• The Korean Journal of Ecology
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• v.28 no.2
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• pp.93-98
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• 2005

The effects of the presence of a submerged plant, Zizania latifolia, on physico-chemical characteristics, including Eh, pH, and concentrations of nitrogen and phosphorus in the sediments were studied under pot culture condition. It was shown that Eh value at reduced layer of the sediments was higher in the planted pots than in the non-planted. It was also revealed that $NH_4^+-N$ concentration of the sediments in the planted pots was lower than that of the non-planted, which might be due to the uptake by the plants. In contrast, $NO_3^--N$ concentration in the sediment increased in the presence of the plants compared to the non-planted, which might be attributed to oxygen released from the roots to the reduced layer. The concentration of organic phosphorus in the sediments was much higher than that of NAIP at the beginning of the planting experiment. However, at the end of the experiment, it was reversed; NAIP concentration was much higher than that of organic phosphorus, possibly indicating the transformation of organic phosphorus to NAIP during the experimental period. Both concentrations of $NH_4^+-N$ and $PO_4^{3-}-P$ in the overlying and percolated water were lower in the planted pots than in the non-planted. The concentration of $NO_3^--N$ in the percolated water, however, was higher in the planted pots than in the non-planted. The data was discussed with regard to the potential effects of a submerged plant on dynamics of phosphorus and nitrogen in the rhizosphere of the sediment.

• 한국환경농학회:학술대회논문집
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• 2011.07a
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• pp.174-176
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• 2011

• 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.

• Ecology and Resilient Infrastructure
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• v.5 no.1
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• pp.11-18
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• 2018

Phosphorous remains as one of the most limiting nutrients to plant growth, second only to nitrogen. Research on use of biochar as a soil amendment for available phosphorus in temperate calcareous soils has limited studies compared with to tropical acidic soils. An incubation experiment to assess phosphorous availability in a biochar amended calcareous soil under inorganic (Fused superphosphate, FSP) and organic fertilizer (bone meal, BM) and respectively, at the dose of 40, 80 and $120mg\;P\;kg^{-1}$ was carried out. Soil was incubated at $25^{\circ}C$ for 70 days. Results show that the rate of increase in available P was proportional to the fertilizer application rate with or without biochar amendment. Biochar did not have a significant effect on soils amended with either fertilizeron the values of available P. However, time had a significant effect (p<0.001) on the amount of available P during the incubation period. Inorganic fertilizer treatments had recorded high amount of available P with time compared to organic fertilizer treatments. Organic fertilizer treatment sample were significantly not different from control and for most of the incubation time biochar acted as a soil conditioner. Further research is required to understand the holistic and long-term effect of biochar.

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.108-116
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• 2001

It is difficult to task to achieve high biological nutrient removal from municipal wastewater because of low organic content. Volatile fatty acids(VFAs) produced from acid fermentation of food wastes can be utilized as external carbon sources for the biological nutrient process. Significant reduction and stabilization of the food wastes can also be obtained from the acid fermentation. The objective of this study is to evaluate characteristics of acid fermentation of the food wastes. Results obtained from the batch experiment of various organic wastes showed that the food wastes had high potential to be used as an external carbon source because of the largest production of the VFAs with low nitrogen and phosphorus content. The fish waste was found to be the next possible organic waste, while the others such as radish cabbage and molasses waste showed high VFAs consumption potential as a results of high nitrogen and phosphorus content. alkaline hydrolysis of the food waste was carried out using NaOH prior to the acid fermentation. As the alkali addition increased, solubilization of the organics as well as TSS reduction increased. However, fraction of soluble COD to total COD became stable after a sharp increase. Alkali addition greater than 0.5g NaOH per g TS resulted in significant increase in pH.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.2
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• pp.125-131
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• 2003

This study was carried out to develop INSUB(Indirected Aerated Submerged Biofilter) which can remove organics, nitrogen and phosphorus with an advanced treatment system. The results were as followed in laboratory model experiment. As for treatment of sewage, when economical efficiency was considered in practice, the highest removal efficiency was at 18hr of HRT, 1.017m/hr of superficial velocity and 40% of media packing ratio. Each removal efficiency for $COD_{cr}$, $COD_{Mn}$, $BOD_5$, T-N, and T-P was 90.6, 85.3, 95.0, 52.3 and 56.8%. To remove the nitrogen and phosphorus With high efficiency, first of all, denitrification have to be completed, then uptake of phosphorus have to completed. Therefor, mixture of anoxic and aerobic reactor was necessary for the high removal efficiency of nitrogen and phosphorus in INSUB.

• Journal of Applied Biological Chemistry
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• v.54 no.3
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• pp.225-229
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• 2011

This research was carried out to elucidate the impacts of dissolved oxygen (DO) concentration to phosphorus release mechanism from soil into water in lakes. $PO_4-P$ contributed to the growth of the total phosphorus (T-P). $PO_4-P$ was steadily increasing because water was accumulating $PO_4-P$. T-P was closely related to turbidity, pH, and DO. We found that DO had decreased because DO was consumed in organic matter decomposition, and that the resulting anaerobic decomposition occurred whenever water had run out of DO. We also found that pH had decreased sharply by production of organic acid by the anaerobic decomposition and that T-P decreased because a decrease in pH removed turbidity by precipitation. T-P was dissolved without microbial decomposition. This mechanism was of great importance in lakes because phosphorus is released from soil into water.

• Journal of Korean Society on Water Environment
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• v.34 no.5
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• pp.470-486
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• 2018

This study is to investigate the allochthonous load and water quality of a typical river-reservoir, Paldang during spring (March ~ May) of 17 years (2001 ~ 2017). Phosphorus loading from point sources seems to have been reduced by 74 % in the 2010s. As a result, trophic state of the Paldang reservoir, eutrophic during the 2000s, has returned to the lmesotrophic state. Along with decrease in phosphorus concentration, standing crops of algae (Chl.a) decreased, and concentration of biodegradable organic material decreased to the past level. Concentration of total suspended solids has decreased, and it is due to the decrease of phytoplankton standing crops since the mid-2000s. As transparency increased, it is estimated that euphotic area increased by 22 % and euphotic capacity expanded by 27 %. In the river/transition zone of Paldang, concentration of organic matter increases slightly due to algal growth, but concentration of all water quality items decreases in the lacustrine zone. Although algal growth rate revealed positive correlation with concentration of phosphorus, it was insignificant. Algal growth appeared to be dependent on renewal of phosphorus by flow, than either flow rate or phosphorus concentration. The empirical model including inflow phytoplankton concentration fit well with observed values, and indicates the Paldang reservoir is greatly influenced by allochthonous loads.

• Journal of Korean Society on Water Environment
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• v.35 no.2
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• pp.165-180
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• 2019

Water quality data of 81 lakes in Korea, 2013 ~ 2017 were analyzed. Most water quality parameters showed left-skewed distribution, while dissolved oxygen showed normal distribution. pH and dissolved oxygen showed a positive correlation with organic matter and nutrients, which appeared to be a nonsense correlation mediated by the algae. The ratio of $BOD_5$ and $COD_{Mn}$ to CBOD was 21 % and 52 % in the freshwater lakes, respectively. TOC concentration appeared to be underestimated by the UV digestion method, when salinity exceeds $700{\mu}S\;cm^{-1}$. In terms of nitrogen/phosphorus ratio, the limiting factor for algal growth seemed to be phosphorus in most of the lakes. Chlorophyll ${\alpha}$ increased acutely with decrease of N/P ratio. However, it seemed to be a nonsense correlation mediated by phosphorus concentration, since the N/P ratio depended on phosphorus. The N/P ratio of brackish lakes was lower than that of the freshwater, at the same concentration of phosphorus. It is worth examining denitrification that occurs, in bottom layer and sediment, during saline stratification. $Chl.{\alpha}$ concentration decreased in the form of a power function with increase of mean depth. The primary reason is that deep lakes are mainly at the less-disturbed upstream. However, it is necessary to investigate the effect of sediment, on water quality in shallow lakes. Light attenuation in the upper layer, was dominated by tripton (non-algal suspended solids) absorption/scattering (average relative contribution of 39 %), followed by CDOM (colored dissolved organic matter) (average 37 %) and $Chl.{\alpha}$ (average 21 %).

• Journal of Industrial Technology
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• v.23 no.A
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• pp.193-197
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• 2003

This bench-scale research investigated the aeration cycle(on/off) as the controlling factors for nitrogen and phosphorus removal in a 2-stage, intermittent aeration process. At this experiment, the aeration cycle time(air-on/air-off) was 30min/30min, 60min/60min, 90min/90min. Organic matter removal was observed more than 90% regardless of the aeration cycle and phosphorus removal was relatively high when the aeration cycle time was 60min/60min On the other hand. For all of the aeration cycle, TN removal was appeared less than 55%. This result was probably due to the limitation of the external substrate for heterotrophic nitrification and aerobic denitrification.