• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.520-529
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• 2012

Geographic distribution and species composition of phytoplankton were investigated in Jinhae Bay for 12 months. Total 158 species were found including 95 bacillariophyceae, 58 dinophyceae, 1 euglenoids, and 4 dictyochaceae. The total cell numbers of phytoplakton ranged from $4.0{\times}10^3{\sim}9.0{\times}10^7\;cells{\cdot}L^{-1}$. Highest and lowest amounts of cells were found in July (Chl.a 13.19 $mg{\cdot}m^{-3}$) and March(Chl.a 3.44 $mg{\cdot}m^{-3}$), respectively. Leptocylindrus danicus and Pseudo-nitzschia spp. were dominant in spring, and Dactliosolen fragilissimus and Pseudo-nitzschia spp. were dominant in summer. Chaetoceros spp. and Skeletonema spp. were domonant in autumn and winter. The amounts of nitrogen and phosphorus were also measured during the survey. Higher ratio of nitrogen (DIN : DIP = 28 : 1) was found in the east Jinhae Bay compared to the ratio of the west Jnhae Bay that showed 14 : 1 of N : P ratio. The total amounts of nitrogen, phosphorus and Chl.a were also higher in the east Jinhae Bay compared to the west area. The geographic differences between the east and west of Jinhae Bay were also discussed along with phytoplankton compostion.

• The Korean Journal of Malacology
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• v.32 no.3
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• pp.203-209
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• 2016

Growth and survival of the hard shelled mussel spat were investigated to confirm the possibe spat culture in seawater pond from September 2014 to April 2015. Also, we measured simultaneously environmental factors including water temperature, salinity, dissolved oxygen, pH, DIN, DIP, chlorophyll a, and abundance and dominant species of phytoplankton in seawater pond every month. Ranges of water temperature and salinity were $4.0-23.4^{\circ}C$ and 18.8-25.2 psu, respectively, which were rather lower than the reported optimal level. Monthly measured survival rates in all the spat cages were over 90%. Concentration of chlorophyll-a and abundance of phytoplankton were very high, and dominant species phytoplankton were cryptomonads and nanoflagellates. These dominant species were considered to be good food organisms for the bivalve spat. The experimental cage stocked 100 individuals per basket ($2,700ind.\;m^{-2}$) hanging in bottom of seawater pond revealed the highest growth in shell height ($7.63{\pm}4.65mm$), but all experimental cages stocked below 200 individuals per basket ($5,400ind.\;m^{-2}$) did not show statistically significant difference. We may expect that seawater pond would be one of the best culture ground for bivalve spats when appropriate measures are available.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.76-83
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• 2017

In order to investigate the characteristics of water quality and heavy metals in Shihwa Lake, concentration comparisons according to land use types and mass discharge through streams were carried out. Based on classification for streams according to land use types, the concentration of DO, SS, POC, $NO_3$ and Chl-a showed higher concentrations in agricultural areas than in industrial and urban areas. However, COD, DIN, DIP, TN, TP, DOC, TOC and heavy metal concentrations showed relatively high values in industrial areas. The concentrations of water qualities and heavy metals were relatively high in March to May and the concentration decreased in summer seasons (July-August). The averages of stream discharges of water qualities were 1,172 kg/d for SS, 151 kg/d for TN, 11.1 kg/d for TP and 389 kg/d for TOC, respectively. The agricultural area, Jangjunbo(S8), accounted for 47.5%(TP)~75.1%(SS) in the total stream discharges. Cu, Zn and Cd in stream waters were found to be more than 92% of the total discharges in industrial area, showing descending order of Zn>Cu>Ni>Pb>Co>Cd.

• Ocean and Polar Research
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• v.28 no.2
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• pp.95-105
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• 2006

To clarify the seasonal changes of the phytoplankton community in seagrass beds, the abundance and distribution of phytoplankton, and environmental factors were measured in seagrass beds: in the Dongdae Bay and Aenggang Bay on the southern coast of Korea, and off Seungbong Island on the western coast of Korea, in October 2002, January, March, and June 2003. Water temperature, salinity, SPM, chlorophyll a, aboveground biomass of seagrass, DIN and DIP concentrations significantly changed within the sampling time. The taxa of phytoplankton observed in seagrass beds were classified as 3 divisions, 3 classes,4 orders,16 families, 27 genera, 65 species. 50 species of diatoms were recognized with 14 species of dinoflagellates, and 1 species of silicoflagellate. The species of genera Coscinodiscus and Thalassiosira were dominant all around the study areas but Peridinium granii, Eucampia zodiacus and Pleurosigma elongatum were seasonally dominant. Phytoplankton standing crops varied from minimum of $0.6{\times}10^3\;cells\;l^{-1}$ (June, Dongdae Bay) to maximum$21.1{\times}10^3\;cells\;l^{-1}$(March, Aenggang Bay). The standing crops and species composition of phytoplankton were relatively lower and simpler than those of other southern and western coastal areas. Seasonal variations of diatom standing crops in seagrass beds were attributed to seasonal changes in DIN and in DIP of water column.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.723-730
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• 2016

Domestic Manila clam production has been reduced due to coastline changes and environmental degradation, but aquaculture industry is facing difficulties caused by an increase in imports. It is important to recognize the integral habitat environment in order to do sustainable aquaculture. The habitat environment of Manila clams (Ruditapes philippinarum) is closely related to the productivity of aquaculture farms. This study investigated 3 indexes, survival (sediment type, hydrodynamic), growth (Chlorophyll a, DIN, DIP) and environment (water temperature, dissolved oxygen, sediment chemical oxygen demand, ignition loss) as indicators of habitat characteristics for a tidal flat farm in Geunso Bay (Pado and Beopsan) from June 2015 to May 2016. As a result, Pado (maximums.; sand 48.76 %, hydrodynamic 10.59 cm/s, Chlorophyll a 12.70 ug/L, exposure time 3 hours, DO 18.65 mg/L) had a higher sand content, faster current speed, more abundant nutrients and DO, providing more favorable conditions for Manila clams than Beopsan (maximums.; sand 37.40 %, hydrodynamic 6.02 cm/s, Chlorophyll a 6.41 ug/L, exposure time 7 hour, DO 14.81 mg/L). In fact, Pado showed a higher density than Beopsan. This study considered the habitat environments of Pado and Beopsan to provide a basis for optimal management practices and potential suitable sites in Geunso bay.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.293-301
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• 2005

We conducted several different leaching experiments for assessing the potential environmental risk when utilizing recycled concrete for stabilizing bridge pier. The methods include continuous batch leaching test (DIN 38414-S4), availability test (NEN 7341), pH-stat test (CEN/TC 292/WG6) and tank diffusion test (NEN 7345). The concentration ranges vary depending on the testing method. Nearly all the trace elements were low, some elements recording under detection limit. The maximum concentrations for trace elements leached throughout the whole tests are (as mg/L); Cd (0.029), Cu (0.437), Pb (0.14), Ni, Zn (0.95), Hg (0.005). Although the testing methods we used in this study are much more rigorous than other commonly adapted method including TCLP and domestic testing method for solid waste, the trace elemental concentrations are under the criteria for hazardous material set by the TCLP and domestic method. The result seems to suggest that applying the recycled concrete on stream water will be accepatable practice as for as trace elements are concerned. However, the influence of inorganics such as Ca, Mg, Ni and $SO_4^{2-}$ on aquatic ecology should be further examined.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.1
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• pp.1-10
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• 2011

To understand characteristics of the water quality on the coastal boundary on tidal flat, field observations between 2008 and 2009 were undertaken twice a month at five coastal areas (Muan bay, Tando bay, Hampyeong bay, Shinan Jido and Yeongkwang coastal areas). Yearly water temperature difference was large with the range between $1.3^{\circ}C$ and $31.1^{\circ}C$. Salinity was about 32 but was the lower less than 20 for the heavy rainfall season. DO was high in winter and low in summer according to the variation of water temperature. pH represented the variation similar to DO. Suspended solid was averagely high over 100 mg/l in Yeongkwang coastal area, especially. COD did not revealed large variation with the value of about 1 mg/l. DIN and DIP concentration were high when freshwater was highly input in summer. DIN concentration was low for winter and early spring but DIP concentration did not show the seasonal variation with the continuous increase from July 2009 to December 2009. Chlorophyll a appeared high for spring with approximately $10\;{\mu}g/l$ and was higher for summer in Yeongkwang coastal area than other sites. The results of principal component analysis conducted to compare the characteristics of water quality observed in study areas showed the distinguishable features as follows. The freshwater input fluctuation appeared as the first factor in Muan and Tando bays, and the change of water temperature was the first factor in Shinan Jido and Yeongkwang coastal areas. The influence mixed with the variation of freshwater outflow and the change of water temperature in Hampyeong bay was to be the first factor.

• The Korean Journal of Malacology
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• v.15 no.2
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• pp.105-113
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• 1999

This study was measured environmental factors of flat oyster habitats and biomass of flat oyster to improve the productivity of flat oyster. Water temperature and salinity of the flat oyster habitat ranged from 5.5 to 27.4$^{\circ}C$ and from 31.2 to 33.4 , respectively. Average concentrations of DO, COD, DIN and PO$\_$4/$\^$3/ -P were 7.11 mg/l, 4.55 $\mu\textrm{g}$-at./l and 0.36 $\mu\textrm{g}$-at./l respectively. Surface sediments at the sampling area were composed of coarse sand, sandy silt and silty sand. Average level of IL, COD and AVS in the surface sediments were 2.6%, 13.70 mg/g dry and 0.33 mg/g dry respectively. In each sampling station, total standing crops of phytoplankton showed peaks twice in February and August. Dominant species of phytoplankton occurred in Haechang Bay throughout the year were Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, C. affinis, C. debilis, C. decipiens, Asterionella glacialis, Pseudonitzschia longissima, Pseudonitzschia seriata, Ceratium furca and C. fusus. Ten species of the bivalves were collected at the flat oyster habitat. Most of bivalves were the eutrophic species Ostrea denselamellosa, Crassostrea gigas, Ruditapes philippinarum, Scaphraca subcrenata, Scapharca broughtonii, Atrina pectinata, Fulvia mutica, Mytilus edulis, Protothaca jedoensis and Megacardita ferruginosa. The mean density of them was 21 inds./㎡ (479.14 g/㎡), while that of the flat oyster was at 0.25 inds./㎡ (231.25 g/㎡).

• The Korean Journal of Malacology
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• v.24 no.2
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• pp.137-142
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• 2008

Growth and survival rates dependent on the density of a pen sell, Atrina pectinata were measured from Duekryang bay in Korea. Annual water temperature and salinity of the study area were ranged from 14.5 to $28.0^{\circ}C$ and from 27.98 to 31.89 psu, respectively. The pH, DO, COD, DIN, Chl-a and SPM in the study area ranged from 7.78-8.35 mg/L, 7.07-7.90 mg/L, 1.20-1.70 mg/L, 2.88-6.02 mg/L, 0.20-0.79 mg/L and 10.8-21.4 mg/L. The IL, COD and AVS in sediments ranged from 4.0-4.6%, 7.28-10.76 mg/L and 0.03-0.05 mg/L respectively. The daily growth rate of shell height and total weight were 0.27%, 0.33%(5 indiv./$m^2$), 0.26, 0.29%(10 indiv./$m^2$) and 0.21, 0.20%(35 indiv./$m^2$). The survival rate also decreased along the density gradient; highest at the lowest density of 5 indiv./$m^2$ and lowest at the maximum density of 35 indiv./$m^2$.

• Korean Journal of Ecology and Environment
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• v.35 no.1 s.97
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• pp.1-9
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• 2002

In order to understand the relationship between succession of phytoplankton community structure and inorganic nutrients and particulate organic matters, a one station in Kyungan stream in Korea during the dry season was chosen. Water samplings were carried out once a week from 18 August to 13 November 1993. The DIN concentration distributed always abundantly, however, phosphate and silicate gradually reduced during the period. Phytoplankton community had a peak chlorophyll a concentration of $90.6\;{\mu}g/l$ in late summer (21 August 1993) and a second peak of $29.7\;{\mu}g/l$ in autumn (2 October 1993). After then late autumn was characterined by relatively low chlorophyll a concentration of $15{\sim}16\;{\mu}g/l$. Seasonal fluctuation of chlorophyll a concentrations were correlated with measured POC and PON concentrations: phytoplankton blooming may be a major factor controlling POC and PON concentrations in this ecosystem. Phosphate plays an most important role as a limiting factor of phytoplankton growth. However, when Si/P ratio low, silicate may be a more critical limiting factor than phosphate. Shifts of P-limitation to Si- limitation the succession of dominant phytoplankton can in duce: diatom to cyanobacteria such as Anabaena, Microcystis and Oscillatoria.