• Proceedings of the Korea Water Resources Association Conference
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• 1999.02b
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• pp.401-472
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• 1999

• Journal of Aquaculture
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• v.6 no.2
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• pp.63-69
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• 1993

Various scales of red tides have frequently occurred in the southern coastal waters of the Korean Penninsula since the late 1970's. Because most shellfish and finfish farms in Korea are located in the southern coastal waters, the impacts of red tides on the aquaculture have been increasing significantly. The Puksin Bay is one of the places where red tides have occurred almost every year since the early 1980's. During $1990\~1991$, mass mortalities of aquacultural species by the red tides were recorded. The causative organisms in this period were Leplocylindrus danicu(November '90 and June '91), Skeletonema costatum(December '90 and August '91), Nitzschia seriata(August '91), and Gymnodinium splendens(July '91). The maximum chlorophyll-a content was $265.7{\mu}g/l$ in the tides. Frequent red tides are associated with the eutropication of the bay. Some relationships between red tides' occurrence and europhication are herein discussed.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.95-104
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• 2000

In order to elucidate chatracteristics of water quality and seasonal dynamics of phytoplankton community in Kyungpo lake, the weekly variation of algal population and 11 environmental factors were investigated from March 1998 to February 1999. A total 121 species of phytoplankton belonged to 57 genera, 4 genera 7 species of the Euglenophyceae, 1 genera 2 species of the Chrysophyceae, 2 genera 3 species of the Cryptophyceae, 1 genera 1 species of the Dinophyceae, 6 genera 9 species of the Cyanophyceae, 28 genera 78 species of the Bacillario-phyceae and 15 genera 21 species of the Chlorophyceae, was identified. Cryptomonas sp., Chamydomonas sp., Nitzschia frustulum, Oscillatoria sp., Lyngbya sp, and Dictyosphaerium pulchellum occurred successively as dominant phytoplankton species from March 1998 to February 1999. Density of phytoplankton cell number showed the peak in early April when Chlamydomoas sp. was dominated. The diversity index of phytoplankton community showed low values in the dominating period of Cryptomonas sp. and Chlamydomonas sp. The concentration of chlorophyll a fluctuated between 1.09 and 107.7$\mu\textrm{g}$ㆍ1$^{-1}$. Water temperature, salinity, DO, conduc tivity and SS were ranged 0.5-27.8$^{\circ}C$, 2.8-25.2 ppt, 4.62-19.21 mgO$_2$ㆍ1$^{-1}$, 5.33-34.76 mS/cm and 0.017-0.184 mgㆍ1$^{-1}$, respectively. Annual means of Secchi disc transparency was 36cm and thai of pH value was 8.5. The concentrations of PO$_4$-P was ranged 0.0012-0.077 mgㆍ1$^{-1}$ , and showed high value from August to October. The concentrations of NO$_2$-N, NO$_3$-N and NH$_4$-N was ranged 0.0011-0.1 mgㆍ1$^{-1}$, 0.074-3.33mgㆍ1$^{-1}$ and 0.0024-0.259 mgㆍ1$^{-1}$, respectively. Among environmental factors, water temperature was negatively correlated with DO, salinity and conductivity, DO was positively correlated with salinity and conductivity. Chlorophyll a, one of the indicies of eutropication in lake, was negatively correlated with NH$_4$-N. The cell density of Cryptomonas sp., which was the most dominant species in this lake, was negatively correlated with transparency. [Kyoungpo lake, Phytoplankton, Cryptomonas sp. , Chlamydomonas sp., Seasonal variation].

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.1-9
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• 2014

Sediment pollutants have been considered an important source for the eutrophication of estuarine reservoir. In this study, the effects of pollutants released from bottom sediment to water column were investigated. Sediment samples were collected each two station from Namyang and Sukmoon estuarine reservoirs in August 2013. The fractionation result of sediment phosphorus indicated that Adsorbed-P ($36.7{\pm}8.84%$) and Nonapatite-P ($29.3{\pm}12.50%$) are the two dominant phosphorus groups in the sediments. For sediment release test, eight sets of acrylic chamber (0.3 m $diameter{\times}1m$ high, with 0.15 m sediment depth) were used with aerobic and anaerobic environment. Under anaerobic conditions, rates of $NH_4-N$ release from the sediments were highly variable, with final concentrations of $NH_4-N$ in the overlying water varying from between about 0.69~1.04 in Namyang and 2.58~4.23 mg/L in Sukmoon reservoir. The $NH_4-N$ release was active at the upstream around the confluence of tributary compared to downstream near the embankment. The $PO_4-P$ release was more obvious than $NH_4-N$ in anaerobic condition. The final $PO_4-P$ concentrations were approximately from two-fold to eight-fold higher than initial concentration. In terms of reservoir water quality management, not only tributary pollutants but also sediment nutrient loading is necessary to consider the water quality contribution.

• Journal of Environmental Science International
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• v.8 no.6
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• pp.691-697
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• 1999

The work on the eutropication of Youngsan river was conducted from Jul. 1997 to Jun. 1998. The value of water temperature in the study area varied from $4^{\circ}C\;to\;32^{\circ}C$ with an annual mean of $17.5^{\circ}C$. DO varied from 4.0 $mg/{\ell}$ to 13.5 $mg/{\ell}$, with an annual mean 10.2 $mg/{\ell}$,. BOD varied from 0.8 $mg/{\ell}$, to 6.4 $mg/{\ell}$ with an annual mean 3.1 $mg/{\ell}$. COD varied from 4.6 $mg/{\ell}$, to 9.0 $mg/{\ell}$ with an annual mean 6.38 $mg/{\ell}$. Nitrate varied from 1.58 $mg/{\ell}$, to 6.77 $mg/{\ell}$, with an annual mean of 3.475 $mg/{\ell}$, Total-nitrogen varied from 2.14 $mg/{\ell}$ to 8.38 $mg/{\ell}$ with an annual mean of 5.083 $mg/{\ell}$. Total-phosphate varied from 0.035 $mg/{\ell}$ to 0.588 $mg/{\ell}$ with an annual mean of 0.128 $mg/{\ell}$. Chl.a varied from 1.8 ${\mu}g/{\ell}$ to 75.0 ${\mu}g/{\ell}$ with an annual mean of 19.55 ${\mu}g/{\ell}$. The euthrophic state index of $Carlson^{16)}$ were showed 61.8(TP) and 71(SD) value

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.800-805
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• 2016

Rapid growth in nanotechnologies promises novel benefits through the exploitation of their unique industrial applications. However, as the production volume of nanomaterials increases, their unintentional exposure to the environment has been occured. Potential impacts of nanoproducts on the environment can be evaluated in the life cycle assessment (LCA). LCA is the systematic analysis of the resource usages and emissions over the life time from the primary resources to the moment of disposal. In this study, we performed LCA for fabrication processes of superhydrophilic oil/water separator using nano-$TiO_2$. $TOTAL^{TM}$ freeware was used to analyze for all fabrication processes, and 6-environmental impact factors (resource depletion, climate change, ozone depletion, acidification, eutropication, and photochemical oxidation) were introduced. In addition, the use of nano-$TiO_2$ in the fabrication of superhydrophilic oil/water separator was actively contributed to the environmental impact factors, compared to the bulk-$TiO_2$.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.605-619
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• 2019

The objective of this study was to analyze eutrophication characteristics, empirical model analysis, and variation of water quality according to monsoon intensity in Hapcheon Reservoir for 16 years from 2002 to 2017. Long-term annual water quality analysis showed that Hapcheon Reservoir was in a meso-nutrition to eutrophic condition, and the eutrophic state intensified after the summer monsoon. Annual rainfall volume (high vs. low rainfall) and the seasonal intensity in each year were the key factors that regulate the long-term water quality variation provided that there is no significant change of the point- and non-point source in the watershed. Dry years and wet years showed significant differences in the concentrations of TP, TN, BOD, and conductivity, indicating that precipitation had the most direct influence on nutrients and organic matter dynamics. Nutrient indicators (TP, TN), organic pollution indicators (BOD, COD), total suspended solids, and chlorophyll-a (Chl-a), which was an estimator of primary productivity, had significant positive relations (p<0.05) with precipitation. The Chl-a concentration, which is an indicator of green algae, was highly correlated with TP, TN, and BOD, which differed from other lakes that showed the lower Chl-a concentration when nutrients increased excessively. Empirical model analysis of log-transformed TN, TP, and Chl-a indicated that the Chl-a concentration was linearly regulated by phosphorus concentration, but not by nitrogen concentration. Spatial regression analysis of the riverine, transition, and lacustrine zones of $log_{10}TN$, $log_{10}TP$, and $log_{10}CHL$ showed that TN and Chl-a had significant relations (p<0.005) while TN and Chl-a had p > 0.05, indicating that phosphorus had a key role in the algal growth. Moreover, the higher correlation of both $log_{10}TP$ and $log_{10}TN$ to $log_{10}CHL$ in the riverine zone than the lacustrine zone indicated that there was little impact of inorganic suspended solids on the light limitation in the riverine zone.