본 연구는 2005년부터 2018년까지 14년간 주암호에서 출현한 남조류의 천이 양상을 분석하여, 남조류에 영향을 미친 주요 환경요인과의 관계를 파악하고자 연구를 수행하였다. 특히 2012년 이후 유해남조류 (Harmful algae) 출현량 급감의 원인을 파악하고자 하였다. 조사기간 동안 두 지점의 유해남조류 현존량은 주암댐: 10~24,891 cells mL-1, 신평: 13~26,043 cells mL-1의 범위로 출현하였다. 전반기 시기 두 지점의 평균 현존량은 각각 2,575 cells mL-1, 2,557 cells mL-1로, 이는 후반기 시기 평균 현존량 (42 cells mL- 1, 82 cells mL-1)에 비해 약 60배, 30배의 큰 세포수 차이를 보였다. 남조류가 상대적으로 많이 출현하는 여름 시기 (6~9월)를 대상으로 상관분석을 실시한 결과, 유해남조류는 TN, 방류량, 저수량과 양의 상관관계를 보였고, 전기전도도와는 음의 상관관계를 보였다. t-검정 결과 TN, EC, 체류시간의 유의미한 차이를 확인하였다. 특히 TN은 0.566~1.292 mg L-1의 범위로 평균 0.862 mg L-1로 보였다. 전반기, 후반기 평균 TN은 전반기 0.912 mg L-1, 후반기 0.811 mg L-1로 감소하였다. 또한 유의확률은 다소 떨어지지만, TP의 경우 평균 차이는 없으나 표준편차가 비교적 큰 차이를 보여 변동성이 큼을 알 수 있었다. 강우량이 집중된 여름 (6~9월) 시기의 전반기와 후반기 강우량 감소하는 패턴이 원인인 것으로 판단된다 (전반기 263.3 mm, 후반기 219.9 mm). 즉, 전반기에 비해 강우량은 감소 하였으며, 이로 인해 TP의 변동성이 감소되었다고 판단된다. TP의 변동성의 감소로 인해 전반기에 남조류의 luxury consumption이 가능하여 남조류의 성장률이 높았을 것으로 추측된다. 따라서 주암호 유해남조류 감소 원인은 강우량의 감소로 인한 영양염의 감소 (TN) 및 변동성의 감소 (TP)의 결과로 사료된다.

2010년 4월부터 2015년 12월까지 영산강 본류에 위치해 있는 죽산보의 상, 하류의 수질 및 식물플랑크톤 변화 양상을 파악하기 위해 연구를 수행하였다. 동일한 기간 동안에 두지점 모두 평균 수온은 17.3°C로 기록되었으며, 2011년부터 2014년까지는 약 16.3°C를 유지하다가 2015년에 17°C로 약 0.7°C 상승되었다. 조사기간 동안 식물플랑크톤의 종 조성은 총 288 분류군으로 남조류 17 분류군, 규조류 74 분류군, 녹조류 154 분류군 및 기타조류 15 분류군으로 조사되었다. 두 지점의 개체군 밀도는 500~29,950 cells·mL-1으로 조사되었으며, Y1지점은 850~29,725 cells·mL-1, Y2지점은 500~29,950 cells·mL-1으로 조사되었다. 두 지점의 평균 개체군 밀도는 Y1지점이 8,180 cells·mL-1, Y2지점이 7,530 cells·mL-1으로 상류지점의 평균 밀도가 더 높게 조사되었다. 우점종은 규조류인 Stephanodiscus속, Aulacoseira속이 높게 나타났으며, Stephanodiscus의 우점 빈도는 59%였고, Aulaocseira속의 우점빈도는 22%였다. 남조류의 전체속의 우점빈도는 17%였고, Y1지점이 19%로 Y2지점보다 2% 높게 나타났다. 그 중에 Microcystis속의 우점 빈도가 6%였고, Y1지점이 7%로 하류인 Y2지점보다 2% 높게 나타난 것을 확인할 수 있었다. Y1지점의 현존량 비율은 규조류가 전체의 52%, 녹조류가 24%, 남조류가 21%였고, Y2지점은 규조류 65%, 녹조류 18%, 남조류 13%로 상류 지점인 Y1지점의 남조류 현존량 비율이 더 높게 나타난 것을 볼 수 있었다. 본 연구는 식물플랑크톤의 천이 현상 및 수질요인들과의 변화에 따른 원인을 파악하고 영산강 죽산보의 특성에 대해 신뢰성 있는 데이터를 제공하기 위해 수행되었으며, 이후 수생태계 변화를 평가하는 기초자료로 활용될 수 있을 것이다.

In this study, a load duration curve was applied to the Jangseongcheon, one of the tributaries of the Yeongsan River, to assess whether the target water quality was achieved. In addition, pollution of the water body was investigated to develop and suggest the optimal management time with respect to polluted flow sections and monthly conditions. The average flow rates of sections JS1 and JS2 were 0.25 m3/s and 1.08 m3/s , respectively. The BOD and T-P for water-quality standards at JS1 were rated at II, whereas the COD and TOC were rated at III, thus indicating a fair level of water quality. By contrast, the BOD at JS2 was rated at III, the T-P at IV, and the TOC at V, indicating poor water quality in this section. The load duration curve was plotted using the actual flow data measured in eight-day intervals for eight years from 2011 to 2018 at locations JS1 and JS2 in the Jangsungcheon Basin. In an assessment using the load duration curve on whether the target water quality was met at location JS1, all of the water quality parameters (BOD, COD, TOC, T-N, T-P, and SS) satisfied the target water quality. By contrast, at location JS2, parameters COD, TOC, T-N, and T-P exceeded target values by more than 50%, indicating the target water quality was not met. The discharge loads of locations JS1 and JS2 were analyzed to identify the reasons the target water quality was exceeded. Results revealed that the land system contributed considerably. Furthermore, the discharge load of JS2 accounted for more than 80% of the load on the entire basin, excluding that of JS1. Therefore, the best method for restraining the inflow of pollutants into the stream near location JS2 must be applied to manage the water quality of the Jangsungcheon.

The purpose of this study at water quality pollutants to propose proper management method for the Osu-A unit watershed which is the influent tributary located upstream of the Sumjin -river among the 13 unit watersheds in the Sumjin-river water system. Analyzed the correlation between flow-pollution loading and the correlation between land use type, BOD and TP items, and analyzed 8-day intervals Cumulative Flow Duration Curve (CFDC) and Load Duration Curve (LDC) to evaluate water quality damage. As a result, both BOD and TP were larger than 1 and the concentration of water pollutants increased with increasing flow. BOD was positively correlated with Urban and Field, and TP was positively correlated with Field with 0.710. As a result of the LDC, BOD was analyzed that the target water quality was achieved with the excess rate of less than 50%, and TP exceeded the target water quality by 50.1%. BOD usually exceeded the standard value (exceedance probability 50%) at low flow zone and On the other hand, TP usually exceeded the standard value at high flow zone. Monthly BOD (April to June) and TP (May to August) exceeded the standard. Sewage Wastewater treatment and non-point pollution control is Osu-A unit watersheds are effective in improving BOD and TP.

In this study, seasonal Mann - Kendall test method was applied to 12 stations of the water quality measurement network of Nam-River based on data of BOD, COD, TN and TP for 11 years from January 2005 to December 2015 The changes of water quality at each station were examined through linear trends and the tendency of water quality change during the study period was analyzed by applying the locally weighted scatter plot smoother (LOWESS) method. In addition, spatial trends of the whole Nam-River were examined by items. The flow-adjusted seasonal Kendall test was performed to remove the flow at the water quality measurement station. As a result, BOD, COD concentration showed "no trand" and TN and TP concentration showed "down trand" in regional Kendall test throughout the study period. BOD and TP concentration in "no trand", COD, and TN concentration showed an "up trand" tendency in Nam-River dam. LOWESS analysis showed no significant water quality change in most of the analysis items and stations, but water quality fluctuation characteristics were shown at some stations such as NR1 (Kyungho-River 1), NR2 (Kyungho-River 2), NR3 (Nam-River), NR6 (Nam-River 2A). In addition, the flow-adjusted seasonal Kendall results showed that the BOD concentration was "up trand" due to the flow at the NR3 (Nam-River) station. The COD concentration was "up trand" due to the flow at NR1 (Kyungho-River 1) and NR2 (Kyungho-River 2) located upstream of the Nam-River. The effect of influent flow on water quality varies according to each site and analysis item. Therefore, for the effective water quality management in the Nam-River, it is necessary to take measures to improve the water quality at the point where the water quality is continuously "up trand" during the study period.

In this study, water quality data of eight main sites in the Geumho River watershed were collected and analyzed for long-term changes in water quality over the period from 2005 to 2015. The results showed that BOD concentration was gradually improved by the Total Maximum Daily Load (TMDL), stages 1 and 2. Recently, a tendency of increasing BOD concentration was observed in the downstream section of the river. The concentration of COD was analyzed to be contaminated throughout the water system regardless of the water quality improvement project, and the TN concentration tended to increase in the midstream of the river from 2013. The TP concentration has clearly decreased from 2012 after the second stage of TMDL. For the statistical analysis of PCA ordination, monthly water qualities (pH, DO, Electrical Conductivity (EC), Water Temperature (WT), BOD, COD, TN, TP, TOC, and SS) and flow rate data for 5 years from 2012 to 2016 were used. Seasonally the Geumho River showed an increase in the TN concentration at point sources during the dry season (December to February). TP showed the effect of non-point sources in the summer, because rainfall has caused a rise in flow rate in the upstream. Besides, the origin of pollution source was changed from non-point sources with BOD, COD, and TOC.

Algal blooming in 4 major rivers introduces substantial impacts to water front activity. Concentrations of algae are increasing at major points along the Geum River. Ecosystem food webs can be affected by algal blooming because blue-green algae release toxic materials. Even though there have been many studies on blue-green algae, its causality to environmental factors has not been completely determined yet. This study analyzed the exclusive correlation between various hydrometeorological, water quality, and hydrologic variables and the cell number of cyanobacteria to understand causality of blue-green algae in the Geum River. A prewhitening process was introduced to remove the autocorrelation structure and periodicity, which is useful to evaluate the effective relationship between two time series.