• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.607-613
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• 2001

The biodegradation rates of diesel oil by a selected diesel-degrading bacterium, Pseudomonas stutzeri strain Y2G1, and microbial consortia composed of combinations of 5 selected diesel-degrading bacterial were determined in liquid and soil systems. The diesel degradation rate by strain Y2G1 linearly increased $(R^2=0.98)$ as the diesel concentration increased up to 12%, and a degradation rate as high as 5.64 g/l/day was obtained. The diesel degradation by strain Y2G1 was significantly affected by several environmental factors, and the optimal conditions for pH, temperature, and moisture content were at pH8, $25^{\circ}C$, and 10%, respectively. In the batch soil microcosm tests, inoculation, especially in the form of a consortium, and the addition of nutrients both significantly enhanced the diesel degradation by a factor of 1.5 and 4, respectively. Aeration of the soil columns effectively accelerated the diesel degradation, and the initial degradation rate was obviously stimulated with the addition of inorganic nutrients. Based on these results, it was concluded that the major rate-limiting factors in the tested diesel-contaminated soil were the presence of inorganic nutrients, oxygen, and diesel-degrading microorganisms. To resolve these limiting parameters, bioremediation strategies were specifically designed for the tested soil, and the successful mitigation of the limiting parameters resulted in an enhancement of the bioremediation efficiency by a factor of 11.

• Ocean and Polar Research
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• 제29권4호
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• pp.349-366
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• 2007

Seasonal variations of various physicochemical components (temperature, salinity, pH, DO, COD, DOC, nutrients-silicate, DIN, DIP) and potential limiting factor for phytoplankton primary production were studied in the surface water of semi-enclosed Masan Bay. Seasonal variations of nutrient concentrations, with lower values in summer and winter, and higher in fall, are probably controlled by freshwater loadings to the bay, benthic flux and magnitude of occurrence of phytoplankton communities. Their spatial distributional patterns are primarily dependent on physical mixing process between freshwater and coastal seawater, which result in a decreasing spatial gradient from inner to outer part of the bay. In the fall season of strong wave action, the major part of nutrient inputs (silicate, ammonium, dissolved inorganic phosphorus) comes from regeneration (benthic flux) at sediment-water interface. During the summer period, high Si:DIN and Si:DIP and low DIN:DIP relative to Redfield ratios suggest a N- and secondarily P-deficiency. During other seasons, however, silicate is the potential limiting factor for primary production, although the Si-deficiency is less pronounced in the outer region of the bay. Indeed, phytoplankton communities in Masan Bay are largely affected by the seasonal variability of limiting nutrients. On the other hand, the severe depletion of DIN (relatively higher silicate level) during summer with high freshwater discharge probably can be explained by N-uptake of temporary nanoflagellate blooms, which responds rapidly to pulsed nutrient loading events. In Masan Bay, this rapid nutrient consumption is considerably important as it can modify the phytoplankton community structures.

• 해양환경안전학회지
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• 제28권4호
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• pp.459-468
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• 2022

천수만과 태안해역의 제한영양염을 평가하기 위해 장기자료 분석과 생물검정실험을 진행하였다. 우선 잠재적인 제한영양염을 평가하기 위해 국가수질측정망에서 제공되는 2004~2016년 동안의 장기 영양염 자료를 이용하였다. 장기자료의 DIN/DIP를 분석한 결과 대부분 16이하로 N 제한이 우세하였지만 N, P, Si의 농도비를 이용한 분석에서는 하계와 추계에는 N 제한이 우세하였고, 동계와 춘계에는 해역에 따라 일부 Si 제한을 보이거나 또는 제한이 나타나지 않았다. 생물검정실험 시 채집된 현장수의 영양염 분석결과, DIN/DIP는 3월과 5월에 모든 정점에서 P 제한을 나타냈고, 7월과 10월에는 N 제한이 우세하였다. N, P, Si의 농도비를 이용한 분석에서 3월과 5월은 P와 Si 제한을 보이거나 제한영양염이 나타나지 않은 정점이 존재하였으나 7월과 10월에는 N 제한이 우세하였다. 실질적인 제한영양염을 평가하기 위해 수행된 생물검정실험 결과 3월에는 특정 제한영양염이 나타나지 않았으나, 5월, 7월 10월에는 NH₄⁺와 NO₃^-가 반응을 보임으로서 이 시기에는 N이 식물플랑크톤 성장에 직접 관여하는 실질적인 제한영양염임을 확인하였다.

• 생태와환경
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• 제36권2호통권103호
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• pp.139-149
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• 2003

팔당호 식물플랑크톤의 제한영양염과 생리학적 성장 특성을 평가하기 위하여 2002년 3월부터 10일까지 팔당호의 수질환경 조사와 함께 실내 배양실험을 실시하였다. 총인의 농도와 Chl. a의 상관성 분석결과, 팔당호의 호수생산성은 인의 영향을 많이 받으며 TN/TP ratio와 식물플랑크톤의 성장잠재력 실험을 통해서도 제한영양염은 인으로 평가되었다. 특히, 봄철이 다른 계절에 비해 상대적으로 용존무기인이 낮은 농도로 존재하기 때문에 높은 인 제한을 받는 것으로 나타났다. 그러나 인의 제한정도는 계절적인 변이를 나타내었으며, 시기에 따라 질소와 규소에 의한 제한가능성도 나타났다. 팔당호 식물플랑크톤 군집의 최대성장률(${\mu}_{max}$)은 0.8${\sim}$l.1$day^1$의 범위로 나타났으며, 반포화농도($K_u$)는 0.1${\sim}$O.8${\mu}M$로 5월에 $0.8{\mu}M$로 가장 높고 9월에 $0.1{\mu}M$로 가장 낮은 것으로 조사되었다. 이는 영양염 흡수에 영향을 미치는 인의 cell quota와 관련이 있는 것으로 나타났으며, 5월에 $0.13{\mu}gP/{\mu}gChl.$ 3로 낮은 값을 나타냈다. 식물플랑크톤의 성장특성 분석을 통해 팔당호에서는 봄에 비해 여름과 가을철에 발생한 식물플랑크톤의 성장이 경쟁적으로 빠르게 발달할 수 있는 잠재성이 있는 것으로 판단된다. 결과적으로, 팔당호 식물플랑크톤 성장은 주로 인에 의하여 제한되며 여름 몬순 이후 수체의 안정기동안 높은 성장을 할 수 있는 생리적 특성을 가지고 있는 것으로 추정된다.

• 환경생물
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• 제31권2호
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• pp.61-68
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• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• ALGAE
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• 제21권2호
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• pp.229-234
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• 2006

For the test organism of algal growth potential (AGP), the diatom in the genus Stephanodiscus which cause blooms in the Nakdong River was used instead of generally used strains of Selenastrum, Microcystis, or Anabaena. AGP results indicated that all the samples in the Nakdong River except for that from the Nakdan Bridge site were eutrophic state. Furthermore, the sample from Kumho River site was hypertrophic state. In the main stream Nakdong River, the value of AGP was lowest at the upstream Nakdan Bridge site and was highest at Koryoung Bridge site which is just downstream of Kumho River confluent point indicating the seriousness of pollution contributed by the Kumho River to the Nakdong River. Changes in the concentration of nutrients before and after the AGP tests and inter-relationship among the nutrients indicated that the growth of the Stephanodiscus in the AGP tests were mostly affected by the nitrate, silicate and phosphate. The limiting nutrient was identified by the nutrient addition experiments and the results showed that phosphate was the limiting nutrient for the growth of Stephanodiscus in the tested samples.

• Journal of Biosystems Engineering
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• 제30권1호
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• pp.45-55
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• 2005

Knowledge of the relationship between crop yield and yield-limiting factors is essential for precision farming. However, developing this knowledge is not easy because these yield-limiting factors are interrelated and affect crop yield in different ways. In this study, data for grain yield and yield-limiting factors, including crop chlorophyll content, soil chemical properties, and topography were collected for a small (0.3 ha) rice paddy field in Korea and a large (36 ha) upland corn field in the USA, and relationships were investigated with path analysis. Using this approach, the effects of limiting factors on crop yield could be separated into direct effects and indirect effects acting through other factors. Path analysis provided more insight into these complex relationships than did simple correlation or multiple linear regression analysis. Results of correlation analysis for the rice paddy field showed that EC, Ca, and $SiO_2$ had significant (P<0.1) correlations with rice yield, while pH, Ca, Mg, Na, $SiO_2,\;and\;P_2O_5$ had significant correlations with the SPAD chlorophyll reading. Path analysis provided additional information about the importance and contribution paths of soil variables to rice yield and growth. Ca had the highest direct effect (0.52) and indirect effect via Mg (-0.37) on rice yield. The indirect effect of Mg through Ca (0.51) was higher than the direct effect (-0.38). Path analysis also enabled more appropriate selection of important factors limiting crop yield by considering cause-and-effect relationships among predictor and response variables. For example, although pH showed a positive correlation (r=0.35) with SPAD readings, the correlation was mainly due to the indirect positive effects acting through Mg and $SiO_2$, while pH not only showed negative direct effects, but also negatively impacted indirect effects of other variables on SPAD readings. For the large upland Missouri corn field, two topographic factors, elevation and slope, had significant (P<0.1) direct effects on yield and highly significant (P<0.01) correlations with other limiting factors. Based on the correlation analysis alone, P and K were determined to be nutrients that would increase corn yield for this field. With the help of path analysis, however, increases in Mg could also be expected to increase corn yield in this case. In general, path analysis results were consistent with published optimum ranges of nutrients for rice and com production. We conclude that path analysis can be a useful tool to investigate interrelationships between crop yield and yield limiting factors on a site-specific basis.

• 한국환경과학회지
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• 제4권5호
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• pp.469-479
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 2$0^{\circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8~96.0 mg$O_2$/l, 5.6~94.0 mg$O_2$/l and 42.0~220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 춘계학술발표회
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• pp.117-120
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• 2006

영양염과 식물성플랑크톤 그리고 식물성플랑크톤과 유기물의 관계를 평가하는 것을 목적으로 하였다. 그 결과 질소가 제한 영양염으로 나타나고 있으며 가장 제한이 되고 있는 계절은 여름으로 DIN/DIP의 비가 4.7로 나타났다. Chl.-a는 겨울철인 2 월에 비해 봄과 여름인 5월과 8월에 79%, 97%가 증가하는 것으로 나타났다. 유기물의 농도는 COD로 나타내었으며 2월에는 0.84 mg/l로서 가장 낮은 값을 나타내었으며 8월인 여름철에 가장 높은 1.12 mg/l를 나타내었다. 영양염과 Chl.-a 의 상관관계는 DIN과의 상관에서 $r^2$가 0.93, DIP과의 상관에서 $r^2$가 0.89로 매우 높게 나타났다. 이와 같은 결과는 식물성 플랑크톤의 증식이 영양염의 감소에 주요 원인이라고 할 수 있다. 또한 Chl.-a 와 COD 의 회귀분석에서 상관계수 $r^2$가 0.78 로서 상관관계가 있는 것으로 나타났으며 회귀식을 이용하여 분석한 결과 유기물의 생산량은 겨울철에는 25%, 여름철에는 40% 가 증가하는 것으로 나타났다.

• 한국수산과학회지
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• 제28권4호
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• pp.475-488
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• 1995

한반도 남서연안에 위치한 득량만에서 1992년 7월부터 1993년 3월까지 계절별로 염분과 영양염류의 농도를 측정하여 득량만 표층수중 영양염류의 시공간적 변화특성과 기초생산 제한인자의 계절변화에 대해 고찰하였다. 염분의 평균농도는 추계에 가장 낮고 춘계에 가장 높았으며, 용존무기질소는 동계에 가장 높고 하계에 가장 낮았다. 그러나, 인산염과 규산염은 하계에 가장 높았으나, 최소 값은 인산염의 경우 추계와 동계에, 규산염은 추계에 나타났다. 계절별로 다소의 차이는 있으나, 염분은 만 입구 쪽에서 북쪽으로 갈수록 점차 낮아지는 경향을 보이며, 득량도 서쪽이 동쪽 보다 다소 낮았다. 용존무기질소는 하계의 경우 거의 고갈된 농도를 보이나, 나머지 계절에는 고염수가 존재하고 있는 만의 입구 쪽 정점들에서 상대적으로 높고 만의 안쪽에서는 거의 고갈된 농도를 보인다. 인산염은 하계의 경우 염분과 상반된 분포를 보이며, 춘계의 경우 만 입구 쪽 정점들에서 상대적으로 높은 농도를 나타내는 것을 제외하면 추계와 동계에는 거의 고갈된 농도를 보인다. 규산염은 하계의 경우 염분과 상반된 분포를 보이나, 나머지 계절에는 염분과 유사한 분포양상을 보인다. 용존무기질소는 하계의 경우만의 전 해역에서 생물생산의 제한인자로 작용하고 있으나, 나머지 계절에는 만의 안쪽 해역에서만 제한인자로 작용하고 있다고 생각된다. 인산염은 추계와 동계에는 전 해역에서 생물생산을 제한하고 있으나, 춘계의 경우는 만의 안쪽 해역에서만 제한인자로 작용하고 있다고 생각된다. 규산염의 경우는 담수의 공급량이 작은 동계와 춘계에 만의 안쪽 해역에서 규조류의 생산을 제한하고 있다고 생각된다. 인산염과 규산염은 하계의 경우 염분과 부(-)의 상관성을 나타내는 것으로 보아 주로 담수의 유입에 의해 만내로 공급되고 있다. 그러나, 나머지 계절에는 용존무기질소와 규산염의 농도가 염분과 정의 상관성을 나타내는 것으로 보아 용존무기질소 및 규산염 농도가 비교적 높은 외해수가 만내로 유입되고 있음을 의미한다.