• Korean Journal of Ecology and Environment
• /
• v.43 no.2
• /
• pp.199-211
• /
• 2010

The objectives for this study were to evaluate spatial and temporal characteristics of water quality, based on long-term water quality monitoring data during 1993~2008. We found that physico-chemical and ecological conditions in the Daecheong Reservoir (DR) were modified by the construction of upper dam (i.e., Yongdam Reservoir). total phosphorus (TP), Secchi depth (SD), and chlorophyll-a (CHL) in the DR showed significant longitudinal decreases along the headwater-to-the downlake, indicating a large spatial variation, and this gradient was more intensified during the high-flow season (monsoon). Nutrient-rich water containing high nitrogen and phosphorus in the monsoon season (July~August) passed through the reservoir as a density current in the metalimnetic depth, and also high suspended solids increased in the metalimnetic depth, especially during the monsoon. According to the deviation analysis of Trophic State Index (TSI), >50% of TSI (CHL)-TSI (SD) and TSI (CHL)-TSI (TP) values were negatives, so that inorganic suspended solids (non-votatile solids) influenced the underwater light regime against phytoplankton growth. Also, ratios of CHL:TP after the dam construction evidently increased, compared to the values before the upper dam constructions, indicating a greater yield of phytoplankton in the unit phosphorus. Overall data showed that ecological and functional changes in Daecheong Reservoir occurred after the construction of upper dam (Yongdam Reservoir).

• Korean Journal of Ecology and Environment
• /
• v.42 no.2
• /
• pp.221-231
• /
• 2009

This study was carried out to comparatively identify characteristics of turbid water influence in Imha Reservoir, Soyang Reservoir, and Daecheong Reservoir in Korea. We used 3 years dataset from 2002 to 2004 and analyzed seasonal water quality characteristics, particular parameters in association with turbidity, and light transparency to figure out the trends. All parameters to be used in the study were total phosphate (TP), total nitrogen (TN), chlorophyll-${\alpha}$ (Chl), suspended solids (SS), Secchi depth (SD), conductivity, and verticallight extinction coefficienct($K_d$), euphotic zone ($Z_{eu}$), and critical depth ($Z_p$). All parameters depend on season and watershed. Suspended solids from Soyang Reservoir were usually caused by TP, mainly related to living wastes and agricultures in upper stream. Daecheong Reservoir was influenced by organic matters related to large phytoplankton biomass in summer and inorganic suspended solids by nutrients in the winter. However, in case of Imha Reservoir, turbid water, consisted in silt and clay through heavy precipitation remained in the waterbody to decrease water transparency along with TP and caused the light limitation in winter. Overall results suggest that it was necessary to establish various management programs because the reasons occurring turbidity were varied according to the reservoir circumstances.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11b
• /
• pp.241-244
• /
• 2003

2000년에 발생한 12호 태풍(Prapiroon)에 의한 성층 호수의 식물플랑크톤 군집 변화양상을 주암호의 복교지점에서 2000년 8월 30일부터 9월 29일 까지 조사하였다. 프라피룬은 복교지점에서 초속 40m의 강풍을 동반하였는데, 이 물리력은 성층으로 인해 불연속적 층을 형성하고 있던 수괴 전체를 혼합시켰다. 수체의 혼합은 격리로 인해 이질적 환경과 생물조성을 이루고 있던 층간의 혼합을 유도하여 식물플랑크톤의 우점 분류군, 종조성, 우점종을 교체시키는 요인으로 작용한 것으로 추측되었다. 식물플랑크톤의 우점 분류군은 태풍 이전의 규조류에서 녹조류로 교체되었고, 후에 남조류로 교체되었다. 우점종은 태풍 이전에는 Melosira granulata였으나 태풍 이후에는 Scenedesmus spp.와 Staurastrum sp.가 우점하는 것으로 나타났다. 개체수의 밀도는 태풍에 의한 변화가 크지 않았다. 태풍에 의해 파괴되었던 성층은 태풍 이후 재성층화 되기 시작하여 6일째엔 안정된 성층이 관찰되었다. Secchi depth는 태풍에 의해 많이 감소하였으나 수체가 안정화되면서 다시 증가하는 양상을 나타냈다. 결론적으로 태풍은 여름의 성층으로 분리된 수괴를 혼합시킬 수 있는 물리력을 가져 수서 생태계 내 생물의 동태에 영향을 미칠 수 있음을 알 수 있다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.3 no.S1
• /
• pp.77-90
• /
• 1997

the observations in situ and the seawater analyses were conducted in July and August, 1996 for the purpose of evaluating the characteristics of seawater quality centered on eutrophication in Mokpo harbour. By applying the OECD standards of trophic classification to the parameters such as secchi depth, total inorganic nitrogen, phosphate phosphorus and chlorophyll-a, the trophic level of seawater in Mokpo harbour was evaluated to be in eutrophic state in summer. By the estimation of pollution index with relation to eutrophication, the seawater quality of Mokpo harbour was evaluated to be under the regular grades and this evaluation was found to be different from the results of evaluation obtained by the environmental index of single parameter, chemical oxygen demand. By the estimation of eutrophication index, the seawaters of Mokpo harbour were shown to have the high potentiality of red tide occurrence.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.3 no.2
• /
• pp.51-61
• /
• 1997

The in situ observations and the seawater analyses were conducted in July and Auguse, 1996 for the purpose of evaluating the characteristics of seawater quality centered about eutrophication in Mokpo harbour. By applying the OECD standards of trophic classification to the parameters such as secchi depth, total inorganic nitrogen, phosphate phosphorus and chlorophyll-a, the trophic level of seawater in Mokpo harbour was evaluated to be in eutrophic state in summer. The estimation of pollution index by eutrophication showed the seawater quality of Mokpo harbour to deteriorate and fall under the regular grades. The results of eutrophic index estimation showed the high otentiality of red tide occurrence in Mokpo harbour.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.3
• /
• pp.173-177
• /
• 1977

Optical properties were studied in the Japan Sea based on the optical observations in nine oceanographic stations from September 28 to October 2, 1976. Submarine light intensity was measured by using a submarine illuminometer (RIGO, Type: 2501-A) : equipped with a filter(RIGO, Type:V-R-60, wavelength: 600-620nm). In the upper 40 m depth layer light intensity was measured at 1 m depth interval. The absorption coefficient for red color in the area ranged from 0.142 to 0.323 (mean 0.232) : the Secchi-disc depth in the area ranged from 15 to 23 meters (mean 19.8 meters). The relation ship between absorption coefficient (m) am transparency depth (D) was m =4.93/D. The rates of light penetration for red color at three different depths are computed with reference to the surface light intensity At tile depths of 5 m, 10 m and 20 m, the rates of light penetration were $23.11\%(15-34.2\%),\;6.49\%(3.04-12\%)\;and\;0.698\%(0.113-1.27\%)$ respectively.

• Korean Journal of Ecology and Environment
• /
• v.39 no.3 s.117
• /
• pp.296-309
• /
• 2006

This study aimed to analyze water quality (temperature, secchi depth, DO, $NH_4$, $NO_3$, $PO_4$, TN, TP, chlorophyll a) and trophic state index during the period of year 2000 ${\sim}$ 2004 in Lake Juam, Lake Dongbok and Lake Youngsan. Lakes Juam and Dongbok except Lake Youngsan were stratified during warm seasons. Water turbidity estimated by secchi disk depth was the highest in Lake Youngsan compared with other lakes. DO concentrations were low in the bottom water when chlorophyll a was high in Lake Juam and Dongbok. Nutrient concentrations were higher in Lake Youngsan than other lakes whereas chlorophyll a was highest in Lake Dongbok. Lake Youngsan was the most eutrophic compared to other two lakes based on the Trophic State Idex (TP) and TSI (SD), The TSI (CHL) was high but the TSI (TP) were low in Lake Juam and Dongbok. These results suggest phytoplankton may be limited by phosphates (P) in Lake Juam and Dongbok whereas light availability in the water column may affect growth of phytoplankton in Lake Youngsan.

• Korean Journal of Ecology and Environment
• /
• v.53 no.1
• /
• pp.11-21
• /
• 2020

In this study, we compared the spatio-temporal differences of phytoplankton communities among 4 lakes in the Boseong River basin. Field research was conducted quarterly from 2014 to 2017 for this study. A total of 345 species of phytoplankton were identified including 107 Bacillariophyceae, 175 Chlorophyceae, 27 Cyanophyceae and 36 other phytoplankton taxa. Lake Boseong showed higher species numbers and density of phytoplankton than other lakes (Dunn's test, P<0.01). Bacillariophyceae such as Asterionella formosa, Aulacoseira granulata, Fragilaria crotonensis was dominated in most research periods, whereas Scenedesmus ecornis and Coelastrum cambricum belonging to Chlorophyceae were dominant species on August. The self-organizing map (SOM) classified 3 clusters with 10 × 7 grid and showed spatio-temporal variation of phytoplankton communities based on significant difference among each clusters. Total 31 species of phytoplankton were chosen as a indicator species using indicator species analysis(ISA) and reflected seasonal phytoplankton succession and diversity and density of phytoplankton according to nutrient concentration. Water temperature, Secchi depth, conductivity and DO were identified as important factors affecting the differences of phytoplankton communities in the studied lakes in Boseong River basin using non-metric multidimensional scaling (NMDS).

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.1
• /
• pp.9-15
• /
• 2011

The first objective of this study was to investigate water pollution status of Meejae Reservoir, Kunsan, irregularly receiving river water for agricultural and recreational purposes. The second objective of the study was to compare nutrient pollution loads of three nutrient sources: sediment leaching, non-point sources and the receiving water. Water analysis results showed that eutrophication was a concern especially in summer and the calculated TSI (secchi depth), TSI (chlorophyll-a), and TSI (TP) were 53.6, 57.7 and 56.7, respectively. Although there was no significant difference in seasonal mean values of sediment T-N, sediment T-P and sediment organic content, mean differences were found for sampling points. However, T-N and T-P sediment release flux showed seasonal mean differences, while showing no mean difference for sampling points. Water T-N data proportionally correlated with sediment T-N and sediment organic content data, while no statistical correlation was found for water T-P data. Comparison of nutrient loads calculated from three sources showed that the highest T-N load was occurred from the receiving (pumped) water while T-P loads of the receiving water and sediment release flux were similar. The first solution would be considered for the receiving water to improve the water quality of Meejae Reservoir. Reduction of nutrient flux from the sediment would be then tried as the second alternative solution.

• Korean Journal of Ecology and Environment
• /
• v.42 no.2
• /
• pp.242-252
• /
• 2009

The purpose of this study was to develop a Multi-metric Water Quality Assessment (MWQA) model and apply it to dataset sampled from Paldang and Daechung reservoir in 2008. The various water dataset used to this study included 5 year data sets (2003${\sim}$2007) in Korean reservoirs which were obtained from the Ministry of Environment, Korea. In this study, suggested MWQA model has 4 metrics that were composed of 4 parameters such as chemical, physical, biological, and hydrological variables. And, each of the variables attributed total phosphorus (TP) concentration in water, secchi depth (SD) measure in water, chlorophyll-${\alpha}$(Chl-${\alpha}$) concentration in water and the ratio of inflow of water into lakes and efflux of water from lakes, input/output (I/O). First, we established the criteria for trophic boundaries. The boundary between oligotrophic and mesotrophic categories was defined by the lower third of the cumulative distribution of the values. The mesotrophic-eutrophic boundary was defined by the upper third of the distribution. Second, each metric was given by a point-oligo=1, meso=3, eu=5. And then, obtained total score from each metric was divided 5 grade-Excellent, Good, Fair, Poor, and Very poor. As the results of applying the proposed MWQA model, the Paldang reservoir obtained "Fair" or "Poor" grade and Daechung reservoir obtained "Excellent" or "Good" grade. The suggested MWQA model through these procedures will enable to manage efficiently the reservoir. And, more studies such as metric numbers and attributes should be done for the accurate application of the new model.