{-1}h^{-1}$ and $87.1{\pm}57.3{\mu}mol\;{g_{FW}}^{-1}h^{-1}$, respectively. There was a positive linear correlation existed between the production rate of dissolved oxygen and the consumption rates of nitrate, phosphate and DIC, respectively, suggesting that these factors may serve as good indicators of P. yezoensis photosynthesis. Further, there was a negative logarithmic relationship between fresh weight of thallus and uptake rates of nutrients and $CO_2$, which suggested that younger specimens (0.1~0.3 g) were much more efficient at nutrients and $CO_2$ uptake than old specimens. It means that the early culturing stage than harvesting season might have more possibilities to be developed chlorosis by high rates of nitrogen uptake. However, N & C demanding rates of Busan and Jeollabuk-do, calculated by monthly mass production and culturing area, were much higher than those of Jeollanam-do, the highest harvesting area in Korea. Chlorosis events at Jeollabuk-do recently might have developed by the reason that heavily culture in narrow area and insufficient nutrients in maximum yield season (Dec.~Jan.) due mostly to shortage of land discharge and weak water circulation. The annual DIC uptake by P. yezoensis in Nakdong-River Estuary was estimated about $5.6{\times}10^3\;CO_2$ ton, which was about 0.03% of annual carbon dioxide emission of Busan City. Taken together, we suggest more research would be helpful to gain deep insight to evaluate the roles of seaweed aquaculture to the coastal nutrients cycles and global carbon cycle.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.203-218
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• 2011

Long-term trends and distribution patterns of water quality were investigated in the Yeoja Bay of South Sea, Korea from 1976 to 2010. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, hydrogen ion concentration (pH), dissolved oxygen (DO), chemical oxygen demand (COD), suspended solids (SS) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 31 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 2 clusters by PCA; station cluster 1 and 2~3. Annual water qualities were clearly discriminated into 4 clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, COD and SS tended to increase from late 1970's, decreased salinity, and increased phosphate from 1991 to 2001 and increased dissolved inorganic nitrogen. Water quality was showed by the input of fresh water same as those of Kyoungin coastal area, Asan coastal area, Choensoo bay, Gunsan coastal and Mokpo coastal area in the Yeoja Bay.

• 한국해양학회지
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• v.27 no.4
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• pp.303-310
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• 1992

Studies on the distribution of nitrogenous compounds, and respiratory oxygen consumption rate were carried out in Masan Bay, Korea where large amount of industrial and domestic wastewaters are discharged. In August 1986 the surface layer was significantly influenced by freshwater input. Below the seasonal pycnocline, an oxygen-deficient condition developed in a large area of Masan Bay. Concentrations of DIN, DON and PN were 735.6, 1261.8 and 48.5 umol/l at the head, and 79.1, 73.0 and 39.5 umol/l at the mouth of the inner Masan Bay, respectively. Phytoplankton carbon production was 2,695 mgC/m$^2$/day at the mouth of inner Masan Bay. Dissolved oxygen contents were lower than 1 ml/l from 3 m depth in inner Masan Bay and from 10 m depth in the outer Masan Bay. The high concentration of ammonium and phosphate in the lower layer suggests the active degradation of organic materials in the bottom waters and leaching from sediments. The ERS activity was 232.1 ul O$_2$/l/h in the surface waters of the innermost part of Masan Bay and respiratory oxygen consumption is likely to proceed at a rate of 442 ml O$_2$/m$^2$/day in the bottom waters of this bay. Nitrate removal rate was estimated to be 0.25 umol/l/day via denitrification in the bottom waters of the Masan Waterway. It is estimated from the ETS activity that, at the mouth of inner Masan Bay, 9.3-10.5% of carbon fixed in the upper layer was decomposed below the themocline.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.16-24
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• 2010

Utilization of dissolved organic phosphorus (DOP) and alkaline phosphatase (APase) activity by Skeletonema costatum, Chaetoceros didymus, Alexandrium tamarense and Heterosigma akashiwo under the phosphorus deficient condition were examined in the laboratory. S. costatum, C. didymus, A. tamarense and H. akashiwo could make use of phosphomonoester and nucleotide compounds for the growth of them as a phosphorus source. APase activity of S. costatum, C. didymus, A. tamarense and H. akashiwo began to be activated at dissolved inorganic phosphorus (DIP) concentrations less than $0.30\;{\mu}M$, $0.33\;{\mu}M$, $2.04\;{\mu}M$ and $0.63\;{\mu}M$ respectively, and their maximum APase activity were $0.01\;pmol\;cell^{-1}\;hr^{-1}$, $0.11\;pmol\;cell^{-1}\;hr^{-1}$, $1.63\;pmol\;cell^{-1}\;hr^{-1}$ and $0.19\;pmol\;cell^{-1}\;hr^{-1}$, respectively. Although each phytoplankton species displayed different APase activity for DOP utilization, their maximum APase activities were higher than maximum phosphorus uptake rates, inferring that these species might be able to keep growing under DIP-limited conditions thought utilizing effectively the hydrolized product of DOP. This result also implies that utilization of DOP might contribute to not only the growth of red tide forming phytoplankton but also the interspecific competition among phytoplankton species in coastal environments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.5
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• pp.586-591
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• 1996

We investigated rhizome yield and growth characteristics of wasabi variety, Daioichigo and Daruma cultured by flowing water from Trout nersery in Pyong Chang. Average temp. of air and water during a year was 14.3, 12.3$^{\circ}C$, respectively in PE film house. Wasabi growth was good and healthy in May and October. Rhizome weight of main stem in Daioichigo was 78.78g per plant and 608kg per l0a, while those of the Daruma was 37.1g per plant and 287kg per l0a. Rate of marketable rhizome was 90% in Daioichigo and 37.5% in Darurna. Rhizome weight of main stem in Daioichigo was increased, up to 21% of the control by the remove of floral axis with two times a year.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.545-554
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• 2017

Birnessite is one of the dominant Mn (oxyhydr)oxide phases commonly found in soil and deep ocean environments. It typically occurs as nano-sized and poorly crystalline aggregates in the natural environment. It is well known that birnessite participates in a wide variety of bio/geochemical reactions as a reactive mineral phase with structural defects, cation vacancies, and mixed valences of structural Mn. These various bio/geochemical reactions control not only the fate and transport of inorganic and organic substances in the environment, but also the formation of diverse Mn (oxyhydr)oxides through birnessite transformation. This review assessed and discussed about the phase transformation of birnessite under a wide range of environmental conditions and about the potential geochemical factors controlling the corresponding reactions in the literature. Birnessite transformation to other types of Mn (oxyhydr)oxides were affected by dissolved Mn(II), dissolved oxygen, solution pH, and co-existing cation (i.e., $Mg^{2+}$). However, there still have been many issues to be unraveled on the complex bio/geochemical processes involved in the phase transformation of birnessite. Future work on the detail mechanisms of birnessite transformation should be further investigated.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.1-10
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• 2008

The seasonal variations of water quality and periphyton were investigated in an artificial stream (the Cheonggyecheon Stream) flowing through the Seoul City. TP showed a longitudinal gradient: 10 to $59{\mu}gP\;L^{-1}$ in the upper stream sites, and 15 to $90{\mu}gP\;L^{-1}$ in downstream sites. POP was a major form of TP in the water, occupying over 60%, while the proportion of DIP was less than 10% except for St. 4. N/P atomic ratio ranged from 78 to 554, which implies phosphorus would limit algal growth more than nitrogen. The biomass of periphyton did not show much difference among sites, and it was relatively higher in spring and fall season $(10\sim20{\mu}gChl\;{\alpha}cm^{-2})$ and lower in August $(<5{\mu}gChl\;{\alpha}cm^{-2})$, possibly because biofilms were washed off during spates of summer monsoon. Cyanobacteria was the dominant taxon in the periphyton community throughout the year. The periphyton standing crop can be classified as a nuisance level. It seems that phosphorus level is sufficiently high even though the input water is treated chemically, and modest water velocity $(20\sim90cm\;sec^{-1})$ and rocky bottom provide optimal conditions for periphyton growth.