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The Change in Patterns and Conditions of Algal Blooms Resulting from Construction of Weirs in the Youngsan River: Long-term Data Analysis

보 건설에 따른 영산강의 조류 발생 및 환경 변화: 수질측정망 장기 자료 분석

  • Shin, Yongsik (Department of Environmental Engineering & Biotechnology, Mokpo National Maritime University) ;
  • Yu, Haengsun (Department of Environmental Engineering & Biotechnology, Mokpo National Maritime University) ;
  • Lee, Hakyoung (Department of Biological Science, Chonnam National University) ;
  • Lee, Dahye (Department of Environmental Engineering & Biotechnology, Mokpo National Maritime University) ;
  • Park, Gunwoo (Department of Environmental Engineering & Biotechnology, Mokpo National Maritime University)
  • 신용식 (목포해양대학교 환경.생명공학과) ;
  • 유행선 (목포해양대학교 환경.생명공학과) ;
  • 이학영 (전남대학교 생물학과) ;
  • 이다혜 (목포해양대학교 환경.생명공학과) ;
  • 박건우 (목포해양대학교 환경.생명공학과)
  • Received : 2015.11.14
  • Accepted : 2015.12.24
  • Published : 2015.12.31

Abstract

The effect of weir construction (2009~2011) was investigated on algal bloom dynamics and surrounding conditions in the Youngsan River by analyzing the long-term (2001~2014) data provided by the Water Information System, Ministry of Environment. The data include chlorophyll a and water properties such as total suspended solids (TSS), ammonium ($NH_4{^+}$), nitrate ($NO_3{^-}$), orthophosphate ($PO{_4}^{3-}$), total nitrogen (TN), total phosphorus (TP) and DIN/DIP molar ratio collected from 12 stations along the channel of the river. Temporal variations were examined using data collected monthly from 2001~2014 and Box-Whisker plot was used to examine the difference in algal bloom dynamics between before (2006~2008) and after (2012~2014) the weir construction. Pearson's correlation analysis was also used to analyze the correlation of parameters. The results showed that TSS affecting water turbidity increased during the construction but decreased especially at the stations located in the upper and middle regions of the river after the construction. Ammonium concentrations increased whereas the concentrations of other nutrients decreased after the construction inducing an increase in N:P molar ratio. Chlorophyll a decreased suddenly during the construction but increased clearly after the construction at the stations where TSS decreased. This indicates that algal blooms can develop in the Youngsan River due to a decrease in turbidity that increases light penetration in water column although the concentrations of nutrients such as orthophosphate were reduced after the weir construction.

4대강 사업의 일환으로 추진된 보 건설이 영산강의 조류발생 형태와 제반 환경조건에 미치는 영향을 조사하기 위해 장기 (2001~2014년) 자료 (환경부 물환경정보시스템)를 분석하였다. 분석 항목으로 조류 발생의 형태를 파악할 수 있는 엽록소 ${\alpha}$와 환경인자인 부유물질, 암모늄, 질산염, 인산염, 총 질소, 총 인, N : P ratio 등이다. 조사 정점은 최상류에 위치한 담양 (DY)에서 하류의 무안1 (MA1)까지 포함 (총 12개)한다. 분석 항목별로 시간적 분포를 시계열로 분석하였고, 건설 전과 후의 직접적인 비교를 위해 전과 후 3년간 자료 (2006~2008년, 2012~2013년)를 Box-Whisker Plot으로 도시하여 분석하였다. 또한 항목들 간의 상관성 분석 (Pearson's correlation analysis)도 실시하였다. 분석 결과, 수층의 탁도를 결정하는 부유물질은 보 건설 기간 중에 부유물질 농도가 보 건설 전에 비해 거의 모든 정점에서 상당 폭 증가한 반면 건설 이후에는 상류 및 중류에 위치한 정점들을 중심으로 확연하게 감소하였다. 암모늄은 건설 이전에 비해 건설 이후 증가하는 경향을 보인 반면, 나머지 영양염은 감소하였고 이로 인해 N : P ratio가 증가하는 경향을 보였다. 엽록소 ${\alpha}$는 건설 중에는 모든 정점에서 감소하였으나, 건설 후에 부유물질 (탁도)이 감소하였던 정점에서 건설 전에 비해 확연히 증가하는 형태를 보여 주었다. 이는 영산강에서 보 건설 이후 인산염과 같은 영양염이 감소했지만, 동시에 탁도가 감소하면서 조류가 대발생 할 수 있는 환경이 조성되었음을 제시하는 결과라 할 수 있다

Keywords

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