• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.967-974
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• 2012

Cultivation of Spirulina platensis using ammonium salts or wastewater containing ammonium as alternative nitrogen sources is considered as a commercial way to reduce the production cost. In this research, by analyzing the relationship between biomass production and ammonium-N consumption in the fed-batch culture of Spirulina platensis using ammonium bicarbonate as a nitrogen nutrient source, an online adaptive control strategy based on optical density (OD) measurements for controlling ammonium feeding was presented. The ammonium concentration was successfully controlled between the cell growth inhibitory and limiting concentrations using this OD-based feedback feeding method. As a result, the maximum biomass concentration (2.98 g/l), productivity (0.237 g/l d), nitrogen-to-cell conversion factor (7.32 gX/gN), and contents of protein (64.1%) and chlorophyll (13.4mg/g) obtained by using the OD-based feedback feeding method were higher than those using the constant and variable feeding methods. The OD-based feedback feeding method could be recognized as an applicable way to control ammonium feeding and a benefit for Spirulina platensis cultivations.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.107-117
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• 2004

Hourly monitoring data from Saemangeum estuary, which is expected to become freshwater, was analyzed to evaluate the water quality characteristics. Higher algal growth at spring season than winter influenced the high ratio of organic nitrogen to total nitrogen and concentration of chemical oxygen demand (COD). About 87.9％ and 59.7％ of organic nitrogen was observed at winter season and spring season, respectively. Daily salinity analysis at the mouth of two main rivers demonstrated that the Dongjin in river was more influenced by tidal effect and showed higher variation than the Mankyung river. The ratio of nitrogen to phosphorus (N/P ratio) was different with site (estuary versus sea area) and season (winter versus spring) remarkably. The N/P ratio was highest (32.74 ∼ 43.93) at estuary in winter and was lowest (1.78 ∼ 3.06) at sea in spring. The high N/P ratio at estuary area implies that phosphorus can be the limiting nutrient factor for algal growth as in general freshwater river, therefore, water quality management practice considering river characteristics rather might be needed in the Saemangeum estuary. The Saemangeum project is nationally recognized for its environmental issues, and especially water quality concern is a critical factor to make policy decision and further assessment with continued monitoring is strongly recommended.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.368-372
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• 2004

The development of a benthic filamentous green algal community formed by Spiro gyra sp. in early summer has been observed in the littoral zones in the north basin of Lake Biwa since the 1980s. The development of a Spirogyra sp. community may have an effect on the increase in the biomass of the benthic algal community in early summer and on the alterations in seasonal fluctuation patterns of the biomass. In this mini-review, the causes underlying the development of the Spirogyra sp. community are discussed on the basis of studies in the seasonal fluctuations of benthic algal communities in littoral stony zones carried out in 1963-1964, 1995-1996 and 2000-2001, especially those focusing on the nutrient concentration $(NO_3^--N)$. $NO_3^--N$ concentrations in June were higher than $100{\mu}g\;L^{-1}$ in 1995 and 2000 in contrast to a concentration in June 1964 of only $20{\mu}g\;L^{-1}$. These results show that $NO_3^--N$concentrations throughout in 1963-1964 period were considerably lower than those in 1995-1996 and 2000-2001, suggesting that the $NO_3^--N$concentration may have served as a limiting factor on Spirogyra sp. growth in 1963. $NO_3^--N$ concentrations in the pelagic zone in the north basin of Lake Biwa have clearly increased from the 1950s under the impact of economic growth and the increasing population in the watershed. The development of the Spirogyra sp. community seems to be the result of a heady increase in the nutrient supply from human activities.

• 한국해양학회지
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• v.24 no.1
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• pp.15-28
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• 1989

A study on quantitative phytoplankton samples, hydrographic conditions (temperature, salinity, dissolved oxygen), and nutrients has been performed in the southern waters of the Korean East Sea in early spring. Phytoplankton community showed close correlation with hydrographic conditions. This study area could be divided into three phytohydrographic regions; 1) East Korean Warm Water Region (a branch of Tsushima Current), 2) North Korean Cold Water Region, and 3) offshore water region not affected by other two water regions. Vertical distribution of phytoplankton is dependent upon stability of water column and nutrient concentration. Nutrient concentration shows characteristic distribution according to water masses. N/P ratio of ca. 3 in surface layer indicates that nitrogen is the major limiting nutrient in this area. N/P removal ratio was 12.54 ($r^2$ = 0.96), consistent with the Redified ratio. Primary nitrite maxima at the nitracline depths are thought to be formed by phytoplankton exudation. Secondary nitrite maximum was observed in coastal area with dissolved oxygen content of >5.2 ml/l much higher than <0.25 ml/l in other areas. The mechanism of secondary maximum is different from that of other regions, and whether it may be due to in situ degradation of organic matter by bacterial activity is still open to discuss.

• 한국해양학회지
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• v.24 no.1
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• pp.52-61
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• 1989

The daily net primary production by phytoplankton and ammonium excretion by macrozooplankton (> $350{\mu}m$) were measured to understand the nitrogenous nutrient dynamics in the southern part of the East Sea of Korea. At most of the staions, water columns were well stratified and strongly developed pycnoclines and matching nutriclines could be found near the 20-60m. Total chlorophyll ranged between $1.22-3.24{\mu}g$ ChI/l and nano-fractions of chlorophyll ranged from 43.2 to 99.6% in the surface layer. The daily net primary production by phytoplankton ranged from 0.75 to 2.04 gC/$m^2$/d and averaged to be 1.5 gC/$m^2$/d. 1t is evidenced that the primary production and chlorophyll content are relatively high in frontal waters where the North Korean Cold Water meets with the East Korean Warm Water. The turnover time of nitrate in the euphotic zone ranged from 0.2 day to 1.6 day and averaged to be 0.8 day. The N:P ratio of the study area shows on the average 13.4 which indicates nitrogenous nutrient to be the limiting factor for phytoplankton growth. Ammonium excretion by macrowoplankton averaged out to 1.3mg at-N/$m^2$/d, and contributed 7.3% of daily total nitrogen requirement by phytoplankton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer approximates 7% of nitrogen requirement by phytoplankton.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.244-250
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• 2000

Algal growth potential (AGP) bioassay were conducted to assess the water quality and fertility in the Kum River from March 1998 to June 1999. AGP values were always the highest at the conjuction site of the Kapchon, which is a tributary of the Kum River. Average value of AGP by Microcystis aeruginosa in the main river and tributary was 17.0 mg dw/l, 48.3 mg dw/l, respectively. AGP values decreased towards the lower part of the river and consisted in the water quality or nutrient analysisresults. Among the tributaries, AGP of the Kapchon, Mihochon and Soksongchon were relatively high, and the average value was 161.2, 50.3 and 125.6 mg dw/l, respectively. AGP value in the Yukuchon was lowest among the study stations with <2.7 mg dw/l. Water quality in the lower part of the Kum River deteriorated in drought season, and the AGP values of this season were higher than those in other seasons. Based on correlation analysis between AGP results and nutrients, limiting nutrient appeared to be P because SRP (r = 0.99) was higher than other nutrients, and N uptake in algal growth was preferred by $NH_4$ rather than $NO_3$. The variation of AGP was different according to localities and seasons, and it was related to nutrient fluctuation in the inlet tributary. Water quality status according to AGP was assessed to be eutrophic.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.475-488
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• 1995

In order to see the seasonal variation of nutrients and the limiting factors to the primary production in Deukryang Bay, both dissolved inorganic nutrients and salinity were measured in the surface waters during the periods from July 1992 to March 1993. The mean value of salinity was the lowest in ?all and the highest in early spring. Dissolved inorganic nitrogen (DIN) was the highest in winter and the lowest in summer. However, both phosphate and silicate were the highest in summer and the lowest in fall. Salinity was generally higher in the outer region than in the inner region of the bay.DIN content was nearly depleted (less than $2{\mu}M$) in summer. From fall to spring, DIN content was nearly depleted in the inner region and relatively high in the outer region of the Day. Phosphate was the highest in summer showing an opposite distribution pattern to salinity, and it was nearly depleted (less than $0.1{\mu}M$) in fall and winter. In spring, however, phosphate content was slightly high in the outer region. Silicate content showed an opposite distribution pattern to salinity in summer. in other seasons, However, the distribution pattern of silicate was similar to the salinity. DIN seemed to be a limiting factor for the primary production at all area of the bay in summer and at the inner region in other season. However, phosphate seemed to be a limiting factor at all area of the bay in fall and winter and at the inner region in spring. Silicate may limit the production of diatoms at the inner region of the bay in winter and spying. Both phosphate and silicate showed a good inverse relationship with salinity in summer, which indicates inputs of these nutrients from the freshwater runoff. In the other seasons, both nitrate and silicate showed a positive linear relationship with salinity in the outer region of the bay, suggesting that these two nutrients were mainly supplied by the inflow of the offshore costal water which had high nitrate content associated with vertical mixing.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.274-285
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• 2016

In order to elucidate the spatiotemporal variations of marine environmental parameters, we collected seawater samples in the middle east coast of Korea in 2013-2014. A high temperature and low salinity were distinctively observed in the summer and a low temperature and high salinity pattern in the winter. The temperature of the bottom water was in the range of $2^{\circ}C$ to $7^{\circ}C$, with the temperature being relatively high in the winter, while the salinity was measured to be around 34, with no large differences across the seasons. The dissolved oxygen concentrations were in the range of $7mg\;L^{-1}$ to $12mg\;L^{-1}$, and it was relatively high in May compared to other seasons. The seawater temperature and dissolved oxygen concentration at the surface layer showed a significant negative correlation in the autumn and winter seasons, based on which it is seemed that water temperature is the main factor controlling the amount of dissolved oxygen in the autumn and winter seasons. The dissolved inorganic nitrogen (DIN) and silicate (DSi) increased 11- and 7-fold, respectively, in the winter compared to the summer. The DIN to DIP (dissolved inorganic phosphorus) ratio for the surface seawater was approximately 16, but it was relatively low in the spring season. On the other hand, the DIN to DIP ratio was relatively high in the summer. Based on this, it is seemed that nitrogen and phosphorus were the growth-limiting nutrients for phytoplankton in the spring and summer, respectively. Water quality was I (excellent) ~III (medium) level at the most stations except for some stations (level IV) during the autumn season, having low dissolved oxygen saturations.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.261-271
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• 2007

Phytoremediation is an economic and environmentally friendly technique to remediate contaminated-soil. In this study, the effects of plants, rhizobacteria and physicochemical factors on phytoremediation have been reviewed. For successful phytoremediation, the selection of plants is primarily important. To remediate soil contaminated with petroleum hydrocarbon, raygrass (Lolium multiflorum lam), white mustard, vetch (Vicia villosa), tall fescue (Festuca arundinacea), legumes, poplar, and Pine (Pinus densiflora) were mainly applied, and the removal efficiency of petroleum hydrocarbon were ranged 68 to 99%. Corn (Zea mays), raygrass (Lolium multiflorum lam), vetch (Vicia villosa), mustard, clover (Trifolium repens), and tall fescue (Festuca arundinacea) were used for the removal of polycyclic aromatic hydrocarbon, and their removal efficiencies were 50-98%. Rhizobacteria play significant roles for phytoremediation because they can directly participate in the degradation of contaminant as well as promoting plants growth. The following rhizobacteria were preferred for phytoremediation: Azospirillum lipoferum, Enterobactor cloacae, Azospirillum brasilense, Pseudomonas putida, Burkholderia xenovorans, Comamonas testosterone, Pseudomonas gladioli, Azotobacter chroococcum, Bacillus megaterium, and Bacillus subtilis. Pysicochemical factors such as pH, temperature, nutrient, electron acceptor, water content, organic content, type of contaminants are consequential limiting factors for phytoremediation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.2
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• pp.90-103
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• 2014

Distribution characteristics of water masses, dissolved inorganic and organic nutrients were investigated in the southern part of the East Sea of Korea in September, 2011. On the basis of the vertical profiles of temperature, salinity and dissolved oxygen, water masses in the study area were divided into 4 major groups, such as WM (water mass)-I, WM-II, WM-III, WM-IV. Their characteristics were similar to Tsushima Surface Water (TSW), Tsushima Middle Water (TMW), North Korea Cold Water (NKCW) and East Sea Proper Water (ESPW), respectively. In the vertical profiles of dissolved nutrients, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) concentrations were highest in the WM-IV, followed by WM-III, WM-II, WM-I. On the contrary, distribution of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) were highest in the WM-I, followed by WM-II, WM-III, WM-IV. Although the DIN : DIP ratio in all of the water masses was similar to Redfield ratio(16), the DIN : DIP ratio in mixed layer was about 5.3, indicating that inorganic nitrogen is the limiting factor for the growth of phytoplankton. However, the DON proportion in dissolved total nitrogen (DTN) was about 70% in the mixed layer where inorganic nitrogen is limiting factor. Thus, enriched DON may play an important source of the nutrient for the growth of phytoplankon in the East Sea.