• 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.

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

• Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.30-37
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• 2006

We performed experiments on the uptake and excretion of dissolved organic phosphorus (DOP) using two toxic dinoflagellates, Alexandrium tamarense Lebour (Balech) and Gymnodinium catenatum Graham, isolated from Hiroshima Bay, Japan. ATP (adenosine triphosphate), UMP (uridine-5-monophosphate), G-6-P (glucose-6-phosphate) and Glycero-P (glycerophosphate) were used as DOP sources in preliminary uptake experiments. ATP was selected as the DOP species for the short-tenn uptake experiment because preliminary experiments showed it to be the DOP source used by both species. Although the $K_s$ values of A. tamarense and G. catenatum (5.63 and $7.61{\mu}M$, respectively) obtained from the short-term experiments for ATP were only slightly higher than those reported for dissolved inorganic phosphorus (DIP), the ${\rho}_{max}$ values (5.04 pmol/cell/h and 13.4 pmol/cell/h, respectively) were much higher. The DOP excretion rate in batch-culture experiments was estimated at 0.084 pmol/cell/h for A. tamarense and 0.012 pmol/cell/h for G. catenatum, accounting for about 30% and 25%, respectively, of the assimilated phosphorus. Our results suggest that the DIP-depleted conditions of Hiroshima Bay favor these two species by supporting their ability to use DOP.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.16-24
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• 2010

Utilization of dissolved organic phosphorus (DOP) and alkaline phosphatase (APase) activity by Skeletonema costatum, Chaetoceros didymus, Alexandrium tamarense and Heterosigma akashiwo under the phosphorus deficient condition were examined in the laboratory. S. costatum, C. didymus, A. tamarense and H. akashiwo could make use of phosphomonoester and nucleotide compounds for the growth of them as a phosphorus source. APase activity of S. costatum, C. didymus, A. tamarense and H. akashiwo began to be activated at dissolved inorganic phosphorus (DIP) concentrations less than $0.30\;{\mu}M$, $0.33\;{\mu}M$, $2.04\;{\mu}M$ and $0.63\;{\mu}M$ respectively, and their maximum APase activity were $0.01\;pmol\;cell^{-1}\;hr^{-1}$, $0.11\;pmol\;cell^{-1}\;hr^{-1}$, $1.63\;pmol\;cell^{-1}\;hr^{-1}$ and $0.19\;pmol\;cell^{-1}\;hr^{-1}$, respectively. Although each phytoplankton species displayed different APase activity for DOP utilization, their maximum APase activities were higher than maximum phosphorus uptake rates, inferring that these species might be able to keep growing under DIP-limited conditions thought utilizing effectively the hydrolized product of DOP. This result also implies that utilization of DOP might contribute to not only the growth of red tide forming phytoplankton but also the interspecific competition among phytoplankton species in coastal environments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.4
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• pp.232-242
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• 2014

We investigated the interspecific competition between the harmful dinoflagellate Cochlodinium polykrikoides and diatom Skeletonema sp. based on the utilization and uptake of dissolved organic nutrients. C. polykrikoides and S. costatum were able to grow using dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) as well as dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). This result indicates that the utilization of dissolved organic nutrients may play a role in surviving strategy in the DIN or DIP-limited environments. The half-saturation constants (Ks) of urea and glycerophosphate (glycero-P) calculated from uptake kinetics experiment of C. polykrikoides was lower than those of Skeletonema sp. This result indicates that Skeletonema sp. have higher affinity for dissolved organic nutrients, such as urea and glycero-P, than C. polykrikoides. Although Skeletonema sp. have higher affinity of dissolved organic nutrients, C. polykrikoides could effectively uptake for urea and glycero-P at sub-saturating nutrient concentrations (${\alpha}$ (${\rho}_{max}/Ks$) of C. polykrikoides was higher than Skeletonema sp.. Therefore, C. polykrikoides by utilization and effectively uptake of dissolved organic nutrients under monoculture may have an advantageous position in the interspecific competition with Skeletonema sp. in the low nutrient environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.540-546
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• 2010

We investigated variations in alkaline phosphatase (APase) activity and alkaline phosphatase hydrolyzable phosphorus (APHP) in northern Gamak Bay from September to December 2009. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) decreased gradually, and the DIN/DIP ratio was higher than the Redfield ratio (16) based on molecular concentrations during most of the observation period. The total APase (T-APase) activity increased with decreasing DIP concentration; i.e., the Relationship between T-APase and DIP showed a high negative correlation (r=-0.80, P<0.001), with APase activity being a good indicator of DIP limiting the Redfield ratio. The T-APase was positively correlated with the concentration of chlorophyll a (r=0.73, P<0.001). This suggests that a major portion of APase activity in northen Gamak Bay seawater is attributed to phytoplankton. The proportion of APHP among dissolved organic phosphorus (DOP) was low in September and high in November. Thus, APase-producing phytoplankton may be able to grow by utilizing APHP as a phosphorus source in autumn when DIP is limiting. Thus, APase activity and the use of DOP by phytoplankton may play an important role in the growth of phytoplankton under DIP limiting conditions such as those of northern Gamak Bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.39-49
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• 2007

Species competition among the toxic dinoflagellates Alexandrium tamarense and Gymnodinium catenatum and the diatom Skeletonema costatum was simulated using a mathematical model. Prior to the model simulation competition experiments using the three species were conducted to obtain data for validation by the simulation model. S. costatum dominated at a density of ${\sim}10^{4}\;cells/mL$ compared to the other species in the medium with dissolved inorganic phosphorus (DIP). The growth of S. costatum was also stimulated by the addition of dissolved organic phosphorus (DOP), such as uridine-5-monophosphate (UMP) or glycerophosphate (Glycero-P), although this species is unable to take up DOP. This implies that the growth of S. costatum may be supported by DIP, which is hydrolyzed by alkaline phosphatase produced from A. tamarense and G. catenatum. The species competition model was run assuming the environmental conditions of northern Hiroshima Bay, Japan, during spring and summer. G. catenatum increased in cell density and neared the level of S. costatum at the end of the calculation. In the sensitivity analyses by means of doubling and halving parameters, depleted DIP had little effect on the cell density of G. catenatum. However the growth of A. tamarense and S. costatum was significantly affected by changes in the parameter values. These results indicate that if DIP depletion is ongoing, species that have a large phosphate pool in their cells, such as G. catenatum, will predominate in the community.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.629-635
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• 2012

This study was conducted to evaluate the removal behaviors of DOM(dissolved organic matter) and phosphorus in eutrophic lake water by coagulation process with PAC(powdered activated carbon). It was observed that the removal characteristic of soluble matter was different from that of dissolved one, and the removal of DOM was effected by both pH and coagulant dosage. It was founded that PAC could increase the removal efficiency by an adsorption of DOM in coagulation process. A formation of soluble and colloidal matters resulted in the degradation of phosphorus removal efficiency in a chemical precipitation process. The phosphorus removal efficiency could be enhanced by an absorption of colloidal matter and dissolved complex with PAC addition. In addition, the PAC addition caused the increase of floc density in coagulation process, that led to the rise of sedimentation rate, and resulted in a significant improvement of solid-liquid separation efficiency.

• 한국해양학회지
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• v.25 no.3
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• pp.145-150
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• 1990

An analysis of collected data on components of dissolved organic phosphorus (DOP) and DOP is made to search for important components of DOP pool and their implications in phosphorus (P) cycling. The significance of dissolved nucleic acids (D-NA) apparently tends to increase with increasing trophic status of oceanic waters. Interestingly the sum of all 5-nucleotide and D-NA seems to dominate the DOP pool. Thus, materialization of D-NA could be a significant pathway of P cycling in surface oceanic waters and it might be of great importance in lakes where P limits primary production. Processes related to death of Microbes are responsible for D-NA and DOP production in surface waters, and incomplete digestion of preys by grazers seems to be an important mechanism in D-NA production.

• Membrane and Water Treatment
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• v.9 no.3
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• pp.181-188
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• 2018

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high $Ca^{2+}$ release compared to other slags, was used to remove $PO_4-P$ from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm) and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color and aromatic organic matter ($UV_{254}$) were 17.6, 41.7, 90.2 and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from $1.64{\times}10^8cells/mL$ to $1.05{\times}10^8cells/mL$. The use of LF slag was effective for the removal of phosphate and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.