• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.150.3-150
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• 2003

No Abstract, See Full Text

• Journal of Environmental Science International
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• v.15 no.10
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• pp.961-966
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• 2006

An algal assay procedure using an indigenous phytoplankton assemblage was tested to estimate the propagation of red tide phytoplankton species and determine the optimal time interval at which to measure growth yield in eutrophic marine waters where red tides frequently occur. Various red tide phytoplankton species were propagated on a large scale by adding nitrogen or phosphorous. This procedure was useful for estimating the limiting nutrient, elucidating the mechanisms underlying red tides, and determining the levels of increases in organic matter in eutrophic coastal waters. The algal assay using indigenous C. polykrikoides showed that this species did not always propagate, apparently because of very low concentrations of trigger elements that are necessary for its growth, rather than as a result of other environmental characteristics, e.g., water temperature or stress from sampling. In the winter, when water temperatures are lower than in spring, summer, or autumn, maximum propagation and the limiting nutrient could be estimated by measuring phytoplankton biomass at 2 - 3-day intervals. However, in the other seasons, when water temperatures are higher, phytoplankton biomass should be measured at 2-day intervals. In particular, daily monitoring will be required to determine precise growth yields in warm seasons.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.31-42
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• 2016

The object of this study was to determine long-term temporal and spatial patterns of nutrients (nitrogen and phosphorus), suspended solids, and chlorophyll (Chl) in Chungju Reservoir, based on the dataset of 1992 - 2013, and then to develop the empirical models of nutrient-Chl for predicting the eutrophication of the reservoir. Concentrations of total nitrogen (TN) and total phosphorus (TP) were largely affected by an intensity of Asian monsoon and the longitudinal structure of riverine (Rz), transition (Tz), and lacustrine zone (Lz). This system was nitrogen-rich system and phosphorus contents in the water were relatively low, implying a P-limiting system. Regression analysis for empirical model, however, showed that Chl had a weak linear relation with TP or TN, and this was mainly associated with turbid, and nutrient-rich inflows in the system. The weak relation was associated with non-algal light attenuation coefficients (Kna), which is inversely related water residence time. Thus, values of Chl had negative functional relation (R² = 0.25, p < 0.001) with nonalgal light attenuation. Thus, the low chlorophyll at a given TP indicated a light-limiting for phytoplankton growth and total suspended solids (TSS) was highly correlated (R² = 0.94, p < 0.001) with non-algal light attenuation. The relations of Trophic State Index (TSI) indicated that phosphorus limitation was weak [TSI (Chl) - TSI (TP) < 0; TSI (SD) - TSI (Chl) > 0] and the effects of zooplankton grazing were also minor [TSI (Chl) - TSI (TP) > 0; TSI (SD) - TSI (Chl) > 0].

• Ocean Science Journal
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• v.41 no.3
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• pp.125-137
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• 2006

Nutrients, chlorophyll-a, particulate organic carbon (POC), and environmental conditions were extensively investigated in the northern East China Sea (ECS) near Cheju Island during three seasonal cruises from 2003 to 2005. In spring and autumn, relatively high concentrations of nitrate ($2.6{\sim}12.4\;{\mu}mol\;kg^{-1}$) and phosphate ($0.17{\sim}0.61\;{\mu}mol\;kg^{-1}$) were observed in the surface waters in the western part of the study area because of the large supply of nutrients from deep waters by vertical mixing. The surface concentrations of nitrate and phosphate in summer were much lower than those in spring and autumn, which is ascribed to a reduced nutrient supply from the deep waters in summer because of surface layer stratification. While previous studies indicate that upwellings of the Kuroshio Current and the Changjiang (Yangtze River) are main sources of nutrients in the ECS, these two inputs seem not to have contributed significantly to the build-up of nutrients in the northern ECS during the time of this study. The lower nitrate:phosphate (N:P) ratio in the surface waters and the positive correlation between the surface N:P ratio and nitrate concentration indicate that nitrate acts as a main nutrient limiting phytoplankton growth in the northern ECS, contrary to previous reports of phosphate-limited phytoplankton growth in the ECS. This difference arises because most surface water nutrients are supplied by vertical mixing from deep waters with low N:P ratios and are not directly influenced by the Changjiang, which has a high N:P ratio. Surface chlorophyll-a levels showed large seasonal variation, with high concentrations ($0.38{\sim}4.14\;mg\;m^{-3}$) in spring and autumn and low concentrations ($0.22{\sim}1.05\;mg\;m^{-3}$) in summer. The surface distribution of chlorophyll-a coincided fairly well with that of nitrate in the northern ECS, implying that nitrate is an important nutrient controlling phytoplankton biomass. The POC:chlorophyll-a ratio was $4{\sim}6$ times higher in summer than in spring and autumn, presumably because of the high summer phytoplankton death rate caused by nutrient depletion in the surface waters.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.1
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• pp.16-28
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• 2015

In order to elucidate the spatiotemporal variations of marine environmental parameters, we collected seawater samples in the south-western region of the East Sea in May, August, and November 2012 and February 2013. The concentrations of dissolved inorganic nutrients (dissolved inorganic nitrogen, phosphorus, and silicate) in surface seawater during the summer season were lower than those during autumn and winter seasons, which the mixed layer is deeper. The low nutrient concentration in spring and summer seasons seems by consumption of dissolved inorganic nutrients by phytoplankon photosynthesis (high chlorophyll a concentration) and the limited supply of dissolved inorganic nutrients from subsurface layer having high nutrients. The low nutrient concentration during spring season seems to be related to the limited supply of dissolved inorganic nutrients from land and subsurface layer because the concentration of chlorophyll a was low. The DIN:DIP ratio was a wide range of average $15.6{\pm}13.6$ in the surface seawater compared to that of average $14.8{\pm}4.2$ in the bottom seawater during sampling periods. The dissolved inorganic nitrogen might act as a limiting factor of the growth of phytoplankton because the DIN:DIP ratio (on average $8.35{\pm}4.67$) was low during the spring season.

• Ocean and Polar Research
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• v.27 no.4
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• pp.359-379
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• 2005

In order to understand the spatial and temporal variations of nutrients and factors controlling their distribution in Gwangyang Bay, this study was carried out bimonthly from June 2001 to July 2003, Inorganic silicate and nitrate concentrations ranged from $0.04{\mu}M\;to\;69.5{\mu}M(avg.\;12.9{\mu}M)$, and from $0.12{\mu}M\;to\;42.2{\mu}M\;(avg.\;7.83{\mu}M)$, respectively. Silicate concentrations measured just after the typhoon were the highest with an average of $43.2{\mu}M$ at the surface layer in June 2001, whereas the highest nitrate concentration $(avg.\;37.0{\mu}M)$ was observed in the surface layer in July 2003. River runoff apparently influenced variations in silicate and nitrate concentrations (r=0.701 and 0.728, p<0.000, respectively) as well as salinity (r=-0.628, p<0.000). Phosphate concentrations ranged from $0.24{\mu}M\;to\;5.70{\mu}M\;(avg.\;1.34{\mu}M)$ and were highest at stations 5, 6, and 7, near a fertilizer plant with an average of $2.01{\mu}M$. On the basis of N/P and Si/N molar ratios, limiting nutrients have varied temporary and spatially. During 2001-2002, nitrogen was a limiting nutrient in the study area, and Phosphate was limited when a large volume of freshwater flowed into the bay. Silicate was limited when the high standing crops of phytoplankton occurred in the whole study area throughout 2003, and in the inner bay in February and August 2002. During the study period, factors controlling the distribution of nutrients might be summarized as follows; 1) inflow of freshwater by heavy rain accompanied by typhoons and frequent rainfall in summer, showing high concentrations of silicate and nitrate, 2) release of high phosphate concentrations from the fertilizer plant located in the south of Moydo to adjacent stations, 3) release of nutrients from bottom sediment, 4) magnitude of occurrence of phytoplankton standing crops.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.3 s.26
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• pp.165-170
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• 2006

In this study, organic matters production was calculated with long term data in Wando costal area where was selected for non influent of fresh water. The objective of this study was to evaluate relationship between nutrients and phytoplankton and, between phytoplankton and organic matter. The result of DIN was the highest with 0.138 mg/L in winter season and the lowest with 0.052 mg/L in summer season. Similarly, DIP was shown to be 0. 017 mg/L in winter and 0.011 mg/L in summer. Limiting nutrient was revealed with nitrogen in Wando costal area. Specially in summer season, nitrogen limitation was the greatest with 10.5 of N/P ratio. Chl. -a was increased 80%, 108% in spring and summer compare with winter. COD was the lowest with 0.84 mg/L in winter and the highest with 1.10 mg/L in summer. The interrelation between nutrients and Chl. -a was high. Relationship $coefficient(r^2)$ were 0.93(P<0.05), 0.89(P <0.05) between DIN and Chi. -a, DIP and Chl. -a. This results suggest dissolved nutrients might be utilized at the production of phytoplankton. Also Relationship $coefficient(r^2)$ was 0.77(P<0.05) between Chl. -a and COD. COD production rate was calculated with regression equation. The COD production rate was 17% in winter and 36% in summer. It was revealed nutrients were decreased according to temperature increasing and then Phytoplankton and organic matter were increased. The Relationship of Nutrients, Chl. -a and COD was very high.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.589-596
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• 2004

In this study, the reduction rates of nutrients were suggested to prevent eutrophication on the Hwaong reservoir in the year of 2008 and 2012. With EPA's WASP6 model, future water quality were simulated. In 2008, T-N would be 1.36mg/L and T-P 0.100mg/L on average. ; In 2012, T-N 2.66mg/L and T-P 0.128mg/L. With all the water quality management plans that the government authorities are carrying out, these results indicate that the reservoir would be reach the eutrophic or hypertrophic state according to the Vollenweider's trophic states. Therefore, the Hwaong reservoir requires additional plans for nutrients management. Here, the target water quality to prevent eutrophication of the reservoir sets into mesotrophic state ; T-N 0.475mg/L and T-P 0.02mg/L.(median of Vollenweider index for mesotropphic state) The reduction rates of nutrients on Namyang and Eoeun streams were estimated with uniform treatment method to meet the goal. The results showed that nutrients from two streams should be reduced up to 78% in 2008, and 84% in 2012. Since the ratio of T-N/T-P would be higher than 16 at target years, T-N was not considered as the limiting factor and was not reduced.

• Journal of Nutrition and Health
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• v.30 no.5
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• pp.529-539
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• 1997

The present study was to formulate a computer program to provide a menu based on a food preference survey of families in urban areas. A food preference survey was conducted by individual direct interviews of infants, children and old people in this study. In case other's food preferences were available, food menus considering all age groups could be made. Database III PLUS package was utilized for this study. The dBASE was loaded with a food compostion table of 339 different food items, along with data for amino acids and fatty acids for 171 and 43 food items respectively. Food preference, unit of food, and recommended dietary allowances were also incloded. This meun program system calculates nutrients in selected foods, and menu assessment was composed of several factors inculding energy ratio of carbohydrate : protein : fat, amino acid score, limiting amino acid, polyunsaturated fatty acid/saturated fatty acid(JP/S) ratio and Ca/P ratio.

• Ocean and Polar Research
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• v.29 no.3
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• pp.217-231
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• 2007

To explore limiting factors of spring bloom caused by waste disposal after dumping activity commenced in the Yellow Sea, we used a 1-dimensional temperature-ecological coupled model. The vertical structure of temperature and vertical diffusivity (Kh) are calculated by the temperature model with sea surface temperature using the 2.5 layers turbulence closure scheme. The ecological model applied results at the temperature model consisted of five state variables (DIN, DIP, phytoplankton, zooplankton, and detritus) forced by photosynthetically available radiation. We simulate year-to-year variations of plankton and nutrients using the coupled model from 1998 to 2000 and compare results of the model with observed data. It turned out that temperature is the growth factor of spring bloom in dumping area. During the winter the weak stratification made sufficient supply of the accumulated nutrients from the sea bed into the upper water column and led to the bloom in the coming spring. Radiation also turned out to be another important factor of spring bloom in the study area. Insufficient radiation of March 1999 showed low chlorophyll-a concentration despite sufficient nutrients in the surface.