• Ocean and Polar Research
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• v.30 no.4
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• pp.509-518
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• 2008

Distribution of bacterial abundance and production was investigated in seawater around Saemangeum dike 7 times during March, $2007{\sim}July$, 2008. In the inner area of the dike, salinity variation was great due to river runoff from Mangyung and Dongjin Rivers and high chlorophyll a (chl a) concentrations up to $124.3{\mu}g\;l^{-1}$ was found. In the outer area of the dike, salinity was higher than in the inner area of the dike, and chl a was lower up to 10 times than in the inner area of the dike. Thus, the area of Saemangeum showed meso- to hypereutrophic conditions. Bacterial abundance and production ranged from 0.3 to $4.3{\times}10^9\;cells\;l^{-1}$ and from 5.2 to $570 pmol\;l^{-1}h^{-1}$ in outer area of the dike, respectively, while in the inner area of the dike bacterial abundance and production was 3 to 4 times higher ($0.4{\sim}12.7{\times}10^9\;cells\;l^{-1}$ and $12.3{\sim}1309\;pmol\;l^{-1}h^{-1}$, respectively) than those in the outer area. In both areas, bacterial abudance and production was highest in summer and lowest in winter. However, the variations of bacterial parameters was very large in each season. These large variations seemed to be related with the supply of organic matter. Bacterial abundance and production showed significant negative correlations with salinity in the inner area, suggesting that allochthonous organic matter input by river runoff could be an important factor in regulating the distribution of bacterial abundance and production. In addition, bacterial production also correlated positively with chl a in the inner area, suggesting that autochthonous substrate might be another regulating factor of bacterial growth in the area. These results suggest that the supply of both allochthonous organic substrates introduced by river runoff and autochthonous substrates produced by phytoplankon could be important in regulating bacterial growth and utilization of organic matter in the area. Thus, to manage water quality in the inner area of dike, it seems to be important to lower the load of both organic and inorganic nutrients from adjacent rivers.

• Korean Journal of Organic Agriculture
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• v.8 no.1
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• pp.101-109
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• 1999

In order to investigate the possibility of treating the different mixture ratios of apple pomace and nightsoil sludge by vermicomposting was performed and the stability of worm casts, and availability of worm casts as plant growth media was evaluated by the analysis of chemical composition. The results were obtained as follows ; 1. The value of cast production at 100% apple pomace treatment was higher than those of other mixture ratios of apple pomace and nightsoil sludge. 2. The highest values of increasing rate and reproductive efficiency were obtained at mixture ratios of 60% apple pomace with 40% nightsoil sludge. 3. The value of increasing rate at 100% nightsoil sludge treatment was lower that those of other mixture ratios of apple pomace and nightsoil sludge. 4. Organic matter, available inorganic nutrients and stability of worm casts showed high values in all treatments. It means that worm casts are an excellent plant growth media source with a high chemical composition and their stability.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.67-74
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• 2011

The objective of this study was to compare concentrations of nutrients such as total nitrogen (TN), nitrate nitrogen ($NO_3$-N) total phosphorous (TP), and phosphate phosphorous ($PO_4$-P) in groundwater under paddy and upland fields, and surface water recharging from a rural mixed land-use watershed. Chinese cabbage and hot pepper were cultivated on the upland field plot. The TN concentrations in upland groundwater showed double peaks (4.7, 4.3 mg/L, respectively) in April 2009 shortly after fertilizer application, indicating that TN concentrations are greatly influenced by fertilization. However, the TN concentrations in paddy groundwater were always lower than 2.0 mg/L irrespective of fertilization. Whereas the mean concentrations of TN and $NO_3$-N in upland groundwater significantly (p<0.05) higher than those in surface water, the mean concentrations of TP and $PO_4$-P in upland groundwater were significantly lower than those in surface water. On the other hand, the mean concentrations of TN, $NO_3$-N, TP and $PO_4$-P in paddy groudwater were significantly (p<0.05) lower than those in surface water. The TN concentrations in upland groundwater were generally higher than those in surface water during early April to early December due to the effect of fertilization, but vice versa in the other periods. In contrast, the TP concentrations in upland groundwater were always lower than those in surface water due to the sorption of inorganic phosphorous by soil. Moreover, the TN and TP concentrations in paddy groundwater were always lower than those in surface water, and therefore paddy groundwater may dilute nutrient concentrations in surface water when paddy groundwater and surface water mix.

• Ocean and Polar Research
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• v.30 no.3
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• pp.335-345
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• 2008

In order to study spatial variabilities and major controlling factors, we measured fugacity of $CO_2(fCO_2)$, temperature, salinity and nutrients in surface waters of the North Pacific($7^{\circ}30'{\sim}33^{\circ}15'N$, $123^{\circ}56'E{\sim}164^{\circ}24'W$) between September$\sim$October 2007. The North Pacific and the marginal sea were distinguished by $fCO_2$ distribution as well as unique characteristics of temperature and salinity. There was a distinct diurnal SST variation in the tropical North Pacific area, and surface $fCO_2$ coincidently showed diurnal variation. In the North Pacific area, surface $fCO_2$ was mainly controlled by temperature, while in the marginal sea area it was primarily dependent on alkalinity and dissolved inorganic carbon concentrations. Air-sea $CO_2$ flux showed a large spatial variation, with a range of $-6.10{\sim}5.06\;mmol\;m^{-2}day^{-1}$. The center of subtropical gyre of North Pacific acted as a source of $CO_2(3.09{\pm}0.95\;mmol\;m^{-2}day^{-1})$. Tropical western North Pacific (i.e. the 'warm pool' area and the subtropical western North Pacific) acted as weak sources of $CO_2$($1.07{\pm}1.20\;mmol\;m^{-2}day^{-1}$ and $0.50{\pm}0.53\;mmol\;m^{-2}day^{-1}$, respectively). In the marginal sea, however, the flux was estimated to be $-0.68{\pm}1.17\;mmol\;m^{-2}day^{-1}$, indicating that this area acted as a sink for $CO_2$.

• Ocean and Polar Research
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• v.36 no.4
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• pp.423-435
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• 2014

Verifying the similarity of environmental characteristics between an artificial impact site and a preserved or reference site is necessary to quantitatively and qualitatively evaluate the environmental impact of mining activity. Although an impact site (BIS station) and a preserved site (called KOMO station) that have been selected in the Korea manganese nodule contract area may share similar environmental characteristics, similarities in terms of the water column environment between both sites has not been investigated. In this study, we compared the chemical properties of the water columns and sinking particle fluxes between BIS and KOMO stations through two observations (August 2011 and September 2012). Additionally, we observed particle fluxes at the KOMO station for five years (July 2003~July 2008) to understand long-term natural variability. Vertical distributions of water column properties such as dissolved oxygen, inorganic nutrients (N, P, Si), total organic carbon below surface layer (within the depth range of 200 m) were not considerably different between the two sites. Especially, values of water column parameters in the abyssopelagic zone from 4000 m to bottom layer (~5000 m) were very similar between the BIS and KOMO sites. Sinking particle fluxes from the two sites also showed similar seasonality. However, natural variation of particle flux at the KOMO site varied from 3.5 to $129.9mg\;m^{-2}day^{-1}$, with a distinct temporal variation originating from ENSO events (almost forty times higher than a minimum value). These results could provide valuable information to more exactly evaluate the environmental impact of mining activity on water columns.

• Journal of Microbiology and Biotechnology
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• v.20 no.9
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• pp.1276-1282
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• 2010

In traditional mixotrophic cultures of microalgae, all the inorganic nutrients and organic carbon sources are supplied in the medium before inoculation. In this study, however, an alternative approach was adopted in Haematococcus pluvialis Flotow, a microalga capable of growing mixotrophically on sodium acetate (Na-Ac). First, the cells were grown under 75 ${\mu}Mol$ photons $m^{-2}s^{-1}$ phototrophically without Na-Ac until the stationary phase and then exposed to five different light regimes by the addition of Na-Ac (e.g., dark, 20, 40, 75, and 150 ${\mu}Mol$ photons $m^{-2}s^{-1}$). Dry weight (DW), pigments, and especially cell number in alternative mixotrophy (AM) were higher than traditional mixotrophy (TM). Cell number in AM almost doubled up from 21.7 to $42.9{\times}10^4$ cells/ml during 5-day exposure to Na-Ac, whereas the increase was only 1.2-fold in TM. Maximum cell density was reached in 75 ${\mu}Mol$ photons $m^{-2}s^{-1}$ among the light intensities tested. We propose that Na-Ac in TM of H. pluvialis can not be utilized as efficiently as in AM. With this respect, AM has several advantages against TM such as a much higher cell density in a batch culture period and minimized risk of contamination owing to the shorter exposure of cells to organic carbon sources. In consequence, this method may be used for other strains of the species, and even for the other microalgal species able to grow mixotrophically.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.518-524
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• 2010

Continuous removal of organic matters (CROM) using freshwater bivalve Anodonta woodiana was operated to evaluate the effect of water current on the water quality improvement (clearance) of eutrophic lake. The CROM system comprised three treatment steps such as flow control, treatment and analysis, and operated at the two different currents ($24L\;h^{-1}$ and $48L\;h^{-1}$) with mussels at density of $312.5indiv.\;m^{-2}$ for 12 consecutive days. Water quality including suspended solids (SS) and chlorophyll-a (Chl-a) was daily measured at the same time. Results indicate that although both the system strongly decreased the concentration of SS and chl-a, a slow CROM system was more effective to diminish the SS contents than a fast CROM system; 82% and 66%, respectively (ANOVA, P<0.0001). Clearance rates, based on chl-a, were also significantly higher in a slow system than a fast system (ANOVA, P<0.0001), although the mussel mortality was conversely. In both systems, there showed a remarkable excretion of dissolved inorganic nutrients (i.e. $NH_3-N$ and $PO_4-P$), while a slow CROM system was higher than a fast system, significantly (ANOVA, P<0.0001). Therefore, it may suggest that a slow current CROM system is more suitable to maximize the efficacy of water quality improvement, but further study is needed to diminish the mortality of mussel and to reuse the nutrient released during the operation.

• The Korean Journal of Ecology
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• v.4 no.1_2
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• pp.25-32
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• 1981

During the period of 1975∼77, a survey and an investigation were carried out to estimate the frequency of lime-chlorosis in the natural vegetation in Korea and the relationships between plants and calcareous soils. The symptoms of lime-chlorosis were observed in flowering plants in the calcareous areas of Weonju (I, II), Yeongweol(I, II), Jecheon, Danyang and Samcheok. Although the species found to be lime-chlorotic on at least one occasion numbered 60, the total quantity of lime-chlorotic foliage observed was small. Severe lime-chlorosis of Capsicuym annuum in agricultural fields was found out at Danyang. However, some of the species which were of widespread occurrence in affected areas showed no lime-chlorosis. The comparison of the inorganic components in calcareous soils in lime-chlorotic and normal leaves showed that the essential mineral nutrients substantially less soluble in water in alkaline than in acid conditions and calcifuges planted on calcareous soils often show visual signs resembling those of P or Fe deficiency.

• 한국해양학회지
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• v.25 no.1
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• pp.1-7
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• 1990

Seawater temperature, salinity, inorganic nutrients and the standing crop of phytoplankton species of the 841 water samples from the upper 125 m at 15-40 stations on the 6 semiannual cruises in the southwestern waters of the East Sea (Korea) were studied during the period from September, 1981 to October, 1984, Among the 235 taxa identified two pennate diatioms, cylindrotheca closterium and Nitzschia delicatissima, were the most common and dominant species. The multiple regression analyses between net phytoplankton abundance (dependent variable) and associated environmental factors(independent variables) were applied to the samples from the surface mixed-layer. In spring the coefficients for the seawater temperature was 1. to 4.2 times greater than those for salinity, while the coefficients for the salinity was 2.1 to 3.4 times greater than those for seawater temperature in autumn. Distribution seawater temperature in spring, and salinity in autumn. Schematically the zone of high standing crops moved about on the T-S diagram in a cyclic manner. The distribution of phytoplankton standing crop was quite closely associated with the hydrographic conditions among various kinds of environmental factors studied.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.630-635
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• 2000

Previous research has not evaluated the effects of various rates and frequencies of manure application and frequencies of cutting on yield and stand persistence of cool-season grasses and alfalfa-grass mixtures. The primary objective of this study was to compare the effects of cutting management systems on herbage yield and stand persistence of orchardgrass (Dactylis glomerata L.) and an alfalfa (Medicago sativa L.)-orchardgrass mixture from various rates and frequencies of dairy slurry application. A randomized complete block design with treatments in a sub-subplot arrangement with four replicates was used. The main plot consisted of 2 cutting management systems (4 and 5 annual cuttings). The subplots were 9 fertility treatments: 7 slurry rate and frequency of application treatments, one inorganic fertilizer treatment, and an unfertilized control. The split-split-plots were the two forage species: orchardgrass and alfalfa-orchardgrass mixture. The study was initiated after 1st cutting in 1995. Cumulative yields of the 2nd and subsequent cuttings of both orchardgrass and alfalfa-orchardgrass in 1995 were higher for the 5-cutting system than the 4-cutting system. The 1995 growing season was abnormally dry. In 1996, an abnormally wet year, the reverse was true, total herbage yields being higher for the 4-cutting system than the 5-cutting system. Species response to fertility rate/frequency treatments was different in both years. Higher application rates early in the season and carryover of nutrients from late season applications the previous year appear to be responsible for the yield increases of those fertility treatments having significant yield differences between the cutting management systems. The stand ratings of orchardgrass were not affected by cutting management. In the spring of 1997, however, the stand ratings of alfalfa-orchardgrass in the 4-cutting management system were significantly greater than the 5-cutting management system. The very high manure application rate significantly reduced the stand ratings of alfalfa-orchardgrass in the 5-cutting system.