• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.2
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• pp.58-66
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• 2016

We have evaluated the ammonium data in seawater as a potential short-term index for marine environment through the following steps. 1. reviewing of chemical characteristics of ammonium in seawater, 2. comparative relationships of ammonium data with other water quality indices such as DO, COD, and nutrients from Typical Marine Environment(TME) and Special Marine Environment(SME). Ammonium data generally represent negative correlation with DO, while positive correlation with COD. In particular, under frequent cases of seawater conditions showing similar concentration of COD or DO, we have limited choice of explanation for such situation. However ODIN(ODIN/RDIN) or RDIN(RDIN/TDIN) ratio could provide advanced information to understand these seawater conditions. Based on these results, we suggest ammonium data as a potential short-period index for transilient marine environment, such as benthic flux of bottom sediment, hypoxia, and algal bloom. Under overcoming several handicaps, ammonium data could be an useful tool for better understand short transformation of marine environment.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.475-488
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• 1995

In order to see the seasonal variation of nutrients and the limiting factors to the primary production in Deukryang Bay, both dissolved inorganic nutrients and salinity were measured in the surface waters during the periods from July 1992 to March 1993. The mean value of salinity was the lowest in ?all and the highest in early spring. Dissolved inorganic nitrogen (DIN) was the highest in winter and the lowest in summer. However, both phosphate and silicate were the highest in summer and the lowest in fall. Salinity was generally higher in the outer region than in the inner region of the bay.DIN content was nearly depleted (less than $2{\mu}M$) in summer. From fall to spring, DIN content was nearly depleted in the inner region and relatively high in the outer region of the Day. Phosphate was the highest in summer showing an opposite distribution pattern to salinity, and it was nearly depleted (less than $0.1{\mu}M$) in fall and winter. In spring, however, phosphate content was slightly high in the outer region. Silicate content showed an opposite distribution pattern to salinity in summer. in other seasons, However, the distribution pattern of silicate was similar to the salinity. DIN seemed to be a limiting factor for the primary production at all area of the bay in summer and at the inner region in other season. However, phosphate seemed to be a limiting factor at all area of the bay in fall and winter and at the inner region in spring. Silicate may limit the production of diatoms at the inner region of the bay in winter and spying. Both phosphate and silicate showed a good inverse relationship with salinity in summer, which indicates inputs of these nutrients from the freshwater runoff. In the other seasons, both nitrate and silicate showed a positive linear relationship with salinity in the outer region of the bay, suggesting that these two nutrients were mainly supplied by the inflow of the offshore costal water which had high nitrate content associated with vertical mixing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.196-205
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• 2011

To investigate the contribution of macroalgae to biogeochemical nutrients and carbon cycles, we measured the uptake rates of nutrients and $CO_2$ and characteristics of fluorescence of Saccharina japonica (Laminaria japonica Areschoug) using an incubation method in an acrylic chamber. From January to May 2011, S.japonica was sampled at Ilkwang, one of well-known macroalgae culture sites around Korea and ranged 46~288 cm long and 4.8~22.0 cm wide of whole thallus. The production rate of dissolved oxygen by S. japonica (n=25) was about $6.9{\pm}5.8{\mu}mol\;g^{-1}$ fresh weight(FW) $h^{-1}$. The uptake rate of total dissolved inorganic carbon ($TCO_2$), calculated by total alkalinity and pH, was $8.9{\pm}7.9{\mu}mol\;g^{-1}\;FW\;h^{-1}$. Mean nutrients uptake were $175.6{\pm}161.1\;nmol\;N\;g^{-1}\;FW\;h^{-1}$ and $12.7{\pm}10.1\;nmol\;P\;g^{-1}\;FW\;h^{-1}$. There were logarithmic relationships between thallus length and uptake rates of nutrients and $CO_2$, which suggested that younger specimens (<100-150 cm) were much more efficient at nutrients and $CO_2$ uptake than old specimens > 150 cm. There was a positive linear correlation ($r^2$=9.4) existed between the dissolved oxygen production rate and the $TCO_2$ uptake rate, suggesting that these two factors may serve as good indicators of S. japonica photosynthesis. There was also positive linear relationship between maximal quantum yield ($F_v/F_m$) and production/uptake rates of dissolved oxygen, $TCO_2$ and phosphate, suggested that $F_v/F_m$ could be used as a good indicator of photosynthetic ability and $TCO_2$ consumption of macroalgae. Maximum relative electron transport rate ($rETR_{max}$) of S. japonica increased as thallus grew and was high in distal part of thallus which may be resulted from the increase of photosynthetic cell density per area. The annual $TCO_2$ uptake by S. japonica in Gijang area was estimated about $1.0\sim1.7{\times}10^3C$ ton, which was about 0.02-0.03% of carbon dioxide emission in Busan City. Thus, more research should be focused on macroalgae-based biogeochemical cycles to evaluate the roles and contributions of macroalgae to the global carbon cycle.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.45-58
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• 2012

For the development of reference values and evaluation of water quality in various environmental conditions, we divided the coastal region around Korean peninsular into 5 distinctive ecological regions based on the influence of surface current, depth, tidal range, turbidity, and climate condition. We used national marine environment monitoring data collected by National Fisheries Research & Development Institute(NFRDI) from 2000-2009. For the reference values, we used maximum seasonal mean from 2000 to 2007 for DIN, DIP, and chlorophyll-a and minimum seasonal mean for secchi depth measured at stations without the influence of river runoff in each ecological regions. For the reference value of bottom dissolved oxygen saturation, we used minimum mean value of 90% calculated from minimal riverine influence stations of whole regions. We calculated enrichment score for each assessment criteria. The enrichment score of DIN, DIP, and Chlorophyll-a was 1 (=< reference value), 2 (< 110% of reference value), 3 (< 125% of reference value), 4 (< 150% of reference value), and 5 (> 150% of reference value). The enrichment score of DO saturation and Secchi depth was 1 (> reference value), 2 (> 90% of reference value), 3 (>75 % of reference value), 4 (> 50% of reference value), and 5 (< 50% of reference value). We calculated water quality index using weighted linear combination of five enrichment score for the comparison of whole regions. From the water quality index distribution calculated from all stations between 2000 and 2007 period, we classified into 5 grade based on the standard deviation calculated from total water quality index. We assigned grade very good(I), good(II), moderate(III), bad(IV), and very bad(V) when the water quality index was less than 23, minimum + 1 sd, +2 sd, +3 sd, and grater than minium+ 3 sd, respectively.

• 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 Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2205-2213
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• 2000

To investigate removal efficiency of dissolved matter by NF and RO, a pilot plant was operated for six months using groundwater treated by UF membrane. After the pilot plant operation, we performed autopsy test to identify characteristics of foulant attached on the membrane surface applying the used NF and RO in the pilot plant test. In autopsy test, we measured permeate flux and recovery rate of flux by chemical cleaning in each membrane. We also analyzed chemical cleaning disposal to examine component of foulant. Permeate flux of NF and RO1 showed rapid decline after 100 days of operation. Especially, reduction of specific flux in RO1 was more serious than in NF. Specific flux of RO2 with a low recovery rate resulted in gradual flux decline. Removal efficiencies of dissolved inorganic matters as a conductivity were 76.3%, 88.2% and 95.3% respectively for NF, RO1 and RO2, and RO2 presented the highest removal efficiency. And those of dissolved organic matters as TOC were about 80% for both NF and RO. The specific flux of membranes declined gradually from the feed water inlet to outlet of the membrane module and it showed that membrane fouling increased along the feed flow direction. Namely, concentration of pollutants became higher and volume of feed water was less as the feed flow approached to the outlet. It seemed that major foul ants were Ca consolidated into inorganic material and Si consolidated into organic material on the membrane surface. Fe was a great contribution to irreversible fouling. The SEM results indicated that the organic matter was attached to the first layer, closer to the membrane, and then inorganic matter with tetragonal shape layered over them. We could not observe biofouling because microorganism, which was cause of biofouling, was almost pretreated in UF membrane.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.133-139
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• 2009

A nutrient-concentrating system was operated to retrieve total phosphorus efficiently from a non-point pollution source. Attached bacteria were expected to play an important role in the system. Phosphorous was concentrated by formation of bacterial biofilms on rubberized coconut fiber media of the system. While concentration of total phosphorus (TP) ranged merely 0.12~0.35 mg/L in the stream water, TP levels in pore water and the media were 0.45~0.86 mg/L and 40.91~242.71 mg/kg, respectively. Total bacterial number (TBN) ranged $0.3\sim2.3\times10^6$ cells/ml in stream water, $0.4\sim4.4\times10^6$ cells/ml in pore water and $0.8\sim1.9\times10^9$ cells/g in media. There was a close correlation between TP and TBN. Based on band profiles in DGGE analyses, bacterial communities in the media were different from that in the stream water. Clostridium spp. were abundant in the stream water while Aquabacterium spp. were dominant species in early stages of biofilm formation in the media. The genera predominant in matured biofilms of the media were Clostridium and Enterococcus.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.129-132
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• 2008

This study was performed to characterize the seasonal variation of water quality and sediment environment from May, 2007 to February, 2008 in 20 stations of Kamak bay. $4.83\sim11.07mg/L$ on surface and $4.70\sim11.19mg/L$ on bottom in DO, $0.16\sim2.03mg/L$ on surface and $0.10\sim1.55mg/L$ on bottom in COD, $0\sim3.04{\mu}g$-at/L on surface and $0\sim15.21{\mu}g$-at/L on bottom in DIN, $0\sim3.04{\mu}g$-at/L on surface and $0\sim2.01{\mu}g$-at/L on bottom in DIP. IN sediment the ranges were 3.80 to 9.78% in IL, $0\sim5.37mg/g$-dry in AVS and $3.09\sim41.01mg/g$-dry in COD.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.133-136
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• 2008

This study was performed to characterize the seasonal variation of water quality and sediment environment from February, 2007 to October, 2007 in 21 stations of Gwangyang bay. $6.03\sim11.98mg/L$ on surface and $4.43\sim10.71mg/L$ on bottom in DO, $0.12\sim3.16mg/L$ on surface and $0.20\sim2.64mg/L$ on bottom in COD, $0.23\sim18.28{\mu}g$-at/L on surface and $0.33\sim9.56{\mu}g$-at/L on bottom in DIN, ND$\sim1.47{\mu}g$-at/L on surface and $0\sim4.56{\mu}g$-at/L on bottom in DIP. IN sediment the ranges were $2.86\sim21.17%$ in IL, $0\sim6.11mg/g$-dry in AVS and $2.64\sim23.23mg/g$-dry in COD.