• 한국산림과학회지
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• 제88권4호
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• pp.541-554
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• 1999

이 연구는 경기도 광주지방에서 잣나무림, 낙엽송림, 참나무류 위주의 활엽수림을 대상으로 임분간 수관통과우, 수간류를 통한 양료유입 양상을 비교하고 수관통과우, 수간류, 토양수별로 양료동태 특성을 알아보고자 하였다. 조사기간동안 총 강우량은 1410.1mm였으며 수관통과우량은 낙엽송림에서 전체강우량의 85%, 잣나무 간벌림에서 84.5%, 잣나무 하예림에서 83.2%, 활엽수림에서 81.2%로 나타나 활엽수림 보다는 침엽수림에서 높게 유입되었다. 수간류량은 활엽수림에서 강우의 2.7%, 잣나무하예림에서 1.3%, 잣나무 간벌림에서 1.2%, 낙엽송림에서 0.8%로 활엽수림이 침엽수림에 비하여 높았다. 강우, 수관통과우, 수간류내 평균 이온농도는 수간류가 가장 높았으며 임분별 평균 이온농도는 양이온, 음이온 모두 낙엽송림, 잣나무림, 활엽수림의 순으로, 활엽수림에 비하여 침엽수림에서 높았다. 수관통과우와 수간류내 양이온 농도는 $NH{_4}^+$-N, $K^+$, $Ca^{2+}$, $Na^+$, $Mg^{2+}$의 순으로 높았으며 음이온 농도는 $SO{_4}^{2-}$, $NO{_3}^-$-N, $Cl^-$의 순이었다. 강우가 수관층을 통과한 후 수관통과우와 수간류에서의 농도변화를 보면 활엽수림의 경우 가장 크게 증가한 이온이 $K^+$인 반면 잣나무림과 낙엽송림에선 $NH{_4}^+$-N이온이 가장 크게 증가하여 수종에 따라 각기 다른 양상을 보였다. 토양수내 양이온 농도는 $Ca^{2+}$, $Mg^{2+}$, $Na^+$의 순으로 높았고, 음이온 농도는 $NO{_3}^-$-N, $Cl^-$, $SO{_4}^{2-}$의 순으로 높았다. 이 중 $NH{_4}^+$-N, $K^+$는 주로 대기로 부터 유입되고 $Ca^{2+}$, $Mg^{2+}$, $Na^+$는 주로 모암의 풍화에 의하여 유입되었다.

• ALGAE
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• 제22권3호
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• pp.235-240
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• 2007

The red tide-causing flagellate Chattonella anticfua can cause mass fish kills by their clogging in fish gills. Thisstudy examined the nutrient requirements of C. antiqua isolated from Korea. C. anticfua displayed maximum growthat the day five, followed by a decrease in cell density. Nitrate and nitrite were the preferred nitrogen sources, alonewith adenosine diphosphate for phosphorus compounds. In medium that contained ammonium, a significantdecrease in cell density was observed. Half-saturation constants, Ks, calculated from the maximum growth ratewere 4.94 U|M for NC>3 and 0.79 flM for P04. The growth of C. antiqua was not within the function of the N:P ratio (RU= 0.29). With an N:P ratio as low as 10, the increase in cell density was apparent, with a higher division rate. At lev-els above 50 fiM of NaNOg or 8 ;uM of NaHUPCU, the growth rates were somewhat decreased. Phosphate was thelimiting factor for C. antiqua growth since the starvation of phosphate had brought about a rapid decrease in celldensity in semi-continuous culture. Studies about the temporal modification of the efficiency of nitrate or phosphateuptake may be necessary to explain the bloom dynamics of C. antiaua.

• Ocean and Polar Research
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• 제32권3호
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• pp.321-329
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• 2010

Photosynthetic pigments, nutrients, and hydrographic variables were examined in order to elucidate the spatio-temporal variation of water column structure and its effect on phytoplankton community structure in the western channel of the Korea Strait in fall 2006 and spring 2007. High phytoplankton biomass in the spring was associated with high salinity, implying that nutrients were not supplied by coastal waters or the Yangtze-River Diluted water (YRDW) with low salinity. Expansion of the Korea Strait Bottom Cold Water (KSBCW) and a cold eddy observed during the spring season might enhance the nutrient supply from the subsurface layer to the euphotic zone. Chemotaxonomic examination showed that diatoms accounted for 60-70% of total biomass, followed by dinoflagellates. Nutrient supply by physical phenomena such as the expansion of the KSBCW and the occurrence of a cold eddy appears to be the controlling factors of phytoplankton community composition in the Korea Strait. Further study is needed to elucidate the mechanisms by which the KSBCW is expanded, and its role in phytoplankton dynamics.

• 한국습지학회지
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• 제14권4호
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• pp.537-545
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• 2012

낙엽활엽수인 상수리나무 낙엽의 지역에 따른 분해율 및 분해과정에 따른 영양염류의 함량 변화를 파악하기 위해 2008년 12월 공주의 상수리나무림과 진주지역의 낙엽-상록침엽수 혼효림 임상에 낙엽주머니를 설치하고 2011년 3월까지 33개월 동안 분해율, 분해상수 (k), 그리고 분해과정에 따른 C/N 비, C/P 비의 변화와 영양염류의 동태를 조사하여 비교하였다. 33개월경과 후 공주와 진주에서 상수리나무 낙엽 잔존률은 각각 $41.2{\pm}0.4%$와 $28.3{\pm}0.6%$, 분해상수 (k)는 각각 0.39와 0.61로 진주지역이 공주지역에 비해 분해가 빠른 것으로 나타났다. 이것은 진주지역이 공주에 비해 연중 기온과 강수량이 높기 때문인 것으로 판단된다. 상수리나무 낙엽의 분해과정에 따른 C/N. C/P 비율은 초기에 각각 46.8, 270.9 이었으나 33개월경과 후에는 공주지역에서 각각 22.0과 106.8, 진주지역에서는 각각 19.2와 170.2로 낮아졌다. 낙엽의 초기 N, P, K, Ca, Mg 함량은 각각 8.31, 0.44, 4.18, 9.38, 1.37 mg/g이었으며, 33개월경과 후 N, P, K, Ca, Mg의 잔존률은 공주지역에서 각각 91.0, 85.4, 30.2, 47.9, 11.7 %, 진주지역에서는 각각 67.0, 54.2, 19.9, 30.0, 40.8%로 Mg을 제외하고 진주지역의 잔존률이 낮았다. 조사기간 동안에 질소와 인은 부동화 후 무기화가, 칼륨, 칼슘, 마그네슘은 지속적인 무기화가 진행되었다.

• 한국해양학회지
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• 제24권1호
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• pp.52-61
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• 1989

해양에서의 식물플랑크톤에 의한 기초생산력과 질소계 영양염의 동적관계를 규명하기 위해 동해 남부해역에서 식물플랑크톤에 의한 일차 생산력 및 동물플랑크톤의 영양염 재생산율 등을 측정하였다. 본 해역은 수직적으로 수심 20-60m 사이에서 수온약층 및 영양염약층이 잘 발달되어 있었다. 표층 총 엽록소 양은 $1.22-3.24{\mu}g$ Chl/l의 범위를 보이며 미세 플랑크톤의 엽록소는 43.2-99.6%에 이르렀다. 식물플랑크톤에 의한 기초생산력은 0.75-2.04gC/$m^2$/d 의 범위를 보이며 평균 1.5gC/$m^2$/d 를 보였다. 북한 한류계 수와 동한 난류계 수가 접하는 경계해역에 형성되는 전선수역에서는 기초생산력과 엽록소의 양이 비교적 높게 나타났다. 진광대에서 질산염의 turnover time은 0.2-1.6일의 범위를 보였고, 평균 0.8일 이었다. 본 연구해역의 N : P ratio 는 해역 전체 평균 13.4로서 질소계 영양염이 식물플랑크톤 생장의 제한요인임을 시사한다. 본 연구해역에서의 질소계 영양염과 식물플랑크톤의 단위 시간당 질소요구량을 규명하기 위해 측정한 동물플랑크톤의 암모니아 분비에 의한 영양염 재생산은 평균 1.3mg at-N/$m^2$/d로서 식물플랑크톤의 일일 질소요구량 중 7.3%를 공급하고 있으며 질산염의 수직확산에 의해 수온약층 하부로부터 공급되는 영양염은 평균 1.2mg at-N/$m^2$/d로서 식물플랑크톤의 일일 질소요구량 중 약 7%를 공급하고 있음이 규명되었다.

• ALGAE
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• 제34권3호
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• pp.237-251
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• 2019

The dinoflagellate genus Alexandrium is known to often form harmful algal blooms causing human illness and large-scale mortality of marine organisms. Therefore, the population dynamics of Alexandrium species are of primary concern to scientists and aquaculture farmers. The growth rate of the Alexandrium species is the most important parameter in prediction models and nutrient conditions are critical parameters affecting the growth of phototrophic species. In Korean coastal waters, Alexandrium affine and Alexandrium fraterculus, of similar sizes, often form red-tide patches together. Thus, to understand bloom dynamics of A. affine and A. fraterculus, growth rates and nitrate uptake of each species as a function of nitrate ($NO_3$) concentration at $100{\mu}mol\;photons\;m^{-2}s^{-1}$ under 14-h light : 10-h dark and continuous light conditions were determined using a nutrient repletion method. With increasing $NO_3$ concentration, growth rates and $NO_3$ uptake of A. affine or A. fraterculus increased, but became saturated. Under light : dark conditions, the maximum growth rates of A. affine and A. fraterculus were 0.45 and $0.42d^{-1}$, respectively. However, under continuous light conditions, the maximum growth rate of A. affine slightly increased to $0.46d^{-1}$, but that of A. fraterculus largely decreased. Furthermore, the maximum nitrate uptake of A. affine and A. fraterculus under light : dark conditions were 12.9 and $30.1pM\;cell^{-1}d^{-1}$, respectively. The maximum nitrate uptake of A. affine under continuous light conditions was $16.4pM\;cell^{-1}d^{-1}$. Thus, A. affine and A. fraterculus have similar maximum growth rates at the given $NO_3$ concentration ranges, but they have different maximum nitrate uptake rates. A. affine may have a higher conversion rate of $NO_3$ to body nitrogen than A. fraterculus. Moreover, a longer exposure time to the light may confer an advantage to A. affine over A. fraterculus.

• Journal of Ecology and Environment
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• 제39권1호
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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].

• Journal of Ecology and Environment
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• 제41권9호
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• pp.235-245
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• 2017

Background: Loading of excess nutrient via bioremediation of polluted sediment to overlying water could trigger anoxia and eutrophication in coastal area. The aim of this research was to understand the changes of overlying water features such as dissolved oxygen (DO); pH; oxidation reduction potential (ORP); $chlorophyll-{\alpha}$ ($Chl-{\alpha}$); and nitrogen nutrients ammonia ($N-NH_4{^+}$), nitrate ($N-NO_3{^-}$), and nitrite ($N-NO_2^-$) when the sediment was not treated (control) and treated by calcium peroxide for 5 weeks. Methods: The water samples were analyzed for measuring physical and chemical properties along with the sediment analyzed by polymerase chain reaction (PCR) including denaturing gradient gel electrophoresis (DGGE) for identifying the phylogenetic affiliation of microbial communities. Results: Results showed that due to the addition of calcium peroxide in sediment, the overlying water exposed the rise of dissolve oxygen, pH, and ORP than control. Among the nitrogen nutrients, ammonia inhibition was higher in calcium peroxide treatment than control but in case of nitrate inhibition, it was reversed than control. $Chlorophyll-{\alpha}$ was declined in treatment column water by 30% where it was 20% in control column water. Actibacter and Salegentibacter group were detectable in the calcium-peroxide-treated sediment; in contrary, no detectable community ware found in control sediment. Both phylogenetic groups are closely related to marine microflora. Conclusions: This study emphasizes the importance of calcium peroxide as an oxygen release material. Interaction with peroxide proved to be enhancing the formation of microbial community that are beneficial for biodegradation and spontaneity of nutrient attenuation into overlying water.

• 생태와환경
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• 제41권4호
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• pp.457-465
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• 2008

The purpose of the study was to evaluate spatial and temporal dynamics of nutrients (TN, TP), organic pollution (BOD, COD), and ionic dynamics (electrical conductivity, EC) in the North Han-River, South Han-River, and merged downriver using the dataset of $1998{\sim}2007$, obtained from the MEK (Ministry of Environment, Korea). Accord. ing to interannual nutrient analysis, TN varied slightly in the North Han-River and South Han-River, but decreased in the merged downriver along with BOD. Longitudinal analysis in the water quality showed that BOD, COD, and nutrients had linear decreasing trend along the main axis of headwater-to-downriver. Concentrations of TP and TN in the North Han-River averaged $26.97{\mu}g\;L^{-1}$, $1.696mg\;L^{-1}$, respectively, which were minimum in the three watersheds, followed by South Han-River and then the merged downriver in order. Ratios of TN:TP in the watersheds were >40 in all the sites, indicating that nitrogen may be enough for periphyton or phytoplankton growth and phosphorus may be limited partially. After the North Han-River water is merged with South Han-River, the concentrations of BOD, COD, TN, and TP were similar to the values of $S6{\sim}S7$, respectively or a little bit higher, but increased abruptly in Site M4 (Fig. 3). Thus, mean values of all the water quality parameters in the reach of $M4{\sim}M7$ sites were greater than any other sites. Seasonal data analysis indicated that BOD and EC in the downstream ($S3{\sim}S7$) was greater in the premonsoon than two seasons of the monsoon and postmonsoon, and no significant differences in BOD between the three seasons were found in the upstream ($S1{\sim}S2$). Empirical models of COD in the merged downriver was predicted ($R^2=0.87$, p>0.01, slope = 0.84, intercept = -1.28) well by EC. These results suggest that EC to be measured easily in the field may be used for estimations of nutrients and organic matter pollutions in the merged downriver and these linear models are cost-effective for the monitoring of the parameters.

• Asian-Australasian Journal of Animal Sciences
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• 제23권4호
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• pp.491-500
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• 2010

Three experiments were conducted to investigate the effects of polyurethane coated urea on in vitro ruminal fermentation, ammonia release dynamics and lactating performance of Holstein dairy cows fed a steam-flaked corn-based diet. In Exp. 1, a dual-flow continuous culture was run to investigate the effect of polyurethane coated urea on nutrient digestibility, rumen fermentation parameters and microbial efficiency. Three treatment diets with isonitrogenous contents (13.0% CP) were prepared: i) feedgrade urea (FGU) diet; ii) polyurethane coated urea (PCU) diet; and iii) isolated soy protein (ISP) diet. Each of the diets consisted of 40% steam-flaked corn meal, 58.5% forages and 1.5% different sources of nitrogen. PCU and FGU diets had significantly lower digestibility of NDF and ADF (p<0.01) than the ISP diet. Nitrogen source had no significant effect (p = 0.62) on CP digestibility. The microbial efficiency (expressed as grams of microbial N/kg organic matter truly digested (OMTD)) in vitro of the PCU diet (13.0 g N/kg OMTD) was significantly higher than the FGU diet (11.3 g N/kg OMTD), but comparable with the ISP diet (14.7 g N/kg OMTD). Exp. 2, an in vitro ruminal fermentation experiment, was conducted to determine the ammonia release dynamics during an 8 h ruminal fermentation. Three treatment diets were based on steam-flaked corn diets commonly fed to lactating cows in China, in which FGU, PCU or soybean meal (SBM) was added to provide 10% of total dietary N. In vitro $NH_3-N$ concentrations were lower (p<0.05) for the PCU diet than the FGU diet, but similar to that for the SBM diet at all time points. In Exp. 3, a lactation trial was performed using 24 lactating Holstein cows to compare the lactating performance and blood urea nitrogen (BUN) concentrations when cows were fed PCU, FGU and SBM diets. Cows consuming the PCU diet had approximately 12.8% more (p = 0.02) dietary dry matter intake than those consuming the FGU diet. Cows fed the PCU diet had higher milk protein content (3.16% vs. 2.94%) and lower milk urea nitrogen (MUN) concentration (13.0 mg/dl vs. 14.4 mg/dl) than those fed the FGU diet. Blood urea nitrogen (BUN) concentration was significantly lower for cows fed the PCU (16.7 mg/dl) and SBM (16.4 mg/dl) diets than the FGU (18.7 mg/dl) diet. Cows fed the PCU diet had less surplus ruminal N than those fed the FGU diet and produced a comparable lactation performance to the SBM diet, suggesting that polyurethane coated urea can partially substitute soybean meal in the dairy cow diet without impairing lactation performance.