• Journal of Environmental Science International
• /
• v.4 no.5
• /
• pp.83-83
• /
• 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 20$^{circ}C$. 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.

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

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.1
• /
• pp.42-51
• /
• 2016

We investigated the distribution of dissolved nutrients, phytoplankton community structure and utilization of nitrogen compounds by dominant species in the southwestern part of East Sea in September, 2014. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) were lower in the surface layer, and concentrations were increased with depth. Dissolved organic nitrogen (DON) and dissolved organic phosphorus were the opposite of dissolved inorganic nutrients. Although DIN DIP ratio in all of the water masses was higher than Redfield ratio (16), DIN : DIP ratio in mixed layer was about 2, indicating that inorganic nitrogen is the limiting factor for the growth of phytoplankton. In particular, DON proportion in dissolved total nitrogen was about 88 % in the mixed layer where inorganic nitrogen is limiting factor. The dominant species Chaeotceros debilis and Prorocentrum minimum were able to grow using DIN as well as DON such as urea and amino acids. Therefore, DON utilization of phytoplankton may play a role as a survival strategy in the DIN-limited conditions of East Sea.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.61-68
• /
• 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.

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

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.20 no.4
• /
• pp.180-191
• /
• 2015

Marine environmental characteristics and primary productivity of phytoplankton were investigated in seaweed bed of northwestern coast of Jeju Island during Autumn, 2014. The trophic state based on dissolved inorganic nitrogen and phosphorus was mesotrophic. The Redfield ratio was less than 16, indicating that nitrogen was the limiting factor for the growth of phytoplankton. Dissolved organic nitrogen and phosphorus accounts for 63 and 46% of the dissolved total nitrogen and phosphorus, respectively. Light utilization efficiency (${\alpha}$) and maximum photosynthetic capacity ($P_m{^B}$) were highest in the Donggwi (third-year marine forest), followed by Gonae (one-year marine forest), Biyangdo (natural seaweed bed) and Geumneung (whitening area). The primary productivity of phytoplankton in the Donggwi, Gonae and Biyangdo also was higher than that in the Geumneung. Although nitrogen is the limiting factor, enriched dissolved organic nitrogen might play an important role to maintain primary productivity. In addition, phytoplankton community through photosynthesis could produce about 14% of phytoplankton carbon in one hour. These results will be able to use the important information for material cycle and ecological valuation of seaweed bed.

• Korean Journal of Environmental Biology
• /
• v.27 no.3
• /
• pp.306-313
• /
• 2009

In the Upo wetland, physico-chemical factors were observed during the period from March 2005 to December 2007 on a monthly basis. In the Upo wetland, water temperatures ranged $3.4{\sim}34.5^{\circ}C$. Conductivities were in the range of 133~806 ${\mu}S\;cm^{-1}$, which showed about 140 ${\mu}S\;cm^{-1}$ below in comparison with the precedent studies. The pH levels were between 6.7~9.1 with lower level in summertime. The dissolved oxygens were between 0.06~18.23 mg $L^{-1}$. COD ranged 4.9~20.8 mg $L^{-1}$, and showed a tendency to decrease every year. Nitrogen nutrients such as nitrate nitrogen ($NO_3-N$), ammonia nitrogen ($NH_3-N$) and total nitrogen (T-P) showed that they were generally decreased in comparison with those in the precedent studies. However the total nitrogen (T-N) is still considerably higher than the standard concentration level of eutrophication and algal blooming. Phosphate phosphorus ($PO_4-P$) and total phosphorus (T-P) were also shown as to be reduced considerably comparing with the values in the precedent studies. However, It was found out that total phosphorus (T-P) was dissolved over the criteria concentration of eutrophication. The average of TN/TP ratio was 18 in the Upo wetland, which proved that phosphorus was the limiting factor to the growth of phytoplankton in the Upo wetland. The chl-$\alpha$ was the highest in wintertime and the lowest in summertime, and especially in 2006 summer when the cyanobacterial bloom developed, it showed extremely high concentration.

• Journal of Korean Society of Forest Science
• /
• v.98 no.2
• /
• pp.170-177
• /
• 2009

There are remarkable differences in growth and morphological characters of roots between mountain and field cultivated Panax ginseng. Growth of root in mountain cultivated ginseng was much slower than that of field cultivated ginseng. However, the factor affecting the retarded growth in mountain ginseng was not known. Soil analysis revealed that phosphorus (P) content of mountain soil was exceptionally low at least ten-fold lower compared to that of field soil. Thus, we suggest that low availability of P in mountain soil may be one of the limiting factors for growth of ginseng in mountain soil environment. We had monitored the growth of ginseng plants after one and three years of phosphate fertilizer application. Three kinds of phosphate fertilizers: fused magnesium phosphate, fused superphosphate, and single superphosphate were applied to mountain soil. Application of phosphate fertilizers increased the fresh-, dry weight, and diameter of ginseng roots and resulted in increased P accumulation in roots. These results demonstrate that slow growth of ginseng in mountain soil environment might be attributed to the low P content in mountain soil. Thus, analysis of P amount in mountain soil will be a good indicator for the selection of suitable site the ginseng cultivation in forest.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.4
• /
• pp.348-355
• /
• 2002

To know characteristics of water quality in Saemankeum area, we were investigated the water quality of surface layer from July of 1999 to June of 2000. The concentrations of COD and chlorophyll a were in the range of $0.64\~6.40$ (mean 1.96)mg/L, $1.95\~51.55$ (mean 11,07)$mg/m^3$, respectively. The annual mean concentrations of DIN, DIP were found to be 21.182 $\mu$g-at/L and 0,655 $\mu$g-at/L respectively, which were exceeding second grade of seawater quality standard. The nitrogen ratio to the phosphorus was lower than 1. Therefore, nitrogen was playing an important role in phytoplankton growth as limiting factor in study area. Mean values of eutrophication index were exceeding 1, which was the eutrophication criteria. Especially Mankyung and Dongjin estuary were shown over 10 as eutrophication index. Therefore, Saemankeum area could be evaluated to possibility area for eutrophication. Released rate for ammonia nitrogen and phosphate phosphorus from sediments were 62.92 ${\mu}g-at/m^3/hr$ and 6.71 ${\mu}g-at/m^3/hr$, respectively.

• Journal of Environmental Health Sciences
• /
• v.9 no.1
• /
• pp.49-62
• /
• 1983

Evaluation of water quality of Yeong San river and Seomjin river by using of newly simplified MBOD method was performed. Of course, thought that there is some differences between nutrient demands of heterotrophic bacteria and those of Algae which obtain it by photosynthesis, but it has little influence on evaluation of Algae Growth potential. The result of this study were as follows: 1) In both river, the value of Chemical analysis and MBOD method of inorganic salts reveals as nearly same result. 2) Though organic pollution of Seomjin river is less than that of Yeongsan but inorganic contamination is somewhat advanced BOD 2.8 ppm. and MBOD 340 ppm. in Seomjin river but BOD 22 ppm. and MBOD 480 ppm. in Yeongsan river. 3) Both river have tendency to reveal higher Nitrogen value is MBOD=MBOD -P