• 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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.885-892
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• 2017

We estimated the limiting nutrient and DIP limiting history based on alkaline phosphatase (APase) activity during the spring of 2017 in the Southern Sea, Korea. In the frontal area, concentration of dissolved inorganic phosphorus (DIP), dissolved inorganic nitrogen (DIN): DIP ratio and Chlorophyll a (Chl-a) were < $0.2{\mu}M$, 23.2 and $2.2{\mu}g/L$, respectively, indicating high productivity despite DIP limiting. The relationship between APase and DIP indicates that the study area had limited DIP because of a strongly reverse correlation (r= -0.81; P<0.001). Relationship between APase and Chl-a (r=0.61, p<0.001) also indicated that APase may have been induced by phytoplankton (ca. 60 %) and bacteria (ca. 40 %). In DIP limiting history in this study area, frontal area and non-frontal areas might have induced long-term DIP limitation and the recent relief from DIP-limitation, respectively, based on distributions of dissolved APase and particulate APase. Thus, these results suggest that by measuring the enzyme that hydrolyzes organic matter such as APase in frontal area, it is possible to estimate temporal and spatial characteristics of limiting nutrient, thereby improving our understanding of biogeochemistry cycles.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.153-163
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• 2004

In order to estimate the nutrient flux of the Seomjin River into the coastal waters of South Sea, and to understand the estuarine reactions during mixing between river water and seawater, we collected surface water along the salinity gradient in the Seomjin River estuary from Mar. 1999 to Apr. 2001. We found that nitrate and silicate were delivered by fluvial input, while phosphate was, supplied from disposed wastes in the Gwangyang Bay. Mean annual flux of dissolved inorganic nitrogen (DIN), phosphate and silicate into the Gwangyang Bay was estimated 10.9 molesㆍsec$^{-1}$(4,820 tonnesㆍyr$^{-1}$), 0.07 molesㆍsec$^{-1}$(68 tonnesㆍyr$^{-1}$), 13.3 molesㆍsec$^{-1}$(11,747 tonnesㆍy$^{-1}$), respectively. An evident removal of phosphate, silicate and ammonium at the mid-salinity zone during the dry season was attributed to the active uptake of phytoplankton, and consequently nutrient flux into the Gwangyang Bay was low. Whereas, during the flood season in summer, conservative or additional distribution of the nutrients was observed in the estuary. As a rsult nutrient flux into the Gwangyang Bay was maintained high. High concentrations of chlorophyll a and the active removal of nutrient during the dry season at the mid-salinity zone suggest that nutrient distribution in the Seomjin River estuary was mainly controlled by biological processes and nutrient fluxes into the Gwangyang Bay might be significantly modified of by the primary production.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.82-87
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• 2013

This research will be utilized as a base line data by researching on growth and the accumulation of inorganic nutrients during the cultivation period of zoysiagrass and also to establish a cultivation strategy of zoysiagrass. It involves the management such as fertilizer and mowing which ultimately led to the difference of growth and accumulation of inorganic nutrients. The accumulation of inorganic nutrients after mowing, the amount of accumulation was small when compared to the amount lost for the shoot, rhizome and root. Difference in the accumulation of inorganic nutrients, but as for K, Ca and Mg accumulation it shows similar aspects to N accumulation. The orders of inorganic nutrients in zoysiagrass were N > K > P > Ca > Mg. The characteristics of inorganic nutrients absorption of such zoysiagrass acts as the foundation of cultivation, and in the aspect of making decisions on the fertilization amount and soil management, it is closely related to the requirement on nutrients. In order to increase the productivity based on the zoysiagrass's growth and density rate improvement, accumulation of inorganic nutrients per growth period needs to be analyzed, and supplying nutrients in an efficient method suitable to the growth period is advisable, so such basic research was necessary.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.1
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• pp.61-66
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• 2006

This experiment was conducted to evaluate the effects of different selenium (Se) products (inorganic, organic A, organic B) added at two supplemental dietary Se levels (0.1 and 0.3 mg/kg) on growth performance, nutrient digestibility and Se retention in growing-finishing pigs. A $3{\times}2$ factorial arrangement of treatments was used in a RCB design, with a non-Se-fortified basal diet serving as the negative control. A total of 56 crossbred pigs (28 male and 28 female pigs) initially weighing an average $28.45{\pm}0.53kg$ BW were allotted to each treatment with four pigs per pen on the basis of sex and weight. Two pigs per pen were selected and bled from the anterior vena cava at 3- weekly intervals to analyze Se concentration. In the growing phase (0-6 weeks), increased ADFI was observed when pigs were fed organic Se compared to those fed the control diet or inorganic Se treatment (p<0.05). Pigs fed inorganic Se had a great ADFI than pigs fed organic Se (p<0.05) in the late finishing phase (7-12 weeks), although there were no differences in whole period ADFI between organic or inorganic Se products. During 12 weeks of the whole experimental period, serum Se concentration increased linearly when dietary Se level increased regardless of Se products (p<0.05). Both dietary Se source (p<0.05) and Se level (p<0.01) influenced the Se concentration of various pig tissues at end of this experiment and Se content was the highest in the kidney. For the determination of nutrient digestibility, a metabolic trial was conducted in 3 replicates in randomized complete block (RCB) design. A total of 21 barrows ($50.21{\pm}0.62kg$ of average BW) were used in the metabolic study. Selenium supplementation had no effect on nutrient digestibility except for crude protein. Crude protein digestibility increased with dietary supplementation of organic Se (A) compared with other forms of Se products or control diet (p<0.05). Consequently, this experiment indicated that dietary Se products and levels had no effect on growth performance of pigs. Se concentration in tissues and serum was increased in proportion to dietary Se level, especially when organic Se was provided. Although pigs were fed organic forms of Se, bioavailability of organic forms varied among products, consequently bioactivity of organic products to the animals should be evaluated before practical application in animal feed.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.2
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• pp.252-261
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• 2006

Four experiments were conducted to investigate the effect of organic or inorganic acid supplementation on the growth performance, nutrient digestibility, intestinal measurements and white blood cell counts of weanling pigs. In growth trial (Exp I), a total of 100 crossbred pigs ({$Landrace{\times}Yorkshire$}${\times}$Duroc), weaned at $23{\pm}2$ days of age and $7.25{\pm}0.10kg$ average initial body weight (BW), were allotted to 5 treatments by body weight and sex in a randomized complete block (RCB) design. Three different organic acids (fumaric [FUA], formic [FOA] or lactic acid [LAA]) and one inorganic acid (hydrochloric acid [SHA]) were supplemented to each treatment diet. Each treatment had 5 replicates with 4 pigs per pen. During 0-3 wk, average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency (G/F ratio) were not significantly different among treatments. However, pigs fed LAA or SHA diet showed improved ADG by 15 or 13% respectively and 12% greater ADFI in both treatments compared to CON diets. Moreover, compared to organic acid treatments, better ADG (p = 0.07) and ADFI (p = 0.09) were observed in SHA diet compared to pigs that were fed the diet containing organic acids (FUA, FOA or LAA). However, during 4-5 wk, no differences in ADG, ADFI and G/F ratio were observed among treatments. Overall, ADG, ADFI and G/F ratio were not affected by acidifier supplementation. Although it showed no significant difference, pigs fed LAA or SHA diets showed numerically higher ADG and ADFI than pigs fed other treatments. In metabolic trial (Exp II), 15 pigs were used to evaluate the effect of acidifier supplementation on nutrient digestibility. The digestibility of dry matter (DM), crude protein (CP), crude fat (CF), crude ash (CA), calcium (Ca) and phosphorus (P) was not improved by acidifier supplementation. Although the amount of fecal-N excretion was not different among treatments, that of urinary-N excretion was reduced in acidsupplemented treatments compared to CON group (p = 0.12). Subsequently, N retention was improved in acid-supplemented groups (p = 0.17). In anatomical trial (Exp III), the pH and $Cl^-$ concentrations of digesta in gastrointestinal (GI) tracts were not affected by acidifier supplementation. No detrimental effect of intestinal and lingual (taste bud) morphology was observed by acidifier supplementation particularly in inorganic acid treatment. In white blood cell assay (Exp IV), 45 pigs were used for measuring white blood cell (WBC) counts. In all pigs after LPS injection, WBC counts had slightly declined at 2 h and kept elevating at 8 h, then returned to baseline by 24 h after injection of lipopolysaccharide (LPS). However, overall WBC counts were not affected by acidifier supplementation. In conclusion, there was no difference between organic and inorganic acidifier supplementation in weanling pigs' diet, however inorganic acidifier might have a beneficial effect on growth performance and N utilization with lower supplementation levels. Furthermore, inorganic acidifier had no negative effect on intestinal measurements and white blood cell counts in weanling pigs. These results suggested that inorganic acidifier might be a good alternative to organic acidifiers in weanling pigs.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.91.2-92
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• 2003

In order to elucidate influence of nutritional status on rice brown spot caused by Cochliobolus miyabeanus, rice cultivation soils and rice straws were collected from paddy fields where ice brown spot occurred severely, moderately, a little and none respectively. Rice plant materials were analyzed to measure inorganic nutrients in rice straws and rice seeds. Analysis of chemical properties of rice paddy soil showed that EC and contents of available phosphate, cation and silicic acid in soil with severe infections were lower than those in healthy soil. This result suggests that amount and holding capacity of nutrient contents in soils collected from paddy field with infection of C. miyabeanus are relatively low compared to those in soils collected from healthy paddy field. Analysis of inorganic nutrients in rice straws showed that amount of macronutrient elements such as silicic acids, available phosphate and total nitrogen, and micronutrients such as copper, iron and zinc in rice straws from paddy field with infection were lower than those in healthy soil. Especially amount of iron and silicic acid were very low in rice straws from paddy field soils with infection Amount of inorganic nutrients such as iron and zinc in rice seeds was the same trend as those of rice straws. These results showed that one of major factors affecting rice brown spot was amount of nutrient contents in soil and rice straw.

• Journal of Environmental Science International
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• v.13 no.9
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• pp.807-817
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• 2004

The modified biochemical oxygen demand (MBOD) were conducted to evaluate the water quality and fertility in the Mangyeong river from november 2002 to april 2003. MBOD method was used to evaluate algal growth potentials and their limiting factors. MBOD depends on the amount of available inorganic nutrient and organic substrate during 5-day incubation in the dark condition at $20^{\circ}C.$ The MBOD assay depends on inorganic nutrients such as phosphorus and nitrogen as well as reduced carbon as called MBOD, MBOD-P, and MBOD-N, respectively. The concentration of pollutants were in the range of 3.08～48.36 mg/L for COD. The concentration of nutrients were in the range of 0.37～111.62 mg/L for dissolved inorganic nitrogen (DIN) and 0.00～1.03 mg/L for dissolved inorganic phosphorus (DIP). The results of MBOD bioassay showed that the MBOD, MBOD-P and MBOD-N values were 15～173 mg $O_2/L,$ 13～165 mg $O_2/L$ and 66～175 mg $O_2/L$ ranges, respectively. The MBOD values are found to be the highest in Iksan River and the lowest in Hari River throughout the Mangyeong River. The relationships of MBOD, MBOD-P and MBOD-N in MBOD method were generally found in MBOD$\risingdotseq$ MBOD-P$\risingdotseq$MBOD-N. But the result of Gosan was appeared to MBOD$\risingdotseq$MBOD-N > MBOD-P. The MBOD-N value was higher 3 to 5 times than the MBOD-P value in the Gosan station. The algal growth potentials expressed as the concentration of chlorophyll-a were maximum 20 times more than algal biomass in the water column.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.164-176
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• 2003

During summer, the DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphate) observed in the Jindong Bay in the southern sea of Korea show much higher values in the inner area of the bay. In general, they have high values in the upper (0-1 m) and lower layers (8 m-bottom), but are relatively lower in the middle layer (1-8 m). These features in their distribution are examined using an ecosystem model with considering the wind, tidal current, horizontal gradient of water density and residual flow. The experiments were focused on how to influence nutrients associated with these conditions. In the experiment with tide-induced residual flow, the values of nutrients appeared lower than the observation, and were well corresponded to it when the effects of wind, tide-induced residual current and horizontal gradient of water density were additionally imposed. A statistical analysis identifies these results. This paper suggests that variation of nutrient in the Jindong Bay during summer should be seriously a(footed wind-driven current by the wind and density-driven current is induced by the horizontal gradient of water density as well as tidal current.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.158-163
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• 2008

This study was carried out to elucidate the relationship between yields and inorganic nutrient contents, and then establish of critical range of inorganic nutrient contents in leaves of watermelon in protected cultivation in Gochang from 2004 to 2006. In considering the yields and nutrient contents of watermelon, the critical ranges of macro-nutrient contents in leaves of watermelon at 20 days after transplanting were in N 5.0~6.6%, P 0.30~0.57%, K 3.5~4.2%, Ca 1.7~3.8% and Mg 0.20~0.42%, respectively. The critical ranges of micronutrient content, such as Fe, Mn, Zn, Cu and B, were not found the regular trend with different growth stages. However, the critical range of micronutrient contents in leaves of watermelon at 20 day after transplanting were in Fe 96~128, Mn 67~201, Zn 40~60, Cu 6~9 및 B $41{\sim}82mg\;kg^{-1}$, respectively. Finally, these results might be used at the indicator for critical nutrient contents for diagnosis of nutritional disorder in watermelon in protected cultivation.