• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.14 no.4
• /
• pp.213-228
• /
• 2009

This study was conducted to investigate spatio-temporal changes in macrobenthic community structure and benthic environmental conditions in Geoje-Hansa Bay, which is the greatest oyster producing site in Korea. Field survey for benthic environment and macrobenthos was seasonally carried out at 15 stations covering oyster farming sites and non-farming sites from February to November, 2008. The grain size of surface sediments was dominated by very fine silt with the mean phi of about $9\;{\Phi}$ and TOC was 1.9% on average. Mean dissolved oxygen content was 8.1 mg/L and lowest in August corresponding to the 2nd degree in seawater quality criteria. Total species number was 351 and mean density was $3,675\;ind./m^2$, both of which were dominated by polychaete worms. Spatio-temporal variation in above two biological variables was great with higher values seasonally in spring and spatially in channels rather than inner bay. Dominant species were Lumbrineris longifolia (21.3%), Aphelochaeta monilaris (17.8%) and Ericthonius pugnax(6.1%), all of which are typical species of organically enriched area. From the multivariate analyses, the whole macrobenthic community was distinguished into two groups of channel and inner bay group. Spatio-temporal changes of macrobenthic community in Geoje-Hansan Bay were related to those of TOC and acid volatile sulfide (AVS). Our results showed that Geoje-Hansan Bay should be intermediately affected by organic pollution, and that such organic enrichment was more remarkable at farming stations in the inner bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.1
• /
• pp.33-39
• /
• 1999

In order to understand the importance of tidal action and $NH_4{^+}$ -nitrification in the removal of dissolved oxygen (DO) and $NH_4{^+}$, concentrations of DO, $NH_4{^+}$, $NO_2{^-}$ and $NO_3{^-}$ were measured with time for water samples collected at different tidal state in the eutrophic macrotidal Han River estuary. Field measurements indicated that most environmental parameters, except for the water temperature and DO concentration, were tightly controlled by the eutrophic freshwater runoff and large-scale tidal action. Dark incubation of the water sample at $25^{\circ}C$ showed that the removal rates of DO and $NH_4{^+}$ in high tide sample were 2.76 ${\mu}M\;O_2\;d^{-1}$ and 1.76 ${\mu}M\;N\;d^{-1}$ respectively, and increased to 5.66 ${\mu}M\;O_2\;d^{-1}$ and 3.36 ${\mu}M\;N\;d^{-1}$ respectively, in low tide sample. These changes indicated that microbial degradation and uptake of organic matter and inorganic nutrients were more active during low tide. $NH_4{^+}$-nitrification responsible for total DO removal in low tide (23.81%) and $NH_4{^+}$ turnover rates due to $NH_4{^+}$-nitrification in low tide (0.18 $d^{-1}$) were approximately 3.7 times and 3 times, respectively, higher than those in high tide. These results indicated that $NH_4{^+}$ -nitrifying bacteria introduced into the Han River estuary during low tide played a significant role in the removal of DO and $NH_4{^+}$. The decreasing removal rates in DO and $NH_4{^+}$ with the increasing tidal level seemed to be associated with the salinity impact on the halophobic freshwater $NH_4{^+}$-nitrifying bacteria. The results implied that anthropogenic $NH_4{^+}$ sources should be treated prior to the freshwater runoff into the estuary for the effective control of $NH_4{^+}$ in the Han River estuary. These results also suggest that parallel ecological studies on the chemoautotrophic nitrifying bacteria are essential for the elucidation of nitrogen cycles in the eutrophic Han River estuary.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.1
• /
• pp.67-82
• /
• 2008

This study was performed to investigate changes in benthic environment and macrobenthic polychaete communities in Gamak Bay where various environmental quality improvement projects have been implemented in recent years. Field surveys were carried out in February, 2005 and February, 2006 and twenty stations were selected to explore whether or not there were between-year differences in biotic and abiotic variables. Of 10 environmental variables measured, only three variables including dissolved oxygen (DO), total ignition loss (IL), acid volatile sulfide (AVS) showed significant between-year differences. Specifically, IL and AVS were, on average, 1.5 and 3 times lower in 2006 compared to those in 2005, respectively, which was more pronounced in the northern part of the bay. A total of 95 polychaete species was sampled from the two sampling occasions. Between-year differences in the number of species, abundance, and diversity were varied from place to place. In the northern part of the bay, fewer species were found in 2006 rather than in 2005, but diversity increased in 2006 due to the reduction in dominance of a few species. On the contrary, in the central part of the bay, the number of species, abundance and diversity prominently increased in 2006. In the southern part of the bay, all the biological indices maintained similarly during the two years. Dominant species in 2005 were such opportunistic or organic pollution indicator species as Lumbrineris longifolia, Capitella capitata, Mediomastus californiensis, Pseudopolydora paucibranchiata, etc. and most of them were mainly distributed in the northern part of the bay and in the proximity of it. In 2006, however, Euchone alicaudata, L. longifolia, Paraprionospio pinnata, Flabelligeridae sp., etc. were dominant and distributed mainly in the central part of the bay. Multivariate analyses showed that the whole polychaete community could be divided into 5 groups reflecting the geographical positions of the sampling stations and temporal variation particularly in the northern part of the bay. According to the results of BIO-ENV procedure, TOC (${\rho}=0.52$) and AVS (${\rho}=0.49$) as a single variable best explained the polychaete community structure. The best combination was made by such variables as TOC, AVS, sorting coefficient, and water temperature (${\rho}=0.60$). In conclusion, between-year differences in biotic and abiotic variables imply that recent efforts for the environmental improvement produced positive influences on the benthic environment of Gamak Bay, particularly the northern part of the bay.

• Korean Journal of Environmental Agriculture
• /
• v.17 no.1
• /
• pp.70-75
• /
• 1998

A model of pond system is developed for treatment and recycling of excreta from twenty-five adult dairy cattle. It is composed of wastewater treatment ponds and small fish ponds. Those are three facultative ponds in series; primary-secondary-tertiary pond and these are designed to rear carps without feeding. A pit is constructed at the bottom of primary pond for efficient sludge sedimentation and effective methane fermentation. It is contrived to block into it the penetration of oxygen dissolved in the upper layer of pond water. The excreta from the cattle housed in stalls are diluted by water used for clearing them. The washed excreta flow into the pit. The average yearly $BOD_5$ concentration of influent is 398.7mg/l. That of the effluent from primary, secondary and tertiary pond of the system is 49.18, 27.9, and 19.8.mg/l respectively. Approximate 88, 93, and 95 % of BOD5 are removed in each pond. The mean yearly SS concentration of influent is 360.5 mg/l That of the effluent from each pond is 53.4, 45.7, and32.7mg/l respectively. Approximate 86, 88, and 91% of SS are removed in each pond. The $BOD_5$ concentration of secondary and tertiary pond can satisfy 30mg/l secondary treatment standard. The SS concentration of effluent from tertiary pond, however, is slightly greater than the standard, which results from activities of carps growing in the pond. The average yearly total nitrogen concentration of influent is 206.8mg/l and that of the effluent from each pond is 48.6, 30.8, and 21.0mg/l respectively. Approximate 74, 88, and 90% of total nitrogen are removed in each pond. The mean yearly total phosphorous concentration of influent is 20.7mg/l and that of the effluent from each pond is 5.3, 3.2, and 2.1mg/l respectively. Approximate 97, 98, and 99% of total phosphorous are removed in each pond. The high removal of nitrogen and phosphorous results from active growth of algae in the upper layer of pond water. Important pond design parameters for southern part of Korea -- areal loading of BOD5, liquid depth, hydraulic detention time, free board, and pond arrangement -- are taken up.

• Korean Journal of Environmental Biology
• /
• v.27 no.2
• /
• pp.183-190
• /
• 2009

Characterization of the analysis of forest vegetation, soil environmental conditions and water quality were performed from March 2003 to March 2007. The two basins were characterized by cultivated area (Kaesim reservoir) and mountain area (Jangchan reservoir), and divided into eleven small basins, where dynamics of pollutants, forest vegetation and soil environmental conditions were surveyed. The vegetation can be divided into 10 types by $Z\ddot{u}rich$-Montpellier school's method. Pearson coefficients between vegetation type and water quality were correlated with dissolved oxygen (DO) in the Quercus variabilis community at the 5% level and total phosphorus (TP) in the Larix leptolepis plantation at the 1% level. Especially total phosphorous and total nitrogen increased in small basins where the proportion of cultivated and residential area increased. The analysis of influences of pollutant discharge on water quality showed that pollutant charge was very low in forest land area ($Y_{T-P}$=-0.0017X+0.2215, r=0.16, $Y_{COD}$=- 0.0395X+8.5051 r=0.47). The soil types of western area were comparatively simple, but those of eastern area were complicated with regosols, red-yellow soils, lithosoles, etc. The pH, total solid (TS) and volatile substance (VS) of the forest and agricultural land soils collected in each site were 5.4~6.9, 75.8~80.2%, and 3.80%~5.80%, respectively. According to the analytical result of soil environmental conditions, heavy metal contents fell short to the mean value of natural conditions. Runoff amount (Y) and depth of topsoil (X) were negatively correlated, $Y_{ron}=-1.0088X_{top}+35.378$ (r=0.68). The correlation was much lower in up-stream but much higher in down-stream, because permeation into soil particle was larger on down-stream due to its more or less gentle slope. Pearson coefficients between soil pH and water pH were statistically significant at 1% level.

• Korean Journal of Ecology and Environment
• /
• v.41 no.spc
• /
• pp.68-76
• /
• 2008

This study examined the inhibition effects of a freshwater bivalve (Unio douglasiae) and a submerged plant (Potamogeton crispus) on the cyanobacterial bloom (Oscillatoria sp.). The experiment were conducted in aquarium $(50cm{\times}65cm{\times}120cm)$ with lake sediments in the bottom of the aquarium in 10 cm thick. Before the experiments, artificial cyanobacterial bloom was induced with the addition of lake sediment and CB medium. Total 12 transparent acrylic cylinders (${\Phi}19cm$, height 40 cm) were placed in the aquarium, and within which bivalves and plants were placed in various conditions such as the control (C), plant addition (P:5 stems), mussel addition (U:2 individuals), and both mussel and plant addition (PU: the same quantity as used in each treatment). The experiment was conducted in triplicate during 7 days. pH, dissolved oxygen (DO), electric conductivity (EC), salinity, cyanobacterial cell density, chlorophyll-${\alpha}$ concentration, and mussel filtering rate were monitored daily. At the end of the experiment, total phosphorus (TP), total nitrogen (TN), and plant height and weight were measured. Overall, a large degree of cyanobacterial growth inhibition appeared in both P and U treatments, and the effect was highest in the U treatment, followed by P and PU. The combined treatment of both U and P did not show any synergic effects compared to the effect in separated treatment. In all enclosures of the treatments chlorophyll-${alpha}$ (Chl-${alpha}$) concentration decreased until 36 hours after the additions of the plants and mussels. In contrast, Chl-${alpha}$ concentrations increased in PU enclosures after 36 hours. The same trend was shown in the cell density of Oscillatoria. pH and DO gradually decreased until 120 and 144 hours, respectively, in the P and PU enclosures. TP concentration increased in the mussel enclosures (U and PU), while TN concentration largely decreased in the plant enclosures (P and PU). Our results suggest that applied bivalve (Unio) and submerged plant (Potamogeton) seemed to have a potential effect on the growth inhibition of cyanobacteria, but their combined application may have an antagonistic effect to diminish the degree of the inhibition.

• Korean Journal of Ecology and Environment
• /
• v.41 no.2
• /
• pp.206-215
• /
• 2008

Temporal and spatial distributions of salinity, temperature, dissolved oxygen (DO), and turbidity were investigated at seven sites in the upper regions of brackish Lake Sihwa with a limited water exchange, from March to October 2005. During the study period, salinity and temperature varied $0.1{\sim}29.9\;psu$ and $4.7{\sim}28.1^{\circ}C$, respectively, depending on seasons and sites sampled. A distinct halocline profile showing the maximum density gradient (difference over $20\;psu\;m^{-1}$ between surface and bottom layers) was observed during the rainy season, due to the decrease of salinity in surface layers by freshwater inflow. This result implies that rainfall event is the important factor forming the halocline. On the other hand, the depth and location of haloeline varied with the amount of seawater through the sluice gates and the operation systems (inflow or outflow). High DO (over 300% saturation) was observed at surface layer above the halocline in April when red tide occurred, whereas low DO (below 20% saturation) was at the bottom layer below the halocline in the rainy season. Turbidity ranged $1.5{\sim}80.3\;NTU$ showing the maximum turbidity at the layers above or upper the halocline. As a result, the distributions of DO and turbidity in the upper regions of brackish Lake Sihwa were largely affected by the variation of salinity. Also, when the halocline was formed, the water quality between upper and lower water layers may be expected completely different. This study suggests that the physicochemical characteristics of water in the brackish regions are closely associated with the causes of eutrophication such as red tide and DO deficit.

• Korean Journal of Ecology and Environment
• /
• v.39 no.2 s.116
• /
• pp.271-283
• /
• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Korean Journal of Ecology and Environment
• /
• v.43 no.1
• /
• pp.129-135
• /
• 2010

The relationship between rainfall variable and zooplankton dynamics was studied in the Upo wetland, an ecosystem of international importance. Water sampling was conducted on biweekly basis from January 2002 to December 2007 in the study site. The annual average of total rainfall was 1,324 mm during the study period. Total rainfall amount in 2003 (1,766 mm) was unusually high, while total rainfall amount in 2005 (975 mm) was exceptionally lower than the average. Most of basic limnological parameters (water temperature, dissolved oxygen, pH, conductivity and turbidity) in the study site were greatly influenced by the flooding events and rainfall amounts in summer. There were statistically significance between seasonal and inter-annual differences in zooplankton abundance and the total rainfall amount (ANOVA, P<0.05). Zooplankton abundance was high in summer (mean${\pm}$s.d.: $1,594{\pm}1,598\;Ind.\;L^{-1}$) and low in winter ($246{\pm}234\;Ind.\;L^{-1}$. The 47% of annual total zooplankton abundance in the study site were observed in summer. The seasonal pattern of rotifers was similar to that of total zooplankton. This reflected the fact that rotifers strongly dominated and occupied ca. 65% the total zooplankton abundance (annual mean: $398{\pm}1,139\;Ind.\;L^{-1}$, n=149), followed by cladocerans ($65{\pm}140\;Ind.\;L^{-1}$) and copepods ($58{\pm}84\;L^{-1}$). Planktonic rotifers such as Keratella cochlearis, Polyarthra spp. and Brachionus calyciflorus were dominant from winter to spring and attached rotifers such as Lecane spp., Monostyla spp. and Trichocerca spp., observed commonly from spring to fall. Among the environmental variables considered, rainfall in summer seemed to play the most important role in determining characteristics of zooplankton community dynamics in the Upo wetland.

• Journal of Aquaculture
• /
• v.21 no.3
• /
• pp.157-166
• /
• 2008

Species composition and standing crop of phytoplankton were investigated in the ark shell Scapharca broughtonii farming areas from March, 2006 to February, 2007 in Jinhae Bay. Water temperature ranged from 7.56 to $25.90^{\circ}C$, salinity from 13.74 to 34.78 psu, dissolved oxygen from 4.13 to 13.20 mg/L, chlorophyll $\alpha$ from 2.77 to 104.98 $mg/m^2$ and pH from 7.83 to 8.65. Dominant species was Nitzschia and Rhizosolenia from March to May, Skeletonama costatum and Prorocentrum from June to August, Skeletonama costatum, Thalassiosira, Chaetoceros from September to November and Thalassiosira, Chaetoceros from December to February. Colonial diatoms were more dominant than the single cell diatoms. Standing crop was the highest in July at three stations. Standing crop of Skeletonama costatum was the highest as 1,760.0 cells/mL at St. 1, 1,075.2 cells/mL at St. 2 and 698.4 cells/mL at St. 3 in July.